f--vc¢£¢y~pf-4p.."b .<-.'T .A ' A STUDY OF THE PLASTIC SURFACED MILK CARTONS Thesis m the beam: 91" M. S.- MICHEGAN STATE UNW‘ERSITY John C. Barnes 1960 1| mum; Iwyujnu u" (I! guns" 1m HIM 1mm ll A STUDY OF THE PLASTIC SURFACED MILK CARTONS By JOHN C. BARNES AN ABSTRACT Sutuitted to the College of Agriculture Michigan State University of Agriculture end Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Departunt of Dairy 1960 Approved 0 o ABSTRACT JOHN C. BARNES More than 50 percent of the market milk is packaged in paper cartons and nearly 90 percent of all nilk sold in supermarkets is in single-service cartons. Host of these cartons are wax coated. The purpose of this investigation was to study, under comercial condi- tions, factors related to packaging, handling and merchandising milk in the plastic surfaced cartons. In order to preform, sanitize, fill and seal cartons with the new plastic surface and an improved closure, a modified Pure-Pal: packaging machine was used. The modifications consisud of heaters and pressure pads for sealing carton bottoms, a hot water sanitizing compartment and a heat sealing mechanism for carton.tops. The flavor of milk, orange drink and cultured buttermilk was not affected by packaging and storing in these cartons. The flavor of milk that was frozen and defrosted in these cartons was not ad- versely affected. Plastic surfaced cartons did not prevent sunlight induced off-flavor when exposed to direct rays of sunshine for 2 hours. Gold milk packaged in plastic surfaced cartons increased in temperature slightly more rapidly than milk in waxed cartons when placed in a warm room for 1 hour. In general, the quart plastic surfaced cartons of milk, cultured buttermilk and orange drink tended to bulge very little 11 ABSTRACT JOHN C. BARNES during 3, 7 and 11. days of storage at 41° r. Cartons of milk had more bulge after freezing and thawing, but it was not excessive. Inability tests designed to indicate the cartons' resistance to rough handling included the Drop, Incline-Impact, Combination and huling Tests. The carton top-seal was sufficiently durable to resist leaker development when subjected to the four durability tests. The plastic surfaced carton appeared to have several points of weakness compared to the wax coated cartons. Slow seepage and leaks appeared more frequently at the bottom-seal and corners, side-seam seal and shoulder-seal when subjected to the Drop, Incline-Impact, Combination and huling Tests. Improper application of sealing material or in- adequate heat sealing may have contributed to the defects. , Consular acceptance on retail milk routes was very favorable. In fact, most customers preferred plastic surfaced cartons over the wax coated cartons. The operation of the modified packaging machine was satisfactory after several minor changes were made. The fact should be empha- sised that the sealing mechanism did not compensate for most imperb factions resulting from the lack of precision in the dies used for cutting cartons.- The temperature increase cf the contents of quart cartons during the machine operation averaged between 2 and 3 degrees I". iii ABSTRACT ' JOHN c. BARNES The hot water (19.00 If.) inersicn bath was very effective in sanitizing regular or seeded cartons. This was true when the seeding contamination consisted of ccmon themcduric organisms such as Lectobacillus themophil‘ug and Micrococcue varians as well as the less heat resistant types of Escherichia go_li and Pseudomcnas {23.5.3 Standard plate and cclifom counts on the new empty cartons that were not imersed in hot water averaged very low (15 organisms per carton) and were well within the maximum limits for milk containers. This experimental work indicated that the dairy industry and the customers would readily accept these cartons for regular use providing the price would be economical. A STUDY OF THE PLASTIC SURFACED MILK CARTONS By John C. Barnes 1 Thesis Submitted to the College of Agriculture Michigan State university of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of Master of Science Department of Dairy 1960 ACKNWIEDGMMS The author owes appreciation to many individuals for their cheerfulness, confidence and forbearance and to others for their willingness to help with the work. Sincere thanks and gratitude are especially extended to those who made this study possible: Professor T. I. Rodrick for his attentive interest and guidance during the stub and his major contribution of assistance in the preparation of this manuscript. Professor 1.. G. Harmon for contributing guidance of research plus direction and help in the preparation of the microbiological parts of this manuscript. A Pure-Pak Division of the Ex-Gell-O Corporation for the fi- nancial support and materials. Professor Carl W. Hall who provided an example of excellent teaching. Mrs. Barnes, Robert, Allan and Patricia for their forbearance, inspiration and optimism. TABIE OF CONTENTS INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . LITERATURE REVIEH . . . . . . . . . . . . . . . . . . . . . . 1. Product Stability in Plastic Surfaced Cartons . . . 2. Durability of Plastic Surfaced Cartons . . . . . . . 3.CustomerAcceptance................ I... Sanitary Condition of Plastic Surfaced Cartons . . . PROCEURES,RESULTSANDDISCUSSIOR ............. 1. Product Stability in the Plastic Surfaced Cartons . ~r u: a: B: A) h‘ 2. Durability of Plastic Surfaced Cartons . . . . . . me®m.................... Results and Discussion . . . . . . . . . . . . . 3. CustomerAcceptance ............... Procedure.................... Results and Discussion . . . . . . . . . . . . . A. Pure-Pelt Machine Operation with Plastic Surfaced Cartons . . . . . . . . . . . . . . . . . . . . . Procedure.................... Results and Discussion . . . . . . . . . . . . . 5. Sanitary Condition of Plastic Surfaced Milk Cartons mudmeeeeeeeeeeeeeeeeeee Results and Discussion . . . . . . . Prom dun O O O O O O O O O O O O O O O O O O O O 0 Preliminary testing 15595 H U 23 27 [,0 [.0 iii TABLE OF CONTENTS Page Testing commercial operation . . . . . . . . . 52 Testing contaminated cartons and immersion water e e e e e e e e e e e e e e e e e e 53 Sanitary condition of cartons and the hot water tank 0 O O O O O O O O O O O O O O O O O O 54 Sanitary condition of "dry formed" cartons affected by cleaning methods . . . . . . . 54 Contaminated 100 e e e e e e e e e e e e e e e 55 Coliform counts on milk from non-iced and iced cartons e e e e e e e e e e e e e e e 56 Results and Discussion . . . . . . . . . . . . . . 