ION | FERMENTED MILK Thesis for Degree M. Agr. F.0. FOSTER 1913 THESIS _——o- of KA Le \. t ry « ' de mwee eere new ae a 8 Pe ape“. $m, - ’ 4 J 4 qr . LIBRARY Ue, Moc! I7AN State TL PR CA IEW a f 4 : , “ = “ & eee. ee oe wot we eee: sf oe we ee ee . . wee oe - oe lee fee bet ee ve De REVO rE Se Ve HL EC ERCP EINES N Sey bro PS hie UE eS ese Dio - ote wat er - soe ee eee para wt wear pa sere rcse re sesh our? Rote, ye eel. le, at si ae sh be rion cyenrgenc i rb ORI, ae oe Fes tM ers Bay PE SS ee Le ea Fe ee me ae SER add]. lowe. ~~ +s = = . Vy % io | es ra Cc C on Panny re . ey 3 q DYCIS ULL: a 0351 1428 MN ly 3 THESIS Mai Bass ligig3 ad he ta eens : pike re x str se eee t¥xositiig gage sahi Simi dle} hai dheatas wa yar: | ‘ ee Ome s »- 4 oY s.. - + Vy r é oremwene eure cee. en sen a a ee H le Unive) RAE M chia State CRO OMY HOO Li deri Sales eheeses eae? ee 4 ar BOUT T ASME CARY fae rll. "7 s+ sev be Oe Bw ey as BLM KS ihre thi hts be abe ded se rina 4 arty die | i AvIS22 ALE NY bo ageag WES | AUVAUIT MAYG- 1913 FERMENTED MILK YOR D¥GRFE “ AS T ER O F AGRICULTURE . i S t monk bee ' ‘ ‘ f . . my nd F.o. FOSTER. FERMENTED ‘:ILK. A study of the subject from a practical business standpoint. Three imvnortant questions answered. 1- Is the tanufacture and sele of fermented milk a profitable underteking for firms engered in the dise- tribution of merket milk? 2. Can the process of manufacture be controlled so ag to overcome tre otjections that have teen raised ereinst it? 3. Has Bacillus Bulgaricus aiy advantage over the corwmon lactic scid cultures? 96510 (2) INTRODUCTION. Many articles roth technical end nopular have reen written on this subject during the last eight years. The most of the erticles published consider the subject from the medical etandnoint, or tne use of tne oroduct on a small scale. It is the vurpose of this study to show the practical application of it and its value to agriculture. Circular 171 of the Bureau of fénimal Industry, U. &. Departrent of Agriculture, entitled "Fermented Milks", gives the most comnlete bibliography send summary of the work done on the sutrject that has heen published to date. Some additional articles of interest in this connece- tion are: 1. Douflass: “The Facillus of Long Life", ational Food Vagazine, “‘sr- 1911. 2. Dunn: "On the use of living lectic acid bacilli to combat intestinal fermentation in infancy", Archives of Pedietrics, Aur. 1907. 3. Kendall: "Lactic Acid Eacilli: Whet they ere and what they are sunvosed to do", Archives of Pediatrics, Aug. 1910. The subject is divided by common apynlication into two pertes: A. Fermented skim milk es a substitute for butter- milk. EB. Swecial fermerited rilk. FRRYENTED SKIM MILK. Skim milk - butter™mil’ or Culture Process Buttermilk. The use of ekim milk fermented with lactic sciad bacteria «as 2 substitute for brutterrilk. Statement of existing conditions. Much tutterrilk sold to-dey in tne large cities is not fit for human food. The demand for buttermilk creatly exceeds the supply of ood buttermilk, and it is common practice among milk derlers to churn all sour milk and cream, end milk and cream returned from the routes which is too old or otherwise unfit to send out azain, and to sell it es and for buttermilk. Sometimes this is ripened over night with a nure cul- ture starter to irnrove the flavor and secure uniform con- sistency. Frequently skim mil’ is mixed with it and all rivened torether. Much of this milk, esnecially in hot weather, is in an advaencec stere of decotnosition, °es indicated ty foul odors, gas rubbles cnd severe ticn of vhey before it is Gurmnec into the vet for rinening previous to churning. The attitude of sore managers and superintendents on the subject is shown by the following: In one inetence when I objected to churrnins and putting out as buttermilk the rotten milk that wes Yreing dunned, the renly of the Sunerintendent wes, "There is a chance for you to show your skill in meking ¢ salatle product out of it. ‘Ye have not enough to supply the derend, aud as lone es veople will pay 5g a quert for it, we can not . o owe % -~ ’ —. pee OT ees - . ~ - at is of ere. tf econerin pnonorte Pome dt fe 4 ~ A at . O, FUORN TeOsu Mloer lie: -« ad we CF os: s ~ oo. La . . e e > c 4 ao kis upd ain une oleae 25 Da cle red , ae 4. +1. ~ oe os sn ~ rn icle, ee oe woh Sn Ge i, Etre yi 4 Ce vy. . + . Cc b YY C95 ee : if er” Cri VC c! ‘ “ rt n a a . / oc o3 a J ¢ s mom o Sen ge . ‘ Cc: 2 re ey Y We UNTO Tl Ler retiea Gk am oie 6 e . tow product is not uniforn end is 2fte- Th ~~ sm CC tb + oO ~~ me - cy @ 3 ty 4 2 : ay 2 ~ SOur wien received, cour rill rety gad eurevlus sive wil. Tris wae r 5 “ wey bes Ly + ee me 43 4. QB oure cultire sterter ere ryr-4ati? ~ | noe ri:ea t 4 Ca yu - 7 woON ww v* aN > ’ Vy a ‘ 9 so. L rs r . i % ~ : *N e -~ Lis er) fron Oo ao rn , wd ~~ = nroe » cave fi & Yes Os +) mo ~~ Ls as a4 Ie Que in u oJ rin) yn eet 1 OP ets w a why a . a wo Py ° . my 1 We tne cr, ~y 4 tay | ais vULY e thet w rou csoretires + . ‘> a a OOOO yoof € + ev > Coke a) “sy 1. aN Oe mo crates 4 ~-.