~ ._...._..‘. INVESTIGATIONS OF DETERGENCY APPLICABLE TO MECHANICAL MILK CAN WASHING Thesis for the Dogma of M. S. MICHIGAN STATE COLLEGE Gienn AIan Ciaybaugh I950 maels,‘ This is to certify that the thesis entitled Investigations of Detergency Applicable to Me- chanical Milk Can Washing presented bg Glenn Alan Claybaugh has been accepted towards fulfillment of the requirements for ii; degree in M— )0r professor mew— 0-169 INVhSTIGATITWS LF DETLliEJCY AP: ISABIE TO L CFLYICAL LILK CAI flAzfllfiG INVESTI?ATT”"S CF JET5H34.CY APPLTQAFLE -:~(fr\*j,'.‘7' 1'. vtTT ' ‘-‘--’ ‘ '137‘1“"‘1 TO .«.l4vl.d-l_;.c.“.L -‘..L..'_J.l\. LA.‘ £I£{J.J_.\1\A by “‘7"' F. .1 \I‘r I} h v: IL. 7"," G JLJ.‘.‘ tkLLLN (.JTjfi‘l It. 211.]: fi A'EESIS Subnitted to the School of Graduate Studies of lichigan State College of Africulture and Applied Science in partial fulfillment of the requirements for the degree of J LAST.? CF SCIEkC' Department of Dairy 1950 ACKJ‘.’ 0.31. FDGIE‘NT The author wishes to take this Opportunity to eXpress his sincere appreciation to Dr. Earl weaver, Head of Dairy Husbandry for making this study possible; to J. M. Jensen, Assistant Professor (Research) of Dairy Husbandry, for his helpful guidance, valuable suggestions, and constructive criticisms given throughout the progress of this study and during the preparation of this manuscript. Appreciation is also given to the other associates of the Dairy Department. Gratitude is also eXpressed to the Kichigan Xilk Producers' Co-op, McDonald Dairy Co-cp, and to the Wilson Dairy for the use of their personnel and equipment used in some of the eXperiments. Deep appreciation is expressed to the Dairymen's League of Poughkeepsie, New York, and to Dr. 1. A. iilone for making the loan of the can shaking apparatus available. (matinee; #3.; 'J' | . .'.~‘ . \A. TABLE OF CCNTENTS INTRODUCTION REVIEW OF LITERATURE A Can'fiashing Studies B Detergents Used in Mechanical Can Washers 1. 2. 3. h. 5. Alkaline Detergents Phosphates Acid Detergents Wetting Agents Methods of Testing Detergency C Testing Bacteriological Condition of Milk Cans 1. 2. 3. h. 5. EXPERIMENTAL Volume and Rinse Material Shaking Procedure Used Number of Organisms Removed Factors Influencing the Rinse Test Type of Organisms found in Cans .‘TC‘ITLK Plan of Experiment A The Effect of Varied Amounts and Volumes of Rinse Xedia on the Number of Bacteria Renoved from Xilk Cans l. 2. 3. Procedure Use of a Non-ionic netting Agent "' . ' VT... ‘1 \1. Lsed in udiious O O s: #3 '33 H I-J . :3 (IQ (+- :3" (0 tr} 'fi H: G) O (+- m 0 H) t .1 I'" I 4 Effect of suffering the Triton Removal The Effect of Nun er r‘f ifnr‘n's and the Time sf .4 J. a o 1 i Y.) . - ‘ v- I r - -. 7-. l -\ p nesi ial B;cteria vOnCth of *(‘i a: 0’) ('D COU'IUI ll l7 19 F) F.) n) +4 h) h) f‘) I. h) -\\ fx) U1 (A l‘.) fx) - J L1 Cr) 0 "\\ rjyriq ‘r VI'. .\ a. 01.1 asulhd ulyn b... l. 3. Percentage of Ba: .ria n moved Fran Trit_ul u_Ls s ~-._..l.t , .. “fix- . . . r‘ - -' . ‘ . M Unix“; 4:...1‘13 .Lhe Edy 'e:.-£11 avJAuv‘V'Ll U- \blj A *WC.‘-‘fi‘d 41“ .4. Ab“: .. 911 ' \‘: . . Oh I ‘ A *0 f Deriscd ;,ez-ue.oal o.tnirg Apparatus ' I f" . (‘f'fi CT - )1 r75,‘ ~. ‘Vy DLHCULSLO” l“ 0L 514—1 P T: r‘ I ~‘ I ' ‘ V .: x t a . ‘, . Wilma. actual 53.11.?) ‘KL.‘]4.'CL1L1H l4.) A--‘.\.r.1;i4£ i:'11 bu.l ...:-._ .._: Procedure Jashing in Sodium Toxin-suoho-p.ate—nettirg :ent utteraent Coibinuticns -9 -.L .0 ' r.+m ,9 - Ts -. - --- .m C. tuft-ct- o- the h . re 4. ..1r in r Ln DJ 'berrcy “hen 11e- D. O h ‘ .“‘0 ~ “lifting “no. I" LUV-2.1215..- ILL.» fr“ rm" ‘.\,,- . .' .2 ; ,p . :— f‘. :v .ne nifect of hul.n5 NuTLUuS “evince ti vczsc 0 LC lebdnlt f",- ., l ., "“. -.L ,_, , + a Ugh "ishlfib pvbcrugub ‘ —L a. In Calégnite and hashing b. Effect of the Nature of T!“ 1 - - ..‘JML. A L- 2:,— °-.._ 7., . “~- c. uflELt of the La ure of “fttr—. 1-31u6 on JCLCICO.PJ Vs'l’l 9n PT (3- "nn 4 pa d. “L‘s/V Rinsing of th Va 2 ture of ;insir and iAf Qr-ili.-.,_.no on detersezcy The Bet ergeicy Action of Six U"“Iplgl Dot Conditions ,. m . t ,_ .. Of 000. Fri-$1.0 J- eLsn‘. -:]‘L-L 17".) I Nature of Dre—Hi se on Detergercy of Sin the Treatleut of the mmercial Detergents Co d. Effect of ”various Types c sz Later on Diterbo1c‘ Tvaluation of Comm;rcial DiiLJ D:ter ents Effect of Comoin ations of V3 sod l‘hc Sp hates and Isa ne, Conderm wetting Agent as Applied to De ta ergency Effect of Versene Combinatitns on Letergency on Two Raw Films a. ‘75 ..L; - r, r“ .°h Svlubion on at Lu; 52.15...) orgeuts ln:.er Jarird (P s a. U) _ 0.1. .. '. 1 «-1. i.o on six Com orcial utter. "i (3 ‘..‘I (D l.) Iilk .'v \A) r‘ \J 7. 8. 9. 10. b. A Comparison of Two Wetting Agents on Detergency when in Combination.with Versene and Condensed Phosphates Evaluation of Several Laboratory—Prepared Detergent Combinations The Effect of Various Detergent Components when Added to a Standard Detergent A Study of the Chlorine-Protein Complex Milk Films Summary and Discussion C A Study of flashing Solutions and of Visual Appearances of Milk Cans 'fiashed with Various Can hashing Detergents 1. Visual Observations of Milk Cans From Plants Using Various Types of Detergents and Can washers 2. Condition of the Detergent Solution as Affected by the Operation of the Can flasher a. Procedure b. Alkaline Solutions c. Acid Solutions 3. Study of Mikro-San, An Organic Acid Can Washing Detergent h. Survey of Home Sanitation Treatment 5. Summary and Discussion D Practical Application of the Preceding Studies to mechanical Can Washing 1. Procedure 2. Use of a Combination of Versene, Condensed PhOSphates and Wetting Agent for Can Washing 3. Use of a Netting Agent in Combination with Calgonite h. Summary and Discussion CONCLUSIONS LITERATURE CITED APPENDIX 69 71 7r.“ I/ 77 £3 'u 82 82 83 8h 99 105 109 111 11h 127 LIT" 2.01} TIC. TIL) l-I Nilk cans are recognized by everyone concerned as beirg of major importance in sanitary milk production. hilk cans cone in contact with raw milk longer than any other piece of equipment. They may, therefore, contribute sediment, flavors and odors, and bacteria to rilk and adversely affect its quality. Such decrease in quality means a great economic loss to both producers and processors. Nhile ouch improverent has been made in periecting the mechanical can washers to the exten, that hot, dry cans are generally uischargei from the machines, with rare attention beine given to the on ration of can washers and to selection of effective detergent uaterials, the state of can cleanliness continues to be faulty. A considerable portion of this study is an application of a detergent found to give superior detergency in washing raw mil; films on farm utensils in a previous study. It was desirable to apply this oetergent in can washers to determine ii cleanliness and low bacteria counts of milk cans could be achédved when the chemical reaction of the detergent was disregarded, and the detergency properties only, were considered. CAN WASHING STUDIES Much criticism has been directed against milk can washing. Jamieson (l9h3) while summarizing his studies on can washing stated that there was too much complacency surrounding milk can washing. He declared that too many dairy plant operators seem resigned to the belief that they are using efficient procedures with the equipment permitted by their finances. Scales (1937), another authority on dairy cleaning, described the can ‘washar as being a problem in detergency, being frequently reaponsible for conditions that result in bacterial contamination and off flavors in milk. Among the first work published that concerned milk cans and can washing problems was that of Webster (1919), who made a study of the bacteriological conditions of washed empty cans at a city railway platform. From his study he concluded that milk cans conStitute a serious source of contamination, and such contamination was sufficient to seriously contaminate the milk that was otherwise produced under sanitary conditions. He calculated that some of the cans would have added to the milk from 2h,000 to 66,000 organisms per milliliter. A similar study was made by Smith (1920), who found that it was possible and practical to secure low counts in milk cans when the proper apparatus was installed and used. He, like Webster, also found a large majority of the cans in a.wet condition. The average contamination from wet cans was reported to be approximately Sh8,000 per milliliter, while the average for the dry cans was 1,870 organisms per milliliter. Prucha and associates (1918) also contributed to early studies. Essentially they determined the influence of the bacterial papulation of freshly washed cans on the bacterial content of milk that would be contained in these cans. One hundred and seventy cans were tested, and they found -2- these cans to contain large numbers of organisms. The average cans would have added to each full can of milk approximately 129,000 organisms per milliliter. In later work, Prucha and Harding (1920) were interested in eliminating bacteria from cans by rinsing with large volumes of hot water just prior to filling them with milk. Their study concluded that the bacterial content of milk cans is controlled principally by the moisture that remains in the washed cans. The first experimental study to be reported on can washers was that of Farrell (1929-b). The principal types of continuous can washers in use at that time were designated as to form, type of circulation systems, and type of Jets. As to form, can washers are usually of the rotary or straight- away types, however, a combination of the two can be obtained. He described three types of circulating systems; motor-driven centrifugal pumps, steamp~ driven pumps, and the so called "steam gun". The jets were classified as intermittent or continuous, as stationary or rising, or a combination of these, such as, rising-continuous. The steam Consumed per can by the steam— operated washers ranged from.h.58 to 5.59 pounds, while the water require- ments varied from.0.85 to h.07 gallons per can. Harding and associates (1922) were interested in the effect of steaming upon the number of bacteria that remain in milk cans. They were interested in determining the time and the pressure of the steam needed to render milk cens"practically'sterile: This work was carried out on 1,157 cans, and it ‘was disclosed that the destruction of bacteria was not secured until two cubic feet of steam had entered the can. It, therefore, appeared that cans should be steamed longer than 20 seconds with more than 20 pounds of steam pressure in order to secure satisfactory destruction of the living bacteria in the cans. -3- Further studies on the "sterilization" of milk cans were made by Ayers and.Mudge (1921), who studied the effectiveness of hot air as a can sterilizing agent. Hot air temperatures of 2h80F., 266°F., and 28hoF. were tested. They concluded that to obtain effective sterilization a certain minimum length of exposure seemed necessary. While the holding period could be reduced as the temperature was increased, there appeared to be a point 'beyond which an increase in temperature did not permit a proportionate decrease in the holding time. Farrell (1929) also studied the heat absorbing capacity of milk cans, and concluded that the capacity of cans for heat is limited by the area of the surface, the coefficient of heat transfer, and the temperature difference between the can and the heating medium. ‘Wet and saturated steam heated the cans at higher rates‘per degree difference,in temperature between the cans and the steam than did the superheated steam. Steaming with superheated steam left the cans dryer than did wet or saturated steams. He recommended using superheated steam.in the last jet of the can washer to assist in the drying of the cans. Studies that have been reported were concerned with the bacterial con— tents of the milk can, and the methods of securing a'sterile'can. Later studies have dealt with the relationship between the visual condition of milk cans and their bacterial content. Studies of this nature have been made by Jamieson and Chan (l9h2), Tuckey and associates (19h6), and Weber (1938). 'Weber made observations of the difference in bacterial content between machined washed and hand washed cans. He found that L7 per cent of the cans tested (322) had less than h0,000 organisms per can, which is generally considered satisfactory. Cans found in good condition and cans washed in the mechanical can washers were generally lower in bacteria content than cans that were in poor condition or that were washed by hand methoas. Causes of high -h- bacterial counts in milk were attributed to cans that were in poor condition or to poorly performed hand washing. The survey made by Tuckey and associates (19h6), of 13 receiving stations, showed that h5 per cent of the cans contained over h0,000 organisms per can. This is quite similar to the bacterial counts reported by Weber (1938). Open seamed cans generally had high bacterial contents. Otherwise, very little relationship existed between the physical appearance of the cans and their bacteriological condition. Cans that were apparently dry, contained enough moisture to support bacterial growth, and cans containing milkstone did not seem.to reflect that condition in the bacterial content of the cans. In a very similar study earlier in Canada, Jamieson and Chan (l9h2) determined the counts of 35h washed cans before they were returned to the patrons. Unlike the low counts of Weber and Tuckey and associates, they found that approximately 9h per cent of the cans contained over 50,000 organisms per can. Also 52 per cent of the cans tested exceeded a count of 30,000,000 per can. These cans were also found to be high in proteolytic and thermOphilic types of organisms. The importance of a clean, well Operated can washer has not been over— looked. Frequent, careful inspections for mechanical condition and physical cleanliness of can washers are recommended by; Abele (l9’48), Bogaerts (19h8), Farrell (19h9), Faust (l9h8), Fiske(l9b9), Heineman (19h9), Hoyt (19hl), Hunziker (l9h6), Moore (19h5), Roadhouse (19h8), Roadhouse and Henderson (l9h1), Schwartz (19h0), Schwartzkopf (l9h7, l9h8), Shogren (l9h8), and Sommer" (1938). As a means of perfecting the mechanical can washer, the addition of another pre-rinse position was studied by Carkhuff (19h8). He noticed a great improvement in the milk cans, both in appearance and in bacteriological condition.when they were washed with this "converted" can washer. The impdrtance cf naizt inin'.j tie proper detergent strenftl in the f wash solution of the can we sher was emptha :3ized h” Scales (1937,1938). He reported this to be the worst fault of can washers today. 1njs was in a ree ent with Aoele (1C48), Davis and cc-wcrkcrs (1944), and Strcn TheL use of a1 fl? he deter gents in the sash sclw+~c1 cf mechanical can washers has ling been estaolished. The fol lowing men have studied alkaline cleaning: Coulter (1942), Fiske (1949), Harding and mrebler (1947), Johnson and Roland (1? 7), Aafiee (1943), Roland (1940), Schwartz (1940), Strong(l946), and Trebler and Harding 1947). After the in oducticn of +he new acid cleaners for rockanicsl can washing, several men studied and compared acid clean?_rg wiin alkaliiie cleaning. These men were Bryant (1945), Finley'an‘ Fotcr (1947), Peter and Tinlcy (19A7), PSPker (1940), Parker and Sheiwich (1941), Eipnen and Bur .ald (1941), Scales (1942—8, l942—b), Schwartzkcpf (1942, 1943, 1947, 1948}. Shogren (194flhas described a 'illefiim3 U583 IN TTCEQJT AL CAN HASHEiS Alkalies and alkaline d3+ergents have been use* primarily or washing milk cans in mechanical can washers. Although some worker: Fave recentl" reported the use of acid cleaners, in the majority of cz1ses 81‘: line types of detergents wil - be found in use. Important change es tlat have ta ken place in the detergent field in recent ye rs have been reoortod by Little (1947), Parker (1943), Tinor (1947), and chorren (1948). Teday ajkal‘ne compounds ere usually mixed with condensed phoschates and these Will also be discxsso d with the all :aline detergents. ~~n .rile discussin s the chemistry of can washing detergency, L ttle C.) \J \e l'\ “ml \2 described the functions of alkaline detergents with respect to physical and .6- chemical actions. The physical action was described as being the force of the wash solution being sprayed into the can, scrubbing the milk residues left in the milk can. The chemical action was described as acting on the milk soil in the following manner: '(a) A physical action, due to wetting action of the solution penetrating through the soil, Spreading out between the soil and the can, and wedging the soil from the can. (b) Base exchange reaction in which the sodium.ions from the alkalies and condensed phosphates convert the casein into a soluble sodium caseinate. (c) Electro-chemical action by supplying polybvalent negative ions which are absorbed on the colloidal soil particles and aid in dispersing them in the cleansing solution. (d) Saponification of the free, fatty acids present in the soil thereby removing them from the soil and breaking the continuity of the film so that the solution can more readily attack the remaining film. This action is un- likely as the pH is not high enough, and the time for this reaction is limited in the can washer. (e) Surface activity resulting in lowered interfacial tension between the soil and the solution so that the soil is more easily dispersed in the solution." Little (1938) also describes a procedure by which the amounts of alkaline constituents of washing detergents may be determined. In reviewing the literature on the use of alkaline detergents, England (19h?) found a wide variance in the reporting of alkalinity. In his conclusions, he recommended calling active alkalinity that alkalinity which is determined by titrating to the phenolphthalein end point; caustic alkalinity, that which is determined by titrating to the methyl orange, minus 2 times the methyl orange, minus the phenolphthalein end point (M.O. - 2(M.Oc-Phenol.) )3 total alkalinity, that which is titrated to the methyl orange and point; and the inactive alkalinity, that which is titrated to the methyl orange minus the phonolphthalein end point. His procedure to report the percentage alkalinity is as follows: -7- Normality Factor of acid X (Volume acid) I milli. equivalent of NaOH X 100 height or milliliters of sample used. The answer thus reported will be in per cent alkalinity expressed as NaOH. Strong (l9h6) recommended the use of alkaline detergents at a pH of 10.5 to 11, with an alkalinity of 0.05 to 0.1 per cent eXpressed as NaOE. ‘Bavios (1939) likewise recommended a pH of 11 as the minimum.to use for alkaline detergents as that was the minimum tolerated by bacteria. Clarin (19147) recommended an alkalinity of above 0.05 per cent as active alkalinity. Bryant (l9h6) in his can washing studies, used a commercial alkaline detergent which contained carbonates and tetra sodium pyro phosphate. He maintained an alkalinity in the wash tank between 0.08 and 0.16 per cent at the phenolphthalein end point. This according to England (19h?) would be classed as active alkalinity. He observed that at this alkalinity and with this product, the wash solution was somewhat severe on well-tinned milk cans. Fiske (l9h9) stated that a correct alkaline washing powder for use in a mechanical can washer should assist in the removal of fats, proteins, and mineral salts, lubricate the moving parts of the machine, have some water softening abilities, have some wetting ability to wet and penetrate the milk soil, be free rinsing and be economical in cost. Working with hot-milk films, Johnston and.Roland (19h?) found that a mixture of tri-sodium phosphate, sodium carbonate, sodium metasilicate and a wetting agent, above 0.1 per cent concen- tration, was effective in emulsifying fat. Parker (19h2) found fault with the alkaline detergents because the cans washed with them contained proteolytic and oxidizing types of bacteria. His observations show that a pH of 6.5 inhibited the growth of these organisms and thus an acid reaction in the can was considered essential to retard the growth of these objectional types. Parker (19h3) does give credit to the alkaline detergents for excelling in emulsifying action, peptizing, wetting - 8 - and dispersing properties, and for being non-toxic. A study in'Which Scales (19h2) compared alkaline and acid types of cleaners, Scales (l9h2—a) used an alkaline compound consisting of polyphos— phates, tri-sodium phosphate, sodium metasilicate and a wetting agent,.mai1taining an alkalinity of 0.07 per cent. In later work, Scales (l9h2-b) tested two alkaline detergents; (l) 50 per cent soda ash, 7.5 per cent metasilicate, to per cent tetra pyro phOSphate, and 2.5 per cent wetting agent; (2) 8h per cent metasilicate, 12 per cent tetra sodium phosphate, and h per cent wet- ting agent as Nacconol N.R.. He found that the number 2 detergent gave much higher washing results than the number 1 detergent. However, an acid cleaner also tested, was considered superior to both types of alkaline detergents. Schwarzkopf (19h?) found several difficulties encountered with alkaline detergents in a "conventional" type of can washer. These were, (1) continued re-use of the wash solution at a low temperature; (2) the rinse water is not treated which may cause scale formation on the cans; (3) the hot rinse and steam are wasted; and (h) bacteria grow in the alkaline wash tank at the low temperatures of operation. He also pointed out that at temperatures above lhOOF., alkaline detergents formed a lime deposit on the cans and washer. Hot water above 160°F. was noted to do the same. Shogren (19h8, 19h9) declared