56 Sanitary condition or cartons e e e e e e e e 56 Control cartons not submerged in contaminated water e e e e e e e e e e e e e e e e e e 57 Contaminated cartons and immersion water . . . 59 Additional bacteria counts on cartons and hot water e e e e e e e e e e e e e e e e e e 63 The effect of three cleaning methods used on themandrelsandhub........... 63 The effect of covering cartons with con- taminated 106 e e e e e e e e e e e e e e 65 SW! AND CONCLUSIONS 0 O O O O O O O O O O O O O O O O O O 69 LITERATUE 01m 0 0 I O O 0 O 0 O O O O O O O O O O O O O O 73 APPENDIX 0 O O O O O O O O O O O O O O O O O C O O O O O O O 76 iv LIST OF TABLES Table Page 1 Effect of plastic surfaced cartons on flavor of whole Milk 0 O O O O O O O O O O O O O O O O O O O O O O 0 O 15 2 Effect of plastic surfaced cartons on flavor of cultured buttermilk and orange drink . . . . . . . . . 15 3 Effect of plastic surfaced cartons on flavor of whole milk subsequent to freezing and storage at -15° F. . . 16 4 Effect of sunlight on flavor of homogenized milk in plastic surfaced cartons e e e e e e e e e e e e e e e 17 5 Temperature increase of water at 38.50 F. in quart plastic surfaced cartons held at 73° F. for 55 to 68 minutes e e e e e e e e e e e e e e e e e e e e e e e 18 6 Temperature increase of water at 449 F. in quart plastic surfaced cartons held at 73° F. for 55 to 68 Minutea e e e e e e e e e e e e e e e e e e e e e e e 19 7 Temperature increase of water at 51.50 F. in plastic surfaced cartons held at 73° F. for 55 to 68 minutes 20 8 Temperature decrease of water at 73° 3. in quart plastic surfaced cartons held at 44.0 F. for 55 to 68 MinUtes e e e e e e e e e e e e e e e e e e e e e e 22 9 The bulge of plastic surfaced cartons of milk during storage 0 O O O O O O O O O O O O O O O O O O O O O O 28 10 The bulge of plastic surfaced cartons of buttermilk held in Storage e e e e e e e e e e e e e e e e e e e 29 11 The bulge of plastic surfaced cartons of orange drink held in storage e e e e e e e e e e e e e e e e 30 12 The bulge of plastic surfaced cartons after freezing and th8W1ng e e e e e e e e e e e e e e e e e e e e e 31 13 Isak development in cartons subjected to Drop Test . . 33 14 leak development in cartons subjected to Incline- Impact Test . . . . . . . . . . . . . . . . . . . . . 35 Table 15 16 17 18 19 20 21 22 23 24 LIST OF TABLES leak development in cartons subjected to Combination T6 at O O O O O O O O O O O O O O O O O O O O O O O O O Isak development in plastic surfaced cartons subjected to HiUling TOSt e e e e e e e e e e e e e e e e e e 0 Summary of customers' preference between plastic surfaced and wax coated cartons e e e e e e e e e e 0 Temperature increase of quarts of water during the top- sealing operation 0 e e e e e e e e e e e e e e e e 0 Temperature increase of quarts of water during machine Operation 0 e e e e e e e e e e e e e e e e e e e e 0 Standard plate counts obtained on noncontaminated plastic surfaced cartons and hot water . . . . . . . . Standard plate counts on immersion water and plastic surfaced cartons contaminated with organisms . . . . . Standard plate counts obtained from: (a) control cartons immersed in hot water, (b) "dry formed" cartons and (c) thermoduric counts on immersion water . . . . Standard plate and coliform counts on "dry formed" plastic surfaced cartons as affected by the sanitary conditions of the mandrels and hub. (Six trials with nine cartons in each trial or 54 cartons in the group). Coliform population of milk packaged in nonpiced cartons and in cartons covered with contaminated ice . Page 37 38 48 50 58 61 INTRODUCTION The general trend shows an increase in packaging of milk in paper cartons since 1937. The consumer acceptance of milk in paper cartons increased very rapidly after the regulatory agencies publicly approved the sanitary condition of the cartons. Currently, more than 50 percent of home-construed milk is packaged in single-service containers. Most of these containers are we: coated. Rectangular cartons with a plastic coating are on the market (since 191.9); but acceptance is limited by inherent problems. However, prospective advantages of polyethylene coated paperboard and its suitability for use stimulated the development of new plastic surfaced cartons as a replacement for wax coated cartons. Q} To solve problems associated with the "gable” type plastic surfaced cartons and the modified packaging machine, experimental work was perfomed in the Michigan State University Dairy Plant facilities, whose sales were comercially competitive but restricted to the University campus area. This investigation was undertaken to study the use of the plastic surfaced cartons as containers for milk and other products. The problems that were studied included: {clip/roduct stability, dura- bility of the cartons under common handling and transportation, cus- taeer acceptance 3f; the cartons, microbiological condition of the x x cartons and adjustment of machine Operations to the use of plastic "(u J . \— “r -1- surfacedcartons.-~~ HEW-‘w' -r\«.. LITERATURE REVIEW 1. Product Stability in the Plastic Surfaced Cartons literature on the effect of plastic surfaces on the flavor of milk and other associated dairy products is meager. Burgess (1950) concluded that polyethylene caused less change in.food products than other'surfacingrlaterials used on paperboard. He referred particup larly to flavor inertness as well as to chemical inertness. Dahle and Josephson (1939) confirmed reports of Doan and Myers (1936) that milk in.paper cartons developed less oxidised and sunshine flavor when.exposed to the sun's rays than milk in glass bottles. Finely ground oat flour (ivenex) and an antioxidant (Avenol) were used in sprays on the carton interface and; in mixtures with paraffin. This treatment of cartons did not prevent off-flavors induced by sunshine. However, Dahle and Josephson stated, ”Cartons made from paperboard which had been sized with oat flour before paraffining aided in de- laying the oxidised flavor induced by exposure to sunshine for 30 minutes." Prucha and Tracy (1943) confirmed the work of Dahle and Josephson showing that milk in paper containers developed an off- flavor when exposed to sunlight. 2. Durability of Plastic Surfaced Cartons Prucha and Tracy (191.3) reported on paper containers that were tested for strength, bulge and leakage. 