¢ (iU- it do osre tiie eee ~— Cie ac his . a .. ea Le — . ‘ .. . 4. f..9 YY . . 2 WES MOu © FOr uot as ma . ’ wa fee ew OU ’ 14 _. 4. -o 3 | may me Durin ; aren ei Rye 4 PO 2.6 S9uL ~! ww ity of cultaire oruvcess buttermilk wos on te Prov 2 ed end ferreorusl skit milk. lt wes icvertisea as me SlLErGy, inecrersé is Cerin dt rvesnite3. la Avril J was Taldscd te Cy ser guart. Contrerg to ex -entat wes no fallin=s off in ssies but » continue’ incre 1O a@tternt war wade to deceive te elunaurer. was made that ltoves resulir tuctercitx. itoweer aid Sutil ¢S reins mete fear Fresh Pasteurized sj ~ : ey rm of ay: = “ +... NR. ka eae a WTS wee ol a -n \ * “ya hence was superior te vuttcryit’ wate Pror old va bos As eos weil = a eve = ° - vey yy - 2. ~ 37 @ 4 ‘ “tes ome ; a creas, Wolen Was wi@ Ofsy wane avy alLearle ain ouny Qu. A * ~e rs ‘p ns \. av, TC rF © rs c+ 7 { ~he J) Oo ow. Cc C2 ct Uther cl: tically the sare as +} Cc Cc Cc Tb 7? ~ rt A “N e- i ~ 3 ‘y‘ ~ 4 tee oO t © © a - 4 of Food vetue, sand more uniform in Plevoer :nd ecrncs The trece vo. tiie stray to ckhout SCC ssllone the suvmer end 3.0 ssllons a ay in tyne winter. Prcoof that tlk.e consurers oreferred the skim ~ Se De ot =Tre trie. ww A u WG b's ct cr 9 wld ma C8 MT fa "* ~ aonvi —T ion . ren ’ . 4 trl. .- we. cloenae - dA oa > 4 6 ; = 7 4 c r 4 duct was nedowhe:r ore dsy the butcermit™’ fron a feir oe q ‘ inz of Pasteurized satnered cream was sent out. complaints cane in. "Tne buttermilk was not ss 7 ual", "It was thin", It wes nart water", "It did riznt”, etc. 90d a claim 4 ‘ ~~ - Lised ty e ac= ane “umerous S use not taste The terrefits to the desler in t' is cvrse vere: Tnererseld sales. = ~ igher orice. A saving of much wills thet wes breint wasved. Petter satisfied custorers. Good will and recommendations of the onysiclians end hnealtn officers. a The consumers sot © surer Touod. Yeunod of hanufacture. « Much of the mil’ brougnt to the Indiensnoolis merket wh is from Jersey cows ens is ric: in total solics. men this milk is fermented tne resultins product is very thick. DPeo- 4* bone ple were used to trin Yruttermilk and corylasined avout 4.3 consisterec,. In order to setisfy tnis idea in tne nublic mind, we founa 1t necessary to dilute the skiyr rnilk tefore fermentins it. After nine dasys exnerirentine with dilu- ~ tions, fraduelly workins down and settine exoressions re- Swe eardini it from tne consumers, we establisted tne rete of 7 five parts skin milk to one pert water, wnich hes teen adhered to and given satisfrction for two years. At this dilution it is still sorewhat thicker than the *tuttermilk from the réesuler churuins end contains stout the same anrcunt of solids. In the cose of crear, the senaretor btowl is flushed with water, tre cress esns rinsed with weter, (somre- times at the farm a:.d azain et the cit; volant), and the vats rinsed with water, and by the time tne buttermil* is drawn from tne churn, it may contain as much water as was added to the skivr mil. fnelysis of buttermil* “er. 21, 1913, cave tyre follow- 9 ing results: The sennles weve taken from thre resuler cally make end renrescent tne averasce run. "7 rrom getnered crea churning: cc 04 “ff fat, 7-&" total rolids, -&S° acid. From diluted condensed svin fermented: 5 fat, 7-260 total solids, .635° acid. A recent report from Gerruny states tnat it was held in tne ccurts that 4 reasonable avrount of water was ver- misserle in tutterriix, anc that no esnvictions for éecdul- teration csuld,be secured even wren tue edded water ran as hish es 25). However we °re not advocating eculteration. I1t is Solely a ratter of catcrinzt ts tre demands of tne consumer. We tried to sive them tne uidiluted erticle end the, ot- jected to it. In worving up &@ new trece for skit milk butterrilx it misnt be veesitle to Ecueste tre consuner to tare it undiluted. Tnat owas done wit a sv-ecial fermented ~ilx very Successfully. “e voraised its consisteney with rernar’s like, "See now rich aud creavy it is", "See how it vaints the glass", etc. Peocle exnected it to be thick and come- pleined wnen it was not so. the adcitlon of sslt to the mixture