that alkaline cleaners should be used two days, followed by 5 days of acid cleaning to secure clean milk cans from mechanical can washers. Phosphates The first record in the literature of the higher phosphates, is that of Graham (1833) and in this country by Hall (193h). Originally the higher phOSphates were used solely for softening water and for threshold treatments as shown by Buehner and neitemeier (l9h0), Gilmore (1937), Reitemeinr and Buehner (19h0), Rice and Partridge (1939), and Schwartz and.Munter (l9h2). -9- Probably the best history and the most comprehensive review of literature of the higher phOSphates has been presented by Quimby (l9h7). Little (19h?) uses the term "condensed phOSphates" as the most logical term to designate the "molecularly dehydrated phosphates". This terminology was also preferred by Roland (l9h2). This is used in preference to the more commonly used terms of "polyphosPhate" and "complex phOSphate". The real value of these condensed phOSphates as detergents was not fully realized until the work in other detergent fields such as dishwashers, Hall and Schwartz (1937) and Schwartz and Gilmore (l93h); milking machines, Jensen (19th) and Mallmann and Bryan (1910). The efficiency of the condensed phOSphates in softening water has been investigated and/or reported on by a number of workers, including Harding and Trebler (l9h7), Jacobsen (19h6), Parker (19h3), Piper (l9h8), Scales and Kemp (19h0), and Trebler and Harding (l9h7). ' The use of condensed phOSphates for can washing has been studied by Razee (l9h8)and described by Coulter (l9h2) and Roland (19b2). Razee found that the condensed phosphates gave desirable prOperties such as emulsifying, dispersing, penetration, and protein dissolving. He found some buyer resistance to their use, due to the additional cost of the detergent containing the condensed phOSphates, and an undesirable precipitate formed on the cans when excess dilution of the condensed phosphate took place. In his eXperience, he observed that phosphates would actually clean up cans that were in very bad condition, containing milkstone and casein encrustation. Schwartz (l9h0) recommended the use of calcium-sequestering agents (condensed phoSphates) with an alkali for use in mechanical can washers. The alkali referred to was sodium metasilicate. He noted that for this cleaner to be effective, hO per cent of the detergent had to be the calcium-sequestering -10- agent. The condensed phOSphate, alkaline detergent mixture with the addition of a wetting agent was recommended by Mann and Ruchhoft (l9h6). Jensen (l9hh) found that combination of 50 per cent condensed phOSphate and 50 per cent wetting agent was a superior detergent for use in farms washing cream separators and milking machines. This was also supported by Trebler (19h5). Jensen (19h6) working with a laboratory washing apparatus also found that a combination of 75 per cent condensed phOSphate and 25 per cent wetting agent gave superior detergency to assorted combinations of alkaline and acid detergents. He suggested that detergency of milk film was not contingent upon chemical reaction of alkalinity or acidity but on the basic properties of wet- ting, emulsifying, and dispersing. The combination, consisting of sufficient wetting agent for fat emulsification and.wetting action plus a condensed phOSphate to perform the function of dispersing milk soils and suppressing mineral salt precipitation, was considered by the author to harmonize in a manner to give superior detergency for raw milk films. A warning note was sounded by Schwarzkopf (19h?) on the use of alkaline washing compounds containing condensed phOSphates. He states that temperatures of 11400 to 1500F. tend to break down many of these products causing a film to form in the can and on the machine. Also related to the condensed phosphates are the new organic chelating agents. The first to recognize the importance and to study the complex ion homologs of ethylene diamine tetra acetic acid and their alkaline earth complexes was Schwarzenbach and Ackerman (19h7, l9h8). In this country the use of chelating agents has been primarily for water softening, Martell and Bersworth (19h8); use with soaps, Hilfer (19h9); and for determining water hardness, Diehl and Hach (l9h9). Listing some advantages of chelating agents, Bersworth Chemical Company (19h?) states, that chelating agents soften water without forming precipitates, are stable at high temperatures and over a wide -11- pH range, dissolves scale and other mineral deposits, dissolves grease and food deposits, and have long storage life. For superior detergency they recommend a combination of condensed phos,hates, chelating agents, and wetting agents. Acid Detergents The first work with organic acids was reported by Scales (1938), and at that time tartaric acid was used to clean high temperature, short time units. The first use of an organic acid in the wash solution of a mechanical can washer was also reported by Scales (l9h0) closely followed by the work of Parker (l9h0) who proposed using acidified steam as a means of inhibiting prolaolytic bacterial growth. Since that time, other investigations have been carried out using organic acids, and a mechanical can washer has been developed for the exclusive use of an organic acid detergent. Parker (19h3 classified acid detergents into two groups: (1) the water- stone, milkstone removers include such acids as hydrochloric, phOSphoriC, tartaric, and citric; and“) the acid cleaners contain organic acids, wetting agents, and a corrosion inhibitor. Lennox (19h6) and Shogren (l9h8) believed that the terminology of "acid cleaners" is a misnomer since acid solutions are not good detergents for removing milk residues, but it is the action of the wetting agents added to the organic acids that actually does the cleaning. This is also the Opinion of Little (l9h7). He states that the action of acid detergents is hypothetical, since no investigation regarding the detergent properties of acid cleaners has been reported. He describes the detergency applied by acidawetting agent solution to grease and protein material as being physical and as being derived from the wetting agent present and not from the.acid. The detergency action ‘was specifically described as acting on the soils as follows: (1) dissolving the milkstone and converting the insoluble deposit into a soluble salt; v-12- (2) wetting and penetrating the soil and wedging it loose from the surface through the physical property provided by the wetting agent; (3) lowered interfacial tension between the soil and the solution, so that the soil is more easily dispersed in the solution. Beechem (19hh) stated that acid detergents must contain a wetting agent to be effective in can cleaning. This has been the observation of Trebler (19h5) and Shogren (l9h8). Shogren states that the wetting agents contribute several important values to acid cleaning. These qualities he lists as follows: (1) wetting agents are organic in nature and stable in the presence of acids; (2) they are essentially neutral; and (3) they are not affected by high temperatures. Organic acids were used primarily to overcome certain disadvantages of the alkaline detergents. Scales (19h2-a) listed the advantages of the acid cleaners over the alkaline detergents in this manner: They are free of objectional odors in the cans; they produce no ill effect upon the milk; they produce a cleaner appearing can, a "more sterile" can with less steam, detergent, corrosion and cost. Advantages in favor of acid detergents as listed by Hunziker (l9h6)'were; their softening action on hard waters, their chemical action on deposited.milk films on metal surfaces, and the possibility that they might be effective as germicidal agents. Schwarzkopf (191m, 19h?) listed the advantages of the acid can washer as follows: All cans are rinsed with clean water; all water is treated to prevent scale formation; the machine is kept cleaner; the cans are "more nearly sterile", dry, and clean; the residual alkali is kept low; the cost of water and steam is also kept low; and the temperature of the wash solution can be increased without difficulty. Beechem (l9bh) stated that when organic acids are combined with wetting agents they will produce foam which contains many of the bacteria found in the wash solution of can washers. This bacteria laden foam is discharged through the overflow, thus aiding more sanitary washing of cans. He further stated that acid prevents -13- insoluble salts from forming in hard waters. Parker (19110), and Parker and Shadwich (19241) did further work with the acidified steam.and material is presented showing the improvement in the bacteria counts of the acidified cans. They concluded that this improvement in bacteria counts was not due to germicidal action but was rather due to a release of the nutrient film holding the bacteria in the cans. In all of their studies, the cans left in this "acid" condition had no offensive odors. This was also observed by Scales (l9h2-a) and Bryant (19h6). Parker and Shadwich found that acidified steam of cans affected a reduction in bacteria as measured by proteolytic and oxidizing types as well as the "total counts". Unlike the work of Parker (l9h0) who emphasized acidified steaming, Scales (19h0) worked with the organic acids in combination with wetting agents in the wash solution for washing cans.. In later work, Scales (19h2-a) (l9h2-b) used an acid can washer (Lathrop-Paulson) and an alkaline type washer (Rice and Adams). In both of these studies he was comparing the acid washed cans'with the alkaline washed cans as to the visual appearance and as to bacterial contents. He (l9h2-a) washed a group of cans with the alkaline detergent for 17 days; the following 17 days the acid cleaner was used in the wash tank of the washers. He observed that there was no evidence of spangling and that 10 acid washed cans ranged in pH from 6.30 to 6.35. The acid washed cans were thought to be dryer than the alkaline washed cans. This has also been observed by Bryant (19L6). In both studies, Scales found that the alkaline washed cans contained higher "total", proteolytic and thermoduric bacteria counts than did the cans washed with the acid cleaner. Jamieson and Chen (l9h3, 19hb) studied the possible use of an acid cleaner for a sanitizing agent for milk cans on the farm and in the plant. Their conclusions were that an organic acid cleaner could be effectively used as a sanitizing agent. .1h- Contrary to the results of the above workers is the work of Bryant (l9h6). Although he used a different type of organic acid, he found no difference in the total counts of alkaline washed cans or acid washed cans. However, he found the acid washed cans contained a predominance of acidpforming types of bacteria, while the alkaline washed cans contained a greater portion of alkali-forming types of bacteria. Contrary to the work of Parker and Parker and Shadwich, is the work of Rippen and Burgwald (l9hl) who also used gluconic acid to acidify the cans in the last steam jet of the can washer.- Of some 200 cans tested, both acidified and non-acidified cans, there was little difference between the total counts and the proteolytic counts of the cans. The pH range of can reactions in the acidified cans was pH h.l to 7.38, while the non-acidified cans had a pH range of 7.1 to 9.7. The work of Lehmkuhl (19hh) and Tuckey and associates (l9h6) substantiates the work d Rippen and Burgwald and that of Bryant. Foter and Finley (19h?) while testing six alkaline and one acid washing compound found that the freshly prepared acid washing solution was initially acidic, but within a few minutes became alkaline. This was also observed by Lehmkuhl (l9hh) where the pH of the "acid" solution was found to have a pH of 8.3. Tuckey and associates (l9h6) found the pH of some "acid" solutions to be on the alkaline side of neutrality. Foter and Finley attributed this to the reaction of the acid with the calcium and magnesium salts of the hard waters. ' The pH of the wash solution should be maintained between 6.0 and 6.5 when organic acid and wetting agents are employed for washing milk cans, state Bryant (19h5) and Parker and Shadwich (l9hl). Trebler and Harding (19h?) recommended a pH of the wash solution between 6.5 and 6.8, while Scales (l9h2-a, l9h2—b) recommended a pH of 6.8. Schwarzkopf (19h3) recommended that -15- the pH of the acid solution in the "conservation" type of washer should be held between 6.3 and 6.8. A rise in pH was noted by Bryant (l9hé) while using hydroxy-acetic acid in a rotary type can washer. The initial pH of this washing solution was found to be 3.8 which increased to 6.h at the end of the washing period. Trebler (l9h5) and Trebler and Harding (l9h7) noted that it was extremely difficult to maintain the proper acidity of the wash solution with organic acid cleaners. This was also noted by Foter and Finley (l9h7) and Rippen and Burgwald (l9hl) who found certain "acid" solutions to be on the alkaline side of neutrality. The corrosive affect on tin-plate by organic acids has been studied by Finley and Foter (l9h7), Kerr (1935), Little (l9h7), chay and Worthington (1936), Parker (l9h0), and by Trebler and Harding (19L7). Parker listed the following organic acids in their decreasing order of corrosiveness. They were, phosphoric, tartaric, citric, aconitic, tricarbollylic, fumaric, and gluconic. Little (19h?) and Trebler and Harding (19h?) found the corrosion rates of organic acids to be correlated with their pH at a certain concentration. Kerr (1935) and McKay and Worthington (1936) have found that the temperature and the dissolved oxygen content of the solution played an important role in the corrosion of tin-plate. Acids alone did not corrode the tin-plate, but in presence of oxygen, the iron used in milk can construction was rapidly pitted by neutral or weak acid solutions. Wetting Agentg The subject of surface active agents and/or wetting agents is quite large and can not be dealt with completely in this report; however, it is hoped that as applied to the dairy industry and to particularly can washing, a few of the important considerations can be presented. -16- In general a wetting agent is any substance that will lower surface tension of water when dissolved at at relatively low concentration. Netting agents are made up of two chemical radicals, namely, the hydrOphobic and the hydrophilic groups. Wetting agents are also classified into three groups with respect to the charge on the alkyl radical. These include, (1) anionic, (2) cationic, and (3) non-ionics. For a thorough background of the subject of wetting agents, the book, "Surface Active Agents", by Young and Coons (l9h5) and the report of Anson and associates (l9h6) should be consulted. A partial list of the manufactured surface active agents is given by Van Antwerpen (1939, l9hl, and l9h3)o An early article concerning wetting agents from petroleum was reported by Flatt (19h2). In the dairy industry, the first report of the use of wetting agents was Scales and Kemp (1939). They noted in earlier work that wetting power of a detergent was one of the qualifications for a good detergent. Thus, others have also reported on the use of wetting agents, until today the majority of dairy cleaners, including can washing detergents, contain wetting agents. The use of wetting agents in combination with organic acid cleaners has been advocated by Beechem (l9hh), Lennox (19h6), Little (l9h7), and Shrogen (l9h8). Harding and Trebler (19h?) and Trebler and Harding (19h?) determined that a wetting agent concentration of 80 parts per million was adequate for addition with other alkaline cleaners for superior detergency. Other authors observing and studying wetting agents are: Eaton (19hh), Jensen (l9hh), Levowitz (1950), Mueller and associates (19h6), Pendleton (l9hé), Smith (19h8) Somers (19h9), and Trebler (19h5). Superior detergency has been reported by Jensen (l9hb and l9h6) and supported by Trebler (19h5) when the wetting agents were combined with con- densed phOSphates. -17- Methods of TestingADetergency Phillips and associates (1928) were probably the first to compare washing powders. In so doing, they employed "practical" tests, as,water softening power,the "washing power" or the detergents (test by using dried- milk films on milk bottles), the emulsifying power, the ease of rinsing, and the action of the detergents upon metals. After testing some 36 commercial detergents, they recommended as the best cleaner a combination of 60 percent sodium carbonate and to per cent tri-sodium phosphate. Several methods of testing detergents has been mentioned by Trebler and Harding (l9b7). These include, actual use-tests in the plant, laboratory tests which simulate actual use—tests, or indirect laboratory tests of certain properties which are generally assumed to contribute to good cleaning action. Such indirect laboratory tests as alkalinity, pH, and surface tension have been widely used. Probably the first workers to devise a testing apparatus simulating actual washing tests were Gilcreas and O'Brien (l9hl) where glass microscOpic slides were coated with different types of films and were then washed and evaluated by use of a photoelectric colorimeter. Scales and Kemp (1939) prepared sheets of metal with an adhesive milk film by exposing 3 inch squares of tinned copper to milk held just below the boiling point. Wilson and Mendenhal (l9hh) and Hughes and Bernstein (19h5) used different methods in preparing films for washing. However, they both used a photometer for measuring the amount of light transmitted through the glass surfaces after washing. Jensen (19h6) also used a mechanical washing apparatus, while studying detergency functions of various detergents against milk films fixed into glass panes. ..1 8... Mann and Ruchhoft (l9h6) devised a performance test for rating dish- washing detergents, wherein an apparatus was used to determine the detergency values. Other experiments followed and modifications were made by Norris and Ruchhoft (19h8, l9b9). Fouts and Freeman (19h?) utilized a bicycle wheel to wash milk coated microsc0pic slides. The washing was accomplished by this "Deter-o-meter" by passing the slides through the detergent solution and passing over a sponge rubber brush. Practical methods of testing the cleanliness of milk cans has been attempted. Tuckey and associates (l9h6) scraped loose the adhering milk soil from a milk can, and found that the total soil removed weighed 8 grams. Roadhouse (19h?) demonstrated that dirt remained on the interior of cans by swabbing with clean cotton swabs, thus suggesting that dust particles were deposited from dust-laden air that was blown into the cans during the drying stage of can washing. To secure information on the nature and extent of extraneous matter in cream.shipping cans, Claydon (l9h8) used a pint of sediment-free water containing some wetting agent. The cans were then agitated and filtered through a sediment test disc. Although the author was not interested in the total amount of sediment found, he did find that as a result of hand scrubbing the cans, so much sediment was removed that the sediment discs became clogged and only part of the rinse water could be filtered. Claydon (1950) also noted when the cans were scrubbed with a brush, that the question arose as, "how much the brush contributeito the sediment, and how much it retained". I Unlike the interests of Claydon (l9h8), Jensen and fiaterson (1950) determined the cleanliness of 180 milk cans by washing them with a quart of filtered water containing approximately one-half tablespoon of a condensed phOSphateawetting agent detergent. The cans were hand washed by means of -19- cheese cloth wads to prevent any carry-over of sediment and to be certain that the sediment obtained did not contain brush fragments. The rinse water was then tested with a sediment tester, and the sediment discs thus obtained were graded. TESTING BACTERIOLOGICAL CONDITION OF MILK CANS To determine the performance of a can washer it is essential to find the bacteriological condition of the milk cans being discharged from the can washer. There are several methods by which the bacterial content of milk cans may be determined. They are: the swab test explained by Standard Methods (19h8), the agar-plate method of Olson and Hammer (1933) and Walter and Hucker (l9hl), and the rinse method also described by Standard Methods (19h8). The latter test has been used by the majority of the workers and thus the review of literature deals entirely with this method. 