0n the basis of the results, -2- they concluded that paper containers were practical for milk Intensitie- Err-gees (1950) stated that polyethylene had water and water vapor resistance at normal temperatures. The folding endurance and flexibility characteristics were excellent and rated highly during seine. The use of polyethylene was advocated as a coating for paper- board because of important properties which included chemical inert- ness, light weight, toughness, tear strength, extensibility, flexi- bility at low temperatures, grease proofness, water and water vapor proofness and heat sealability (Anorvmous (1950)). The plastic could also be colored by pigments and dyes for advertising purposes. The polyethylene extrusion processes were accomplished by first melting polyethylene crystals at 500° to 600° 1". (Anonymous (1950)). Then by use of a screw the hot liquid was forced through a tubular screen onto the applicator roller which applied the thin coating of polyethylene onto the paper sheet. The polyethylene was cooled im- mediately. John and Stannett (1956) described four techniques for apply- ing plastic to paper. They were tub sizing, saturation, coating and lamination. Booth (1956) reported his survey of the coating methods by machines. as presented a line drawng of the coating application by using one furnish-roll (which picks up and applies liquid coating material on paperboard). The roll was partly submerged in a supply vessel. Another method was an offset gravure coater with two furnish- rolls partly subserged. A third system utilised one or two furnish- rolls with attached inclined-blades holding and spreading the supply of coating. The fourth method consisted of a supply between two counter running hrrnish-rolls. Eb stated that most of the methods of coating were developed by individual mills to fill specific needs. The American Society for Testing Materials (ASI'M) (1957) ex- plained the use of vibrating equipment and tentative methods for simu- lating conditions of transportation. To determine the ability of a container to protect its contents and to withstand rough handling, cartons were subjected to the simulated conditions of rough handling. Transportation by truck had certain ranges of vibration frequencies that predominated at '70 to 200 cycles per second in combination with shock. Container failure occurred when the contents spilled, when predetermined damage occurred or if some contents were removed with- out firrther damage to the container. A second method involved the controlled dropping of filled con- tainers on the edges, corners or faces of the containers. Extent of damage was observed. A third method outlined the Conbur tester (Incline-Impact) which subjected containers to impact stresses, such as rail car switching shocks. The tester consisted of an inclined track, dolly and rigid bumper. Containers of filled packages were allowed to slide down the slope against the bumper. Usually containers were sub— Jected to the impact stresses on the four faces but sometimes were tested on edges and corners, depending on the handling conditions to be simulated. Bickerman (1959) stated that adhesionahle properties of poly- ethylene were improved by the removal of low molecular components. Tb improved processing eliminated the formation of objectionable surface films having low mechanical strength which sometimes existed on comercial polyetlwlenes. 3. Customer Acceptance Paper cone bottles were used for milk containers (The Milk Dealer (1929)) and (Business week (1932)). Wheaten, mock and Tanner (1938) reported a general trend toward an increase in packaging of milk in single service paper con- tainers. Paper containers were lighter in weight and needed no bottle deposit at stores. Bottle cleaning was eliminated. Tracy (1938) stated that the advent of store selling of milk brought on the development of several paper containers. it the same price a slight majority of 221 customers polled preferred to buy milk in paper instead of glass containers. The customers believed sanita- tion was better in paper and few customers noted any difference in flavor. less space was needed in refrigerators and cartons were pre- ferred on picnics. Tracy's survey of consents from customers included favorable reports about paper cartons such as: no bottle washing, no bottle return, no breaking or chipping and more easily handled. Prucha and Tracy (1943) conducted surveys which showed that 95 percent of 136 customers who returned questionnaires preferred paper con- tainers instead of glass bottles. The customers' opinions indicated that paper cartons were sanitary as well as practical for packaging fluid milk. ' The paper carton was referred to as an outstanding innovation in the promotion for health and safety in manufacturing plants (Anonymous (1942)). Production time of workers was not lost through accidents due to broken bottles nor by returning empty bottles. Pitman (1946) advocated that research workers measure the ef- ficiency of packaging performance by using adverse as well as practi- cal conditions involving time and temperature of storage, exposure to sunshine, gain or loss of moisture by the product or package, bacteria, appearance, product flavor and general palatability. He also sug- gested test marketing for customer acceptance, taste panels and com- parison with competitors' packages. Sealking plastic coated cartons gained favorable customer ac- ceptance (Anomalous (1949)). Williamson (1955) wrote that Tetra-Pak had been used for the three previous years in Stockholm, Sweden. Based on information from the manager of a large dairy in Stockholm, Mr. Williamson stated that the reaction of customers was variable. Occasionally, a customer reacted strongly against the awkwardness in handling the tetrahedron container. Adverse reaction by consmners had diminished gradually. The manager found that it was necessary to have a separate filling machine for each size of Tetra-Pal: packages. He also had difficulties if the seal was incomplete or the paperboard was of uneven quality. 4. Sanitary Condition of Plastic Surfaced Cartons In order to show the sanitary condition of paper mill: con- tainers, Prucha (1933, 1939) stated that paperboard could be made practically free from: bacteria and could be converted to paper milk cartons having a satisfactory microbiological condition. He stated that cartons paraffined at 185° F. for 30 seconds were practically sterile and were safe for use. Inuersion water at 185° F. practically sterilised cartons in less time than paraffin at 185°. To standardize the testing of the cartons, Wheaton, Lueck and Tanner (1938) suggested the use of 20 n1. rinses and plating of 10 ml. of rinse water. They found 80 percent of the cartons contained no bacteria and 20 percent had fewer than 5 colonies per carton. Tests for W 3;; on the waxed cartons were all negative. Sanborn (1938, 1939, 192.0. 