of milk end wseter at the rate of ine sounc to SUC sallons was found to be beneficial to the flavor. (13) a The entire nrocess of weniutfsctiire 1s carried on sate ~~ — mew te ty 8 4, re 4 wh al etevrizivcr faa rinenins vat, vhich ny ale P isfectorily in one is connected with stean, cold weter ene hrine cr ice weter. The milk ig nut into tre vat anc the water aud salt added. The mixture is then heated to 150 desrees or hissner, cooled to 70 to 50 Gegrees, 2 to 5% of pure culture starter added, and allowed to stand 12 to 15 hours or until about 7 of acid nes cdeveloned. The baten is then cooled to Cc cesress or lover, agi- ep) 3 tated at the sere tire to thoreuchly bres the curd, strain- ~ ed tnrousn ¢@ wire resh or verforate?d metal strai:.er to re- move any lumos of curd revéeainin= untrokein, tottled and kept cold until delivered. Vigorous churnins or reoid aritation should be avoid- ed durins the latter wart cf thie coolirns or after tre oros duct is cold. If a numn is used to trensfer tre tuttermilk to 2a bottle filler, it shoul* run et © slov sneed. These precautions are necessnry to eviid foarings, which sives trouble in fillinz, causes amass of foamy curd to gather C2 in the necks of the bottles, end cuuses nocxets cof whiey to e senarate as the air bubbles work out. "nen it is desired to use the butterzils obtained from churnins the Pasteuvrized crear - snd it freguently hapnens thet sone of it is fit to use, esnecially when the cream is sraded =- the skim mil snovla be ferrented undiluted and cfter bkeins cocied, the other butiternilk (14) may be mixed with it at the rate of one wert of buttermilk to three or four narts of fermented s*im milk. Tnis will tive a product cf sbout the sere concistency and not dif- fering from tne usuel run enouch to ecnuse trouble. A trace worved up for the predict must te suorliedc throughout the year, ona et times when tre trilxk is needed for the resular milk trace sometning must be done to re- tain the butter rvilk tusiness. tJ o meet tnis difficovlty, triels were first made with milk flour or @ried ekim rilk. ‘Ctner firms had renorted fairly satisfactory results, and tre sun oly house claimed they coulda not set encuzh flour to sunnly tye denand. vy trials were ovi1ty partially successful. The vnroduct had - strornsz flavor of cooked milk, end the curd was not ss food as that from skim milk. ‘the flour wes not completely scolutle and an undissolved portion was always left in the bottom of the vat. The flour wes not uniform, one b=rrel beins stronser flavored, nsarder to dissolve end envosrently wrede from wril*® that was nearly SOUL. Tne better crates of flour could te used with fair results in prensrins sterter, but the vnroduct was not sate isfactory to sell as rutterril*. Condensed s*im milk wes next tried. ‘This was ottain- ed from {hicaso, Ill. and Newark, Chio.e It was claimed to be made from fresn skim milk concentrated four volumes into AT ~~ (1 one. the Chicazo sroduct nroved quite uniform et that density. At first the Newerk vroduct wes very variable, ranging from 21/2 to 1 to 41/2 to 1, and every shipment had to be tested and the dilution calculated. Later «after considerable corresnondence and adjusting of methods at the a of uniform density. D condensery the vsrodcuct was oPtain This condensed skim milk diluted to its original vol- ume when to be mixed with otner truttermil’, or to a spnec- ific gravity of 1-020 when used alone, made a buttermilk which could not te distinzuisned from that mace from fresh skim milk. Uwnwards of 250 gallons of tnis tuttermilk were bottled and sold daily for seversel montns during tne fall and winter of 1912 «© 1913 without comnlaint. Tris diluted condensed milk was Pasteurized and fer- mented in exactly tne seme manner aes tre fresh skim.- It 4 ’ not only held tne trace durins the snortaze in the sunnly of milk, but was hendled «et a sood nrofit. At the same time the firrs condensins= it were rekins a orofit, and trie farmers in tneir territory had amsarket for their milk, althoursn being too fsr from a lersze market to send the ilk in in its neturael state. During the last year there was sold in Indiananolis at the lowest estirate 150,000 gallons of culture orocess butterrilk for a sum exceeding #25,000. If the other cities in the Waited States, havins a nonuletion sbove 120,000, were to consume it at the sere rete ner canita, the aznount sold in these larver cities yearly would exceed 12,000 ,COO gallons with a selling value of 22,000,000. Speciel Fermented “ilk. Culture Studies. (17) Bacillus Sulgericus. The writinzs of Professor