8 Volume and Rinse Material The first worker to observe and test the bacteriological conditions of milk cans was Webster (1919). He determined the bacterial content of the milk cans by rinsing the cans with 200 milliliters of sterile water and plating portional samples. Cans that were wet as a result of improper drainage following washing, were tested for bacterial content by directly plating portions of the drained water. Smith (1920) used methods similar to those of Webster's. In the majority of the studies that have been made to determine the bacteriological condition of milk cans, 100 milliliters of sterile rinse medias were used. Investigators using this amount of rinsing portions include, Ayers and Mudge (1921), Bryant (l9h6), Carkhuff (19h8), Foter and Finley (19h7), Milone (l9b8), Milone and Tiedemann (l9h9), Parker (19h0), Parker and Shadwich (19L1), Rippen and Burgwald (19h1), Shutt (19h5), and weber (1938). Prucha and associates (1918) determined the bacterial content of the -20.. cans following the use of 1000 milliliters of sterile water. Some of the cans were rinsed with 1000 and 1500 milliliters of sterile water respectively, and others With 2000 milliliters of sterile water. Others using 1000 milliliters were Prucha and Harding (1920) and later Harding and associates (1922). working with acid and alkaline washed cans, Scales (l9h2—a) used h60 milliliters of sterile tap water. In later work that same year, Scales (l9h2-b) used h50 milliliters of sterile tap water and wasted 100 milliliters of the sample by pouring that amount over the lip of the can. In preliminary studies of bacterial contents of milk cans, Jamiescn and Chan (l9h2, l9h3-a) followed the rinsing methods proposed by Standard Methods (1939). However, in later work, Jamiescn and Chan (l9hh) used the agar-plate method of Olson and Hammer (1933). In later work, he combined the swab method and the agar-plate method and applied his own "seeing is believing" method described by Jamiescn and associates (l9h6), Chamberlayne (l9h8) and Jamiescn and McLeod (19h9). The recommendation of 500 milliliters of sterile water was given by Holmquist and associates (1937) and Sommer (19h6). Sommer believed that by holding the cans for 12 to 2b hours after the time of washing, gave more significant results of the actual bacterial content, than when the determination was made as the cans came directly from the washer. In order to check the efficiency of can washers, both rotary and straight-away types, Tuckey and associates (19b6) used hOO milliliters of sterile buffered distilled water containing sodium thiosulfdte. Likely before most of these afore mentioned workers started their investigations Standard Methods was consulted. Standard Methods in (l93h) recommended the use of 500 milliliters of sterile water. Later Standard Methods (1939) recommended the use of 100 milliliters of sterile sodium thiosulfate solution of approximately 0.1 N concentration. Still later, -21- Standard Methods in (19hl and l9h8) recommended the use of 100 milliliters of sterile tap water, sterile buffered distilled water, or sterile standard nutrient broth. Several of the workers of Great Britain have recommended normal saline solution or quarter strength Ringer's solution. Barkworth (19h1) recommended and used 500 milliliters of 0.9 per cent saline solution. Provan aid Treble (l9Ll) used either 500 dr 1000 milliliters of sterile water, sterile saline solution, or quarter strength Ringer's solution. Neave (19b3) rinsed the milk cans with 500 milliliters of quarter strength Ringer's solution 28 hours after they had been washed. The Hilistry of Agriculture and Fisheries (19h5) recommended that churns (cans) be tested one hour after washing using 500 milliliters or larger amounts of quarter strength Ringer's solution. Their recommendation of 500 milliliters or larger is based on the fact that volumes smaller than this will need elaborate methods of shaking, which would be cumbersome and difficult to standardize. Shaking Procedure Used Aside from selecting an effective rinsing material, the mode of contact is also important in order to set free and secure the highest possible number of bacteria from the cans that are tested. Prucha and associates (1918), Prucha and Harding (1920) and Harding and associates (1922) thoroughly shook the cans after the rinse material was added. It was then poured out and plated and the number of organisms taken from the water was taken as the number present in the cans. Three investigators reported using Standard Methods (19hl), however, only Foter and Finley (19h?) reported using the shaking apparatus pictured and described by Holmquist and associates (1937). Others reporting using a mechanical apparatus for their shaking determinations are kilone (l9b8), Hilone and Tiederann (19h9) and Tuckey and associates (l9h6). The others -22- following the shaking procedures of Standard Methods was Ayers and Mudge (1921), Bryant (l9h6), Jamiescn and Chan (l9h2, l9h3), Rippen and Burgwald (l9hl) and Weber (1938). Scales (l9h2-a), after placing the inse material in the cans, vigorously shook them by holding each can by one of the handles and the bottom rim. They were shaken five times from top to bottom, then rolled over and again shaken as before. The same procedure was followed in the later work by Scales (l9h2-b). The shaking techniques was not mentioned by Carkhuff (19h8), Parker (l9h0), Parker and Shadwich (19hl), or by Shutt (l9b5); however, it is assumed that some standard procedure was used to keep this factor constant. Presumably Standard Methods (19hl, l9h8) were followed. Webster (1919) rinsed the interior of the cans, after adding the rinse material, by "shaking and rolling the cans", while Smith (1920) "thoroughly shook" the cans. Only two investigators, Neave (l9h3) and Provan and Treble (l9hl), used a scrubbing agent along with the shaking techniques. Neave rolled his cans and allowed them to set five minutes after which the cans were thoroughly squeegeed with a sterile rubber squeegee attached to a metal handle. Provan and Treble used a sterile test tube brush to scrub the milk cans before shaking the cans by hand. Standard Methods (19h8) recommended shaking the cans vigorously by hand or by a suitable shaking apparatus, one of which was pictured. For hand shaking cans, the can is graSped under the cover with one hand and under the uppermost side of the bottom rim with the other. The cans are rapidly shaken lengthwise 10 thes, with an excursion of about 18 inches. The can is turned one-quarter turn and the process is repeated until the solution has been agitated over the entire surface. E_nber of Organisms Removed When the rinse method is used for determination of bacterial contents of 9 milk cans, the total number of organisms present in the cans is not removed. Iilone (19h8) stu'ied the amount of organisms that the rinse mat rial removed (U from the cans. His results showed that when cans with a high bacterial content were tested, the first rinse removed from ll to 7b per cent of the total bacteria found when the total number removed by S successive rinses is equal to 100 per cent. When the cans contained medium counts, he found the initial rinse removed from h to ’8 per cent, while with low count cans, the initial rinse removed from 3 to h3 per cent. The results of Prucha and associates (1918) show that approximately 75 per cent of the bacteria are removed on the first rinse when 1000 milliliters of rinse was used. The total removal by h successive rinses was considered equal to 100 per cent. When the volume of rinse material was increased to 2000 milliliters,the per cent removal by the initial rinse was increased to 77 per cent. Barkworth (l9hl) found that approximately hS per cent of the bacteria were removed by the initial rinse and approximately 86 per cent when two rinses Were used. These figures were based on the assumption that the total number of bacteria that were removed by h successive rinses was equal to 100 per cent. Factors Influencing the Rinse Test The factors that affect the inse test results have been outlined by Milone (l9h8) and they consist of the following: a. Time and intimacy of Contact of the rinse medium with the utensil milk contact area. b. Temperature of the rinse medium and utensil. c. Evaporation of the rinse medium and utensil. d.> Amount of rinse medium used. 6. Presence of substances not incorporated by the rinse medium. f. Presence of clustering and chain forming organisms. g. Presence of micro organisms embedded in insoluble deposits. h. Adsorption of rinsing medium to the walls of utensils. -2u- 1. Adsorption of rinsing medium by deposits present in the utensils. 3. pH of the rinsing material and substances possibly present in the container. k. Toxicity of rinse material to micro organisms present in utensil. 1. Presence of organisms which will grow in the media used and at the temperature of incubation recommended. Type of Organisms Found in Cans As early as 1923, Whiting (1923) studied the types of organisms found in milk cans. He classified the organisms into twenty-nine types, finding a large quantity of thermoduric types of bacteria. A similar study was made in England by Thomas et co-workers (l9h6), who determined that the predominant types of organisms were found to be Microbacterium, Micrococci, and Spore— forming rods. Another study from England by McKenzie and associates (l9h6) concluded that farm milk cans were an important source of thermoduric types of bacteria. Fabian (l9h8) and Fiske (l9h9) declared that milkstone found in milk cans_ may well serve as an ideal focus for seeding the milk with thermOphilic bacteria. Contrary to this work, Milone and Tiedemann (l9h9) found that the role of the milk can in the initial, total, contamination of the milk poured therein, except in extreme cases, was not as important a source of contamination as is generally believed. Parker (l9h3), Scales (l9h2—a, l9h2-b), Schwarzkopf (19L3) found alkaline washed cans to contain proteolytic and oxidizinc types of bacteria. They found these organisms growing in alkaline solutions and at temperatures of 1700 F. Lehmkuhl (19th) studied the milk can as a source of coliform organisms. Of all producers cans tested for coliform, no positive tests had been found. Contrary to this work, Provan and Treble (19h1) in England found large numbers of coliform organisms in shinping cans. .L The work herein reported was done with the purpose of studying the bacteriological condition and *Fysical cleanliness of washed milk cans as they are d'scharaed from the mechanical can washers. The factors that ‘4 may affect these two conditions were also considered as to their effect upon the desired results. The specific object of this experiment consisted in: 1. Determining what type and volume of rinse material Would give us the highest possible per cent renoval of organisms contained in the milk cans. A desired type of shaking asparatus was also needed by which this factor could be kept constant, and still allow us to transport it to different testing ooints. 2. The use of a quick and effective method by which the physical cleanliness of the milk cans could be determined, and still fit into the can washing operation wit'out disrupting it. This was to be accomplished along with the determination of the bacterial contents of the ni k cans. 3. The analysis of the commercial detergents on the market as to their value in can washing detergency, and if possible to formulate some type of laboratory prepared detergent that could be used in a mechanical can washer. 4. The study of the washing solution of can washers throughout the day, as to concentration of the detergent, ph, and total hardness. ,. Putting into use the findings 0. l, 2, and 3; studin; them under practical field conditions. T"E El $ECT 0F VARIED JQ NT3 AND VOLUILS 0F Elba? MEDIA OH TEE NUWFER OF . fiCT KIA R3 CVED FPOM IILK Cakj One of the means of evaluating the sa . ation of milk cans is determining their bacterial content. It is import .ant to use methods for such determinations that are practical in application and that will be representative of the can's bacteriological condition. Also it is desirable to know how the results that are secured may compare with those of workers using various procedure as a means of determining bacterial conterts of cans. PfiOCEItRE For these experiments, six new lO—ga llc n milk cans were as ected and marked from A through F to identify them for repeated study. The cans ani covers were thoroughly and completely gleaned with? a wetting agent—conLensed phOSpnate detergent betwe -n each trial. After washing, the cans and covers were sterilized in an autoclave at 15 pounds steam pressure for 15 minutes. The cans were then cooled to room temperature and each :as inoculated with 1000 milliliters of a 24 hour milk culture of licrococcus cascolyticus, by rinsing each can sufficiently to wet the entire inside surface. After inoculation, the culture was poured out of the cans, and the cans were inverted on a wire platform to drain and dry for a twenty-four hour drying period in a 35°— 370 C. incubator room. after a twenty-four hour drying period the cans were rinsed with various kinds of rinse media. With the rinsing solutions transferred to the cans, two sterile parchmznt papers were placed on the pouring lip of each can before replacing the cover. All cans Were shalien, unle ess otherwise noted, with the mechanical can shaking ap aratus described and illustrated by lilone (1948) and by Figures 1 and 2. A .Mrr r:ins:En , the rinse medium was poured into ’26- a sterile container and bacteriological determinations were made by plating the various dilutions of the rinse medium according to Standard Methods (l9h8) procedures. Use of a Non-ionic'Wetting Agent It seemed desirable before further experiments were carried out on various rinse media to test whether a dilute wetting agent solution could be used since wetting agents possess detergency properties and should,therefore, aid in setting free the dried bacteria—laden films. A non-toxic, non-ionic wetting agent, Triton X-100, made by Rohn and Haas Company of Philadelphia, Pennsylvania, was selected for this eXperiment. Concentrations of 0.1, 0.075, 0.05, 0.025, and 0.01 were used. The cans were prepared with a dried caseolyticus film as described under the procedure. The results of this experiment are shown in Table 1. Table l. The effect of a non-ionic wetting agent (Triton X-100) on the removal of organisms from inoculated milk cans.* : 3 Can 3 % concentration of 3 Bacterial counts per ml. Number 3 wetting agent : A. control: distilled water 1,770 B. 0.1 830 C. 0.075 620 D. 0.05 920 E. 0.025 1,110 F. 0.01 3,300 *two trials According to Table l, the highest removal of organisms occurs with the 0.01 per cent solution of the non-ionic wetting agent, Triton X-100. As the concentration of wetting agent was increased above a level of 0.01 per cent there occured a decided decrease in the removal of bacteria as measured by the bacteria counts obtained. Approximately twice the number of bacteria were removed by the 0.01 per cent solution than was removed by the distilled water. -27- It was thus apparent that the wetting agent solution has a desirable effect upon the removal of organisms. However, it agpears also that there is a maximum amount of wetting agent that can be added without a reduction in bacterial count due to increased surface activity and/or poor sampling due to excessive foaming at the higher levels of concentration. Comparing the Effects of Different Rinse Hedia Used in Various Quantities on Can Rinse Cbunts The review of literature and Standard Methods (l9h8) do not show that there is a difference in bacteria counts secured with different media or with different volumes of medium. It was de med necessary to compare some of the rinse media that have been recommended in varied quantities to determine which would remove the greatest number of organisms with the initial rinse. Thus the rinse media removing the largest numbers of organisms should give a more accurate presentation of the bacteriological contamination of the cans. The method of Holmquist and associates (1937) was followed, with certain modifications as outlined in the procedure. In this study five rinse media were compared, three as recommended by Standard Kethods (l9b8); namely, distilled water, buffered distilled water, and nutrient broth. rap water and a 0.01 per cent solution of the non-ionic wetting agent, Triton X-100, were also used. The buffered distilled water and nutrient broth were prepared according to Standard Kethods (lQhS) procedure. All rinse media were sterilized in an autoclave with a steam pressure of 15 pounds for 15 minutes. A control of the sterility of the media :;d of the dilution blanks was made. All were founi to he negative, thus the controls are not thorn in Table 2. Lach of the five rinse media were tested in quantities of 100, 200, 500 and 1000 milliliters. Four trials were conducted on each rinse media at e (13 ch ill... by. During such a study,difficulties arise due to the lack of uniformity in filming cans with the M. caseolyticus cultures, thus the total number of bacteria removed by the Table 2. -28- The influence of different rinse materials on the removal of bacteria from inoculated milk cans. ‘Total bacteria counts *(x 10 : : CO) Of 11 bCLLa , z z from inoculated cans when asing: Rinse media : Tria :100 200 500 1000 Tap_water ($1. 1. 9,8L9 6,500 9,333 19,078 . 6,093 8,930 9,LSL 36,968 3. 3,28h 25,h5§ 12,26h 5,063 8. 3,1t3 7,551 18,831 13,938 log. ave. 3,510 10,280 11,980 18,9L Distilled water (Cl Non-buffered 1. 3,150 1,333 2,h00 11,296 2. 2,850 3,070 11,128 55,357 3. 5,368 h,773 18,538 21,519 b. 6,000 2,392 12,868 15,2L6 log. ave. 3,971 2,615" 8,862 21,770 Buffered (D) 1. 11,02h 7,333 7,733 10,078 2. 2,781 5,023 58,988 23,21h 3. 18,9h7 15,909 8,670 10,886 L. 5,821 2,837 12,208 10,000 log. ave. 7,219 6,335 12,700 13,730 Nutrient broth (El 1. 37,795 35,000 80,667 178,078 '2. 3L,L37 80,000 126,hoh 819,683 3. 16,h21 88,182 78,302 h3,038 h. 30,71h 69,388 33,766 63 93h 10g. ave. 28,7460 SD, 100 60’ 710 119, 100 Non—ionic wetting agent LE1 1. 7,878 1,550 10,667 59,259 2. 5,629 3h,hl9 11,7L2 62,500 3. »11,578 27,500 57,183 16,076 b. 12,857 17.183 16,393 log. ave. 9,015 12,600 19,h00 31,TEO '* All counts have been converted to represent anoriginal inoculation of the milk can with a culture containing 1,000,000,000 organisms per milliliter. -29- Figure 3. Logarthmic averages, of bacteria counts showing the influence of different rinse media on the re- moval of bacteria from inoculated milk cans. .. . — Nutri ent Broth ‘ —--— Triton X—100 -——- Buff. Distilled ———— Tap Water —- Distilled I 100 200 500 1000 ml. of Rinse Media Used -39- rinse media would depend on the bacterial population of the culture. Therefore, the bacteria counts shown in Table 2 have been converted to equal a culture count of 1,000,000,000 organisms per milliliter, thus enabling a comparison of the total number of organisms removed by the rinse media. To show more effectively the difference between the rinse media, Figure b has been included along with Table 2. Table 2 and Figure A show that the highest total counts recorded were obtained with the nutrient broth in all volumes tested. There was a definite tendency for the rinse media to remove larger total numbers of organisms with increased quantities of media used. At the 1000 milliliters volume, the de— creasing order of removal of organisms was found to be; nutrient broth, non- ionic wetting agent, non-buffered distilled, tap water, and buffered distilled. At the 500 and 100 milliliters volume, the decreasing order was found to be; nutrient broth, non-ionic wetting agent, buffered distilled, tap water and distilled water. Second best to the nutrient broth in all volumes tested was the non-ionic wetting agent. “The tap and buffered distilled waters yielded lower but practically identical results. However, the non-buffered distilled water gave somewhat lower removal. Altogether, the results show that there is considerable variation in the removal of organisms by the different rinse media and at the various volumes tested. Effect of Buffering the Triton X-100 Solution on Bacterial Removal While a high number of organisms was shown to be present in cans when rinsing with the non-ionic wetting agent solution, it was considered that a buffered wetting agent solution might cause an increase in the bacterial counts of rinsings. In this eXperiment, only buffered distilled, buffered wetting agent solution and the non-buffered wetting agent solution were tested. The buffered wetting agent solution was prepared by adding non-ionic wetting agent, .3.1... Triton X-100, to buffered distilled. The results obtained amashown in Table 3. Table 3. The effect of buffering, non-ionic wetting agent in the removal of organisms from inoculated cans. Rinse medium Bacteria counts in (x 1000) in volumes of 100 200 500 1000 Buffered distilled 7,123 12,hho 51,650 60,000 Wetting agent Non-buffered 6,900 31,600 177,500 h0,000 Buffered 8,500 h9,520 86,320 1L0,000 The results shown are from an average of four trials. They clearly show that by buffering the wetting agent, a higher bacterial count from the can rinsings may be expected. The non-buffered non-ionic wetting agent solution gave highest bacterial counts at 500 milliliters quantity; however, in all trials either the buffered or non-buffered wetting agent solution, gave higher counts of bacteria than did the buffered d3stilled water. This corresponds with the results shown in Table 2. 0n the basis of these results, a buffered wetting agent solution would be favored over a non-buffered solution. The Effect of the Number of Rinsings and the Time of Drying on the Residual Bacterial Content of Cans Trials were made to determine the effect of the drying period on the total bacterial counts of cans. Five cans were inoculated and tested for total bacterial contents at various stages of the drying period. It was also the purpose of the eXperiment to determine the number of organisms removed with each successive rinsing. The periods of drying used in this experiment were 6, 12, 18, and 2h hours. Control cans were rinsed immediately after a ten minute drainage period to allow the milk culture to drain from the cans. The rinse medium used was 200 milliliters of nutrient broth, each can receiving 10 successive rinses. Because nutrient broth was used, all -32- plating was done within 2 to 3 minutes after the rinse medium had been re- moved from the can. The results of the experiment are shown in Table h. Table h. The effect of drying period on the number of organisms removed from inoculated cans, and the number of organisms removed by successive rinsings. Rinse : : Bacteria counts (x 1000) per ml. Control a Control : ‘Dryihg period in hours : : 6 12 18 2h 1. 