191.1 and 191.2) stated that sanita- tion in the manufacture and use of paper containers involved: use of virgin pulp only; microbiological control at pulp and paper mills; protective packaging of the finished board; mechanical handling at conversion factories and milk plants; eliminating human contact with paperboard, adhesives, wax and the final containers; adequate protec- tion fron contamination, dirt, flushing water or insects and use of nontoxic gemicidal substances which had no effect on milk. He stated that the bacteria count of paperboard should not exceed 500 colonies per gram. In the preparation of sanitary standards for paper :11): con- tainers, the combined data from various studies on the containers were examined and used by Sanborn, Yale, Breed and others (1938). They presented the sanitary standards which were agreed upon by a group meeting sponsored by the International Association of Milk and Food Sanitarians. The following principles of sanitation for the manufac- ture and use of paper containers for milk were recommended for the industries. 1. 2. 3. 1.. 5. 8. 9. They involved: Use virgin pulp free from dirt and slime and protected from contamination during processing. Protect paperboard with sealed wrappers. Convert rolls or sheets of paperboard into containers by sanitary means and mechanical handling, because containers must be clean and free from chemical re- agents and foreign materials. Use sterile adhesives of synthetic thermoplastic types. Package finished cartons in sealed, suitable wrappers or shipping cases. Use shipping cases having the ability to withstand rough handling and to protect the contents in transit. Protect the shipping cases from contamination in the milk plants. Avoid use (in carton manufacture or filling) of germi- cidal or bacteriostatic agents which would be toxic or have an effect on the product. Ihndle paraffin by suitable, clean and sanitary means. 10. Use containers made from paperboard containing less than 500 colonies per gram (reduced to 250 in 1939). 11. Control average bacteria counts at 50 or fewer colonies per container. 12. Use shipping containers which are uninjured, neat and clean for filled cartons. 13. Use single service containers for milk deliveries to hospitals and quarantined residences caring for infec- tious diseases. Twelve hundred containers tested for E. 29;; were negative when examined by Tanner (1938, 1939 and 191.8). Over 90 percent of the con.- tainers had negative bacteria counts in the rinses. The average mi— crobiological population recovered from paper containers was much lower than those reported from some glass bottles which usually con- tained less than 10 organisms per bottle. Special methods of making paperboard were necessary to have a large reduction in viable bacteria. Tanner also found that imuersion of cartons in hot paraffin resulted in a further reductionin viable bacteria. In 1939 data indicated that some mills consistantly made paper- board with not over 100 organisms per gram (Sanborn (1939)). The following year, Sanborn (1940) reported that 13 different mills made paperboard which contained few counts in excess of 500 per gram (2,879 amlyses). Fifty percent of the counts were less than 10. Huntley and Torrey (1940) stated that mills processing paper- board controlled the microbiological condition of paperboard by a 10 chloramine process and cleaning methods. The drying operation was one of the most effective sterilizers. Water on the rolls was treated with chlorine. The next year, Sanborn (191.1) stated that 73 percent of the counts on paperboard were less than 10, and 99 percent were less than 100 per gram of paperboard. The Baltimore Health Department specified not more than 50 organisms per quart container and Boston permitted only 25 with a proportional standard for the other sizes of containers. According to Rice (1912) there was a closer relationship be- tween the degree of sterility of paper containers and the microbiologi- cal condition of paperboard from which the containers were made than there was between the degree of sterility and the supposedly germicidal effect of moisture proofing with paraffin at high temperatures (150° F. and above). Preformed cartons were examined by Foord, Crane and Clark (1943). Tests showed that 78.5 percent of the cartons were sterile and the other 21.5 percent contained less than three organisms per carton. When 10 m1. of rinse was left in the cartons and agar was added, 87.5 percent were sterile. Methods for the microbiological examination of various kinds of products in paperboard mills were reported by Appling (1945) and were incorporated into a suggested standard in the Technical Associa- tion of the Pulp and Paper Industry as T-u.9 em 40. Because dairy products had been packaged in paper for many years, it was not 11 surprising to find various methods of examination being used by re- search workers and technicianswith the American Public Health Associa- tion. Microbiological studies by Reed (1951) showed that mill systems had a problem with surviving sporeforming bacteria in paperboard. His sumnation of data indicated that organisms in paper containers were due to converting processes and other handling and processing methods, and were not due to the material from which the units were made. PROCEDURES, RESULTS AND DISCUSSION 1. Product Stability in the Plastic Surfaced Cartons Procedure To determine how the plastic surfacing material would effect the flavor of dairy products and orange drink, cartons were filled with pasteurized homogenized whole milk (3.5 percent milk fat), cultured buttermilk or orange drink. These products were stored for periods in excess of conneercial practice at refrigerator temperatures varying from 33° to 60° r. They were examined at specific intervals depending upon the product. Competent dairy product Judges carefully performed organoleptic tests for possible changes of the products due to the plastic material. Pasteur-iced homogenized whole milk packaged in quart plastic surfaced containers was frozen and stored at -150 1". from 15 to 34 weeks. The milk was defrosted for 4 days in a refrigerated room at 41° 1". After mixing, each sample was examined for off-flavors in.