Flie Metchnikoff advoceting the use of lactic acid cultures, or soured milk, as a means of controlling fermentations in the digestive tract and preventins auto-intoxication have had more influence on the minds of physicians than is fcenerally sSuoncfed. Physicians in toth Furove and America took un the subject and the ~edical journels contain numerous articles givines reports of trials and recommending methods of use. As a result most nhysiciens cre familiar with the practice and will make use of and recommend it frequently where a reliable nroduct is obtainztle. The Bacillus Pulsericus, isolsted by Grereroff from sour milk from Rulsaria, was the lectic scid nroducings organiern recommended by YVetchnikoff, and is the one fener- ally advocated. The claims made for ©. Bulgearicus are: It produces much greater aquantities of lectic acid than the common lactic cultures. Its ovntimum temvnerature is about the terpereture of tne body. It will crow readily in the intestines, and tecoztins established in the lower intestines, will inhitit the growth of undesireple organisms or cause a more fevoreble fermentation. It i8 not attemoted in this study to prove the claims from a medical standpoint further than to note that favor- * Poisoning of the tbody by surstances resultins from the nrocesses incidental to its life.------Herschell. (15) able results were alrost inverisbly obtained by vhysicians in using the nroduct. Whetner the sane results would have been obtained witn a oroduct fermented by tne common lactic cultures can not be stated. The fact that the Pulserian or “etchniroff Racillus has such a nrominent rlace in the minds of the physicians and hes received so much nutlicity through nonuler maga- zine articles, gives a nrocuct containing it e great ad- vantage in placing it on tne market. “ilk fermented with this organism alone is not pal- atable.- It is very viscous or slimy in consistency and has a strons ecid tastee After a few trials of the culture, when I first began making fermented milx in 1910, I rejected it and went back to ry ol¢c “Starter". A year later, on taking un tne worry for tre Polk Sani- tary “ilk Coe they said, "Because of its advertising value and tne ohysicians derand for it, we rust put tne Pulgearian culture into it, if only in small quantities". So I started an investigation to determine: 1. What cultures would associate with the Rulgarian culture to wroduce the test results. O> How much @Wvlerrian culture could te used and make a vnalst- able oroduct wnich would sell for a teveraze as well as for a medicine. 3- Could these cultures te grown in association and tne milk fermented with a combined culture, or would they do tretter separately, the nrodcucts being mixed after fermrent- ing. (19) 4. What temneratures were rost favorable in eitner case. 5. The best metnod of manufacture to secure a uniform product from day to day. 6. How rich the milk should be to give a desirable flavor. 7+ Was there any benefit in adding yeast to the cultures of bacteria. Trial of Cultures. As this thesis was not olanned at tnat time, only general daily notes and conclusions were recorded. The complete data of each trial is not st hand. No attemot was mace to trace out the characteristics of each culture witn a view to establisnins tye identity of tne snecies or veriety- “ach culture was vlated to determine wnether it wes a nure culture of lactic acid wroducing pbpacteria, end was carried along and kept in a vigorous condition by daily transfers into sterilized milk. The tests were made under nractical working condi- tions, to determine which would stive the best flevor and consistency. The milk used wes taken from the daily run of mixed nights and mornings milk, and was Paesteurized in quart milk bottles in the laborctory. One or more cultures were also set esch day in two callon cans in order to have larger quantities for testing, jucsinz end exnerimentines with mixtures. (20) Cultures used. Name or source In what form purchased Yricsson's Putter culture In rilk Hansen's Lactic Ferment Powder Douglass Eutter Culture Liquid Keith's Lactic Acid Culture " MAC Lactic Culture "ilk Keith's Pacillus Tulssricus Liquid Bulgara Culture (Walker-Gordon Lab.