6,600,000 h0,000 60,000 2S,h00 1h,600 2. 620,000 20,000 h0,000 7,600 5,200 3. 70,000 t,000 2,000 3,060 1,000 8. 29,000 1,080 nth 1,800 L00 5. 25,000 220 1h0 900 100 6. 20,000 180 71 S20 67 7. 3,780 120 hi 173 26 9. Loo 110 30 7b 38 10. 102 62 lb 33 30 TOTAL 7,370,920 65,916 102,768 39,638 21,501 Per cent of total removed in S rinses 99.7 99.1 99.8 97.8 99.1 The results of Table b show that as the period of drying cf the inoculated cans increased, the total number of bacteria removed from the cans decreased. Although the bacteria counts after 6 hours of holding was less than at 12 hours, there is, nevertheless, a marked decrease when the 2h hour holding period is considered. 'Although the bacteria counts after 6 hours of holding was less than at 12 hours there is nevertheless a marked decrease when the 21 hour holding period is considered. There was a high number of organisms that were removed from the control can when Compared with the counts from the cans in the drying period. This indicates that the control can contained a larger volume of the culture and thus gave a higher bacterial content. There may be three conditions that are responsible for the reduction in bacteria counts of the cans when compared with that of the control. These are, (l) the loss of culture due to added drainage, (2) inhibitive action of tacterial growth due dessication and (3) the bacteriauladen film was more difficult to remove with increased drying time. From the results it seems logical to eXpect a large percentage of the total bacterial content of the cans should be removed by the initial rinses of the rinse media. Table h also shows that for all practical purposes, five successive rinSes will give the approximate total bacterial content of the cans. Thus five successive rinses removed approximately 99 per 'cent of the total bacteria when the total removed by ten successive rinses is equal to 100 per cent. The results also show that when the bacteria—laden film is in a moist or wet c ndition, such as found in the control can, a larger percentage of the total organisms would be removed by the initial rinses, than when the bacteria-laden film is dry. Percentage of Bacteria Removed From Initial Rinses The data secured by previous workers have not been consistent in regard to the total bacteria in a can that are removed with the first rinse.. However, most workers have found that over 50 per cent of the bacteria are thus removed. Milone (l9h8) found the removal of organisms depended on the total number of bacteria present in the cans. In this eXperiment, the cans were inoculated as previously described and 1000 milliliters of distilled water was used as the rinse medium. The per cent of bacteria that were removed on the initial rinse was determined on the basis that the total numbers removed by five successive rinses was considered equal to 100 per cent. The results that were secured on the first rinse of 15 cans are shown in Table 5. Table 5 shows that the initial rinse removed from 31 to 83 per cent of the total bacteria present in the inoculated cans, with an average of 56.2 per cent. This percentage is based on the fact that the total number of organisms removed by five successive rinses is equal to 100 per cent. The range of removal by the initial rinse is rather wide, being from 31 to 83 -35- Table 5. The percentage removal by the initial rinse from inoculated cans. Trial Number 3 Per cent removal by initial rinsesfi l. 83 2. b3 3. 61 h. 51 S. 31 - 6. 52 7. 76 8. SS 9. 59 10. 60 11. 6h 12. 52 13. D? It. 61 15. b8 Average 56.2 *Based that the total of five successive rinses is equal to 100 per cent. per cent; however, this may be eXpected on a group of cans, such as were tested according to the conclusions of Hilone (19h8). The average of 56.2 per cent is in accord with the findings of Milone (l9h8), Milone and Tiedeman (l9h9), and Tuckey and associates (l9h6). Comparing the Bacterial Removal of the Milone A;paratus with a Devised Expgri— mental Shaking Apparatus Because of the difficulty one might have in tran5porting the machine constructed by Milone (19h8), (Figures 1 and 2), an apparatus was designed that could be tranSported by automobile. This apparatus was built by the Building and Utilities Department of Michigan State College. It was patterned somewhat similarly to the one built by Tuckey and associates (19h6). The apparatus as constructed is shown in Figures L, 5, and 6. A comparison of rinse counts were made when the cans were shaken by the Milone apparatus and the one built for this study. Twentysfour cans were prepared, handled, and -35- inoculated with the 2b hour milk culture as previously described. Duplicate cans were rinsed with the same type of rinse medium and at the same volume; the only variation being the apparatus used to shake the cans. The apparatus devised was rotated at a Speed of b0 r.p.m. for 30 revolutions. Milone's apparatus, run by an electric motor, was operated as outlined by Milone (l9h8). The total counts were then compared and are shown in Table 6. Table 6. A comparison of counts from inoculated cans of two shaking apparatuses : Bacterial counts per ml. rinse medium Trial : 3 Number : Milone's (19h8) : Emperimental 1. 360,000 500,000 2. h80,000 920,000 3. 1,080,000 1,h00,000 h. 1,120,000 1,700,000 S. 1,u00,000 1,150,000 6. 2,020,000 1,860,000 7. 2,050,000 h,300,000 8. 2,320,000 l,Sb0,000 9. 3,h00,000 2,650,000 10. 6,800,000 12,100,000 11. 8,800,000 12,300,000 12. 9,500,000 7,500,000 Log. ave. 3,277,000 3,996,000 Table 6 shows that of twelve trials, the experimental shaking apparatus gave higher bacterial counts in seven trials, than did Milone's apparatus. The logarthmic average of the eXperimental apparatus was 3,996,000 compared to 3,277,000 for Milone's apparatus. It, therefore, appears that equal or slightly higher bacterial counts may be expected with the experimental apparatus, when compared with Milone's apparatus. -36— Discussion and Summary The preceding series of experiments show that the bacteria counts that are secured from.mi1k cans depends a great deal on the kind and amount of rinse media that is used. This appeared to be a more important consideration than the manner of rinsing. While nutrient broth as a rinse medium gave the highest bacteria counts of the media tested, it was not a practical product to use in field testing, for cans had to be quickly handled without opportunity for re—washing before returning them to the producer. A nutrient broth solution provided food for growth of bacteria in cans that would be decidedly objectionable from the scepe of sanitation, when it is considered that cans are held approximately 2h hours before they are put to use. Also, it was not possible to plate the rinsings immediately after they were made. This is highly important when nutrient broth is used, since bacteria growth would be encouraged. The buffered non-ionic wetting agent solution at 0.01 per cent con- centration gave results that were close to those secured from nutrient broth. This solution did not provide food for bacteria outside of that possibly made available from the cans that were tested. Thus, it is believed a buffered, non-ionic wetting agent solution at 0.01 per cent concentration may be practically applied without the hazzards that follow the use of nutrient broth. Consideration was given to reasons why increasing wetting agent con- centration in rinse solutions above 0.01 per cent gave decrease bacteria counts. It was thought most likely that the higher concentrations of surface active agent Which caused increased sudsing, lessened the possibility of securing representative samples, possibly because the bacteria were concentrated in the foam. These solutions were not considered to be germicidal. The other rinse media used gave highly inconsistent removal of organisms. This was surprising, since Standard Methods (l9b8) recommends sterile tap, -37- sterile buffered distilled or sterile nutrient broth for rinse solutions to be used in securing can sterility tests. The volume of rinse media used also had to be considered. Although Standard Methods (19h8) procedure calls for 100 milliliters, this amount did not appear to give as effective rinsing as larger amounts. The highest total counts of cans were secured when 1000 milliliters of media were used. This amcunt was not used because of having to process and tranSport amounts of media that were unwieldy.. The data show that there was a marks increase in the total bacteria count as the amcunt of rinse medium was increase from 100 milliliters to 200 milliliters. The increase from using 500 milliliters or 1000 milliliters over that of using 200 milliliters of rinse medium was not as significant. This, the amount f rinse media were established at 200 0') O milliliters. The shaking apparatus that was devised for this study was found to give equal or slightly higher bacteria counts than a Special mechanical shaking apparatus that was designed by Nilone (l9h8). Although the Iilone shaking dachine may be more precise in covering all parts of the cans being tested, and in performing shaking technique, it must be censidered that exact precision in these respects was of less consequence than the items of amount and kind of solution that have been studied. _38— AN EVALUATION OF DETERGENTS APPLICLZ 3 T0 Hacnixicii can gASUTNG The aim of mechanical can washing is to secure clean, dry, sanitary milk cans that may be used either for farm delivery of raw milk or for storage and transrort of a finished pasteurized dairy product. The detergent used in the wash tank of mechanical can washers is a primary consideration given by most plant owners and operators. Most operators desire to use the best possible detergent; consequently, they are continuously looking for another "better" compound that will secure the desired results. A thorough study was obviously needed of can washing detergents, thereby enabling the selection of good detergents for can washing use. PROCEDURE The detergent qualities of all of the detergents tested was determined by preparing raw'milk films on glass panes and by washing with a mechanical washing apparatus to measure the efficiency of the detergents. Preparation of Raw Hilk Films on Glass Panes In th se eXperiments, a double strength, B-type glass made by the Pittsburg Glass and Paint Company was used and was cut into 3 inch square panes. All glass panes were washed between trials with a condensed phOSphateswetting agent detergent, rinsed with distilled water and allowed to air dry at room temperatures. The milk used for these experiments was well mixed, fresh, whole, raw milk from the college herd. It was held at a temperature of LOO - 500 F. for the preparation of the milk films. AiréDried.Milk Films The air-dried milk films were prepared by twice immersing the glass panes into the milk, thoroughly covering the glass surfaces. The coated panes were then placed on a metal frame at approximately at h5° angle to permit draining and drying for a period of 15 minutes at rcsm temperatures before washing. The air—dried films were repeatedly coated and after each washing treatment the panes were examined for per cent light transmission. By repeated coating and washing of the panes, it was felt that the efficiency of the detergents could best be determined. Heat Treated Films The heat treated films were prepared by twice immersing the glass panes into the milk, thoroughly covering the glass surfaces. The coated panes were then placed on a metal frame at approximately a h5° angle to permit draining and drying for a period of 15 minutes in a hot-air drying oven held at 180°— 1850 F. They were then taken out of the oven and twice immersed in a 0.3 per cent detergent solution at a temperature of approximately lOOOF. The detergent consisted of h9 per cent tri-sodiumpphosphate, h9 per cent sodium carbonate, and 2 per cent wetting agent (Nacconol). They were not agitated to remove all of the film, but simply immersed to remove the soluble portion of the film. The panes were placed back on the metal frames at the L50 angle and replaced in the oven for a 15 minute drying period. This sequenqa was followed until the panes had been immersed in the milk 5 times, and in the detergent solution b times. It was felt that such a film produced would simulate a milkstone film that would be left after several incomplete washings with a detergent that had low detergent qualities. Chlorine-Protein Complex Films The chlorine-protein complex film was prepared by twice immersing the panes into the milk, thoroughly covering the glass surfaces. The coated panes‘ were then placed on a metal frame at approximately a h5° angle to permit draining and drying for a period of 15 minutes at room temperatures. After the drying period, the coated panes were immersed in a 250 p.p.m. sodium hypochloride* solution, and replaced on the frames at approximately a h5° angle to permit *Hanufactured by Klenzade Inc., Beloit, Wisconsin 1. 1 —£7U— n ‘ . ' ,, ‘ ,i ,1 , A .._'- ! dreinir g and dryinQ -ir a zerlcd Ll lv d v ' . i. . ' L . .... a ‘ ' L . . ' 1 I'J L .' .. A. - .l ' ' ‘i .' r (N I y ‘f_ v‘. ‘ . . I (‘ . ,v . , . V ~ .. ‘\ I ‘ r. y - , . .. :1 the ,Lnit has .Len imm«is\d -n the till , L,“ s, are in ch- .31 line sluti: n L tiixes. A fresh chlor i we Sqldbltfl mas ;reparel for v at immersicn. of Cllcrlhc eliti;ns were uscd on the farm as the sanitation Step. Hashing the Faces All :anes were Lashed With the mechanic; washing apparitxs previoisly described by Jensen (lTLE) and as shc.t 2y Iigu:e 7. the washing'was accomplish i ty use of a xator—ii c_ldi bar to vhic the glass parse WLre Ltt3\hrd “n a "aunt“ that each w:s wished in a sepi.a;, wzszr tilt containing 1:50 millil:tors cf the different washing detergent solutions. The glass Lire? w*r? prep lled at a rate :f L5 oscille t one per minute and for one minute wishing time, preceded by one rirut e cf -suklr“ Pro—rinsing and after—rinsing ‘snsistrd of impelling the milk—coated glass panes 5 complete oscillations through tne rinse we er at a distance of 3 inches in a manner to force the water across the face of the glass. After W'ashing anl re-rin si ng and/or a: t:r— _rsing, the panes were returned to the metal frames for dryin, at rooan temperatunss before the measuring of the light transmission. Measuriig Ligh+ *pansrission of the dashed Glass Panes the drying period, the per cent light transmission was determined the washed glass panes. Iour reaiings w re octrined on each pane o3 placing the corners of each square in the filter position of a Canoe—Shears Spectrophotelometer. Flea dings were m de with adjustments of entrance slit at 2 mm., exit slit at 20mm., and a LOO mm. wave length. after a 15-20 minute warming up period, theg ' alvanomet r was adjusted for zero r3: in; with no light transmitted and for 100 with lig ht tren nitted throu h a clean glass pane. This ;ane served as the standardizinr control throughout the e:< eriments. t; K.) Hyfr03en ion Concentration All LH det (D rains ions on then detergint solutions were sale by means glass ' l 1'.I w- P Jloh a \L of a Beckman pH meter, ~'odel G (latcratcry model), equ'Lgt electrode. The potentiometer was stanlardizedinuedLaoflv be ore eac use nith a buffer solution at pH 7 Llus or minus 0.02 at 300 0., made by adding one Coleman certified buffer tablet to 100 nillilit 31s of carbon dieiide free water. All read.ings were recorded at a to omLerature of 230 C. Surface 1191191011 When determined, the surface tension re1L ngs were made by a DuNouy tensiometer. The Lrocedure followed in all cases was that recommended by the manufacturer. All readings were made at 23° C. and in each case the tens iorueter was standardized cyo uble distilled water. Three readings were made and the average of the three has been recorded. $1388 of Eater Used The tap rater used for washing, pro-rinsing, and after—rinsing contained a total hardness of between 370—1001‘30P-m- calculated as calcium carbonate, as determined by the Versenate method, Diehl and Bach (19L9). Zeolite water was taken directly from the Zeolite softener and contained a total hardness of less than 50 p.p.m. calculated as calcium carbonate. The water was treated to contain 0 hardness by addition of Versene or Versene-wettin3 agent com- bination or a conhination of 75-2 5 sodium hexanetalihos hate—wetting agent. Versene is an organic chelatin3 a ent, chemically knOVJn as ethylene diamine tetra sodium acetate and manufactured by Bersworth Chemical ComLany, Framingham, Massachusetts. All dry detergents were tested using a 0.3 per cent solution while the liquids were tested using a 0.2 per cent solution. Source and Cogposition of Commercial Detergents The composition of the following listed detergents with the exceLtion of the Mik‘o-San, was secured from the Cherry-Em wrell Cor ,oration handbook. -h2- The composition of the Uikro—San was secured through Beechenl Laboratories. Detergent Congosition : Cc omronent Xanufacturer Dreadnaug nt 50 sodium metasilicat Cherry—Burrell Corp. to sodium tripolyphosphate 5 sodium bicarbonate S wetting agent Mikro-San LS wetting agent LathrOp-Paulson Corp. 3h water 10 hydroxyacetic acid 8 gluconic acid 3 leulinic acid NU-Foam 91 water Beechem.Laboratories 7 wetting agent 3 tetra-sodium—pvro; :hosPhate Seco 10 . 3O tetra—sodium—pyrophOSphate Seco Hilk Plants 25 sodium tripolythosphate 25 borax 12 tri-sodium—phosphate 2 wetting agent Calgcnite 60 sodium metasilicate Calgon Inc. hO sodium hexametaphOSphate 1 'v -.URIE.‘ EYTPL Previous investigations, as retorted in the literature review, hav found condensed phosrhates highly valuable as detergent comgonents. when retorted in levels of 50 or 75 Per cent, it was regorted by Jensen (19L6) to be highly effective as a detergent amg anst air-driedr raw milk films. Also, this investigator regorted that the manner of washing as relating to rinsing before and after v.ashing with verious detergv ent solutions affected washing quality. Further studies were conducted to re—evaluate these Conditions and to ascertain washing practices that might affect can washing. A series of laboratory washing testS'waxamade of glas s ranes that were prepared by coating previously cleaned panes with raw milk films as described -b3- by procedure. These films were washed variously by different detergent components and pre—rinsing and after rinsing practices as shown in Tables T'through ll. ‘kashing in Sodium Hexameta—Phogghate-Wetting Agent Detergent Combinaoions Ten successive milk pane preparations were made, each of which was followed by washing at 120° F. in detergent solutions consisting either of wetting agent detergent, or wetting agent detergent and sodium hexameta— phosphate. The latter detergent combination compounded to contain 75 per cent sodium hexametaphosate and 25 per cent wetting agent. The results of these washings are shown in Table 7. High or practically complete detergency was obtained throughout all the ten trials with the "75-25" combination. An accumulation of milk and detergent solids occurred with successive treatments when the wetting agent detergent alone was used. This was illustrated by photometer readings that started at 95 following the 'first washing and after ten treatments only 59 per cent light was transmitted through the glass. Alsq,an average of .100 per cent light transmission for the ten treatments was secured when the "75-25" wetting agent, metaphosphate, detergent was used in contrast to an average reading of 73 per cent when a wetting agent detergent alone was used. These results support earlier in- vestigations by Jensen (l9h6). Effect of the Nature of Pre—Rinsing on Detergency To determine the effect of the type pre-rinse on detergency, hard water and solutions of sodium hexametaghosghate and wetting agent,Versene,and Versene and wetting agent,were used. Versene was mentioned in the review of literature and was described as a chelating agent. These chemical agents were agplied in sufficient amounts to yroduce O hardness in water as measured by the versenate ftrative method, Diehl and Hach (l9h9). netting agent was also used in a pre- 00H (W p. (K L \ O- L\ Cf) In m \0 (:3 \9 CV [\- [‘- f... If\ Q1 H C» 1\ C\ I l COM mo 00H mo 00H 09H OOH OOH OOH OOH OUH w mm _ -u . my «bummed .QH .m .m .N .0 .m .; .m .m .H « m+mrgmoim « » Imwmnmmos u phone » a... floom « mcflwpmrs « Teas pnmo gem . D \I)\/ “w d a “.3: if“) 0 {‘94. Jlu) .13 In I )1 J {H J. ..vU 1)....- 4 «.wJ 1. )...|dJ1. <1 .1 “ “pcu..pHnU.