- duced by the polyethylene. The protection provided by the plastic surfaced cartons against sunlight-induced off-flavors in pasteurized homogenised whole milk was investigated. Cartons of cold milk (39° F.) were exposed to direct sunlight for l to 2 hours. Immediately after exposure, the samples were placed in a 41° F. refrigerator for 24 to 48 hours be— fore their flavor was evaluated by dairy product Judges. -12- 13 Liquid milk products have ample opportunity to change in tempera- ture during handling, especially in the home. The rate of change is important in preserving freshness of flavor and in preventing micro- biological growth. To ascertain the rate of temperature change in the contents of plastic surfaced cartons, water was packaged in the cartons and allowed to become unifbrm in temperature by storing in a refrigerated room at approximately 38° P., 44° F. or 51° F. for 5 days. Control samples (wax coated cartons) were handled in the same manner. After the 5-day bold, cartons at each of the three temperatures were placed in a room for 55 to 68 minutes with 50 percent relative humidity at 73° F. The arrangement of the cartons on shelves allowed uniform.exposure of air to all sides. After exposure the cartons were inverted six times, and the temperature of the contents was read to the nearest 0.5° F. To observe the rate of cooling, cartons of water were held 5 days at 730 F. and then transferred to a 41° F. refrigerated room with 88 percent relative humidity. After holding for 55 to 68 minutes the cartons again were inverted six times and the temperature recorded to the nearest 0.5° P. Results and Discussion Data in Table 1 show the plastic surfaced material in contact with the milk did not cause an off-flavor when held 7 to 14 days at 33° F. or 41° F. Additional trials with milk samples held in storage at 50° and 60° F. for 4 and 7 days indicated sufficient microbiologi- ¢ n.H m.mv o.Nq om H.H o.Hm m.om Nod m.h« b.o# c.o m.N< e.H< 9H H.H e.Hm “.0“ e.” o.ne m.oe o.H “.me m.He ma ~.H e.~n N.om n.H m.oe «.04 m.H o.me m.He ea a.” H.Hn 0.0m m.H m.se o.oe o.H m.He H.oe ea N.H H.Hm @.mv N.H N.b< 0.0e m.H m.H< o.o¢ nH «.H H.Hm h.mv 0.H m.hw o.m< m.H m.Hv o.o¢ «H Q.H o.Hm o.mw N.H o.b¢ m.m¢ m.H n.H< o.ov ma e.H o.Hm o.oe m m.H o.oe s.me m.H m.He o.oe NH e.H o.am o.oe m m.H o.oe s.m< m.a o.He m.om Ha o.a H.Hm m.oo w N.H o.oo o.no o.H N.Ho o.on oH H.H 0.0m m.oe _ e.H o.oe e.me m.H o.He m.om o m.H o.Hm m.os _ m.H o.oo «.me s.H ~.Ho m.om m o.” “.0“ m.os m m.H o.oo “.me o.~ o.Ho m.om o H.H m.om e.oe . H.H o.oe «.me 4.” o.oe N.on o e.H m.om e.oe , m.H o.s< «.me a.” o.He m.om m 4.H m.om H.0q o.H H.b< m.m< m.H n.o¢ o.cn < m.H n.0m o.w¢ H.H m.o¢ «.mq m.H m.oq o.¢m m H.H H.om o.oe m.H o.oe e.ne m.H m.oe o.om N m.H n.0m o.oe m.H m.oe ~.ne m.H m.oe o.om H .uuan wmmwson neokmoo .uuua wnafldee noemmev .uudn mquHsoe noymmwv nonsnn do o$& USEH .mo 334 Hflfifl do «33 UEHH Hflé sowushoao mnafleonlaoa on» madame hope: as nausea no oaeouond.epsushonaeallmn ”nude 49 approximately 500 F. The increase varied from 1.00 to 1.60 F. and averaged 1.290 F. The increase in the temperature of the contents of the cartons, attributable to the sealing operation, did not exceed 2.o° r. and was usually less with the quart volume. This was not considered to be serious although any increase in temperature is undesirable. Table 19 presents data on the total temperature increase of quart containers during the regular'machine operation. The cartons ‘with an initial temperature of appreximately'ADlo F. showed an average increase of 2.u.° r. The range was 2.o° F. to 2.9° 1?. The range was 2.00 to 3.0° F. with an average of 2.38° F. for the 20 cartons with an initial temperature of approximately 45° F. The third group with an initial temperature of approximately 50° F. increased an average of 2.07° r. with the range from 1.7° to 2.5° r. The total heat effect from machine operation should be taken into consideration.when thought is given to the temperature desired for the packaged milk. The milk should be cooled 2° to 3° r. colder to compensate for heat transfer into the plastic surfaced cartons dur- ing packaging. The increase of 2° F. and more in quart containers suggests that heat transfer into one-halfbpint containers might be serious. After the heating elements are standardized for normal operation of the machine, one-half—pint cartons should be checked and temperature difference recorded in various locations within the cartons, es- pecially at the top. so.~ mo.Hm mm.c< mm.~ mo.c< Hm.ne ee.~ no.~< cH.oe omdwo>< .ho o.~ n.Hm m.ce ~.~ ~.ca o.ce m.~ o.oe m.ee on c.H c.~m o.Hn m.~ o.ce n.0e m.~ o.ne «.me ca o.~ e.~m 0.0“ m.~ «.me o.ee n.~ m.ee m.~e ma H.~ H.Hm o.o< m.~ m.m< o.oe H.~ m.me 4.n< bu o.~ o.Hm o.ce o.~ o.ce o.se n.~ m.me N.He ea o.H m.Hm «.oe i o.~ o.me o.oe H.m o.e< c.H< ma m.m m.am o.oe m.~ o.me m.me m.~ o.me n.mm ea o.~ o.Hm o.ma o.~ o.me o.ee m.m o.ne m.oe ma H.~ H.Hm o.ce m.~ «.me o.oe m.~ n.oe o.mn ma H.~ m.om «.me H.~ H.me o.ne o.~ m.oe m.wm HH H.~ e.~n “.0“ m.~ o.me m.me c.~ m.oe m.an on c.H m.Hm o.oe m.m «.54 «.me m.~ >.mm ~.sm o H.~ c.~m 0.0m e.~ N.ae m.ee ~.~ o.~e m.cm m e.~ n.mm H.Hm m.m o.mv «.me m.m m.o¢ b.bm b o.~ m.~m n.0m o.~ o.ce o.me o.~ o.~e o.oe o H.~ >.~m 0.0m m.~ o.se m.ee m.~ m.H< o.mm m o.~ “.mm n.0m n.~ o.oe m.ne m.~ e.ne H.He e m.H «.mn «.0m o.m m.oe m.me ~.~ «.me o.oe n m.~ >.Hm m.oe m.~ m.me m.me m.m o.~e m.om w m.m o.mn m.om m.~ o.oe m.me m.~ o.me m.o< H 33%: 8.3 as 33 arena eeee< eeee< wepu< Henna w .h neaop .5. 89p...a.u.g.e.oa coupons—o aqueous mundane keen: Mo granny Mo sneer—"on.“ gnuehonaeenlafl Sada 51 Additional problems may occur with long operations and with the use of cartons in sizes other than quarts. In general there were no problems which could not be worked out satisfactorily for larger op- erations under comercial conditions. 5. Sanitary Condition of Plastic Surfaced Milk Cartons Milk cartons must be in good sanitary condition and suffi- ciently durable to protect the milk during handling, holding and dis- tribution. The modified Pure-Pal: machine which forms and fills these cartons had a compartment in which the cartons were submerged in water at approximately 190° F. for 8 seconds. The purpose of this stuw was to determine the sanitary condi- tion of the plastic surfaced milk cartons with and without imersion in the hot water before filling. Investigators were also interested in the bacteriological condition of specifically contaminated cartons and immersion water. Procedure Preliminag tegtigg. In preliminary work four trials were per-‘ formed in which cartons were sanitized by submersion in hot water and then were removed from the machine immediately after passing through the hot water tank. Twenty ml. of sterile buffered rinse solution were added to each carton. The tops were closed and covered with aluminum foil held in place with clamps. Total and coliform counts were performed on rinses from the cartons according to Standard lethods (1953) using 