HEALTH NOTES

Evening Post, Volume CXI, Issue 106, 7 May 1931, Page 17

HEALTH NOTES

MILK : ITS COMPOSITION

, ADULTERATION DANGERS

' (Contributed- by the Department of ;., ' ■'.'>•. Health':) . ■ Milk is a.-substance which varies considerably in composition oven in ani- .'. mals of "tho siitno species.. The basic y ingredient is water, in which tho rc;>m;i.iniug components, .arc cither dis- ! solved-or.hold in-suspension. Ordinar.iily milk:edntains approximately S7 per cent.'. of-'.water, and at loast 3.25 per bf-butter-fat and 8,57 of solids -other/th,an!?fat. When the solids fall /below;this.the purchaser does not re- . ceive full Viihie for. his expenditure. On "this account legal standards have been -adopted in practically all'countries. '; Pat is one of the most valuable con- /. stituents of milk. ..It is.present in the ■ form of an emulsion, the droplets being ' held in suspension'and giving the milk .' its normal colour. ,;The amount of fat varies considerably, many cows produe,iug a milk which contains as high as : 5 per cent;-of butter-fat, while with '; other breeds , the. percentage is much "lower. .;.. : i - Milk strippings are richest in cream, s while the first milk drawn is poor in this ingredient. Unfortunately, the of a milk cannot in every ■instance be determined by the thickness .; of the cream layer, although most house- :^ wives- place entire, dependence upon ■■j this method. Milk" which has stood : • but a short time will necessarily ' have ' only a thin stratum' of cream,' while , that which has been agitated may show >■ Jiono at.all, "the iat being '-. evenly dis- ■ ! tribu'ted. ..Again, milk -whiclr.has been , hoatcd beyond a certain' temperature 'shows only: a slight cream; layer. , ; . It is to'.;be realised that a deficiency Q in a small .amount of fat is;not nearly 5- as important 'as-' other considerations, " such asj..t.h)9 presence of- disease bac- ' tcria.- -"." ;•", IMPORTANT AS FOODS. \;. A number of substances, called pro- .■- teins, of complex chemical composi■••f tion, are also : found in milk and are "'.' important as foods. The principal one .is casein, familiar as the curd-in" sour ' ■"<:, milk. "When milk is taken into the stomach the casein is precipitated from ' its watery solution by the ferment ;ren- ;. nin used in eheeseniaking. ; The case- £ in of cow's milk when precipitatedVin. ' this.manner, during the.act : df.digestion' ' "iorma much "larger and tougher curds ■-than the'casein of mother's, milk, and Whence.is: more difficult of■'■■.digestion; • Other proteins, known as albumin and. ■■ globulin, aro also present.;-"Protoins are .'always present evoa 'in skim.. milk, : and for this reason milk, deprived: of V its fat has still considerable food value. l': A third constituent of -milk "is lac-. "■ tose or milk sugar. This substance is similar'to- ordinary ■sugar in conipositioi, but differs from, it in sweetness and other properties'." It" chars-upon-heating, thus giving the milk a brown colour when the temperature approaches the boiling point. When the sugar _is acted upon by bacteria in the milk, it ferments and the product of thig fermentation is lactic acid. The.latter causes old milk to taste- sour, and throws down the casein in the form of curd. "While there is approximately 7 per cent. o£ milk sugar in mother's milk, there is less than 5 per cent; in cow's milk. Lactose is to bo preferred over other sugars in the preparation of wtants food. -, c Various salts, notably compound of .time and phosphorus, aro also .present in milk. ABNORMAL QUALITIES OF MILK. A bitter taste may bo caused by certain plants or weeds eaten by cows or it may be due to tho action of bacteria. In tho first instance tho milk is bitter when drawn, while in. the second the bitterness docs not develop until several hours later. Bitter milk is never desirable, although it may not be directly injurious. A change- in tho colour may be brought, abbuf by a number of causes. It mirv\ tie due to the' consumption- by cows of-certain plants containing a large-amount of pigment, or it may result from contamination with various bacteria producing a red or blue discolouration. Frequently discolouration is duo to the presence; ot blood resulting from inflammation of tho uddor. The use of milk of this" character is dangerous; thcreforo, any variation from tho normal colour should be recognised as a warning signal. __ SUiny-mHk-may-be dae;Jo..infiammatidn;.of ;-Wojudder,.to,age, or *e;^re Sonceotf bacteria.'^Milk ; showing these. prppertifef'should;bo;re]ce.tcdas unfit.f or consumption, n;. ;-,;..,- ■:,' ■>~ .', .'•.. %, .-,L ■■ !Milk: readily .absorbs odours,- and tne flav'6ur.:rnay- be modified' by ;many atftir clcs; with--which iit: comes in contact., Thus; millc which, has ■been stored -with foods'' wiich possess a,';distinct oddur,. often■ dqvejops. thej 'characteristic scent, even-when exposure has,boon of short duration., Cattle;which have been fed on fermented .foods', ensilage that is too greenVimoiiMy grain, etc, almost _ mvar?(ib'ly^sc«reto milk';, of,a distinctive colour.- (. '■'■ '''/■■'"■'•:■ ■'■■ '■"■ •:•■, '.''.'•/ .'-MILTC ApijLTERATION. . '-'JChß' addition' of water is unquestion-. ably • the oldest form of adulterating milk;' 'In proportion to the amount of. water-added it causes a diminution in the Various elements, and if the water'is'contaminated it may. bring abdutkho 'development of typhoid fever, dysentery, ,and other water-borne diseases. Sldmruing is the least objectionable form of adulteration from a health standpoint. It consists in removal of the:*at - by, a separator or by abstraction of -the. top milk or cream. The legal standard :in-New Zealand is that milk shatf contain at'least 3.25 per cent, -of ■ ■M^lkiS^ccasionally.adultoratod with colouring. a;gents'to:give it the appear? anee of ■ ricKiresS. •' ■; '. ;■ •' •' ■ ':;. :';■?•,;.■;•;; ::.'bSeservaxives. iifilk is'an. exceedingly'perishable piio'ducifc,.compared;in^ this respect with' fls;h. meatj'etc. It spoils most readily if. 44tfmaintained, at a proper temperature, fiii'd ifi cleanliness is not exercised in the- haiiclling-'';Certain- chemicals have, .'be'eW-fb'iirid-ta-.delay or retard this .docomposition, ami those substances, known as milk preservatives, were at ono time widely in use to prcservo milk. Chemicals' are not to be, regarded as Bubstituto for cold-and cleanliness, tho only satisfactory preservatives, and their use is a plain indication that the ordinary and customary precautions in handling have not been exercised. These adulterants, now prohibited by law, are easily recognised by suitable tests and samples, which are constantly e-xam-incd for such by the-Department. ACCIDENTAL IMPURITIES. Prom a health standpoint the, accidental impurities of milk are more important than those just discussed, the adulterations intentionally added by men. Illuoss seldom arises in adults from tlio abstraction of any. element contained in milk, but serious maladies may result from contamination which is. accidental: though nevertheless proyentiple. Carefulness in production; and handling ia as much to be esteemed' as/strict honesty in composition, although in .'the past: the averago porsonj has .'given more consideration to tho formec'tHan-to the latter. BACTERIA IN MILK. Invrtriiibly accompanying and intimately associated with dirt in milk iivc other substances far more injurious than dirt in itself. These are bacteria. All milk contains bacteria in greater or less degree. Certain of these organ-