-Balto.) Milk Bulgarian Culture (Perry L. Hobts, Cleveland) Milk The last two were combination cultures from which I isolated the organisms and used them the same as single cultures. I also isolated some lactic eacid becteria from the regular milk supnly tut did not succeed in getting any as satisfactory ase those nurchased. The above named cultures showec no ccontarinstion and ell develoned readily when transferred to sterilized ~ilk. Fach common lactic culture was srown lone and in defferent vronortions when mixed. ‘The time of develonment and effect on the oroduct was noted. After about ten weeks of exnerimenting the following conclusions were drawn: (21) Time. The product was no better when develoned in a few hours with a high rer cent of inoculation, than when a lonrer tire was taken with 2 lower ner cent of inoculation. As it is convenient in practice to let the mil’ ferment over night, fifteen hours was adonted as a convenient stend- ard and the ver cent of inoculation adjusted to bring the fermentation to the riegnt stege in that time. temperature. The temperatures tried ranged from 70 to 1C0O degrees. The most favorable temvoeratures for fermenting milk with common lactic cultures was 70 to 50 degrees. For the com- bined cultures 75 to %5 degrees wes most satisfactory. For the Rulgarinan cultures alone, 90 to 100 desrees fave best results, the higher tervnereture teins noreferred. Inoculation. The per cent of inoculation was varied from 1/4% to 10% with differences in the temoerature and time, and also with chanses in the visor of the culture. About .957% of acid was nreferred by the majority of consumers after the pnroduct was established on the market, although the acidity decided on in the latoratory trials was Oo to 9%. (22) One to 11/2% inoculation st 70 to /5 desrees cevel- oped the right acidity in the latoratory trials. Later it was found necesrery to raise both the rate of inocu- lation and the temnersture, 6% inoculation at 50 degrees being the other extreme. The following table giving tre avereszes for sixteen months, wes teken from « deily record and shows the varia- tion in temnercetures and rate of inoculation found necess- ary in vrectice to secure the proper development of the product. Month cuentity ner cent B to Temper- Time Acidity 1911 made caily ineculese L A oture Hrs. 90 ticn dererees fF. April Lab. trials 1 1 to 7 70 15 .& to.&6 May 170 etl. 2 1 to 6 75 to 80 14-17 June 165 - 165 3 le 5 75 14 July 16C - 190 3 to 5 Les 7 w- 60 16 Aug. 160 = 190 5 - 7 1-5 V7 - 0 15 Sept. 140 5 1- 6 50 15 Oct. 90 Ae § 1-6 V7 - 30 15 Nov. 120(3 a week) 5 1 - 6 50 15 Dec. 120 " 5 Ll - € 50 15 1912 Jan. 120 " 5 1-6 SO 15 Feb. 126 " 4-0 5 l- 6 75 2-50 15 195-1 Mar. 120 (KoD)” 5 1-6 75 = 40 15 Apr. 120°" 6 1- 6 EO 15 1 May 1-21 160 "™ 6 1-7 0 15 95 May 22-20 110 daily 6 le- 4 50 15 June 120 = 140 5 1- 6 0 15 295 * Every otner day. (23) During the remsincer of 1912 the quentity ran ae little less than in 1911, the averege per cent of inoculation was 5. The combination varied from 1 - 6 to 1 - 4, and the temperature from 75 to 30 desrees. In case of shortase or accident it is rossible to greatly hasten the process of manufacture. On one occasion I made a 100 gallon fratch in six hours, ty using fifteen per cent inoculetion and setting et 55 degrees. Association or Corbination of Cultures. In the first laboratory trials, the best results were obtained when one part of Kulgarian culture was used to five or six parts of common lactic culture. The culture increased in vigor and the rate was cut tol - 7. Later the proportion was increased and during the winter of 1912 & 1913 one part to four was used. Greater amounts of Bul- garicus gave a strong acid flavor end too sreat viscosity. Some differences in flavor develoned in the common lactic cultures end in this trial Ericsson's and Hansen's gave the most palatable product. The addition of Bulgaricuas in auantities not greater than noted above rather iroroved the flavor tran otherwice. co" wos secured that wane etsent co A pleasant "bite"or "tween when Bulfericus was not used. (24) No difference could te seen in the finished product, whether the milk wes ferrernted over night with the combin- ed cultures or the rilk civided, the woarts fermented with separate cultures and mixed after fermenting. The practice adopted after the preliminary work was to inoculate the milk at night with the two cultures, the cultures teing srown severately up to this vnoint. After nearly two years following that method, the method of div- iding the milk, fermenting the parts separately, and mixing it efter fermenting wes used for several months with equally food results. Combination Cultures. Triels of cultures rousht in combination all provec unsatisfactory. They contained an excess of Bulgaricus. When the orgenisms were isolated and used in the rignt proportions they produced good results. AS an exarvle, tne following was noted regarding a culture obtained from the Walker-Gordon Latoratory, Eal- timrore, iid. In severel triels using from 1/4 to 3% inoculation, and setting at ©O to 95 degrees, there wes too strong a flavor of the Pulsarien culture. Two ounces in one suart curdled in three hours at O05 degrees. One per cent inoculetion et oO degrees devel- oped 1.52% acid in 15 hours. 