10 m1. portions divided among three plates. Also several 52 trials were made in which skimmilk was packaged and similar counts were performed. Testigg thp_ggmmgggigl,gpgzgtion. After procedures for com- mercial operation.were established, about 1,000 quarts of homogenized whole milk were packaged each operating day. Total and coliform counts were completed before the milk was sold. One empty carton and one carton of’milk were removed from the processing line during the fore, middle and latter periods of packaging. Milk samples and rinse solutions from the empty cartons were plated as later described. Fre- quently during carton forming operations, samples of water were re- moved from the hot water tank and plated to determine the number of total and thenmoduric organisms present. In addition to counts made by Standard Methods (1953). some samples of milk were plated with trypticase soy agar and incubated at 89.60 F. Bacteria counts were made on control cartons formed in the machine and processed as indicated below: (a) Cartons not immersed in water (subsequently re- ferred to as "dry formed" cartons). (b) Cartons which were removed frdm the machine im- mediately after passing through the hot water. (c) Cartons which were passed through the hot water and sealed. Bacteria counts were also performed on samples of hot water taken from the rinse compartment after the control cartons had passed through. 53 Testing contaminated cartons and immersion m. In an attempt to determine the sanitary efficiency of the machine, cartons‘and im— mersion waters were contaminated with five different organisms com- monly found in a dairy plant. The organisms used were Micrococgg m (11.8. 102), mgctegum w Lgctobgcillug themephilgg, ash-prisms can and Wand no real. gctgbacillus thermophilug was propagated in nutrient broth containing 0.5 percent protease peptone and was plated in tomato Juice agar. The incubation temperature was 127° to 131° F. The other four organisms were propagated in nutrient broth at 89.6° F.* Ten m1. of each culture was added to 90 m1. of sterile buffered water. After mixing for 1 minute in a dilution bottle, the contents were then uniformly blended with 5.9 liters of sterile buffered water. The flat, unformed cartons were contaminated by submerging 10 at a time for 30 seconds in the 6 liters of contaminated buffered water. The water was poured into the hot water rinse compartment of the machine after the contaminated cartons were processed through the machine. Bacteria counts were made on rinses from contaminated cartons formed and sealed. in the machine and processed as indicated below: (a) Cartons which were conveyed through the empty hot water compartment receiving no rinse. (b) Cartons which were conveyed through lukewarm rinse water at 90° to 100° F. “The organism, tentatively classified as Pseudomogs _f;_agi and used in this work, grew satisfactorily at 89. 6° F. 51. Bacteria counts were also performed on: (a) (b) (c) (d) Inoculated buffered water used to contaminate the cartons; Hot water from the rinse compartment after the con— taminated cartons had passed through; Hot water from the rinse compartment after the in- oculated buffered water had been added, and Cartons which had not received the contaminating treatment and were formed, passed through the con- taminated hot water and sealed in the machine. Sanitgrz audition of cartons and the hot water tank. Total bacteria counts were performed on representative noncontaminated car- tons which were formed and: (a) 0)) Passed through hot water at 190° F. and removed be- fore being sealed. Passed through the empty hot water compartment (re- ceived no rinse) and removed before being sealed. Imediately after the cartons indicated under (a) immediately above were processed, samples of hot water were removed from the tank and plated to determine whether thermoduric organisms were present. MMfi"M" mam—f ctod azaleas— inscribe.» In order to determine the relationship between the sanitary condition of the mandrels which were given a cold water spray . and the total bacteria count of “dry formed" cartons, three methods of cleaning were used on the mandrels and the hub. The first method 55 employed a hot water rinse once a week on the mandrels and the hub. The second method employed a daily hot water rinse of the mandrels and hub. The third method involved a hot water rinse, a chlorine solution rinse and another hot water rinse. After each of the three cleaning procedures, the mandrels were occasionally coated sparingly with a silicone compound. Qggfiggipatggbigg. Ice cubes containing figghgzighig,ggli_were prepared by adding 30 m1. of nutrient broth culture of,E..ggli to water containing 5 percent glycerin, 1 percent sucrose and 1 percent nonfat dry milk solids. After 200 pounds of the solutionnwas frozen into cubes, it was stored at -8° F. Coliform counts were performed on the inoculated solution prior to freezing and on a composite sample of the melted ice. A randomly selected case lot of'milk (20 quarts) in plastic surfaced cartons was taken during normal operation and was stored overnight at 349 to 369 F. Controls were removed from the conveyor line immediately before and after filling each random case. The next morning the case of milk being used in the trial was covered to a depth of 2 to 3 inches with contaminated ice cubes, held in place by paperboard supports. The cartons in the case were then transported for A to 5 hours over about 10 miles of retail routes. The samples were then replaced in storage until early afternoon when the slush ice was removed. The cartons were rinsed with tap water, wiped dry and taken to the laboratory along with the control samples 56 which had not been iced. The slush ice was promptly examined for colifbrm population. The procedure was repeated eight times using plastic surfaced cartons and two times using wax coated cartons. WWQQMWMMMfl as- The cartons were opened in the normal manner. Two samples were removed from each carton. First, 10 m1. of‘milk was removed carefully with a pipette without contacting the pouring spout; then 50 m1. of milk was poured from each carton into a sterile flask. Coliform counts were performed according to Standard Methods (1953) by using 10 ml. of milk. The milk was divided into three plates which were covered with violet red bile agar. The plates were incubated at 95° F. Results and Discussion w ggndition 9_f_ grtong. The coliform counts on eight samples of skimmilk from plastic surfaced cartons were all less than 0.1 per ml. and total bacteria counts varied from 200 to 800 organ- isms per