+fluq ..CHJL t? dc» L#\~&.H.nflr\c+ 05. DO‘OC LU 1C+Lf 4L_(_.rmmwfl4rmr» ..H+ +£i .rfi PCQU crmnm . « mo maopmz .QOHpn om pummnmpme ammo pom m.o m mean: mmsfimcflaaaopmw no mnemcfiauoam on m.m OONH Pm MCflmea .sofipdaom 2mm: was ca poems msepwos m mooaamoa opmstocmmpoedNon Edfleow dons hocmwnmpmv no poommw one .5 oapwe -Lg- rinsing series, using a 0.1 per cent solution. In this series, the panes were not rinsed following the washing treatment. Ten cycles of washing treatments were applied in these studies and the results are shown in Tables 8 and 9. The pre—rinsing as shown in Table 8 was carried out at 950 F., while the pre—rinsing shown in Table 9 was carried out at 600 F. There appeared to be no important difference in detergencr when pre— rinsing was applied usin the various pre~rinsing materials when followed by washing in detergent solutions containing the "75-25" combination. However, when wetting arent only was used in the wash solution, the treatments of the pre—rinse improved the detergency results. The hard water pre—rinse give the lowest results of the three treatments studied. The effect of treating the pre—rinse with 0.1 per cent wetting agent or us;ng a "75-25" Versene-wetting agent combination is shown in Table 9. Either treatment gave excellent results when the "75—25" detergent combination was used in the washing solution. This was observed to be superior to any of the pre-rinse treatments shown in Table 8. No benefit was derived by pre-rinsing with a wetting agent when the detergent used for washing consisted of a wetting agent only. The Versene—wetting agent pre—rinse combination gave similar results to that secured when using Versene only or a combination of 75 per. cent sodium hexametaphosphate and 25 per cent wetting agent. Effect of the Nature of the After—Rinse on Detergenqy Rinsing after washing is a general practice in order to remove washing solutions and to give further assurance of cleanliness. The effect of this rinsing on cleanliness was studied here, using rinsing solutions similarly prepared to those used from the pre-rinsing studies. The temperature of after- rinsing solutions were maintained at 150° F., while the washings were carried out at 1200 F. In this series the pre-rinse was not used. The re ults are shown in Table 10. “MN I mwv enema msflppms one oposmmonmmmmemxon enHfiom* mm mp mm Ow .Hw Om Hm mm 4m 0m mm tum.31wxmm mm mm 4m am am mm mm mm mm OOH OOH mcomnm> me me we 8 5 mm mm om mm R K have...» ease I. 03 mm OOH OOH OOH mm mm OOH OOH mm OOH mm *.m.klmxmm mm mm mm mm mm OOH OOH hm OOH OOH OOH mcmmpm> mm mm NO >0 mm hm OOH OOH OOH mm mm hmemg vmmm mp mm . . .; u « opwnmmosa u omsrd 00H 0% cm 0% 00 cm OJ om. 0N 0H « n. Impmnaufimfl n Pfimlm t—ua- mwcflnmes one mpcmspmoap o>meoooom ampmm coflmmfismcmap panH ammo pom vow: omeanlaopmm mo oedema Someom «mqmwwos poms paoo pom «pammaopoa mo oedema psoo hog m.O m moan: mmchcflnloam on .moapSHom pcomhopoo m.m oomH pm mnemeaalaopmw m.m oomH pm mowemmg .noedeom new: one as pummw msflppos m moomHmom mpenwmonm Impoamwon esfloom eons Heenmpss omsflplnopmw mo mafia one mo hosomaopoo so poommo one .OH oHpma -59- When the "75-25" combination was used in the washing solution, the after- rinse treatments had little effect on the detergency. This was very imilar to the results found with the pre-rinse treatments as shown in Table 8. It appeared that the "75-25" combination treatment was more beneficial when added to the after—rinse than when added to the pre-rinse water. when a wetting agent was used for washing, very Similar results were found with the after-rinse treatments, as were found with the pre~rinse treatments. This was perhaps due to the high washing qualities of these pre—rinse and after—rinse solutions. The Versene treated after—rinse again gave the highest detergency results. Effect of Nature of Rinsing_on Detergengy When Pre-Rinsing and After-Rinsing In the immediately preceding tests, Various combinations of pre—rinse after—rinse solutions were used. In this series of tests, the same type of solution was used for pre—rinsing as for after-rinsing. Ten successive treatments and washings were made and the cleanliness of these panes as measured by the per cent light transmissions are shown in Table ll. The washings were carried out at 1200 F., pre-rinsing at 95° F., and after-rinsing at 150° F. Excellent results were obtained with all treatments of pre-rinse and after-rinse, when the "75-25" detergent combination was'usedfor Washing. Lower detergency results were secured when hard water was used for pre—rinsing and after-rinsing, when the wetting agent alone was used for washing. however, fairly high detergency readings were obtained with the wetting agent wash, when the Versene or the "75-25" co bination rinse solutions were used for the pre- rinse and after—rinse. The Effect of Adding Various Amounts of Versene to Calgonite, a Can Washing Detergent Calgonite is a can washing detergent containing 60 per cent sodium metasilicate and to per cent sodium hexametaphOSphate. The latter being an inorganic sequestering agent. sets were made to determine the washing properties that would be secured when Versene, an organic chelating agent, was used in mm I mwv @cnmm wuflupms new mus2mwomgspoim:mx Gdflnome .5, H 8 a). 3 ,3 ,5 on R mm ms, mains (a ma t- me am so »a ma ma an aa 0a aramgma ow Hm mm 34 ma om mw an as mm mw amen» Undm It QOfl we OJH 00H OOH 00H ocw mm a 4m mt mm .mm.z1msem mm mm mm am we we we mm 00H on ma oedema» mm mm am to mm mm mm mm am we OOH hope; was: me mm . . . . . . mpmnmmozm » 3w om>4 03%. .0 0% cm. .0 om 02 on 0N 0H H fimmfi H prmfiaxmfl u Pgwm o o 1 J @« MEM4wm; . - , .r 3 \ . new u come pcmo pom was unmapwmpw m>ammmoodm heave QOflmeemmwpp pntfla pcmo ham n mmcaplnmpww.n . . . . .pcmmnmpmm « mo waspmz » mo mazpmz .Goapnfiom pummempov name Hem m.o « . 0 .1... . I t q - . m wcflm: ..m coma pm mafimCflpIpopmm m.m 0mm Pm hcqocflp mag ..m oomH pm mCflsmn? .moapsaom awn: map :a pqomm wCpr¢§.w mmomammh mpmnmmosimpmemxmn Edflcom cons Hmflhmpme mwcflplhmpmm new meflhIopm mo mmhv one mo mommmnopmo co pomMMm mnB .HH magma -51- irious ccxtinati ens with this can washing detergent. Versene and Cal uni were used reagectively in the following combinations, 10—90, 13—35, and 20-80. A series of laboratory washing trsts were made on glass panes that were Pregared by coating previous ly cl; died genes with raW'nilk films as described by the procedure. These films were variously wask1ed by afferent detergent comfcnents and ire—rinsing and after—rinsi ng grantices as shown in Tables 12 t;:; gh 16. 1 o . '1— ' a. - (‘—_.. ’44 "’1“; in Ca-gl A ite and Li'onite- arsene o;ie rations Ten successive nilk pane pzreparations were ma ie,each of which was followed by tashi ng at 1200 F. in detergent so litions C n Sisting either of Calgonite, or Calgonite—Versene c nbinations of 10-90, 15-85, and 20-80. In this series of tests, the yrs-rinse or after-rinse was not used. The results of Table 12 show that as the per cent of Versene increased, in combination with Calgonite, there w is a t :nancy totard high er deter rgency values. The 20-30 coni_* nations giving the highest values of light transmission. erct of the Na ture of Prerhin 3 ng on Laterg 3n CV In this series of eigerimeits, the glass ta anes were fire—rinsed with various pre-rinse solutions before hey were washed with the Calgonite or Calgonite-Versene combinations. The :re-rins ing solutions used were hard water and water treated with Versene, Versene—wetting agent, sodium hexameta— ghosthate—wet ing agent, and wetting agent only. Ten successive treatments and washings were made and the Cleanliness of these panes was measured as shown by Tables 13 and 1h. fl shings were carried out at 1200 F. ith no after-rinsing. The pre—rinsing as shown in Table 13 was carried out at 95° F., while the pre- rinsing as shown in Table lb was carried out at 600 F. The results of Table 13 show that the treatment of the pre—rinsing solutions influenced the final detergency results. As the per cent Versene was increased in the Ca1gonite~V ersene ccnbinations,en1increase in detergency resulted. This (Y) O" 0 J t - O {N (Y'\ OJ m 03 LR C73 0 U \ m 0‘ \f U . U\ (7‘ (f Um [a 03 J‘ 0‘ O O\ CO 0\ N we as as He «a mm om mm ma mm 0H we mm mm no no on we so wx am mm o omuxrm 09H arm .3 ON. 00 o\ 0+.u om 0N .H n .J , c . n n mpvmmowa mo « mcmomadon ”J u .u - .. I- 1 ) x. .. . . -.1 . . ,nnl. . \r 4. a. mam 4L0. mmflwfmmfi fi;w mxneh¥w¢Lg Q?wmmmoofim hmpkw chwmmFmEMHp PLLwH vLQO Lmfl « m D « pros you 4 oCOHVSHOm pcmnnmpmo psmo nod m.0 m when: «mummcflplpopwm no mCHmCflplopm on m.h00ma mpwgomamo op mommamb we mowpprm;U my wasp m_wdwm we kosemtmpom no pm msfizmmu .mnoepdaom poowmm 0:9 .NH manme Germs plan 9:39. end mafiamofifimassa 530m. i. .wisnmxom Hm mm _ 00 H4 be 0% an mm so we mo #5 mm have: chem ma be 00 we on so so on mm no «a mo *.w.:1mwom on. 3 as R 3 3 no me or .8 mo 883» mm mm we ow hm ow me mm am we no Hope: chem 0H 3 on 8 an 3 .R 3 so 2. mm 8 Reinawwm 00 an mm «m 00 em No we Mb mm «0 onomno> m4 mm we mm 0% pm nq mq rm do No hope: when 0 amenabd .OH .0 .w .b .0 .m .Q .m .N .H H vows H ovdqomaeo u 03'8“ a gown—”nu; mmaanmm: one manosumoup obammooosm hoped scammfiamnona vanH econ new a . . ocomnop . mo onupez a ammo mom .aoapsaom anomhopov acme won «.0 u,ma«ns_aon: «unamaeunuopmw on «.monm no wqamnauloum «.mooma pd meanmwa .unoapsaoo opdnomado o» unequiou¢.oeomno> Ho moapdendnv ascend? use: Huanopda omnauuonm.uo ooh» esp Ho.honumuopov_ao soommo ona .MH canoe -54- om om em mm mm pm mm mm mm no em .m.eum:mmnm> . ., \ s O - ..)...- .. . mm Hm mo mm uo om m mm em .m um pawns trapper Om om wm mm mm om om mm om em mm em .m.a1mnmmnm> ma a He ma ma as as ea ea a as peso. museums ma ma so ea ma as ma aa aa aa OOH ea ...g..emmame I \ \ \ II \..\ a n} n all . Hm o» as No He mo am so mm ac em arses newest? OH om mm mm om mm am am as we mm mm .m.;1wemmna> mm at so we we be Hm mm mm em mm pawns snapper 0 amp“ I .. o\ u.J o .0 o o o o o o o \J OH O a N K m q m N H u « mpHQChHmD a u u some « mzflomaomn L - :m L... J: x :3 Eat. . 2 +2. . . u. - $.33. .4 in.-- - . i. - ._ m:cfl. ea m m+ c lease o>emumoo m nmwam Coernw r w.p by TH psmo Hop « omnfialonm « ozomsm> I u we onnpmz u ammo pom .COHpsaom pcommopom sumo pom m.o w when: “mnemCfln mopwm on mmOOQ pm mewmQHMImnm .hOONH pm wnfigmmw .mzoflpzaom opficowHMn op omens new mcowno> so mmwpwscwed mnoenm> Gena «omcflhlong a no phone mcflpeos m new: odomnmp ucfluwnsoo mo nonmeopmo no posses one .VH mapme -55- // was similar to the results as shown in Table 12. The hard water pre—rinse seemed to be detrimental on detergency, however, the"75—25"combination or the Versene treated pre—rinse improved detergency over that of the hard water. Similar results were obta ned when these treatments were apflied to the after-rinse water as shown by Table 15. when a Versene—wetting agent treatment was apylied to the pre—rinsing water, as srown by Table lb, a imfirovement in the detergency resulted. The effect of pre—rinsing with wetting agent alone also had a greater effect than was eXPected. This improvement can be gartially exnlained as being due to the absence of a surface active agent in the Versene-Calgonite combinations. Effect of the Nature of After—Rinsing on Detergency The effect of after—rinsing on cleanliness was studied using rinsing solutions similarly prepared to those used from the Ere-rinsing studies. The temperature of the after-rinsing solutions was maintained at 1500 F. while the washings were carried out at 1200 F. In this series, the pre—rinse was not used. The results are shown in Table 15. Data on Table 15 show that the detergency obtained with these after— rinsing solutions are similar to thosaob ained when these solutions were used for pre—rinsing (Table 13). Similarity was noticed in the fact that the hard water gave the lowest readings, Versene treated, the next highest, and the "75—25" combination the highest detergency readings. The same type of pre—rinsing and after-rinsing Solutions were used in this exteriment as was used in studying the after—rinsing only. The temyerature used for the pre-rinsing solutions was held at 95° F., while the after-rinsig solutions were held at 1500 F. All washings were carried out at 1200 F. The results of Table 16 show that the ideal ire—rinse and after-rinse treatment would be with the "75-25" combination, although good results were Germ“; Emma mfifim: e8 Sfimmofiafiafimn Haven * so as R R. as 02 8 as a R. 3 $65.33 Hm mm mm hm mm mm N0 no mm 00 cm cammho> Hm mm Hm mm 00 «w #0 ow #0 >0 hm Moan: chum cm as as 8 as as 02 R. R. a a. 3 fitting no em vm 00 Ho ow mo o¢ mm 50 mo anomho> hm om mb Nm 0w am ow No H9 N0 «0 Hopw3.69wm mH ma 8a 8 8 8H 02 3 8 8 we 3 hazing ow Ow Nb am 00 00 00 no ww >0 #0 ocamko> em 05 iv ow om No #0 «a. om do Ho Hop»: yuan OH ha OOH 00 mm mm 0w mm 00H «0 00H «a tw¢.31nxom 0® mb be Hm rm no em «a mm 0a ow adomhop mm mb Mb wb mm om No N¢ «a so 00H hops: UHmm o Omgmbw CO 0 m 0 o O 0 2‘ o 0 0H « ”on” u H w t . m m N saga . mime“ mwdanmmz was madcapwmup obfimmmoosm hopmd cowmmfiamndhp pnmfla puma Mom . omnahlohn . uaomuo> a no cuspwz u ammo Mom a « .:0dpsflom paomnovov page you m. o a made: a. moana pd.wq«mnapnaopmw ..momo en mawmcanuonm «. mooma pa madness .mcowpsaom opwnomado op vowed one onomuop mo uoaaapawsv msoahmr non: Huanopus oquHIHopmw new omqahloua Mo on»; can no hoaowuopou no poomuo onH .OH candfi —58- obtained with the Versene treated rinses. The hard water rinses gave the lowest values of the three rinses tested. As the per cent Versene increased in the Calgonite-Versene combinations, the detergency values also increased. This has been shown also in the preceding table. The Detergency Acticn of Six Commercial Detergents Under Varied Washin Conditions C7 Q Six comnonly used commercial detergents were selected and tested under varied washing conditions that could be found with practical mechanical can washing operations. The tests were conducted to determine the influence of the temperature of washing, a wetting agent pre-rinse, and the addition of raw milk to the wash solution, on the final detergenqy of these commercial detergents. These detergents included, Dreadnaught, Mikro-San, single and double strength, Nu—Foam, Seco 10, and Calgonite. They were selected because they were typical of the range of can washing detergents in use. They represented the alkaline compounds, the organic acids, and the near neutral compounds, which appear on the market. All washings, unless otherwise noted, were carried out at 150° F. A series of laboratory washing tests were made of glass panes that were prepared'with the air—dried raw milk films as described by the procedure. These films were washed with the six commercial detergents, using different rinsing practices as shown in Tables 17 through 19. Influence of Washing Temperature on Six Commercial Detergents To determine the effect of the washing temperature on the detergency of these six commercial detergents, two washing temperatures were studied in this experiment, 120° F., and 150° F. The results of this study, without pre— rinsing or after-rinsing of the glass panes are shown by Table 17. Seco 10, NupFoam, and both Mikro-San's show no influence of temperature of washing on detergency. The temperature did have an influence, however, on the Dreadnaught and the Galgonite. The Dreadnaught gave the higher results a; me mm mm am no to am as em mm omH mm am we mm mm me am no mo mo an OmH me.c m.o mpwcosamo mm mm No mm 00 me am mm vs Hm om oma ca ea sq ea as ea as we mm mm co ONH ea.m m.o OH comm ow he om on mo on me me we am do oma me am mm mm at my me 3a em as mm oma Om.a m.o smoeusz me No me we cw mm N: m) m em mm oma cannon am ON as ea a my a” Ha me we la Qua 9;.0 m.t emanatxas «a em as om Hm mm mm mm om om um cmH sauces mm om em om Ho Hm Hd mm mm >0 mm QNH no.“ m.o :mmncnxwm me as we mm m um mm mm om mm mm oma - Ha we on me we ow Ho cm on ma om oma mo.sa m.o vehemeemsnc .5 .2 a a a a m .a .m .N a . a a u n . o a ma «.omoo « oEmz . mmwcmmn m i . t adamant; new mpcmepmmsp o>Hmmmoonm ncpam moammfiamcmap pgmwa pzoo hem . . mo « u manpmammemw « pammpmpmm .mnemCHalnmpmm no mCHmCHnampm on m.mooma pm muwgmma .mpCmmhmme mrmrmms mme Hmfiohmeeoo eroflamb hp ang mane emaaelnwm eo Hmaoemp ere no easumnmaemp acres mea map mo poowwm mxe .NH mapme -40- at the lower temperature (120° F.), while the Calgonite gave the best results at the hi her temperature (150° F.). Effect of Nature of PreeRinse on Detergency of Six Commercial Detergents To determine the effect of the ype of pre—rinse on detergency, two pre-rinsing solutions were studied — hard water, and a 0.1 per cent wetting agent solution. These pre-rinsing Salutions were held at 60° F., while the after—rinsing was accomplished at 150° F. The results of this study are shown in Table 18. The wetting agent pre-rinse did not influence the results of the Dread- naught, single-strength Mikro-San, and the Seco 10. The Nu—Foam was greatly aided by the wetting agent pre—rinse, while the double strength Mikro—San and the Calgonite were only slightly aided. Effect of the Treatment of the Wash Sclution on Detergency of Six Commercial Detergents. In many mechanical can washers, the same wash solution is used through- out the entire days operation, thus milk solids are constantly being added to the solution. Therefore, it was considered that a study should be made to show the influence on detergency of raw milk additions to the washing solution. In addition, Versene was added to the milk—wash-water solution in order to determine whether a chela+ing agent used in this manner would prolong the detergency of washing solutions. No pre~rinsing or after-rinsing solutions were used in this trial. Ten successive treatments and washings were made and the cleanliness of these panes as measured are shown in Table 19. The results of Table 19 show that in all cases, the addition of 10 per cent raw milk decreased the detergency values of the six com ercial detergents. However, the decrease was noted to be more rapid when the double—strength Mikro—San and the Nu~Foam were used. By adding Versene to the wash water, excellent results were obtained with the six detergents, and these values were -fil- no N mm mo Ho No no no oo oo oo enema meappez mm ss mm os so oo mo Ho no no so ewes: ewe: m.o eeaeomaeo mo oo mo co co co so -oo . so . co , mo enema weaeeez mo mm Ho no «o no mo so mo co co wees: euem m.o 0H ooem ss «0 no es ms we es ow no om oo enema meaeees em as Hm an on no «e we ms mm ooa nope: seem ~.o . _aeoawsz os mo oe as ow ms os ms no em no enema seesaw; as He me we as we as am em mm no eepes ween «.0 .epe caesee aemneesaz mo ow om Ho mo no mo eo no no eo enema meeppoa Ho em so om om om mo «o no no mo nope: chem m.o .eee oawqae swatches; oo so mo oo oo .oo mo ooa ooa mo cod enema manage: mo mo oo oo so mo oo oo oo eo ooa neee: seem n.o enmeeeeeeen omgobm .04” .o .m ..s .o .m ..w .m. .N ..n- u vows « .280 . ofimz . . é 35.7.0.3 «I u mwfifimm: 98 mvcmfimohp ohammooodw .3pr noammaamqgv ”Em: .53 mom a mo ogaz u anomaopon » . .soofl ea meanness. es. 3&8 we musing race? 3 «5:3: .opnomuopou wad?!» 93 Hmaohofinoo 26??» hp mad.“ flog mo Hwboama 05 no 8333» 35.7.93 05 3 enema $530: 950 Mon .10 was?» no $00.30 can. .3” 0.33. v .1“ A UL treatments a. solution on the SUCCESSTVG water wash fter hers .1857 on a YISJ'N ., rz‘. .ene to ht tr \a-.... mi Per cent 1i 'J ’30 raw ..3 "ans r dr ‘00!“ a1. (.1 washing at lj s Var N” Tilk removal of deterrents. ave . “.8718 l ‘u 13. L"\ 0 ‘LI\ C5.) 0! r‘r\ .,_ \Q 10 Y‘ I: v’ ' ordaineuu .. — . - ‘11:. O\ -’3 :Q‘\C\ (3\ UK 0\ UK 0\ [\- : O\ (A O~ ‘4') O“. {J‘\ C\ Q LNG. (I\' 73 C”. C‘\ m LI’\ (1‘ U\ C‘sU‘. [\"U\ H ‘UK (“T\ 0' 11“! (W ( ’T\ ovu\ c cu C‘ O r’i (\J O (‘\ C (J U) I <1) 0 E‘? :r' ,.‘ L. 0.1 nr—f r-w U) 10 2 :’\ V. ’ Y I r. (A ‘1 .{TO-“) \(0 \L.) 91 06 100 10 I-Foam N 04 100 100 oo 0.25 o “N 'A O\ O\ 93 (\ .1 {I (:0 ‘L.'\ . H (1 0‘. f“ C O) O‘\ (‘1' C . CC C1 (j\ ., F- 00 3.; leeirq <1 ’37:. (‘W O w Ox OJ .q s‘ O\ >- (I. (\| C:\ O . C\ V CT} (1.} 'J\ 'LI \ U \ _ ' 0: ( 3 o (J C‘ C) r4 r4 0"; l C) O H C) C. (‘\ (‘1 r-{ Cr) C‘~ J [\V U“ r—i ".3 ff: 0 .fi :3 11‘? f‘ ‘4“ n L ‘3‘ ‘\ 11K U“ (Jr:‘ Hf~ 0.?- -;\ C) u, \ a.) V1) 00 \U\ C (_ ‘1} \ Yum ? \J x7\ x". U\ 0\ L:\ ‘L‘: \ CV (‘d bro -63- only slightly reduced when 10 per cent raw milk was added. This shows that the Versene does ros sess some property that will disperse, and dissolve the milk solids, and still aid in the removal of uilL soils. The fi’fect of Various Tyécs of Soft datvr on Deter;ency Kany milk plants throubhout the country have difficulty with ha d. aters and many times the cuestion is raised, "Is it Hdv ntag sous to Soften water for the washing of milk cans in a mechanical can washer"? This, of course, p. s a difficult question to answen as a ,ccd many factors are involved. However, one of the co ns iwier tions w-uld be the reaction of the detergent in the softened water to further aid in etc rgcncy. Tour tyies of wet e-r reitening treatments were studied; um elv Zeclite, distilled water sodium he 94—4 3 softened, and Versene scftered waters. Com;ariscns were made on five cc nercial Q. T) (D ’1 a; :3 ("F m P p. m r_J (3" 4—. ... . -. .- n'rc’ oc’n -.—- a... m mr ti, :rsrared the ‘,-e, stable + n The ' '4 H I‘ . '3. '1'1 I‘ 1. . “A, I“ !" ' .- were Lru,ared with en :lr-dllfii rew nilk film as bTrvlquslg descr‘rel. .en 0 ‘- , - . A 1 n '0'!" r— 4 r: 's. . q r I + r r. -. r ‘ t x 1‘ h D ‘1‘. r‘ - -\- t \- SSJ-CCQSSL etT‘bC-{y UAALCIL Us a) .d 1" is: -‘ 1.? 8 yr. r‘.) AA-.;\'\A€‘ .lr‘cl L‘h‘h 1- J- :-s:.1-‘.n€. M C.- tr K F'g l C|‘LCS '- w* s "L " ‘ r a \’1 " r“ ‘ 1 an as Cesured b the II Ce. L ll 'e transit": one (.19 shew”: in l ”I” ---. ‘ - 7“; r 1~ 4 ‘T V ‘ — r '.‘\ " ~. “. n r ‘.‘ ‘ J t“- " 7 H h (1" ‘ V 0‘ I. - . v Tnx; Mr QQ,3.1.T‘L...~Oht/, l.u-—L'Ud..-, DCCL 1k ’ ..4...‘ Ln . J ‘/-L_’ Cx-....o.l.1".-..-.~Lr. QuiV 123 "'\ n-L ’ v -\ a bra Tr » agprcliraeelv tne sin- 1a 01* “‘3 rs: 1+3 ‘ on US:t in listllle,, tors r2, t1 1 ,. .. . 9.-..-- ".J “r . +. - ' "-- * .4. .. - CO, I). I flu-’4' L~-; tj‘q}J(JbrhC~U6 SM ‘ l ‘ (A. f... *I‘ S~Qb$c tr: 4.4- .. ’ L‘f“ HLL‘l-Lte UI‘GMLCK .. , --..-.. ‘ .- .-. .4.1,.. ..I. ..-,- .. . , - .3 water 53v; lunbf detergent, results than the ether three trea.icnte tastes. The Calgsnite gave the lowest ictergency with the Versere treatei t;tcr and A . - a L - t .3 + .: 1 1 - - - 1 - the highest oatcroe c; with .ist_;iei 'at?‘ a $1.,r131nuly r;t_fl ”'C”’ "e ' 1 - .. - .- - w: ;.-11,-‘ ...4.., ., . 1:: _~: - " 3 11. get ‘Jl‘s JZICJT T‘DS| ‘].t ed ("B CR «_.,_. r L»..'._.L C a). ‘v-ML";: 1"}, 5‘ .25... 'I'J. ‘ r... “I? *i’.rb“'u :y‘. 0 T :1 ~ - 4“« -' ‘3 ,.. r, - t A _ O ’ . - I «~‘ 4-. . . -\ in an eifert to t.£1ain tti- activr, the " or the deter ent boluthhS were taken ani were f;uni as shout in Title 20. Th-“a 'V rrtiir“3 were as 11“."... ., '1 '. + - f, r" - . " ' .-.+.' '1...