1/47 at 90 gave too much acid in 15 hours. (25) Microscopic examinetions of combined cultures show- ed the Pulserian Pacillus in numbers : bout eaual to the associate organism. Combined Cultures Possible. Trials were made with cultures combined in tre lator- atory which cerried successfully for seven to ten dzys.- corbined culture vorepared as for shinment was held tvo cays at room temnersture (7C to “O ceprees). It curdled in less than 24 hours. At the end of two cays microscopic examination showed Eulsericus oresent in relation to other lectics erout one to four or five. Another one cunce culture, inoculated 1 to 6, curdled in 20 hours, was left five days et 70 to OU decrees, then transferre’ to 2/4 quert of sterilized milk. The rilk curd- led in less than 24 hours and the microscone showed Pulgar- icus nresent in considerable numrers, tut in a smseller pro- nortion than the culture used. Jther triels were mede in “hich the cultures carried in satisfectory vronortions for G6 to 7 days. A culture inoculated 1 to 6, mailed and returned for better cddress, wes left et room temrereture for two drys, ae) then nut in a refrigeretor «et 55 desrees “or days. This culture nlcced in 2/4 nint of mil’ Ceveloned 2 food eurd in 15 hours, rut no Pulsericus covld be found by vnlat- ing or ricrosconic ecxnrinetion. (26) A culture inoculated 1 to 6 was transferred daily and csrried for 1/7 days at /0 to 20 degrees. tc Bulsaricus could te found at tne end of that time. A culture was sent to La Crosse, ‘is. on Auge 9th, anid carried as a starter until Oct. let. sy my request a samole of the starter was then returned which proved to be oracticelly a oure culture of the com~on lactics. The Racillus Fulgaricus hed dcied cut. I sent combined cultures to Dubuque, Ia. weekly from Aug+ 1911 to Freb- 1913, 75 cultures in all, with but one complaint: To St. Paul, Virn. weekly two sumrers and bi- weekly one winter with no compleints; To Los Anceles week- 4 ly for severel months, end to vericus other pleces for short periods end et irreculer intervals. Tne only difficulty net with was in shinning to Spoke m ane, Wesn-. The cultures were five deys on tre road and did nit cevelon pronerly 2st First. Py inoculeting with a very smell ver cent at cbout 50 degrees, trey went ‘through all right during tne wirter. As warm weatrner came con mrore trourle erose end eeper:te cultvres were cent. Conclusion: I1f combined cultures ere used they shceuld be inoculated in the rigcnt rronortion erd e fresh culture secured weekly. vO, ta PO ~ ~~” Uniformity of Product. Herscnell has written , "The comvrercial suovly of soured milk can not nossitly succeed ¢8 an industriel enternvrise, end as awmwatter of fact, in Peris the majority of firms which heve embarked in the business have now nracticelly erandoned it, as they have found their sales cdecre:re day by day- The main reason of this was thet they found it irnossitie to de- liver to their customers e rilk which resembled triat sucrlied upon the nrevious day". /nd further cn in the srme wore, mye must ehsolutely intercict tke use of commercial soured milk suynnolied ty dairy cornanies end nrivute individuals for grin". Again in his conclusion, "Do not under eny cire- cunstsnces order & comrercial preneretion of soured milk". Dairy conditions rust have been very tad in London when Herscnell wrote the ebrove, Tor in one rlace he stetes, "First of all there is the eifficulty cf vroecurine, at sny rete in London, a milk which contains ulsolutely ovo nreser- vative of aeny kind whevever". In our cities et t'.e nresent tire rreservietive in tre milk is = rare cccurrence- It is st most tires en easy matter to fet milk in food concition, so thet wit ~-ocern machinery and methods of Pasteurizcetion it is nossirle to manuf:cture a nrocuct nractiertlly free from undesirertle organisrs, cr nesrly cc nure culture of Lactic acid becterie. ¥ Sovured rilk, 1909 Pal. (25) Given pure cultures and food milk, the successful produc- tion of a beverage cenends upon céreful ettenticn to details in the process of monuf:cture. The separation of whey in the finished product is the most frequent cause of comvlaint-.