ml. Coliform counts from eight empty cartons were all less than 1.0 per carton. These results suggested that there was little, if any, contamination from the cartons. After cartons passed through the immersion water, the cartons were tipped by the machine to permit drainage. Some water absorbed into the inside raw edges and visible droplets were apparent on the inside surfaces. By holding and shaking the cartons against a 57 horizontal surface, most of the water was collected in a bottom corner of the carton. A maximum of 0.7 ml. of water was recovered from any one carton. The average recovered from 20 cartons was 0.46 ml. This is a little less than remains in quart glass bottles. The arithmetic average of total coliform counts on 71 samples of milk in plastic surfaced cartons was 1,200 organisms per ml. Total counts on 54 of the 71 samples ranged from 240 to 1,000 per ml.; 14 varied from 1,100 to 1,800 per ml., and 3 ranged from 8,500 to 11,000 per ml. Twentybone of the 71 samples of milk were plated in both stand- ard plate count agar and trypticase soy agar and were incubated at 89.6° F. The arithmetic averages of total counts were 840 per ml. on plate count agar and 1,000 per ml. on trypticase soy agar. The 71 milk samples contained an arithmetic average of 0.6 coliform per ml. Forty-nine of the 71 milk samples contained less than 0.1 coliform per m1. and 16 contained 1.0 per ml. The colifbrm count of 6 samples ranged from 2 to 15 per m1. Rinses from 71 empty cartons all showed less than 1.0 coliform organism per carton. The arithmetic average of total counts on rinses from 39 empty cartons immersed in hot water was 2.0 organisms per carton. Thirty- five of the 39 cartons contained less than 1.0 organism per carton, and L varied from 10 to 30 organisms per carton. All cartons contained less than 0.1 organism per ml. of milk. Control ggrtgns get submezggd in contgmingted ggter. Data in Table 20 show the arithmetic average of total counts on rinses from 58 leomH 03H «.0 8. H.0v H.0v 0.~ 3 H.0v 0.0 3 H.0v 0.0 3 H.0v 35.8 00 .0000 .0 0.0 H.0v H.0v «.0 «.0 0008 owe-83 .0 £000.30 3000a 0.33 0000.30 3 0.3000 .3003 0000005..“ 00m 0 0 0 0 0 5.3.03 00 .0. 00A 320003on 0.3.: no 000 man—"0000000 0:00.30 .00 000052 .0 o.m 00 04V 0.0V o.~ o0 otnv on 00 04V mb 00 0...” V 000.30 .Hoa 000500 he owned .0. o.~ otnv 04 V o.m 1m H3930 .Hom 08.60 000034 .0 30083000. M00300 000 $5930 603000000 03 .h 000." 00 .3003 00003.55 £96.30 @0003 003.30 0.x 0 o o o o h0000n00 mo 2d: .39 “3300030 0.35 .3 000 mu.“ 030000 0000.30 00 .3952 .0 0H 8. 0.Hv 0.Hv 000 3 0.Hv 0.0 3 0.7 0.0 3 0.3 000.23 .80 3008 .00 00000 .0 m.m 04v o.m N.N m4 03.30 .30 0300 0m090>< .0 .m 003 00 .3003 0000355 £090.50 300000 000.00 500000055" 00.3020 000 59C egosou 0000.30 8 o m m m 0 500.0030 0o .de .39 $100330 0.85 no 00o M00 $000000 000030 No .3005: .0 mm 00 0.HV 22m. 00 04V oooamm o0 04V 08.0m 00 04V 0N0. 00 04V ao0.30 .39 00§o0 no 0m3m .p 0.0 mm 000; 000.0 3 03.2.0 .80 £38 .0322 .0 3000.30 308.30 0.3.; .3003 5 0003.50 00: 0000.30 3 s a HHH LH-H _H.-- .00 H0009 . .- 0 .0.00 .a- wow-003m.-. 010mg u o 0560 0 000.0... 0. 0 0- .0000 05 . .‘7‘lt- tllvl|lllPlllll|lil I‘ll! l'l it'll" IIVI 'i’li‘l." 'llfll‘lIi"1'."-‘|’Il?""i'!i .3003 000 000 ‘“0000.30 00000.30 0000000 0000003000000 00 0003000 005.00 000.3 2000000....8 3mg. 59 groups of 40 cartons which were formed on the machine. The cartons were conveyed through the empty hot water compartment (not immersed). The counts ranged from 5.4 to 4,000 organisms per carton. High counts were recorded for some individual cartons which could have been con_ taminated during the forming process on the mandrels. Also, some contamination could have occurred while the cartons were being cut, printed and glued. The fact must be emphasized that the cartons were essentially "hand made" and handled individually at least eight times. In normal production, cartons are "bunch handled" by hand only about three times and are handled in ways to minimize contamination. The arithmetic averages of total counts on groups of 40 control cartons which were removed from the machine immediately after passing through the hot water varied from less than 1.0 to 5 organisms per carton (Table 20). The arithmetic averages of total counts on groups of 40 control cartons which were passed through the hot water and sealed in the machine varied from less than 1.0 to 5.1 organisms per carton (Table 20). Total counts on samples of hot water varied from less than 0.1 to 3.2 organisms per ml. (Table 20). Intermittently, thermoduric populations were determined in water taken from the hot water compart- ment and varied from less than 0.1 to 12 per ml. Qggtgggggtgg gartons gag immersion gate . The contaminated water in which the flat cartons were submerged contained from 3,000 to 60 7,500,000 organisms per ml. (Table 21). The groups of 40 contaminated cartons which were passed through the empty compartment had total arithmetic averages of 400 to 59,000 per carton. The data also show that the arithmetic averages of total counts of groups of correspond- ing cartons which passed through.water at 90° to 1000 F. ranged from 3 to 3,700 organisms per carton. The arithmetic averages of total counts of 40 contaminated cartons which passed through hot immersion water at 189° to 190° F. ranged from less than 1.0 to 4.2 organisms per carton. Data in Table 21 also show that total counts of samples of hot water taken immediately after the passage of contaminated cartons varied from less than 0.1 to 0.7 organism per m1. Total counts of samples of hot water, taken.immediately after the 6 liters of con- taminated water was added to the hot water compartment and after the temperature had returned to 189° to 190° F., ranged from less than 0.1 to 0.4 organism per ml. The data show that the arithmetic average of total counts of noncontaminated cartons which passed through contaminated hot water varied from less than 1.0 to 8 organisms per carton. In connection with this work, bacteria counts were performed on 600 contaminated cartons and 200 noncontaminated cartons. Data ' indicate that cartons submerged in hot water at 189° to 190° F. for 8 seconds consistently complied with requirements published in the 143.11: Ordinance and Code (1953). which state that "a milk package shall 61 .7003 so: 0 o o o o hpaodudo no .3 you Advsaasdmno 0.85 so oso m3 Inwdpsoo 53928 no panama .o 0mm op oéuv 04V 04V mm op otnv «m ow o...“ ..v nophdo pom nedsoo mo omsdm .n 06 04V 04V m4 no nofido you 958 omdneaé .d h ooma pd head: Edausdpnoo mu confide.“ econ—Leo 0% mo 953 among... 