Part 3 (2/2)

~Bacterial standards for city supplies~ It would be very desirable to have a hygienic standard for city milk supplies, as there is a butter fat and er ordinary bacterial determinations (on account of time required) makes the selection of such a standard difficult Some hold, as Park, that such a standard is feasible The New York City Milk commission has set a standard of 30,000 bacteria per cc

for their certified milk and 100,000 per cc for inspected milk

Rochester, N Y has attempted the enforceood results it is claial limit at 500,000 per cc Quantitative standards would seem eneral city supplies, where the wide range in conditions lead to such enormous variations that the bacterial standard seems too refined a method for practical routine inspection

~Other tests~ Any test to be ofquickly applied The writer believes for city milk inspectors that the acid test would serve a very useful purpose This test measures the acidity of the milk There is, of course, no close and direct relationshi+p between the developeneral way one follows the other at normal temperatures Where the teo on without reat ree of acidityperiod of incubation, or high terowth has been possible Either of these conditions encourages gerrowth and thus impairs the quality of the milk

The rapid determination of acidity may be made in an approxih-can or intake The test is best made by the use of the well known alkaline tablet which is composed of a solid alkali, and the indicator, phenolphthalein The tablets are dissolved in water, one to each ounce used A number of white cups are filled with the proper quantity of the solution necessary to neutralize say, 02 per cent lactic acid Then, as the milk is delivered, the proper quantity is taken from each can to which is added the tablet solution A retention of the pink color shows that there is not sufficient acid in the milk to neutralize the alkali used; a disappearance of color indicates an excess of acid The standard selected is of course arbitrarily chosen In our experience, 02 per cent acidity (figured as lactic), has proven a satisfactory point With carefully handled ht to be reduced to about 015 per cent The acidity of the milkto action of acid on the metal

[Illustration: FIG 15 Apparatus used inrapid acid test A definite quantity of the alkali solution and indicator is placed in the white tea cup To this is added the quantity of e measure which would just be neutralized if the acidity was 02 per cent A retention of the pink color shows a low acid h acid milk]

~Kinds of bacteria in milk~ The number of bacteria in milk is not of so much consequence as the kinds present With reference to the nun er the number of varieties found in the same While reat majority of them have no apparent effect on human health In their effect onupon their action in rouped into three classes:

1 Inert group, those producing no visible change in the ar with or without the forroup, those capable of rendering the casein of ested

A surprisingly large nu to the first class Undoubtedly they affect the chemical characteristics of the milk somewhat, but not to the extent that it becomes physically perceptible Eckles[46] reports in a creamery supply from 20 to 55 per cent of entire flora as included in this class

By far the roup is that embraced under the second head

It includes not only the true lactic acid types in which no gas is forases and various kinds of acids These organish they do not predominate when the milk is first drawn Their adaptation to this rowth, in which they soon gain the ascendency over all other species present It is to this lactic acid class that the favorable flavor-producing organis

They are also indispensable in cheese-

The third class represents those capable of producing a liquefied or digested condition on gelatin or in ain access froh powers of resistance due to spores h they are materially held in subjection by the lactic bacteria The number of different kinds that have been found inbeen described hly In all probability, however, many of these forms will be found to be identical when they are subjected to a more critical study

~Direct absorption of taints~ A tainted condition inupon various constituents of thethese in such a way as to produce by-products that impair the flavor or appearance of the liquid; or it ht in contact with any odoriferous or aromatic substance, under conditions that permit of the direct absorption of such odors

This latter class of taints is entirely independent of bacterial action, and is largely attributable to the physical property whichable to absorb volatile odors, the fat in particular, having a great affinity for many of these substances This direct absorption may occur before the milk is withdrawn fro odors

It is not uncommon for the milk of anily marked odor and taste; sometimes this is apt to be bitter, at other times salty to the taste It is a defect that is peculiar to individual animals and is liable to recur at approximately the same period in lactation

The peculiar ”cowy” or ”animal odor” of fresh milk is an inherent peculiarity that is due to the direct absorption of volatile elements froerated when the aniarlic, leeks, turnips and cabbage The volatile substances that give to these vegetables their characteristic odor are quickly diffused through the system, and if such foods are consu, the odor in the milk will be most pronounced The intensity of such taints is di is not done for some hours (8-12) after such foods are consuree to reen fodders that are reen rye, rape, etc

Not infrequently, such fodders as these produce so strong a taint in milk as to render it useless for human use Troubles fro li Under such conditions the taint produced is usually eli The milk of swill-fed cows is said to possess a peculiar taste, and the urine of animals fed on this food is said to be abnorrains and distillery slops when fed in excess also induce a similar condition in the milk

Milk may also acquire other than volatile substances directly fros, as belladonna, castor oil, sulfur, turpentine, jalap, croton oil, and many others have been used as medicine Such ht hours after ingestion, and persist for a period of three weeks before being eli~ Ifdrawn from the animal, it will absorb them readily, as in the barn, where frequently it is exposed to the odor ofbeen a popular belief thatas it is war air, but from experimental evidence, the writer[47] has definitely shown that the direct absorption of odors takes place much h under either condition, it absorbs volatile substances with considerable avidity In this test fresh nated with odors of various essential oils and other odor-bearing substances Under these conditions, the cooler milk was tainted very much less than the milk at body temperature even where the period of exposure was brief It is therefore evident that an exposure in the cow barn where the volatile emanations from the animals themselves and their excreta taint the air will often result in the absorption of these odors by the milk to such an extent as to seriously affect the flavor

The custo been deprecated as inconsistent with proper dairy practice, and in the light of the above experiments, an additional reason is evident why this should not be done