‘ L 10. U3. q -1... J»V.&- -L'ng U'7i’...’.. u", -.‘v, U...pc~'_.. Al, '0 ’ .~..-_~...’. ‘.4\~‘V ?.32. The cau:e cf lcw dfitflTgphCY is undoubtedly exilaired by the low 1% of .~ ,.'. - - .. -'.-3-L.1.‘ - l’ - .,.’ 1-. .l- ‘. b.10, causing a graci,itieion oi the Nile ,ro-e_r l. V 'J) mo OOH OO OOH mm mm mm OOH OOH OOH mm flmmhwb OO OO OO OO OOH OO OO OOH OO OO OOH OOOEONOO OO OO OO OO OO OO OO OO OO OO OO OOHHHOOHO HON-OOV mm OOH mm 00 OO OOH OO OO b0 OOH mm opHHooN moo .m.31wxmm HO «O OO HO «O OO OO HO HO OO OO OOOOOOO OO OO OO OO NO NO OO mO OO OO OO OOOOOHOO OO «O HO OO OO OO HO OO OO OO OO OOHHHOOHO om Hb Ob mb mm HO HO HO 00 mm 50 wfiHHOON m.O mchodeo OO OO OO OO OO OO OO OO OO OO OO Quanta» OO OO NO OO OO OO OO OO OO «O OO Opoaaxom OO OO OO OO OO OO OO OO OO NO OO OOHHHHOHO 00 HO OO HO NO do no mm %O 00 OO -opHHowN m.O OH comm OO OO OO OO OO OO OO OOH OO OO OOH OOOOOOO 0O OOH OOH OOH OOH OOH OO OOH 00 mm OOH mpmfidxmm mo «O hm m0 mm mm mo OOH 00 OO OOH fiwHHvaHQ 00 OO 00 OO OOH mm mm HO HO mo OOH OPHHOON Noo _Ed0hluz OO OO OO OO OO. OO OO Om HO . OO OO OOOOOO> NO.O OO NO OO OO Om OO HO «O OO HO OO OHOOOHOO NO.O O O O N O O O. O O O NH OOHHHHOHO OH.H OO OO OO OO OO OO OO OO OO OO OO OOHHOON OO.O ~.O OOO.OOHH2 OO OO OO OO OO OO OO OO OOH OO OOH OOOOOOO OO OO OO OO OO OO OO OO OO OO OO «Hoaaxmm mm OOH mm 00 ho mm 00 bO OO mm mm UoHHvaHQ OO OO OO OO OO OOH OO Om OO OO OO OHHHOON O.O HOOOOOOOOOO OOOOOOO . .OH .O .O .O .O .O .H .O .m .H HOOOOOOOHHM ma ”.OOOOO oaaz mmnwnmmz and manoapwohp obammoooam HopHd nadmmdamthp pnMHH ammo Ham “mewmmwwwmm paamnopom .mnaunaunhoamd no unamnahlohm o: «ohUOnH 9w.mdagmu3 .mpnomhopou mdanmmz goo Hddahoaaoo usedhufi.bp mEHHH xHHE_3mn coancjafiw Ho Huboauh any no beam: sum: 0:9 0» voHHmmu updoapdohu maHnopHom have: no vacuum any .om canoe ”-“J- , - l l - .1. - 1- .. , w 1 1"\ an atteir. was -aie t3 -trtd c,nci+ s and u.;;h chr .ro—oan . - n.- ,~ .1 _ - ,, 3 . 3 ~.,, , ..z . n , H: .- 1‘. woald Old detezaelcy. This was done o; $TGrufi-hJ O._ 10: ce“t “-Lco-Oan solutions, this being a*growirat~ly the concentration recommendal by the nanupacturer. To this sol1ticn, chemicals were aided in inactitiés vcrih" f on 50 to 5C0 ;.p.u. ”hen those s;litiuhs were used for washin* air—dried raw x‘lk films variations in iot'rbcrcy were ensured and are shown in Table 21. It will be noted that sodium hyiv Lido even in 50 l.,.m. xia-olti“° gave clear glass gar -es. Sodium carbonate also materially aided dater ency 5- at 50 and 75 p.p.m. This was increased, however, when 100 and 500 p.;.m. was A +C) A \H' (D used. Sodium bicaroonate in rov:l date: one; when 500 g.p.m. was us araroximately the same eytent as 50 4.3.x. sccfi um tdircnidc. Forever, when only 100 p.p.m. was used, there was only clcanin* to some degree, however, less cleaning was ct servci than when 15ing the rntreated Hikro-San solution in hard water. It thus ayiearei that the hyircgen ion concentration adversely affected the detergency, whethe froz1 acid or so diva bicarbonate. likewise , it no ld be noted that rota ssium hydroxide increased dc wt erge ncy as did calcium carbonate, magn. ium ca rhxnate, and tri-s odi um ghosghata at 500 p.p.m. quan nt-ti 4. There was some improvement in detergen cy “.hen such products as sadi.m chlcri 1e, sodium sulfate, potassium on oriie, calcium chloride, and dashesium bicarbonate were used at 500; .p. m. 3valuation of Commercial Dairy Dete rg3r rts It was not possible to make a comglete washing study of all of the detergents that are being marketed for can washing purfcses and to determine their manner of use that would yield the highest deteréency. However, a washi n" D performance study was made of 35 additiozial commercial du ry d at mts. In previous studies,only air—dried raw milk films have been used. Also, in Table 21. The effect of adding basic ions to a $.29 per cent titre—San solution in d Stilled water. Chemicals added : Amount of chemicals added in n.o.m. 3 539 : 133 : 7S : SO KCH KCl Ca CO3 Ca slnc \‘ \I \I x l \ \ . \ '39. '3‘“)? 7 r; "‘I 2‘le '15“. \ 1“ €9.14)? .V. 'L" w. ‘2'." ' J-L V "—V n n :~"'"n '3‘ n I”)? n :V’ox n" l I \l \ I \ ‘ .r - 15-ir‘n‘ .x "..‘L m A ".."..‘.".. - “4933‘. 1\ l\ n')‘ 'n I.Il ". .‘l 3’.) ..‘L A A l n __\r__\! v _ ‘ LN. .333 58‘ n onate - .31.; '_)’ r. I\ I\ Key: *%** cleaned milk soiled glass panes ¥** cleaned as well as likro-San alone in hard water cleaned to sons degree - added to soil formation \ v 7?? I“ -67- these trials air-dried fila1s were used as well as heat tr eat 3d and the chlorine—protci n complex films. The edetergents are listed by rm axe in Table 22. lo determinations was made of the co m; itio other than to I? note the pH and the surface tension of the detergents at a 0.3 per cent concentration ( oowder), or 0.2 fer cent concentration (liq did). It will be noted that pH or surface tension in the detergents that are generally classed as alkaline proluctsr aterially affected their washing quality. ln this group of detergents, two products were outstanding; namely, Seouet , and Flo-tron. These products were known to consist of essentially the same ingredients as the "75-25" combination uh t has been extensively studied. The majority of the alkaline detergents gave good results on the air- dried.milk fi us. However, many detergents failed to clean the heat treated or the chlorine—protein complex films. Such filns are bfl ieved to be quite prevalent in producers shipping cans and detergents for can washing must process detergent qualities that will remove them. The acid and the non-ionic detergents were generally low in washing qualities. It can be stand that generally as the pH of the acid solutions decreased there was also a decrease in detergency. Since Versene had been shown to have some beneficial detergent properties when in combination with other components, tests were conducted to dete1nine {hat effect small additions of this compound wouldh ave on the various co imercial detergents that were used. These results are also shown in Table 22 and are indicated by the double asterisk in the heat treated and chlorine—protein com- plex films columns. Excel t in one instance, there was an increase in detergency when LO per cent of the detergent was reflaced with the Versene. Table 22. An evaluation 010 commercial -dairy detergents. ~as-ing at 1200 F.; n0 pre—rins -n.*; after-rinsing at UK)0 ;.3 uslng a 0.3 per cent detergent solution (dry , 0.2 per cent SOthlOn (liquid). Detergent f Per cent lig ht transmission after washing 3 Name 3 pH .Surface= Milk films "7 fl 3 :Tension: Air—dried : Heat treats : Chlorine—protein = pH 3 : : trials = trials 3 trials : Al : z 3 3*: 10 : l = l¥¥3 1 3. 18* 3 ‘ Alkaline Calglo 7.15 32.2 93 82 86 98 E8 81 10.20 Surf 7.27 30.2 95 87 52 78 52 95 9.33 Calgon 7.60 51.5 93 81 9 85 relyar 7.76 29.1 99 99 56 95 48 94 9.11 Nytron 7.79 34.6 97 88 49 SO 48 73 9.00 Bio-tron 8.08 32.5 99 99 95 96 . Kleer-mor 8.64 31.3 94 90 49 65 48 76 9.28 Tide 8.80 26.4 98 97 85 86 Seco 10 8.86 48.1 99 99 77 96 58 98 9.40 Sequet 8.86 32.7 99 99 99 99 Super 88 9.00 31.5 94 9o 48 2 49 93 9.47 Farm Dairy 9.46 32.6 95 89 E9 91 91 78 9.61 }.20. 3 9.68 33.1 99 99 65 99 47 93 9.58 G.L.X. 9.88 42.7 93 83 63 69 53 68 9.40 8.0. 66 9.90 34.5 95 90 63 92 51 ‘ 87 9.89 Solvay 600 10.00 39.7 97 91 60 84 69 79 10.10 Sup. cleaner 10.09 32.1 95 92 S7 92 48 93 9.91 C.‘.K. 10.09 42.4 97 93 68 63 47 58 10.70 1&3. 42 10.14 35.5 99 93 62 77 48 98 10.36 8.0. 6 10.37 41.3 91 37 71 69 S3 87 10.12 Tykor 31 10.39 38.4 96 92 62 67 48 5 10.36 Tykor 51 10.44 39.7 98 96 6 88 E4 84 10.22 Dreadnaught 10.5 41.9 98 35 63 9 SS 98 10.23 Saigonite 10.57 -79-2 9 91 62 72 . EflrSpeed 10.60 33.1 9 96 62 83 47 87 10.32 Can cleaner 11.10 47.7 98 93 69 69 45 66 10.70 Aeid ‘77 acid* 2.70 39.4 49 45 47 4? :siistone* 3,25 37.7 69 66 80 59 46 47 4.12 Im-kleen* 5.70 32.1 7 71 48 51 47 59 6.12 Pean-salt8 6.08 43.7 52 49 46 51 45 El '.25 Iikro-sa 6 .57 32.0 83 80 S 50 47 59 6.89 single str.* 6. 69 31.2 84 79 49 49 47 55 7.01 double str.* 6.68 43.7 73 61 46 49 47 55 7.09 Ion—ionic ‘b—Foam* 7.27 32.0 70 57 46 48 46 5 9.02 Sharples 218* 7.81 32.7 87 80 48 52 50 79 9.09 -=?byg affiiquid detergent, ex-‘Verscne ad eJ to deterg3::t in 40-60 curb nation, # pH of Versene-deterg ent combine tisn solution. -59- Effect of Combinations of Versene, Condensed Phosihates and Wetting Agent vas Kpplied to Detergency The preceding experiments indicated that the addition of Versene to candensed phosghates and wetting agents might prove to be a combination that would give desirable detergency results. Therefore, a study was made of laboratory prepared combinations of these troducts and their application to other detergent components. As was shown by Table 22, different detergency values could be expected with the three types of raw milk film . Effect of Versene Combinations on Detergency on Two RaW'Nilk Films One set of glass panes was prepared with air—dried raw milk film and the other set prepared with a heat treated raw milk film. Ten successive treatments and washings were made on these panes to determine cleanliness as measured by the light transmissions are shown on Table 23. ‘Hashings were carried out at lhO0 F., with no pre—rinsing or after—rinsing. The results of Table 23 show the influence of these laboratory pre- pared detergent combinations cn the two films. Here also detergency was secured on all the air dried films. Highest detergency of the heat treated films was secured with detergents l, S and 6. It seemed significant that the one common ingredient absent in these detergent com inations was tri- sodium phosrhate. It was syeculated that tnis product interfered with certain functions of detergency that was provided by sequestering—chelating—wetting agent combinations. A Comparison of Two wetting A;ents on Detergency When in Combination with ‘Versene and Condensed PhOSEhates The glass panes were again prepared with the air-dried raw milk film. Two wetting agents, Nacconol (alkyl aryl sulfonate) and Draft (sodium laural sulfate), were comtared in this study. Two washing sclutions were used in the comgarisons of the two wetting agents, hard water, and 10 per cent raw milk addition. Ten successive treatments and washings were made on these -70- ON ON ON Om 00 ON om Om ON om 0% 00 ON ON ON ON ON ON ON .0 ON .m ll .Q II on ON .N ON oH .m.m.s «waves "hamm Hus «deposdxmm ”pnowwtmqflppmx ”ocmmnwWL mkmflfifld pcomuopum,oewwflm.* t so co co so so mo so so mo mo so e383 some oo oo oo oo oo oo oo oo mo mo oo umaneunaa om.m .0 so to so so so so so so mo mo mo empwmap swam mo mo mo mo mo mo so mo oo mo mo seawenwsa mm.m .m S om om S we on so so no mo mm cosmos. some co no so mo so so no to co co so cassette. $.m .q R ma om mm 3 s. on on oo om om cosmos some mo oo oo oo mo mo mo mo oo mo mo eoaueunae mm.m .m 3 mm on mm .3. on on en es ws om cosmos pawn oo oo oo 02 03 oo oo oo oo oo oo Banana: ems ..s. so so go so so so so so oo oo _ so @383 some oo oo 8.” 8H 03 oo 03 oo oo oo 03 Esplanade 91w .H omag“ .OH 00 ow ON. 00 on OQ om ON OH W EH.“ m a u 00' V «I . MO .li a .x. u u mmflanmg Una demfideu. mbfimwooodm HOPHN GOHmmflEwfith pgwdfl #GOO .Hmm u édz u #flomfiSGQ .qoapsaom pnomhopoo pace Mom m.o w muses mwcamcwunaopmw.uo wafimqflnuohm o: m.h0bqa pd Moanmm: .55 .3 35 08. no *mqofivunfinaoo nepmnmmond voonmoaoo cad enema museums accomno> mo poommo.hodomuo¢oc ens onN canoe -71- panes to determine cleanliness as measured by light transmissions are shown by Tables 2h and 25. Table 2h shows the results using Nacconol; Table 25 shows the results using Dreft. 'Washings were carried out at 11400 F. with no pro—rinsing or after rinsings. ~ There seemed to be no difference between the two wetting agents when in com ination with the condensed phosphates and Versene. A slight reduction in detergency was noticed in both wetting agents when raw milk was added to the detergent solutions. However, this was not as great as the reduction that was previously described when using commercial-detergents (Table 22). The combination of 20-hO-LO, wetting agent, sodium hexametaphOSphate, and Versene, shown in Table 2b, gave the highest possible light transmissions in all 10 trials. Evaluation of Several Laboratory-Prepared Detergent Combinations A more complete analysis of the detergent qualities of the laboratory prepared combinations was deemed worthy of investigation. The glass panes were prepared with three raw milk films, (1) air-dried, (2) heat treated, and (3) chlorine treated. These have been .described previously. Three detergent components, tri-sodium phosphate, sodium metasilicate, and sodium bicarbonate were used with the Versene—condensed phosphates-wetting agent combinations. All of the prepared detergents were thoroughly mixed, in the percentage indicated, by means of a Waring Blendor. washings were carried out at 120° F., after-rinsings at 150° F., with no pre—rinsings. The results of this investigation are shown in Table 26. All combinations, without the components, gave good detergency results on the air-dried milk films. A decrease in detergency was noticed on the heat treated and chlorine treated films when the components were added. The first three combinations of Versene, condensed phosphates and wetting agents gave the best all-around detergency readings. Throughout the results, there seemed o4 oq ON .0 S 3 2 .s so as on .s ON or OH cm ow ON .N co 2 A is??? REE—EH Paw H306 0M .x. 1 s.so so so so so so so so so so o as :8 s2 5.03 03 8a 8a 8a 8a 8a o3 8a 8a 8a not: Ems .s s.so so so so so so so so so so so flag as." s3 s.oo oo 03 oo 03 03 8H 02 oo oo 02 use: sass .s o.so so oo so so so so so so so so flea :2 mos s.oo 03 8H 02 oo 8H 8H 02 oo oo 03 “Ba, sass .s «.oo hm 50 cm b0 om mm was #0 00 50 Mada bah. A“0..” s.so oo oo oo oo oo oo oo so so so moss: sass .s s.so so so so so so so so so so so is. at s3. s . oo oo 8H 8H 8H 8a 8a oo so 8a 8H “3.2, sass . m s.so so so so so so so so no so so one. :2 s2 s.so oo oo oo oo oo oo oo so so 02 93s: 2% A 0wggfl 0% 00 cm ON #0 on {Maw on 0N 0H « L ”soapsaom nws3u .02 HO u .1. mm use: And apnmspsonp obsmuooosm you e no mmsswnshp 9 one no ..u a.“ U m as. «$3 as m pgdaau pnomuopoa . .noapsaom pqomnopoo peso nod m.o a mass: anasnaunaophdsno qusndunohm on n.h0Q«H no wasnmms .naafim MHHfinswh coandjhdd no Honooooz one savannmonm somqquoo soaonhop Morenospmnanaoo 0» sound aun3_honomuopov no xadansuu Ho poommo any . <1 D-l ,_J 0'“. *‘5 F D.) L ..3 a rd; {J t .L-J b D ’71 J. 1120, “hi 3 the 3 an ad the total hirine ess remained o nstant. The active alkalinity also doors aseds s1 only, h W'V““ the proper al_kelinity was xaintswn- .L throughout the day. ‘ Detergent solutions from zwo mechanical can washers, Plants and C, A .1 using an organic acid cleaner, Kilro—San vvore studied in this trial. Plant A 5.) 1"1 was using the nikro —Son by adding one—half pint of the detergent to both the -39- wash tank and the ste_i1e rir se tank. Plant C was not addir~ an, deteréert to the wash tark, and the feeder s stem was deyendez on to surbly enouoh detergent to the wish tank. In oath Plants, a 2.5 per cent deterbent solution was used in the feeder S‘ste1.oth wash- rs w: re sing a tenierature of 1700 E. in the wash tank. Plant A was using a sterile rf-se Voter of 1300 F. Plant C,using a rot"r3 washer, did not have a sterile rinse tank. Plant A was washing aparox1nately 1600 milk cans gar dal, w1.ile PlantC as washir' aggroxigatsly L00 cans per day. The results of these studies are shown in Tables 3b and 35. Table 3h also is characteristic of several “nalyses of the The results of the aralbsis of the washing solution of the can washer located in Plant A are shown in Table 3L. The concentration reading of the wash solution decreased slowly as the dags 01eration progressed. Thi was noticed with a reading of 2700 at the beginning of the day (0900) and a reading of 1800 :t the close of the day, (1"30). he ch' t the tesinning of the can washing of ration, 6.7, nas ids: al according to direcu1o“" cf the detergent manufacture. However, in one hour's time, (1000) the pH was on the alkaline side of neutrality and this was noticed to increase as the day's ogeration progressed. Thus at the end of the day (1500), a pH of 9.0 was observed. The total hardness of the wash solution slovl; decreased throughout the dvy. This is the Opposite of what was found with the alkaline detergent (Tables 30, 32, and 33). The results of Table 35 show the analysis of the wash solution from Plant C. Here again a slow reduction in the concentration reading is noticed as the day progressed, and again the pH of the "acid" solution was found to be on the alkaline side of neu‘ra lity. The ;H was observed to be 7.30, 8.30, .and 8.uo. With an addition of the acid detergent, a reduction was noticed in the pH. However, the wash solution was still alkaline, pH 7.6. The total hardness likewise slowly decreased as the day prorressed. This was very similar to the results obtained from Plant A. -90- Table Bh. Analysis of the washing solution of a straight—away LathroP-Paulson can washer, using Mikro-San, a1 organic acid detergent, Plant A, September 22, 19L9. . 3 Cone. 3 _ 3 Versenate Tlhe : Reading 3 PH Hafdness 3 3 p.p.m. 0900 2700 6.70 h30 1000 2600 .20 tho 1100 2500 8.30 392 1200 2100 8.80 350 1300 2000 8.80 337 1L00 1950 8.90 32h 1500 1500 .9.00 331 Table 35. Analysis of the washing solution of a rotary Lathrop- Paulson can washer, using Kikro—San, an organic acid detergent, Plant C, October h, 19h9. 3 3 Versenate Time Egggggg : pH 3 Hardness ~ 3 : p.p.m. 0900 900 7.10 350 0930 825 8030 333 1030 825 d.h0 321 {ore Mikro—San added to washer 1130 925 7.60 331 1200 '900 7.30 311 -11.. Study of Mikro~San, An Organic Acid Can Washing Detergent It was noticed in the preceding study (Tables 3b and 35) that when Mikro-San, an organic acid can washing detergent, was used in the wash solutions of the mechanical can washers, the pH of the wash solution was on the alkaline side of neutrality. Other investigators, as reported in the review of literature, have also noticed this; however, none have given reasons for this reaction. The producer of organic acid detergents recommends that an acid reaction should be maintained, and also that the ideal pH of the wash sclution should be 6.5 — 6.8. Whether or not an alkaline reaction is desirable for acid washing has not been determined in past studies; however, it was the purpose of this study to determine the cause of this phenomenon. As a means of determining the chemical reactions that may be secured with one standard organic acid detergent (Mikro—San), potentiometric-titration curves were determined on Hydroxyacetic acid and Gluconic acid, both know to be present in this acid. These curves are shown in Figures 8, (Hydroxyacetic acid); 9, (Gluconic acid); and 10, (Nikro-San). The Hydroxyacetic acid gave a typical weak-acid, strong—base curve as shown by Figure 8; however, a modification of this curve is noticed when Gluconic acid was titrated, Figure 9. This modification is characterized by a hump which starts at pH 6.6 and ends at pH 7.2, and then continues following the same pattern as that produced by the natural weak-acid, strong—base curve. When the Kikro—San was titrated, (Figure 10), the same modification in the curve was noticed to be similar to that secured for the Gluconic acid. This modification is interesting because of the fact that this plateauappears at approximately the detergent solution pH that is recomuended by the manufacturer of this acid. When just a small amount of base is added after reaching a pH of 7.2, a sharp up-swing takes place in the curve. This may explain the reason for the observed alkaline -92- reaction that is secured with the use of Hikro—San.’ A reaction between basic ions of the water and the Hikro—San would be eXpected to take place, causing this rise in the curve and as a result an alkaline pH. Determinations should be made of the pH to be maintained in the detergent solution that would yield the highest detergency readings. This modification of the typical weak acid-strong base curve that occurs with gluconic acid is eXplained according to Leermakers (1950) by the presence of delta and gamma lactones which are in equilibrium with the C'luconic acid. It is thus possible that slow hydrolysis of the lactones during the titration modifies the curve which would normally be eXpected. A partial eXplanation of delta and gamma lactones is given by Isbell and Frush (1933). Surggy of Home Sanitation Treatment The nature of the home sanitation treatment that producers follow may greatly affect the condition of the cans, and either aid or decrease the detergency action of the can washer detergent. This home sanitation program has been blamed by plant operators for the abnormalities of cleanliness noticed in washed milk cans. A brief survey was made in Plant D, to determine the producers home sanitation program used for milk cans. Only a limited group of producers were contacted, however, it was interesting to note that a majority of these producers were hand washing their cans, either weekly or monthly. A majority of these producers were rinsing the cans just prior to milking. Approximately 50 per cent were rinsing with clear water, and hO per cent were using chlorine solutions. These results, although limited to one plant, gives a trend regarding the method whereby producers are handling their cans on the farm. (1‘) r-i )w .1... .‘Z 04:: (.1: C r\ k» r . one on oo 1 1 ‘ clc 'drcyg I 1"" . 1. u ,- D L»: _§_ (1 7 4" 0117“ ’ . 03. :‘n L :' H‘: «L Lil C. 4- f0 1V...- ctr 7v Potention igure 8. ‘C‘ - L‘ésme ’4. i.) .V 3. . .o ‘r-citlc ,- ic—ti -r~ v1. . ..-... ‘.:| 01 ULUCUALL’. (AcaLu-Lo l CJ rd fi 4 - O -5 130 0 IA \ r! 120 < ) LA " v PM. , AA-L . U.. ‘ I .4-U -95- -z -.. ' N s :L .J.' ... v . abuutlunxti1C~L..L:I‘r.;Lv-'..