- This may te due to bace- terial development from bad milk, improperly Pasteurized milk or contarinated cultures. lt may be ceused ty hand- ling the nroduct too warm, or by a ranid agitation or vump- ing which causes foaming when the voroduct is cold. The latter conclusion is drawn from the following: During “arch 1911, rilk was fermented in a vat, cooled, pumped into a churn and churned 1/2 hour which nroduced much foam. In this product the whey sevarated quite badly. A new vat was then used which broke the curd sufficiently withcut churning, the foaming was reduced end very little whey senurated. In “ay 1911, we started vumnine fermented milk with aonumo running rother fast. It nroduced much foam anda subsequent senaretion of whey. The synced of the vumn was Lowered, svoiding tre foam erid the trourle ceased. November 12, 1912 a new tank was installed for snecial fermented milk. ‘the agitator was ceared to run fast, which oroduced much foem end whey senarated. Another gear was nut on fSiving two sveeds. ihe high speed was used for break- ing the curd a:id nartly cooling the batch, then the low speed used to finisn the coolines. This nrocueced no foam ond there > “etnods of Vostevrizineg "ilk. Tne regular rethod adonted was to hent the milk to 150 to 2U0 denrecs, hold it et thet temo-ratore for 1/? to one nour, and cool to tre settings temoersture. oeveral tests of tnis rilk sfter Pasteurizing gave a count cf two ns nd trree colonies oer slate when diluted 1 to 1UC. _ The lowest terrerature ever sllowed wee 150 decrees anid cooled witnhsut roldcine. fit tires tne mil’ ves received in voor condition. Cften the count ren sbove 25,000 ,CCO tLecteriz ner cc. Tr Re Suttilis wee very numerous ut some s Dm asonSe ln extreme ceases srnecial methods vere resorte:’? to. TO. Vantard . 1 mave fre@fce$ milk +. \ Tan 2 7 , ~ . a4 (tae eee 1o5 decrees for tnree hours end rece or two montke Io oracticet renting to 10 - 195 de- crrees for two to tinree blours witn mood results. , to. 06€«ds , fA... ye 4d v See Lewin . 4 Aeeia Sor four rvonths I Peseteurired et VW acy C2 ct C* ry © © cerrece for ]/é to 1 hour, cecole? to "0 desrees, let stend eix hours enc renasteurized at 100 for 1/2 hour. oi * 7 wm ey > a er - , Cc ou . ~ 7 — aA ‘ . “3 4. > Scorcre&® Tleveor if Lerrely overcore Fy tie srolvece Ss Nee ; %. c . o % a co A a + .”* + “” : ‘ c~ _ ’ . wt tion of «cole, ard edds 2 not unnlessant taste to the “ro- an 4 c a ~a } °C =, on c r cn duct. 1°05 decrees for three hours fave too stront 2 scorehed i Oy a Dey Me Une vyilk 4 so re oeiver dn roo3 Cui Tationw la wee Tore voy it eof ss cat ie Fe oto ry bt2 we be) oe im ye cM y t/t } ry, eorl uel . ye ra ~ u “Se . - an ows v * Soe wi ‘ 7 Ls a | wal Live Lui WW t feu - Cor uti ft oatal e 1 Types at tl. Uecy Ue pir ce ee yh ole PV Ae aet toe & sresét ervtent the verret nriteec of tre nrostceu. Lt wie Centre 4 a“ Leo oda the mereet a Leverere trist would be sold et «& orofit at the nonular price of 5 cents. In some cities whole milk was fein: used and the vro- duct sold at ten cents a bottle (1/7? nints or 1/3 auarts), but a large trede could not re worked up at that price. It was to be sold aes a teverege and health drink, not as whole rilk, nence there wes no nerticular reason for leaving in sll cf tne expensive butter fet. At the same time it should te rich enoush to have a pleasant flavor and he considered as a bevereee in @ cless above buttervrilk. After trying rilk verying in richness by 1/2 per e¢ents from skimmed milk to four ner cent, it was decided that two per cent fat, or e€auel vnarts of whole milk and skim milk, met all of the reguirerents. An effort was merece to imnrove the flavor of fermented milk by the use cf yeast. VYefir and Youmiss, two vroducts that heve teen ~aede in small auentities for wany years, and for which metnods cf mexing ere given in meny dairy bocks, botn contain yeast in association with lactic tacteria. Two samples cf YFeremil-lac (the most widely known fermented rilk now on tne market); which I exatrined, cone tained a yeast in very small quantity. Sore articles on fermented milk advocated the use of yeast, and while no product that 1 had exanineG wes suvere- lor in eny way to the nroduct thet 1 was raking without yeast, i did not wish to overlock any onrortunity for im- oroverent. I triec cultures of yeust from the followings sources: Yeast isoleted from *eremil-leéc. Yeast isolated from Yefir Crains. Fleischmenn's yeast. Fottom yeest from tne Indiananolis Krewing Co. Yeast isolated from a sersle of starter from roovane, vasn- - Yeast from a Kraut culture imvorted from Germany by the J. T. Polk Canning Co. Trials were made with end without the addition of susar, glucose