0 o o o o bpaodado mo ad: you advafluddmuo egos no go mu“ Inddadoo unopudo .uo 255.2 .o Na 3 0.7». 03V o.m ca 02nd 0H op 04V «N op 0.." V nofido you 3560 no omddm .9 m.N otnw oth o.~ NJ nofido you 053 omdnobd .d .m 003 ad head: :30th smacks... cocoa nnoaudo usaadpmoo 0... mo $860 $823 on o o 3 fin hufiodado Mo 2?. non Advsmaadwpo 0.36 so 93 wad 153:3 unotdo no .3952 .o 80.8 3 8m 8” 8. 0.7. 8 3 0.7» 08.2 3 02 083 8. 04 8.28 .80 358 so has .p 8a..m 0.m 0.m 80; 80 acts .30 s88 009.25. .a h 000..” cu om pd n32» 5 003255 33.30 03.05.5808 0% mo vasoo omdugd 3 8 H 3 on .3338 «c .3 sea Auvsmucdmuo 0.33 no «so mad Infidvcoo acofido mo none—:2 .o 80.02 3. 80.0 08:3 3 04v 81H 3 0.3 80.3 c» 85.; 08.3 3 80. 03.08 .80 3008 cc has .n 80.0“ 8H. 0 8e 80.2 80. 8 03.28 .30 €08 amass. .c «3.2; a.“ "seduces.“ won ecofdo covenasdvaoo ow no #580 omduebd gun; .a . hag gggg egawho spa: weagsdpnoo Hdcofido voodubfi 30.»an cad hood: 333.355 do mvgoo madam Edging mama. 62 0.0 3 0.0,. 0.0 3 H.0J «.0 op 0.01.. 0.0 3 H.0v ....0 3 0.04 £003 .80 358 no 005.0 .0 .104 .70.» .70 «.0 «.0 30080 000 3500 000.025 to uocvd dd: £3008 wcfipdfiaducoo .0380 03.03 vow 0.0 3 0.0.,» 0.0.4 H.0v 0.0 3 dov 0.0 3 do 3008 .30 358 00 005a .0 H.0v adv H.0v 0.0 0.0 305.. .80 2:8 009.2: 3 £050.33 00339 203.03 03.038308 03.: 038» nowmhog 30m 08.000 80.000 80.00 8068.0 80.0.: 3030 .80 00:8 00822 .0 5:08 050805080 a .n o 0.35 o. g 5830 a .200 0.30% 0.304008% 944.3380: 303032040 0.0.0.003 - I i -0003 .28.: 800.. 003 03 5:08. 003055008 03.00 .0303 won AD 93 £96.05 000000 0d: 00303 033080000 03.20 good: was A3 .5320 mcavdmwfipnoo bCluo the no.» 3580 adooe cggvaooliam “Rafa 63 not have more than one organism per ml. of capacity when determined by rinse and swab tests". mamemmmm. Data in Table 22 show that the total counts on control cartons removed from the machine imediately after passing through the hot water varied from less than 1.0 to 10 organisms per carton. The themoduric popu- lation in the hot water through which the above cartons passed ranged from less than 0.1 to 12 organisms per m1. Total counts on rinses from ”dry formed” cartons which passed through the empty compartment varied from less than 1.0 to 900 organ- isms per carton and less than 0.1 to 0.9 organism per ml. of capacity. Cold water was employed to cool the mandrels. During operation some water migrated back and forth between the mandrels and the hub. Some of this water probably was retained in the cartons and represented a contamination hazard to cartons which were not subsequently passed through hot water. mmmmmmm . Mummm 11933. In the regular cleaning procedure (Method I) the mandrels and hub received only one hot water rinse each week. Intemittently swabs from the surface of the hub showed a range of total counts of 200,000,000 to 1,000,000,000 organisms per 8 sq. in. of hub. area. when using cleaning Method I, the total counts performed on 5!. "dry formed" cartons ranged from less than 1.0 to 8,400 organisms per carton. Colitorm counts from 47 cartons were less than 1.0 organim 64 NH op H.0Jv o.m Heap» nose ma sagas» snow 3 song» common on: mnovnmo seems .m oomH as hops: moweueesH .o Amado amenemadu no «Heap» 0v .Ha_uea assoc .h come as mops: nowmuoESA causbosuonp no .Ha non gmsoo cansuoa mo ewnom then» no ommno>m capoenvau< coo op 04V 0.0m so?» nose ca shopped Many vnesapsmaoo nova: haqae one smacks» mad lemma menus hflenmduessfl copes use one peas: aw composed p8 cases .6058 5.. on .9 0H op otnv can 33.3 some a.“ escapee ”33 .m oofi as 2%: £385 sauna note 53325 vesosen unopumo Hoponoo on .e cofiadno 9% Amman paflamufio no 923.5 8 Oflgdmmlmdmll season Have» mousse pom mumsoo Mo omsmm Hevov no ommue>s onpoenafiud 'Il'i l.’ ho¢s3_nofinnosad no epnsoo oakscoehena on one mmouheo :vcsuom have ADV hope: no: ca compose“ escapee Hoapnoo any ”Seam condenno cannon epeflm vamumopmalmm mummy 65 per carton, and '7 cartons varied in coliform population from 2 to 12 per carton (Table 23). when using cleaning Method II which included a daily hot water rinse on the mandrels and hub, the total counts on 18 ”dry formed" cartons ranged from less than 1.0 to [.8 organisms per carton (Table 23). Seventeen of the cartons contained less than 1.0 coliform and one contained 1.1. coliforms. When using cleaning Method III which employed a hot water rinse, a chlorine solution rinse and another hot water rinse, the total counts on 54 "dry formed" cartons ranged from less than 1.0 to 150 organisms per carton. Coliform counts were all less than 1.0 per carton (Table 23). Obviously the mandrels and the hub must be properly cleaned im- mediately before each operation. As a result an internal cooling sys- tem for the mandrels was installed which eliminated this source of contamination. fig effect .Lf covering Mons with contamggted _i_c_e_. The coliform count on a composite sample of the contaminated solution be- fore freezing was 1,100,000 per g. Immediately after the solution was frozen and stored, the coliform count was 450,000 per g. The coli- - form count of samples of slush ice which covered the cartons during transportation varied from 60,000 to 500,000 per g. (Table 21.). Analysis showed that milk in the non-iced plastic surfaced and wax coated cartons contained less than 1.0 coliform organism per 10 1111. (Table 21.). o.H V o.Hv w 3. N 0.0 0H o.H V o.H V OmH op N HN bNON H33 some 000m c.HV o.HV NM 3 o.H v .NH 000 top can: mops: non 9029000 can .005.» o.H V o.Hv Nm 3 N N6 bNON noHesHoe 00H.H o; v 0.7 mm 3 m S 0me node .3 83:8 o.H V o.HV NOH 09 0 «UN ommH 005E nope) pom .HHH .3 3 o.H V 0.0 3 3 o.Hv 0H 83 H33 node 0.8.39 o.H V o.HV e 0» o.Hw o.H.V ome 02:.H n30: pom .HH 0; V 0.3 80; 3 93 OS om o 3 04 v H; 81m 8. m 80 om 0 3 o.H v o.H v ONH 3 NH we om o 8. 04v 0.? 8.}, 3 S oR.~ 2 NH 3 04v 04 8a; 3 a. 80 S as... no... 88 o.Hv o.Hv 0.3 3 N 00 bNoN 80H.“ 08.03 0.0m .H 03.30 000.30 mom 03.30 000.30 men 035:: mqusoHo mo cocvfia ( pea £300 0560 E08300 no you 08.80 08.60 H.309 Mo 90H EofiHoo emcee: 030.5524 H.093 no 093% emcee: 03055.24 03.30 mo om 300nm nooemH 003.30 .R no Hers. some 5 33.30 on? 53 3.3.3 REV .00: 00.0 30.603 0:» no 00033000 b03800 exp .3 0300.38 no 0000.30 00009.50 030.03 i653.“ he“... no 3:000 EouHHoo use 303 cemvssmeIMN 3mg. TABLE ZAP-Califom population in milk packaged in non—iced cartons and in cartons covered with contaminated ice .— 5“..- Cartons covered with contataninated ice (2O cartons in each trial) Plastic surfaced (six trials) Wax coated (two trials} Description of samgle I II III IV V VI I II 1. Escherichia coli per ! gram r-‘f ice 500,000 250,000 60,000 76,000 160,000 145,000 f 140,000 86,000 2. M"1‘; 1:1 iced cartons: f A a. Average Per ml.