isms.may be derived from tho udder.of' cither diseased or normal animals, others may have their source lit- filthy conditions.: in tho' -milking....sheds, or .they may occur'from contamination 'in handling.and aro. therefore aii. . index, 'of faulty, milking or methods of handling of milk. - ..A good milk nia'y contain .very few bacteria, and there aro undoubted instances of untreated (raw) milk containing as few as 100 bacteria per cubic centimetre.

When milk is exposed to a temperature of 343 degrees 1\ and is. held at. tliiit point for 30 minutes, all diseasoproduciiiK organisms arc destroyed. If tlio supply is then immediately chilled further multiplication ot! Ilio remaining genus is temporarily inhibited. This treatment of milk is taken advantage of in the process known us "pasteurisation." . , ...

Tho difference between pasteurisation and boiling is only one of degree, tho former destroying only harmful organisms, while tho latter kills practically all varieties, "harmful and harmless alike. Boiling, however, is open to the objections that it produces a change in tho colour of"tho milk, re-, tards the rising of the cream, ■■• leaves a "cooked taste," and destroys certain vital principles which are found in raw milk. It is a very certain way, however, of making a suspicious milk absolutely safe. ..'. . . ; For adults' pasteurised milk is as nutritious as raw milk, and. the digestibility of the two is the same. JTor infants, however, there is _ the objection that pasteurisation partially destroys the anti-scorbutic vitamin. This is of little moment, for in all cases of infants fed artificially the addition to the diet of the juice" of. fresh fruit, such as the orange, effectively and simply prevents, scurvy. The process of pasteurisation" is not a substitute for cleanliness; which pievents .access• of dirt and bacteria, nor for cold, whichpreve'nts their- rapid increase. It merely.■supplements,.';;; theje measures, providing an additional and a more thorough'safeguard. KEMEMBER. Thero is only one method', by which disease germs can be eliminated from our milk supplies—that is,; scientific pasteurisation. Pasteurised milk is more economical because it keeps longer... It is safer because the germs of disease are killed. Dirty and adulterated milk is dangerous. Impure water added.to iraOs. may result in. outbreaks-. o£ typhoid;r fever, dysentery, and other water-borne diseases. > Persons engaged■:in. ;thei. milking !of reovra» or in.^ the - : distribution, orhandliigof milk: 'should keep- their clothing.',and person;scrupulously ;elean.' 'Anyone who is incontaeti w_ith; a case of infectious disease and continues to handle and distribute niilk may be responsible for bringing disease ■ and possible death to the households supplied.