-T‘. C 1’ “‘9 U... .._' r .' ‘ .T F. - .,. an organic deiu detergent. K I h. o- 1*! 100 C) ‘M.’ (J (J l2 ~96- Summagz and Discussion In this study of can washing, it was apparent from.the observations made, defective can washing resulted partly as a result of the detergent used. It was particularly noticed that cans washed in acid detergents became rusty to a greater extent than when cans were washed in alkaline detergents. Although the detergent used in the can washer plays an important role, this does not mean that the detergent alone plays the only role in securing clean milk cans. The condition of the cans when washed with the non-ionic detergents was similar to those when acid detergents were used. Mechanically controlled feeding of a concentrated detergent solution to the wash tanks was found to be essential to maintain proper detergent strength. I When potentiometric-titrations curves were made on.Mikro-San, an organic acid detergent, a modification of a weak—acid, strong—base curve was found. This modification was noted by a hump at the pH where the manufactuers recommend that the rushing solutions of the mechanical can washer by held. It is thus expected that on this short plateau is the area where most washing solutions are found at the beginning of the washing period. It is apparent that when the basic ions of the hard waters react with the Mikro-San, the solutions follow the pH curve upward, and alkaline solutions are found. It would appear that at a pH of 6.8 to 7.2, several concentrations could exist, and give an identical pH. It would also be logical to assume that at the above pH range, or on this hump, the best detergency results would be received with this organic acid. This modified curve is noticed to a greater extent with the Gluconic acid and not with the Hydroxyacetic acid. ThEBHydroxyacetic acid giving a typical weak- -97.. and, strong-base curve. Thus, the products being formed with the basic ions of the hard waters and the Mikro—San might be Gluconates. -93- PRACTICAL APPLICA,ION OF THL PRECEDING STUDIES TO MLCEANICAL CAN WASHING The proof of actual detergency in can washing is measured only by determining the washing performance that is secured with mechanical can washers on producer-used cans, using specific detergent compounds under carefully operated conditions. Fortunately it was possible to secure cooperation of dairy plant Operators who permitted can washing operation with such detergents as were considered desirable to test. 'These detergents were purchased by the dairy plant operators. Guidance and tests made on cans for the extent of detergency and for bacteria counts, were made by the author. Three can washing operations were given particular attention. For convenience, these are designated by the letters A, D, and F and also refer to these machines in the section of the report that dealt with analysis of the wash solutions. Plant A employed an acid type can washer (Lathrop—Paulson) while Plants D and F both employed alkaline type washers. PROCEDURE Bacteriological Condition The bacterial content of all washed milk cans was determined by the rinse method that was found most satisfactory in the early portion of this study. The rinse media used was 200 milliliters of a sterile buffered 0.01 per cent Triton X-100, nonvionic wetting asent solution. The media was added to cans selected at random after they emerged from the can washer. Next the cans were placed in the shaking apparatus shown in Figures h, S, and 6. The lid was replaced after a sterile parchment paper was placed on the pouring lip. The shaking apparatus was revolved for 30 rotations at a rate of hO r.p.m. At the end of this time, the cans were removed from the shaking app atus and -09- the rinse media poured back into the sterile container. The rinse media was then plated according to Standard Methods (l9h8) procedures on Tryptose Glucose Extract agar, and incubated at 35° — 37° C. for h8 hours. The counts shown in the following tables represent the total count of the cans. The counts were secured by multiplying the colonies that developed on the plate after h8 h urs incubation by the dilution factor and by 200 (milliliters). Physical Cleanliness The physical cleanliness of the milk cans could not be entirely determined through visual examination, thus a more accurate method of determining the soil in the milk cans was needed. In these studies, the procedure of Jensen and Waterson (1950) was followed. The sediment or physical cleanliness of the washed cans was determined by ad ing one quart of sediment-free tap water at a temperature of approximately 1000?. with approximately one—half tablespoonful of a wetting agent-condensed phosphate mixture to the washed milk can. New, clean, cheese cloth squares were then used to hand wash the entire inside surface. By use of a Lansingtamp4Wheeler sediment gun, a sediment disc was secured of the wash water in the cans. The discs thus obtained were graded frOm one to four, according to the standard established by Jensen and Raterson (1950) and as shown by Figure 11. Class ard 2 sediment scores were considered to indicate cans that were in a good state of Cleanliness, while the Class 3 pads were considered to indicate cans that contained excessive f'1ming of milk SOilo Use of a combination of Versene, condensed :hc:*hates and wettin" V .A ‘ Q Q I. I ' 'urr. elk: T‘. Can nail_a m1 ' _‘ / a “ V ‘ ‘ I w l n ‘ 'I"; ‘u ‘1 _, ["n‘ “5 I 7 ":\-‘ I - ‘ . ’t _ciu type can wasting machine \Iat lop-”auiSon) had teen u3.n } J m' 0.3 h ‘I likro-oan lrcm the tire the machin‘ was 1.._:~.C:.,d in operation. This was the :H J. ..‘h 7‘ a ,- _‘,‘ .. p . a], a o._ .__,_H n ‘.. .h H _..‘ _ , A :~.- .- fiist mi-hio, undo! study. .ns the aCid typ- can thhglo ale CuLSLTthed uiLh u H.:- . r . ,.i - . '2 .E, ”ii a . * t - . 4 2. '5- J iv,. 1 an aluminium c; Ling, cote ing LJL rash tank and tuc sides, an ajLfiliffl oa_e: int _ g‘ u‘ .' u -‘ Q V ‘ o h r|fl 3‘1 V1.1“ '- uses: r'.‘ - ”net's 1 .‘ It. or Ii cc- -~:1'w - ~-r+e ‘em sad—Ls Juc -.J y‘) u... .n .4 .LLJa. d LQLAUL...'V bbLh ‘...L‘.- - 1*- Q. yr :31, u.-lb bbk» 9.5!.00 .L;.!'.« detergent selected for this study conzsist-ed of 10 pa; cent Verssn., l; be? w *v'-"' '- " - - r‘ a 4“ -1 H " ‘ ' “ . 1. " F "‘ "- m . h" -‘ 1. fir. '- Cent wetting agent, and 7) per cent Saiium he inn-t—Ihosphu... .his cotoini.i.n n i. . ' . l. - .. .3 . ..1. ,4- w. n, .1 M.-. I . has seen shown in Irc- nous SUUULJS to be a sapczior actcig~yz ;-r threw Cv;.3 v. p --: 1' '\ y‘ a- '- q 'r.‘ . 91’ .-. I J—‘ n -24.. ff“ 1....1-Ix f; —¢b: (TLLJG LE) 0 hit: CVu;~./.¢.. QULv-1 i do a“ £1.32A tap ' n v I H + 'I‘filf Q . a, r" r’ r - ,1 '7 1 w —"v.. .L . . - .\.‘.-= L3 -. Januaiy 9, 19:0 at the race ti 0.; It: -enc, thin; .he suit ocaoihccicn was 4 - a 4. 1. .-L 1 - ,1- “ r" added to the freier tann gv the ra.e el 7.; r. ‘ ~ + _ 1,} _' ' \‘_ "if . n . '. ,_ I‘m,“ ,— -‘ ,. .4 P . ,‘I‘ I: .'. _ ,._ (.4 £ . treated a ch sociam heiamttaptospdate at the rate i 0.- per c.n.. ihe . I ‘0 -’ v“ _: , ~ .- . ..: . te p1 rature of the wish tank was held at 303' - 1650 r., while the steri e (:1 U1 0 I H ‘1’) O O P; rinse tank was held at l The can washer was D}rintlr‘ at the rate of 16 cans per ninute. Na other changes were made in the washin with the exception that a new w;:h tank T;S insta‘led Janu nary PS, lPSO due to a leak that had develooed while the can masher as using the r--oxm~r’ acid bacteriological counts and sediment tests Acre made on the 3011091”; ' m" H h .» V . . . ' r‘ - . P w -'r\ dates, January L, la, and 9;, reLruery ll, haren 1, April 1, and 1L, and Kay 31, Pa H: he results 0 those tests are shown in Table 3o. Phot0“rn~hs of the selimrv . ,‘ ‘ A n ~~ - -v n r. - vr‘ A discs are also -z'n in rigurcs 1?, 13, an; _;. another ,hotOgrth of sediment discs from cans washed in Plant G with the S'ne acid C‘+Lr~9Pt and same t;Ie O ‘1fv1‘vo ..UAe m l- i 2 (\ * ‘3 O ') .J b {n CT (2 *1 (D {O O—rj H E J (+- p.- 0) *1 (I) C) n d '75 The sediment scores of the washed cans before ary ch'nge w:: ends in the detergent are shown in the January L, column of Table 36 and by Figure 12. At this time the sediment scores show T2 per cent of the cans were graded cith.r 3 or b. As the trial period Irogr ess ed, no definite i £ICVLnQnt in the cans was noticed in :hysical cleanliness until February 11. At that time, it was observed that for th -first time a,majvrity of the cans (60 per cent) were graded l or 2. After that time, a majority of the cans were graded l or 2. Sediment discs taken April 1, and April 29, are shown by Figures 12 and 13 Summary of sediment scores and bacteria counts of Plant A. Table 36. Sediment :1. 3 May Apr. 29 AT Aggr. ll 1 Mar. Feb. 11 : Jan.gg§_: Jan. 14. 4. : : Jan. : No. :,$ No. x % 8 No. :J—z Classification of cans as to sediment scores a No.:: i :No. :fi: N94313No.: % .0000. Scores : % 20 32 5. a O. 50 z 10 29 6 47 z 10 50 3 8 ll 55. x 9 30 6 6.: 2. -1oi—* 33 55 10 16 4 27 48 13 3. l9 4. Bacteria to bacteria counts Classification of cans as A— vi No. %> L N00 1% 85 15 0. LAND. N 2 3 i% O ‘ .% : NO. i g N00 .% 40 1 N09 .% : No. Counts O—lOT -‘O::DOO O. O. lOT-ZOT 25 15 10 2OT-40T 2 47 7 over ACT .1 'i ~102— Hes ectively A definite imIrovemcnt in the bacterial content of the cans was not iced after the "lQ—l 5-75" detergent combination was started. It was noticed that on January 1h, L7 per cent of the cans contained over h0,000 organisms per can and 53 per cent contained less than L0, 000 organisms per can. After January 1h, a large majority of the cans contained less than £0,000 organisms per can. It was also observed that on February ll, Karch ll, AIril 29,and Kay 1, no cans were found to contain over h0,000 organisms per can. Besides these two tests, visual examinations of the cans show a marked imIrovcment of the cans. The outsides were b ighter than at the st T't of the tests. The inside of the cans and covers did not contain a "greasy" film and only a few contained milkstone. On March 2, 1950, the a dditicn of the 0. 0? Iar cent sodium iex n:ta~ phosIhate was omitted from the sterile rinse tank as a precipitate of calcium polyphosIhate was forming on the walls of the sterile rinse tank. This was presumably due to the high temperature used in the sterile rinse tank. It was also assumed that some of the "l -lS—7S" detergent coabination would be carried over by the cans from the wash tank to give threshold treatment. On April 1, 1950, it was recommended that a cotton filter cloth be placed on the air-intake of the can washer. From the Con-'tions of the receiving room, it aIIeared. that some of the sediment might be due to this source as suggested by Roadhouse (l9h8). This filter was changed every three days for the duration of the study. The condition of this filter cloth after a three day 0; erotion is shown by Figure 15. In An Alkaline Washer Two alkaline can washers (Rice and Adams) were used, one of which (Plant D) was using an alternate cleaning method us irzg alkaline,acid washing solutions every second day. The other washer (Plant F) had been using Nu-Foam for a proximately a six months It riod rior to the change to the "10—15-7 5" r P -103.- detergent combination. The washer in Plant D was changed to the "10—15—75" combination March 30, 1950 and was used until May 8, 1950. At that time, due to running out of the test detergent, Dreadnaught can washing detergent was used until May 26, 1950, when again the "10—15-75" detergent combination was used. This resulted in a delay in establishing data on detergency results and less results are available for study than were presented.with the acid type can washing machine. The "10—15-75" detergent combination was added at the rate of 0.3 per cent to both washers. At Plant D a 22.5 per cent solution was prepared for the feeder system, while in Plant F, a 7.5 Ier cent sclution was used. The feeder system concentration of Plant D was not used according to the directions that were given, but was the washing procedure that the plant operator desired. No other changes in the operation of the can washer were made during the duration of the study. Both can washers were using a t nperature of lh5° F. in the wash tank, and 1600 F. for thesterile rinse solution. I The results of Table 37 show the sediment scores and bacteria counts of washed cans from Plant D. Photogrths of the sediment discs secured March 16, April 22, and June 27, are shown in Figures 16, 1?, and 18 respectively. On March 16, only 15 per cent of the cans were graded and 55 per cent were graded h. March 29, results show that 30 per cent of the cans were in the l or 2 grades, while 70 per cent were 3 or h. After approximately a months operation with the "10-15—75” detergent combination, b5 per cent of the cans were graded 1 or 2 and 35 days later on June 27, again LS per cent were graded as l or 2. As marked, an increase in physical cleanliness was not noticed as occurred with the use of the acid ter can washer, however, the bacterial contents show a great improvement over these secured at the start of the tests when the Dreadnaught detergent was used. Before the start of the trial, March 16, and March 29, from 15 to 20 per cent of the cans contained 4 u , a n ma m u I- - “ mm m . om e i you Hope u n u n m H “ mm m u OH N « mm b u Boqtaom 0H N u oe m n mm m u as m “ eo~:eoa “ u a “ Ob «a . mm b u 04 w a on o “ aoano » . u u “ wlq. .oz 1m . 4. 3:500 .3980 mangoes. op mm memo no, nowpwoawmmwwmo « » «Hugowm u n u u “ mm m “ ow v u ON a . mm Ha “ .q n u a “ om o " mm b u on 0H u on o u .m u u a u _ mm b “ ow m " om q a in I u .N W ; n n a u . OH N u m .n . OH N a 3” m n ..n u u u u wu.ozu Rudz « oz” «.ozu .mohoom pcmfivom op ms undo mo dogwoamammflno u . « monoow hm mash; mm 334 u on ..SE « 0H awe: u u w a « puma—6mm condemn non: 3de u a .9 959m mo 3560 33903, use 3.33 passage mo buggm .bm 0.53. -105- over L0,000 organisms per can. At the first test, no cans were found to be over L0,000 per can and the last test, June 27, only 15 per cent of the cans contained over h0,000 organisms per can. As the decrease in per cent cans containing over h0,000 was noticed, accordingly, an increase in the per cent cans containing less than h0,000 organisms per can was observed. The results of Table 38 show the sediment scores of washed cans from Plant F. Photographs of the sediment discs secured April 2L, and June 13, are shown by Figures 19 and 20 reSpectively. In this study, no bacterial contents of the washed cans were made, because no counts were taken before the change in the detergent was made. However, improvement in the physical cleanliness of the washed cans is shown by the sediment discs. The sediment scores presented in Table 38 from April 18, 19, 2h, and 25, and of May 10, are of the washed cans when Nu—Foam was being used. Only one test was made after the "10-15—75" detergent combination had been in use. The cans from Plant F, were in the poorest condition of cleanliness of all plants studied. This is shown by the fact that 50, 78, 68, 77, and 92 per cent of the washed cans tested were graded h. In these studies, when NuFoam was used, the highest percentage of l or 2g;ade cans was found to be lb per cent. After approximately one month's use of the "10—15-75" detergent combination in the wash solution, 2h per cent of the cans were graded l or 2. However, 57 per cent were graded h. This shows that an improvement in the Ihysical cleanliness of the cans was being made and that a greater length of time was needed to completely free the films contained by these cans. Use of a Wetting Agent in Combination with Calgonite A rotary Rice and Adans can washer which had been using Calgonite for a period of approximately three years was used in Plant E. A washing temperature of 11:00 F. was used in the wash tank. The machine was operated at a rate of 6 cans per minute, washing approximately h50 cans per day. On February 7, 1950, 06- " u u a u “ hm NH u No NH u vb bH u we mH a mu wH u 0m HH " .q u u n u n u 0H q “ II I " mH q " mH q « mm m . mm m u .m 0H q u w H u n H u o N . II I u a N n .N u w u n u u m H a II I « II I u m H u II I u m H u .H u s u u u u a u .02 u m « .02 a m,” .02 » fl,» .02 u &.« .02 u m u .02 " mohoom pcoaHeom ow mm memo mo cOproHMHmmmHo " « mohoom MH mash « 0H .Ndz « mm .HM4 u «N .un« u mH .hn< « me.HQ¢ u omaHsnxo non: woven u pamaHvom .m panm mo mmhoom pcmaHbom mo hymeazm .wm oHan ..107- an addition of 0.025 per cent wetting agent (Nacconol) was added to the wash tank, along with 3 bounds of Calgonite. No other changes were made in the washing procedure. Ser'ment scores were made of the wasted cans January 19, and 21, February 7, and Earch 11, 1950. A photograph of these discs are also shown in Figure 21. The results of this study is shown by Table 39. The data from Table 39 show that before the addition of the wetting agent to the Calgonite, the majority of the cans were graded 3 or b, (January 19, and January 21); however, on February 7, the majority were graded l or 2, and 38 per cent were graded 3 or L. A partial eXplanation of this seemly improvement is given by the fact that during the month of January and February, the detergent strength was maintained at a uniform level. Approxima ely one after the Nacccnol was added, Farch 11, 80 per cent of the cans were graded 1 or 2, and only 20 per cent were graded h. ~108- .Umdflaqwunw flwg mewQ OH N « 0H ..V » Mm. 0 u mm a». u 1N OH N u OH ..N u Oh me u N..\ m u .M mm a. u we 3 u S m » mm m u .m u u u u ,. WV 0 u 0 N n I... I. u all I u oH u u . u n J u .02 n W «00.2 «I1 m M .02 n “l” .02 u monoom pamanom op mm memo mo :OproHMHmmeo u monoow u HJHH dlhwz u M. QQOFR u HN oflmh 1.? “H 1.55 n Pflmaflmvmm u .m pdde mo monoom pcmanmm mo hhmsanm .mm odeB . ~109- Summary and Discussion The results of tnese can washing can be eXpected in can clezziliness when are used. Such mata ials as were found ..J r.- J) ang.. :inilar :ashing resa- The combination of 10 per cert wetting agent, 75 per cent sodium hexametafl two alkaline mechanical can washers has results washing tests to give excellent of the organic chelating agent, be desirable for the ren-o val of all tyg Versene also has some additional being stable to 1900 F. te ,er fihate used as the djte Versene, and condensed phOSp to ..S' (’5 studies show that high improvement pre-erly effective in laboragcry w :hing with mefharILJl can washi n'. been shown previously in on three raw milk films. A co of {-9, advent 5+ 5." gent in one acid and seened to ilms pres ent in producer cans the labora, age in use for can washing by atare, therefoie, it can be use d to advantage over condensed Ishoso hate in the final rinse. In thi manner, lixzing of and can washer piping would be avoided. It has been observed at times, when the detergent is changed in any mechanical can washer that the film that is present weeks operation. Thus, this as one which had excellent detergency this old film is removed, combination 'as used in other over a pcriod of time. the films were being renoved, It was noted in these studies that of a milk film which appeared on the yellow film. the sanitation program of these producers excessive amount of chlorin ne for new detergent would be another is formed. C (3.113 This film could be found on Thus, be for ethe "lC—lS- 75" can washers, the results of Plant A Watre st with no new film being formed. $01118 C831" and on the discs as a sediment all cans of the sm me producer. were checked, all were using an rinsing the milk cans pr‘.or to milking. classed by the Operator action. However, immediately after It was observed in Plant A and the other plants that {I This selected detergents materials udi itinaticn is removed in two to four F. contained a heavy coating hen I'3 “-‘J type of film did not appear on producers cans where chlorine vas not used as a rinse prior to milking. It was thus assumed that this film was a chlorine- protein complex similar in nature to that used in previous washi-g scadies. This was substantiated by the milk plan ficldman and by haulers of milk, who investigated the producer methods. In gro in tances,whe1e direct chc wok» was made following testing the cans and heavy discs were secured, the prod acer- prepared rinse solution was found to contain above 500 p.p.m. chlorine. It may be of interest to note that none of the producers cans coming into a plant handling only manufacturing milk, contained this film, whereas it could be found at any time in the plants handling flui milk. These observations show ag ain the importance of using a detergent in the wash tank of mecharical can w: ashers that will be effective in removing all types of milk films that may bef ound in producers cans. It appears that the "lO—lS—7S" dete gent combination consists of materials that together will remove most types of films fcind in produc ers cans. At the same ti me , there seems to be no reason whys ns washed with this combination should have excessive high bacterial contents. lll CONCLUSIONS The effectiveness of the removal of bacteria from milk cans by the rinse method defends largely on the nature and the amount of the rinse medium used. Nutrient broth gave the highest removal of organisms, while tap water, distilled, and buffered distilled all gave agproximately the same removal. A bugfered non—ionic wetting agent, Triton X~lOO, gave high removal of organisms, corres;onding to nutrient broth. When the largest volume of each media was used, the highest percentage of organisms was removed. Lower numbers of bacteria per can were removed with 100 ml. than with 500 or 1000 ml. A mechanical rinsing a;paratus was devised that Was studied in congarison With a mechanical machine devised by Eilone (l9h8). This devised agparatus gave higher and equally