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Show MILK PASTEURIZATION Chief Function Is the Destruction of Disease - Producing Organisms Clean Milk Made Safer. That there ls non valid objections tc pasteurization when properly performed per-formed and that tho process makes safer oven tho most carefully handled and Inspected milk, ls tho conclusion of a new professional paper of tho department, in which aro set fortu tho most recent conclusions of scientists scien-tists in regard to this matter. It seems probablo, Ba8 this paper, tint within tho next two years n lnrqo proportion of tho milk supp'y in tho large cities will bo pasteurized Thero ls already a marked tendency In this direction. About ten yearB ago only G per cent of tho milk supply sup-ply of New York City was pasteurized. pasteuriz-ed. In 1914, 88 per cent was treit-od treit-od In this way. At tho present tlmo 80 per cent of tho milk supply of Boston Is pasteurized, and thero aro corresponding Increases In many of tho smaller cities, Beforo the valuo of pasteurization as a hygienic meaBuro was as well recognized as It Is today, It was practiced prac-ticed In secret by a number of milk dealers as a means of preserving tho milk and preventing It from souring. Its commercial nlucj In this respect Is undoubtedly great, but Its chief function ls tho destruction of dUeaso producing organisms. Proper pasteurization pas-teurization should destroy about 99 per cent of all tho bacteria In tho milk, although when tho bactorlal count of tho raw milk Is low tho reduction re-duction may bo somewhat smaller. Tho efficiency of tho process, It Is pointed out, can not bo based on tho porccntngo but rather on tho character charac-ter of tho bacteria destroyed. Tho kinds of bacteria that remain alive nfter pastourlzatlon depend on tho temperaturo to which tho milk Is heated and tho species of bacteria which aro In tho raw milk. Three processes of pasteurization, known respectively as tho flash process, tho holder process, and pasteurization In tho bottle, aro now practiced In this country. In tho flash process the milk Is raised quickly to a temperaturo of about ICO degrees r. or moro, held thero for from thirty seconds to a mlnuto, nnd then cooled quickly. In tho holder process tho milk Is heated to a temperaturo of from 140 degrees to lf0 degrees F. and held thoro for halt nn hour. "When pasteurization In bottles Is practiced tho raw milk Is put Into bottles with watertight seal caps which aro lm-me: lm-me: sod In hot water nnd hold for from 20 to 30 minutes nt a temperaturo tempera-turo of 145 degreos. In this wny tho pasteurized milk Is not subjected to any danger of reinfection. On tho othor hand, tho seal caps must ho absolutely tight, nnd this Involves n creased cost. In general, It may bo said that tho holder process Is coming com-ing Into greater favor than cither of tho others. This process permits of tho uso of lower temperatures, which for various reasons, Is highly desirable desira-ble Another method of pastourlzatlon, pastourlza-tlon, or a rother a modification of tho presont holder process, suggested suggest-ed by tho department Investigators, Is that of bottling hot pasteurized milk. Tho process consists In pasteurizing pas-teurizing milk by tho holder process nt 145 degrees F. for thirty minutes, then bottling It vvhllo hot In hot hot-ties hot-ties steamed for two minutes Immediately Imme-diately beforo filling. After filling, tho bottles aro capped and mny bo cooled by any of tho systems In whch tho caps aro protected. The bottles nro sprayed with water or cooled by forced air circulation. When milk Is hold at 145 degrees F. for thirty minutes, nil tho dlsoaso producing bacteria, so far as can bo ascertained, nro completely destroyed. destroy-ed. At tho samo tlmo a larger percentage per-centage of tho bacteria that causo milk to sour and a smaller percent-ago percent-ago of thoso that causo It to rot aro left than when a higher temperature Is omployed. Pastourlzed at a low temperature, milk undorgoos no chango which nffects Hb nutritive value or Us digestibility. Subjection to a temperaturo of 150 degrees F. or moro, howovcr, doog result in cor-tain cor-tain chemical changes. Finally, pasteurization pas-teurization nt low temperatures ls moro economical becauso tho expenses expens-es of heating and cooling Is loss. This, of courso, docs not mean that Insufficient pastourlzatlon should over bo tolerated. As a matter of fact, tho process of pastourlzatlon Is frcquontly performed Improporly. Tor tho holder process, 140 degrees F. Is tho point at which Investigations havo shown that disease producing bacteria aro' killed, but In practice It is advisable to uso a temperaturo several degrees above this minimum of safbty. When tho flash process Is used, Investigation has shown that very, many dealers fall to heat tho milk to a sufficiently high tempera turo. This appears to bo another argument for tho uso of tho holder process, although conditions in this respect aro snld to havo been Improved Improv-ed greatly In recent years. Another common defect In tho piocess of pasteurization Is carelessness careless-ness In tho handling of tho milk ntt or it has been treoted. As has been said n'ready, this U ono reason why pasteurization In bottles Is advocated. advocat-ed. Ono false step In handling tho milk after It has been pasteurized will undo all tho good effects of tho process. The milk should bo cooled ns rapidly aa posslblo to about 10 degrees F. and kept nt that torn-peraturo torn-peraturo until delivered. If this Is done, thero Is only n slight bacterial Incrcaso during the first twenty-four hours, it has been hold by somo Investigators that bacteria grew faster fast-er In pasteurized milk than In rav milk. This point, howovcr, Iiob nuv-cr nuv-cr been thoroughly established, and other Investigations Indlcato that tho rnto of lncreaso is approximately tho samo. Another objection thnt has been raised to pasteurized milk ls that tho bacteria which causo It to bouV nre destroved nnd that without their restraining action tho putrefying organisms or-ganisms which survive form toxins and putrofactlvo products In tho milk. As haB been pointed out, this Is truo only of milk that has been pasteurized pasteuriz-ed nt a high tempernturo. As a matter mat-ter of fact, tho bulletin concludos pasteurization by tho holder process ls today tho most cffcctlvo means of obtaining snfo milk. This Is especially es-pecially truo of cities' which con-sumo con-sumo such great quantities that thorough thor-ough Inspection ls nlmost impossible. Now York City In 1912, for example used 2,500,000 quarts a day. This was furnished by nbout 350,000 cows, nnd somo of it wns transported moro I ban 100 miles. One hundred nnd twcnty-sovcn thousand persons, It Is estimated, wero engaged In handling It. Under such clrcumstnnccs pasteurization pas-teurization Is a necessary precaution. It Is, howovcr, to ho rogarded not as a substitute for.fbut as a supplement to, caro and clennllness In tho production pro-duction of milk. |