end dextrose; at verious temperatures, and with various ver cents of inoculstion. (32) In no case wes there any imnroverent over a vroduct mede at the same tire without the yeast. In most cases an undesirable yeasty odor and taste vas left in the fine ished product. If the inoculation was small enough or the fermentation carried on at temperatures to vrevent this, no difference could ve noted tetween the products made with and withcut the yeast. Reliability of Cultures. Nearly all cultures nurchased in milk or other liquid media, were nure and in a vigorous condition. Most tatlet vrevarations were very unsatisfactory. Sollowinge «re the results of some of the trials: Lectone = Parke, Pevis & Co.; Tablets nurchased et drug stores. Several trials were made during two years, end In most ceses S28 and bad flavors develoved and the mic- roscone snowed foreign organisms nresent. A few vnlated out pure and ceveloned a sood curd, but in these ceases the fla- vor was not ss cood as that in some other cultures. Bacillus Bulgaricus - Parke, Davis & Co.; Tablets obtained directly from the laboretory in Detroit. ¢* pure culture and very food. Fermenlactyl - A foreisn culture obtaine? from e Crus estore. | rupposea to te a combineticon of E. Bulesricus and a corron ry C4 lactic. Contained no Tulgericus but many “. Subtilis. (33) Yogurt - From Good Health Publishing Co., Fattle Creek. Obtained direct. Tablets loose in a vnaner tox. Sunnosed to be a Bulserian combination. No B. Bulgaricus or other lactics present. E. Subtilis and a yeast numerous. The following is an exemrvle of the condition of the tablet trade: In January 1913, 1 called at a vrominent down town drug store in Indianspolis and asked for lactic cultures. They were out cf Lactone tablets, but offered me two kinds of foreign tarlets. One rottle wes dated Jan» 1912, ( a year old). The other was dated Sept. 1912, good for four months. At the next drug store I found some fresh Lactone tablets, which hannened to he pure. Culture Studies. The effect of temvoerature on the crowth of RF. Bul. Rottles of milk that had been Pasteurized twice were inoculated with a vigorous culture of Facillus Tulgzericus xt the rate of 1 cc to 1/2 nint, and set at three differ- ent temperatures, viz-, Room at 72 desrees, Flectric incut- ator at 92 decrees, (was set et 6&5 and rose in a few hours to 92), and Gas incubator at 100 degrees. The acidity waa tested at 17, 41 end 65 hours. 72 degrees 17 hrs. not curdled .2% acid 4 1 "8 " "1 . 3 2% vs 92 degrees 17 " " (1 20K 41 " curdled (under 30 hrs.) 1.42% " 65 " 1 .93% " (34) 1U0 dezrees 1/7 hrs. curdled 1.242 acid Al " 2.1] 5 1 65 " 9 Or 1" The viscosity was sreatest in the culture et Je de- prees. ff eulture from Hansen's Lactic ferrent wes used at the same tire at 72 and 92 desrees. 72 degrees 1/ hrs. curdled 93% acid 4)" 1.08% " 92 degrees 17 " n 5%; " Vitality in cold. 12-30-1511, P. D- Co. Bul. after standing 13 days in the refrigerator, developed reedily in ev hours sat 37 de- grees C. with 1/2% inoculation. 1-1021912, Walker-Gordon Eul. efter 23 deys in the refrigerator developed in °4 hours et 27 degrees °C. with 1/2% inoculetion. Number of Facilli in “ilk. 11-21-1912, A vigcrous culture contained 114 ,Q00 ,UU0 per cc. 5-3-1911, Fermented milk, 1/70 gellons, set with 57 started (Bul. 1 to TA 7) 16 1/2 hours et /8 degrees, contained §,000,000 Bul. per cc. 10-10-1911, Milk Pasteurized three times, set 15 hours at 75 degrees with Ful. 1 to LA 6, made an extra good pro- duct with smooth and thick consistency. Gelatine plates at 20-25 degrees showed 500,000,000 lactics ner cc- Whey agar pletes at 27 desrees showed 4,000,C0CO Pul- per cc. 12-15-1911, Fermented milk, 1°C gallons, Pul- 1 toTAé 7, inoculetion 5%, set 15 hours ct c2 degrees. Product con- tained 6,000,000 Ful. and 5¢0,000,C00 lactics per cc. “iecroscopic exarination not a sure method of judging purity of avlture. 7D ©. Puleericus varies in size under different condi- tions of fsrowth, sometimes annesring as long slender rods, at other times mucn shorter ana thicker. It usually is much longer then eny other bacillus likely to get into the milk, and microsconic exarinetion will show when other organisms are present in any lerge numbers. Herschell ssys, “Always mske use of a voure laborstory culture wnich has teen standardized and examined microscop- ically for contaminating organisms." When B. Bul. is in the form of short rods it would be difficult to be sure whether others were present or not. On Feb. 16, 1912, my culture did not sct right, but the microscone showed nothing Put lons rods.