comparable counts on the various media to that secured by the Kilone machine. It had the advantage of being simple and dismountahle for tran porting by automobile. Commercial detergents marketed for can washing varied considerably in detergency qualities. When the commercial detergents were used to wash three different raw milk films; namely, air-dried, heat treated, and chlorine treated, a wide variance was noted between the cleaning quality of those detergents. The heat treated and chlorine treated films were extremely difficult to remove. Only two commercial prepared detergents, Sequet and Flo—tron removed all three films effectively. When the detergent qualities of laboratory prepared detergents consisting of a combination of the condensed thosthates, chelating agent, and wetting agent, were studied on these three raw milk films, varied results were also obtained. When tri-sodium phosPhate, sodium metasilicate, sodium hydroxide, sodium bicarbonate, sodium.carbcnate, sodium chloride, and tetra sodium pyrosthOSEhate -112- ’ were used to supplement or replace the basic combination of condensed phosphate- chelating agent-wetting agent detergent, a reduction in detergency resulted. The greatest reduction was found when LO per cent of the detergent solution consisted of these alkaline components. Combinations of "ZO-hO—LO", "IO-hS—LS", wetting agent, Versene, and condensed phOSEhates gave excellent detergency results on all three films. The organic chelating agent, Versene, was observed to have advantages over those of the sequestering agents in tying up water hardness salts. It was stable at high temperatures, effective over a wide pH range, and did not precipitate hard water salts at any of the concentrations used. Versene increased detergency when combined with condensed phOSphates and wetting agents. A study of the chlorine-protein filming revealed that chlorine solutions react with the lecithoprotein and/or the whey protein of milk to form a denatured film that is extremely hard to remove by ordinary detergents. This film was observed on producer cans where eicessive amounts of chlorine wewzused.for a rinse of the cans prior to milking. Under simulated washing tests, it 'as shown that soft water or softened water was highly advantageous with commercial detergents for use in the wash tank of mechanical can washers. There was no significant difference between the results obtained when Zeolite, distilled, and Versene or sodium hexameta— phosyhate treated water was used for washing milk films with commercial detergents. A wetting agent, as a supplement to one commercial can washing detergent, was found to improve can washing. When a detergent without a surface active agent was used for can washing, films were present on the can washer and on the cans. This condition was corrected in a month’s time by the addition of a wetting agent. When an organic acid detergent was used for mechanical can washing, an alkaline pH was found. The pH recommended by the manufacturer for the washing ~113- sclution ras extremely difficult to maintain. It was shown that this phenomenon was likely due to the gluconic acid that was present in the acid deterg nt. This resulted in a modified weak-acid, strong-base curve upon a potentiometric- titration. It was progosed that the basic ions of the waters reacted with the acid to form gluconates. Under practical application, it was observed that commercial deter;ents do not Contain the proper detergent qualities to remove all the films found in producer's cans. However, when a combination of a chelating agent, sequestering agent, and wetting agent were used in these same can washers, superior detergency resulted. It was evident that cans in poor physical cleanliness could be cleaned by the mechanical can wasner without using hand methods by use of this detergent. On the whole good detergency as measured by clean milk cans and low bacteria counts was secured w th deter ent I" 0 compounds that were low in alkalinity and that were shown by laboratory washing measurements to produce high detergency. (l) (2) I“ W ‘J (6) (7) -lL¢— JT; P1ATU.EC ITLD Abele, C.A. 1943. Can washer operation and maintenance. 27th Ld. bonf., Dairy Plant Opesetors, Univ. Of Vermont, Bnrlinyton, pp. 41—44; Canad. Dairy and Ice CTBET J;u1., 2:“) 99—34, 93, 1949. American Punlic Health Association I‘ f “ - ‘r‘ i -..' ‘- ‘ - r: I - n v a —' T- ' rd ' '\ 1 1934. standard yetrcas of Lllk AH1]‘th. tth cd., 0; pL. plus “ —".- M - hlll. Pew :o k: anew. Pub. health assoc. American Public Tealth Association 1939. Stancard aet‘ois For the Efraination of hairy Products. 7th hd., 190 to. plus xi. how Bork: Axer. Puo. health assoc. American Piblic h ation 21D ‘93 H H-d- ’ {3‘ 3» HUI U) 00. 1941. Standard Le.ho; 0‘.r the Eya~inaticn of Dairy Products. 9th .-,. 9 "’5 . ,i 1.. °. 1 . . “.3- *-,..,1L' .-,.. ..‘Ju. , ._ nu pp. 3;)..an xvi. 2:98? .;.<.‘T‘1{o nHLUFo I'M). ILGULLJII :ioSOC. 1 American Public Health Association 1943. Sta’.ard etEc;s for the 37_vjnation of hairy Products. 9th 73 pp. plus xxi. New Yora: Amer. Pub. health assoc. Anson, 1.L., Ackley, 3.1., Eisc her, E.K., Gans, 3.1., Hassialis, f.h., Hotchkiss, h.B., Price, b., Vals+3n A.u., Shedlovshy, L., and Valko, 3.1. 1940. Surface active agents. Annals N. Y. Acad. Sci., 45: 347—530. Avers, 3.P., and Image, 0.3. 1921. Po air sterilization of utensils. Jour. hairy Sci., 4: 79—30. IZarlmorth, H. 194‘. Testing the sterilitr cf settles. hairy Inaus., c(2): 35-17. {‘4 qeechem, ILA. 1944. Cleaning with acid cleaners. Ell. Eersworth Che ical Company e m dern chelating agent, Virsene. Persworth Chemical ' - r (K . ~v“ I ‘1 (a ' T 7“ ' ~ borpany, Framingzdfi, $935., Tecu. ,ull. l. 2439. Poqaerts, P.J. 1943. Can washinn in creameries and mils nahuiacturin; plants. Canad. La Pinya no Ice Cream Jour., 27(3): 74, 7c, 78. T‘zr'yant, L.R.. 1946. Fbscrvations of mils can wa sh: 3 Id methoe. Canad. Dairy and Ice Cream Jour., 25(3):b 30-32, o5. I '\ 1.4 U0 V (16) (17) (2O) (21) (22) (23) (24) (2 ) \I‘. -ll§:_ T“ Buehrer, T.F., an: Pe1temeier, r.:. 1943. The infieitin" action (2f minute amounts of terat.tajro state on the precioitatmon o: calC1 m carbon ate from a maniacal solutions. T7. Jowr. Phys. whom., 44} 552—574. Carkbuff, F.P. 1948. Can washer, aes rm construction and coération. Ann. Rpt. N. Y. Assoc. 1115 " t 9 Chamberlayne, 3.0. 1943. The Jamieson kit, its construction and use. dour. niLk and P‘coa Techn11., 11: 301- 210 Clarin, D.X. 194?. .ashi1g and coca tioning milk cans in her; water areas. An“. Rpt. K. Y. Assoc. 1112< Sa::?t., 21: 79—55. Clayuon, T.J. 1948. Extran2cus matter in e pty shippin; cans in cream stations. Katl. utter and Cheese Joor., 39(7): 34, 35, o4, oo. Clayoon, T.J. 1950. Personal 00 rre socr'gence, flarch 7. Coulter, S.T. 19A2. Proper mibtures for the can washer axe types of sequestering agents. Amer. Putter Bev., 4(7): 111—119. Davis, J.G., Ward, S.J., and Tddoiard, P.D. 1944. .A detergent strength meter with automatic oosaje control. Froc. Soc. A r1. act. 1.1.3.3. pacer 821. Die 11, TL, 8611 1.33311, C.C. 1949. The )anarzelba"h titration for total Larax. Chexn ical CC11an),iox 507,9 n1es, Towa. (d 0') I1 0 "T O V Eaton, J.T. 1944. Surface active agents-what they are and how they NUTL. Rayon Texile Monthly, 12: 395-;94. En land, C.w. 1947. Inconsistencies in testing an? reporti_n3 the strength of alkaline cete :ge.ts solJtions. -i Fla nt Lonthly, jo(7): 1 85-90; ‘11{ Deale , 3;(9): 49-50, 51, E‘abt-en, F'.‘.j,". 1949;. Strame favil‘ies in the bacterial wcrld. I—LLer. I 11!: Reva, Ea all, AO-I. Q9—a. The continuous can washer for oa1j‘y plants. talif. Afri. Exo. Sta. Bul. 400. 31 pp. r’\ R) (' L) V r\ \U <30 ~116— 11e ac: A: 5.. Farrall, 1" (“‘1 1y2s-9. T-“ ,q , f ._ r - s ' .I,'Cl.'-.‘ 37 rfqfl‘ __ l ‘.1.10 l r. o adlr‘] _ 1 o ’ I ‘. 21-er l‘[., ;l . . . r‘~ . - 1'fi.,1.°‘ ,1 . .. A. -, r _. . - ‘ 1 1;42. Ja1ry 211reJr1n . 4‘fi3fihp 5113 AV. 4 1 rs: oath : '1 . r r: . 4-1.33 c111 sons. . 2. . .3 LC'LI: ', I 0.: O o n. ,, 11 ,1 . . l 4' , - . .-.. - .- n- 191-. Lati‘ha.h 8‘s. 2 '15 :31. .;I?1., Jd]J'\ Plfiwlt \ 3e citC b, Ice rJ‘rEa‘q (3.1.27.4:‘3 ’ 118". “If"? €1.00. 0 fl J. L]_L ..Jt), L. ‘1" . - ' , --r- _~. 1 .. 7‘. c a; T : ~ ' w ‘-- . 1942. ’34 “ ”7t" 1r“( '1: 'J 1 ‘ '.|“.."‘.. I; 7 o :11“ [-1 1. ~19 ”t. “‘9-"- 1 fl -" 1 ' 1...) "5L 9 10C., 2 ): L “14-34'J. v.- d - '. ~_ .4.-- 1:? - r f l.Il.LL‘“/, .11)., ’ L11.) 1CbC1", 0U. "‘ "7 “.3... 2. ,- a '. 5‘- .. ' ‘5 -£. - .~- ~.- .’ ,-. ' ~ 194;. a; set 1‘ a s a; *}e corrcslor o. t1n :310 9 15 as“ Wa»h1n . ' ' , “ . 711 1- - " -' a"; 0.. 1“ 14" 'J\.'Viy‘. ,1 r ’y\f l‘)(\‘- AC fi( ‘1‘.’ IL): JVJ‘CIJ , 171]“. Fj.: Lo, 0L. 1 1 ’0 (3‘ O \o ..J H A (\J V o. \J) ‘ 1 - r ' a l.‘ . v V 7‘. Pete? .... a_x. L1nle: -J-a. 9 J u ) r3317 . .; - p 1, .- \ er - .r‘ ' -- ; h... -.. 14., ‘1 1~».. a 5+1nf cl tre gar" c11c1 ,111C1eno, «1 Ca” 115.1; 1t-cu nos. 2. 7 .-. ‘ . “'7 1. x ‘ , I Tczr. 1‘15 and Iced :r31noL., 13: 2,7-2u2. _‘ 77' T r« , ,1“ r-~v:f\ m 71 F011to , _ I. J. ’ (3.1;) L r€’~‘.'.C-TL, '- C .. f "I '7 A V: v o ‘ .'. 0 1:. I _‘ -— '_ 1:1 . n aet1ce to axe La ate? -: r . v- ? “ ‘\ V. - k‘ attereent.. CUJTO 4313? N F: 1"!“ 1 ”(T "i "‘ t“ V" ' T- ."lql 13‘. :3, .. o-ao, c‘I‘T). 'fi'irlen’ LToJo 19410 E11111 ‘3 V8 1'13 12111:: 3913.9 {‘71 9111.8 . 313 lfl3—1EO. f1“. Imp-(‘9 T: 1," ....' ”.s. J u. C 1937. Preveot1on of calcilm fie 1"1 —' "I . ’7‘ (“‘f‘ go In. Lnem., 9°. C 4-;flu. O P3111. \ ‘1 m. .- I)” r"’\ 1&33. .rces. 1-1: 2.; 7o°tehiie“ 2 - 9'1 1 Iaochato“? studies of met? A (..- . .1.) J. 4c. tte ef“:tiv=orss of‘ia17fir ' ’2" ’ A 1,. J}: '31-\.3. , “ 'Ar cleaning of eating utensils Aver. Jonr. Public Eealtt, 1n DTOC'SJGJ waters. Tnaus. ENC. ‘4. V r 1 '5 f v~ ,-‘,—- 5:, 1 ~t ,- .J- " 1,. “C1 1.1-, "0' ‘0 , Lu .1 .."x, 3‘1 '9.” 1.. , J 0 ’V “ ‘J ._F ..1 1‘ .. .".-, _ a- '_, \ ' "-‘.,.—,—- ' . 1S57. :TY1 a ‘ V .We 0' cOdluI r ta31oso at- in 31s: a1t1n . .1 1 -\:‘ " '. ‘ .I‘ ‘7 1“ ,‘ ' q A ,4 Trlullvo ..l‘..._ ill. wfl‘. 3H. 2g: [’21_l'?L1.‘10 (40) (41) (42) (43) —117- T' ~' ". w~ Hardinc H.A., Prucha, ..J., Jester, ;. ., and Qtamce“s, H.;u 1‘2L. Effect of Shea-min“ mean the germ l??e 1'n Jil. cans. JQJr. Dairy Sc ci., 5: 232—990. \ leviinz, P.G., and Trebler, F.A. 1947. DBtQTXBHtS for caiTY Clerks aha methoqs cf tLe’r evalvaticn. Feed Technol. 1: 470-493. Neinemann, H.W. 1?fl7. *"Jemati7CW‘EMui inspectixrlcxf can W98}Efl\i. j]; ;;ea1eP, , 1 1‘ o r -~ 7 (ll): lfiw-lflu. Hil*er, EL li49. Chelating afents. Drug and Losmetic Indus., 94(1): 40—41. , J.A., Frank, L.C., Irwin, R.E., Tisgale, 5.3., and r, ?.A. . 70t air ster1l zaLion C 1 . ..~ .=w health Assoc. Yearbook, 193t—1937, hp. 150-159. re 1941. T*at cleafiiwg chore. .ilk sealer, 30(7): 33-31, 7F-73- s, E.L., ahd Terns+ein, P. 174?. Vaccine 9*sbmes‘1n‘ cenQOWnUs. Incws. ;u:in. Ufiefl., 37:173-173. H1nziker, U.F. 194C. Cone? ensea fill? a»: Til“ Pewcer. St? E}.., 500 p0. plus xv. La Grange, ILl.: by author. ell, F.§., {rd Jrugh, H.L. 1933. P 199 arathVS 9rd rrcc'rties of aldonic 5.0 iris a'd their la ctones and basic Cale mm salts. ?. 3. etl. Bur. Standards, Jour. Res., 1: c49-cé4. Jacobsen, D.E. 1946. Labor saving methods and waterjals ‘or hafivy plapt cleanin;. 'ilk Plant ionthly, 35(11): 24-27, 30. actors influencin the sanitation of gairy 0309. Games. Lairy and Ice Gleam Jonr., 22(1): 21-25. Jamiescn, T.C., and bhan, T.I. 1942. A stuJy of new oetergevt: and steciljzifig afents. Caaac. Dairy anc Ice Cream Jour., 21(11): 29-31. Jall‘iGS OH, 3.77.. C‘ o , all“. knnld. 7’1 , 7 o ::o 1943. 'Fhe effectiveness of some new sarltlzlr" ajents. Canad. fiairv and Ice Cree? Jo r., 22(C): 23-31, 93. ‘JI ‘ J /A\ r‘\ \er ‘u/ I“ kn (J\ \n 4 —q \J ‘J‘t \J ‘0 \)1 O\ /\ 12.“:‘5V3fl, 0:0, '2. ll « i‘vl‘ékn.’ -_.:“:o 1944. Srpvlefionta“y be“? saniuation c‘ fiilt sPip~th sans. Canad. Fairv afld 7C9 C“F°fi ,'“r., 23(“): 55—53. Jamisson, T.C., Chem, P.K., aJd ”llLijep, 9.5. 1949. basin" is 57159Viflf in sdfi7+°"v fortrul. sata;. sm;ry arfl Ice OvelL JU‘T., 27(7)‘ 9?-;5. Patisson, T.C., an; .0 Leod, H.Q. 10d“. Cleaner .! “y ekuiu"0“t ~733Q. pairy an; 103 brpsn ;ewseh, J. . “ ‘ "r - . r ' . ' . .- h A .‘ . . .' ,1-.. M .. A. ..L‘. .‘ .. 1944. :avw uawrv utensils Na.P€d sf ect1.:L: ww n»fi '%~““1%. w - ~ n .. - 11., , 1.4.. "' . . ';~ -* ‘ ' rs" r" ’3 - :1 C". 3‘._ Ifij o -.2-1 Nho 4‘ 'ua 0 (Bart. ll. 3 L33 (1+ ): 2 ( /"';_).L.2 o LTCnSG'l, Jojo Q1 1‘) O C - C“ ( 153/ r“ D'l .qy“..l. _,.- ,—~‘-;— ...~. A ~ ’31. 4.‘1'-~‘f\L-., "V‘C '— rq ‘ f“; “\ . 'h'o .. .4'» S .L. 1;» \l'; ‘11:. L .k; v . L114. '. z.‘1 ~, -3 J. 4.. I J ’ ' . r “L' . : vv \ —= :- . Lfi‘tr‘T‘\ G 7 ,9 a a ')“C‘PGI1.J_"P:> a EU .I. L; _ L’ f 1 ,L 1, 'JJ E. 311498. 10“ (if '3 war ‘1, ' r“ .(‘11 ""2 ' ' V. j.“ ‘ \HW "'i‘] 2 7r\ (I 1' 1. - 1%.. r, “CL; :1- ; 4 ' nah: '1 ‘1 ..«u ) .‘.L_L J J. U l . ‘ d n \. I-., ’1 - 1 -, A .6. 3 .I _;-4»_). ’ -. 1 7 n .—4. A - - 1 UG“!Q'2, {O 0. 51-11“ cr‘ :‘SL,’ , 'v. “T‘HN '\ , ‘ ;‘ ._ _‘ .|‘.‘ ‘ _ '1_~ __ 1 o ‘H CH . SM 0 -'— “”0117” 7' OF *‘3‘ ’7 "' TN 9 Cl" afl-Llll-’-LSS 07 Li”. C7 ”R. ‘ ~o ., . - r1 7 ’... 4‘“ r “h gour. ;4_27.2001 tDCLWNJL., 13: ('£-}u<3cess) Jansnn. J.J., and holarg, Q.T. 1940. Stu v of lairy clashinj profilems. I. E on Pot m5lf 903* meat. IT. Effectiven o. of a1 alias ° .2 .« .- P .-.L A -.r '. . =. 1‘. in rnrovmna best flew‘blueu .LlA SblLJS Gus ugfte“;dt ~ I -- Illms. Jour. Lalr\ ;ci., 2”: 457—439. 1935. The use of sodium sulfite as an &QditiOH t aLkaline - -- -~ 3.. ,: ,. 'x . ardento .or tLJno- varc. DOC. V Ieerwakors, J.§. )- PQTSCUZE correg—‘Pth encc , Jay 1L. LePfikvll. A.E. 1944. Ccliforn hact?-ia in Dasfiewrized w . * '. ' ' ' n '3 ‘x' r" ' -x. - — v f .-- -- - n . ... '. .. V. T' ' ' UDLQL an 3.4; -ete.,o‘t “or can «asLln . Afin. nut. .. Y. J. _ -. o ‘1 1 2‘ .-~ ‘ _o 1 f‘. 1 [“I Assoc. v1.& quLto, 13: 147-L3u. T " a " fiflf‘L‘ga, ‘. 0:0 . __ fl _, ' ' n ‘ . -. -. r ‘ . —. r, . - " 0— 19A). 30(51)an '1 (iota n 120191} 11“ _ ‘Hdtel' “ OT‘ 9.5!? .I T! Lvolf‘ftr .:ld"tS o .fifi I " . - f w T f" r _ f‘ \‘ '>.' ._ '3 -~ ’- .1111“ in'Tfi;*§ mecfliines. Jm r. ua_Ufi; bcij, Q1— ;27 Rae bJU O ‘A- ' ," v '1 7‘)‘ w I}, p ' I“. .1 ,enU, u.L., aUU UUCU1oit, J.L. 1 C45. Sequestration 0' calciur and ma nesiUm in the presence of alkaline detergents. U. S. PUD. Baalth Serv. Hpts., 01: 530—545. Kenn, E.H., and Ruchhoft .C. ‘ / 'I - ' ~'- ~‘ - *0" . 1 r‘ . " '1 IV ' 1“," r " 1943. A p.rior:dUCa t t for Latin; aisl.¢s11U deterieUts. ’ ” l ber V. ilptSo ’ C : 377-3370 a 1943. Amino a -1iLf e ants. Proc. Toiljt Coous Assoc., ’2 do fry, R.J., emu Jorttin ton, L 1930. Corrosion QeUi. non of leta ls aUd A1 lovs. 429 pp. Pew York: Reinhold Bub. ~o. PD. 221— 229. - MC Ienzie, D.A., Lorrison, 1., ari I¢r1beit, J. 1940. Further studies of ther novuric beCteiia in milk. Proc. Soc. Applied fiact., 1: 37—39. :EiliK‘b, I’oaio A. . _ _ o I. ~. g » ~ - ‘ .' _ : A’ r‘ o 1 194 . AU Qvalietion cf tlge 11188 Lost for pafi TWLHLH; Stcrtlltj cf - - 5 , . - . . "\ Uéik Cine. Ann. , pt. .. Y. assoc. ;1lk :an1t., 22: lfij—lfll. Uilone, N.A., and TieiCma., U.D. 1949. Fifect of tre COUlitiou 0: ‘he Uiik can on the microbial content of pre—pastenrized milk. J0 r. Lilk icoa Technul., 12z‘332—347, 369 Ifnistr; of Agriculture and Lish9“i€S, Inndon. 1949. Examination of was C milk churns. Iin. A_ri. and Fish., London, England. 30 n No. C. 204/TPY. 3 pp. 5 c. 'lT‘OI‘, L. H. 1947. Developments in cleaning coprLnas for the dairy inaustry. Iilk Dealer,3 1(9): 49—53, 52, 54, 50. <77) (79) ea) (31) (82) (~93) -l2 0- Yoore, 6.1. 1945. P- 1r3estions on cleanfn" an: sterilizing. Cleese Jolr., 32(2): 17, l“, 20. - t P: h 1- 1‘ 7 '-1 W ' :3 p1eller, H.b., “ernett, 1., u lle , 1.5. 1945. Iact er‘ci: al oroocrties of acne SUrFace active agents. Jour. Dairy Sci., 29: 791-709. Neave, F.K. 1943. yilk cans bacteriolo71cally satisfactory 28 hours after 'was in;. Proc. Soc. A;ri. ~act., (Abst.) N. I. R.D. paper. Norris, F.I., and Ruchhoft, C. C. 194,. Some improvements in tre performance test for rating dis ash aetergents. U. 3. Pub. health Serv. hpts., 03:17-7109. Ferris, 7.1., and R1CLLoft, C.C. 1949. 1valuatL0n of JCI“”fPY s, cozrela flcn of wasking per1ormance wits cissolvinf and netting ability. Amer. CLeU. Soc., (Rast.), 116: 73, 10. Olson, H.C., anc Hammer, 5.“. 1933. The agar disc method *or Stwulnfi tLe contamination from metal surfaces. Ia. A ri. prt. Sta. Bul., 593. 4 PP° j ‘.- 1’“ Aer, ..m. 1940. fiben is cleaned equOUeUt reallv clean? 3001 Inaus., 12(10): 39—42. Parker, 1.3. 1942. Corrosion tests on acid cleaners used in dairy sanitation. Jour. TJilk Icchnol., 5(1): 37—40. Parker, V .E. 1943. ilesto1m es in uairy deter-ency. Proc. Amer. outter lr stit., 3?: 128-147. Pa CrLker’ b-0160 1943. anual of dairy deterients aUU cleaninge1 act1ces. Food Indus., l§(7): 73-803 li(8): 71-72, 131; lé(9)3 00-07. Parker, :-:OL_.0, and. S: :a: Y”UTILCfl, 0. 11‘. 1941. The role of acid cleaning afients in aairy meter ency. amen. Eutter Lev., 2(6): 205, 209, 210, 212. Pendleton, H.L. 1946. The us and abuse of wetting a ;e1ts as aopl: d to tie cleaninr of milLiU; machines. _ilr Plant :CUtLlV, 39(12): 30-32, 70, 72 __ (93) (94) (95) A VI) 1) V -121— / Phillips, A.fl., hack, L.J., and Frandsen, J.j. 1928. washing powders for aairy use. gass. A “i. 419. Sta. Tech. Bu1., 15. 9 o,. Finer, P.E. 1948’ H0" scale ?TeV€ntjon cuts bottle washiflfi cost. Food InuuS-, 19: 1024-1025, 1158, 11§9. Provan, A.L., and Treble, A.E. 1941. C1urn Cleaning and sterilization. Lair? Inans., 5(1): 3~7. Prucha, ”.J., and Harding, E.A. 1920. Elimination of gerws from dairy utensi1s. 111. Agri. Eyp. Sta. Frl. 233. 29no. Prucra, I.;‘., Neeter, H.L., and Chambers, u.s. 1919. Germ consent of rilk. Ill. Airi. pr. Sta. kul. 204. 40 pp. Qrim y, O.T. 1947. The chemistry 1f so 11o :rospnates. bhem. hev., 4d: 141-179. Razee, A.H. 1943. How pvlvprospbates ixprove can washing. 27gb . Dairy Plan' Operators, Univ. of Verront, flurlingt a A on . 4 ’ pg. 45-52; Canad. Dairy and Ice ”r av cour., 2§(.): 80-90, 1949. Reitemeier, H°F-: and ”uehrer, T.F. 194L. The inhjoi tin action ”5 Tifiute amounts of IcflamefaJ cspfizte on tne perc pitate of calcium carbonate froT. ammoniacal solutions. I. Jour. Prgs. brem., 44: 535-551. Rice, 0., and hartrioge, E.P. 1939. Trreshold fleatwent.1ndus. fingin. Cben., 31: 53-03. Ripoer, A.L., and :u.:wa1d, L.F. 1941. The effect of acidified cans on tre qualiib 0? dairy prosacts and on the noosoraoase value of cream and batter . ii 1 Plant inn+h1y $13). 55-59 ioadh H0159, C.L. 1048. The nilk can nrobler. Jowr. 1115 Tec"rol., 1(2): co-773 I"ilk Plant Zonthly, ‘ LCl) 73-30. —_ Poasrcuse, 0.1., and Henderson, J.L. 1941. The Terket T3'11: Ind'str:. 624 pp. plus xv. New York: kc Graw 111 Luo. 30., 5. Y. Toland, C. T. 1942. The aooli on 01 tFe no er sins hates in oairs (aeration. 1a Ca ;b ‘nfif11‘ 31(0): N , 45-15, (110) (111) -l?2- Scales, F.h. 1939. FLt or ‘188 meth 3ns of contrciling waPhiL: and sterilizint. Jour. M111 Fecrnol. 1: 39—47. 308.105, E o o 1942—a. Ac' T4 ~ rlA 1" h ‘ v ‘fif‘»" . l w‘ 71' n- .- ~~ q 1 defer a't fo<€b cans warn caultdr». .303 1n3ab., :+ U‘ U. _J D {D (n ‘_+ Q) ‘3 H La -v' y. 3 O . J b. “ore resqlts with an aciu cater Washer. 111v 1ealfir, 32(2 es , - 1939. The a“?liC&tiDfl of rygter watnr to flair? 6rd 331k ola‘ t. F. Y. Assoc. Lairy Lil: Inspect., 13: 79-92. Schwarzkvpf, J. 1942. fiffective can wa511ng. Crea:nery J01r., 53(3):13. Sc1la:Z‘{-wf’ V]. 1943. ”aurin' an: nit? as}: Cleaners. ; 1k P13 t Lonthly, ,Jr ‘ZC‘W dr’ai’cgf, 7. 1947. Jethod~ (1 '63 *ng, st“r373?3n“, '34 Cr"“n Cifis. .11k “1 r— H A‘ I ’- r1ant Jflfiafi3l 3 3((): BJ—JZ, 34 —j0, 53. .4C‘1"hal“z'f’0p X]. -, 1 . ‘ ~ ~ / ’ '4 1?A8. how to yet cans clgag. ‘11chlant wonthly, 37x3): 43-:1. Scbw23+z, G. 3540. metergents 3a the 31”y *n3‘str, 93*. “,t. '. Y. 335:0. Maury ”11k Insp~ch., 13: 2’7-279. Schwartz C., an: Jilvorc, 7.E. 1934. Sad 3mm rotafi} Sp 3" r .. v" f"« t~jq ,‘ \ ..‘JI' :Lrlo L;}.9 o , L‘-’: EL] V'~'1_\.\4 . SCFT9“tZ, 3., 83C "Tnt€r, C.J. 1942. P303933tes in wata” CUTQ7t10“:27. :hd s. an;in. CEQ3., 4: 32-13... Schwarherback, 3., 87‘ 53ker38~n E. 19’7. Coyflax ions V. Etr"7010 did“a133 tetraacetic a141. hel C33” act§., 30° LTWQ—IQOA. >c‘ :ayznwxr-nr5 3., tat: .u_kor3c4 3 . IL 7””8. Cr“ 131 3135 111. ”0 ’7v 3 4 9+” 1 n3'3?‘ “PtCt‘EaC‘t C Sciu 53* #35.“ al‘ilwv' ”A3t? C “13'TS. 191". 6.1 . icta., 31: 1029-1141. L .4 4;. /\ ‘V (‘13) \ (117, (124) 10 .01 I‘\ r'\ ‘ O I" \J Shi‘it'h, T‘ 1020. finmaws jun/1c. Vhwmer, 1‘10 C.‘ < ,- "trnr1' , T1" (W 1945. as, (“a t o 0 act AC- 21(9): n “I U. ,1. Reid "1¢V~r's—t’” r v fl. - ' 1‘1 .- J. ’ :nvLH., FLctu ueét., ’1 U. J . r w .. . ‘C‘Drrlc: l caqx .da‘éps u' -.- n /t—- 1' -4 I 1L_ hecLer, 3;\,): 7: i“ I“; u. . T A. J- .- .. ;L not (a wet CuHu on . "‘ " , ,, 7 . EVE; “C9 Y‘QCL L0 4.1". ’ ‘J T. ‘-0-L0 u ./ :ilge EM ’WK @1‘ 4e. -' \ . I 1. " . V o ,--1' k.LL‘ t l’ntL'] - I). (‘V‘DF‘FF‘IV‘J T .1“ .r 1': U . ’5- 4. .. U AL 0 , t%;e Q‘le;*‘ (T _I‘.. l‘ P, €en+s a mm» f*c wa+ (1 r~ . AL : 1 7 ,1n2 a c:Us. ”L .‘t‘:‘ '3187.+3. T T 4.0.... ow to :‘100t uet*rger — P, A./ - . z () )1 4.”.-4‘4w.’ 91(3): 2Cb’29’3’ A2‘"[“/ijo '.| I Frbvt ‘41“ I 9 ilff>3 P“0"~Cf°. x1*r. a; isnf , 31".: 7V arxt‘x r. 9 l A—.". gV‘ici;rt can ‘Aa‘Lu rn-rattrd. ”(Cl/Q -_ ,,..\,): 2d 27. {fl .1 7 ‘-f‘ LV "\ -< Tl T'- I.- '-).F., (1?; .‘q‘ .2'0'15', A." C \‘li?s’ L. Q, Trebler, 194E. Tia—g" (nitric I lIv-Va n: ,1 - v. t I.. .~ nvnd. o T urs .r 1' TL_'-Ig.(?'( , J. 'o 1.“ ‘ '2' h.- .L\'[":JO J"sn 7'11 - v ‘78? ‘ALn-f'v"J-f_} v.v“‘—_jr ‘3 A 1‘, : ”Hr L , J 1 Q .. _ .— ”x 4 1195 330+ vicroflora of a; ".' C3 J. 1: >1'/ 0 _ .r . .v "." 4 r ‘3 hall] 0199Q9lo. '_ L] V, ‘ ‘Q _ :y (‘ Luz? rn-, ..;. news-trey? cvnfititnents L; A /‘-d7. 3 . m .1, :1 mllkA, lv‘. 0" lljapd, PO..C’ -.l- z—J' ‘ "D . '- v - ,uwuwcs. iron. -81‘3 H “I vs / -' v \ ‘_ 2“.~:a;g. \ .JVTEDb/ . "r ‘ Cfive a 63*8. i1,'u.