A STUDY OF SOME INFANTFOODS IN COMPARISON WITHMOTHERS’ MILK.By R. H. CHITTENDEN, Ph.D., Professor of Physio-logical Chemistry in Yale University. Reprinted fromthe New York Medical 'Journal, July 18, 1896 : : ;

THE DEFICIENCY OF FAT INDRY MILK-FOODS FOR INFANTSBy R. H. CHITTENDEN, Ph.D., Professor of Physio-logical Chemistry ifPYale University. Reprinted fromthe Dietetic and Hygienic Gazette, October, 1895 ; : ;

THE CONTENT OF FAT IN DRYMILK-FOODS FOR INFANTSBy R. H. CHITTENDEN, Ph.D., Professor of Physio-logical Chemistry in Yale University. Reprinted fromthe Dietetic and Hygienic Gazette, January, 1896 : : :

A STUDY OF SOME INFANT FOODSIN COMPARISON WITH MOTHERS’ MILK.

R. H. CHITTENDEN, Ph.D.,PROFESSOR OF PHYSIOLOGICAL CHEMISTRY IN YALE UNIVERSITY.

Reprinted from the IV. V. Medical Journal, July 18, 1896.

The tendency in infant feeding at the present time isclearly toward as close an approximation as possible towoman’s milk—to the scientific rather than the empiricalmethod. In view of this fact, it has seemed to the writera matter of importance to ascertain how near some of themore widely used infant foods approach to this nowtheoretically accepted standard.

Owing to the varied nature of the so-called “ infant ”foods—to the lack of any recognized standard of com-position for the various sorts of foods, farinaceous,malted, Liebig, etc.—it becomes evident that the mostpractical and most satisfactory method of comparing aninfant food with mothers’ milk is to analyze the food asit is prepared for the nursing bottle. Due weight mustnecessarily be given to the directions for preparing thefood for use ; for these are plainly of primary importancein determining the real food character and value of theproduct. It is the food in the nursing-bottle that is fedto the infant, and it is the composition of this productthat we need knowledge of. Some of the directions, how-ever, are so vague and offer such a wide variation in theproportion of the several ingredients that it would seem

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as if they were purely empirical and designed simply togive some food which would in some way agree with thechild.

It should be pointed out, however, that many of thesefoods do not specifically purport to resemble mothers’milk. The general tenor of their makers’ statements isthat they add something to enrich or improve cows’ milkfor the nutrition of an infant; for instance, that cows’milk is, by the process of manufacture, by the dryingwith farinaceous and saccharine matters, made moredigestible and wholesome for the infant, or that the ad-dition of malted grains renders the milk more suitable,or better adapted for an infant’s food. Moreover, thephysical properties and characteristics of most of thesefoods are such that it would be difficult to suppose it was

ever intended that they should resemble mothers’ milk.It is, however, contended for nearly all these foods thatthe casein is in some way rendered digestible, so that itwill curdle like mothers’ milk, etc.

In preparing these foods for analysis, the directionsgiven by the manufacturer have been followed as closelyas possible, and where, as in the case of some of thefoods, different proportions are recommended for differ-ent ages, the food has been prepared as directed for in-fants of six months, this being deemed the best courseto pursue for comparative study ; thus placing all on a

fair basis, each to the other, as to the relative composi-tion of the foods as actually in use at six to twelvemonths.

The analyses, therefore, present the composition ofthe several foods when ready for the nursing-bottle, withwater, milk, and cream added as specified in the direc-tions. The accompanying table gives the results ob-tained, expressed in parts per hundred.

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Composition of some InfantFoods as preparedfor the Nursing-Bot-lein comparison with Mothers' Milk. Prepared according to Direc-tions for Infantsof Six Months.

In the following discussion of these foods, it is thefood as prepared for the nursing-bottle that is to be un-derstood as referred to.

A careful study of these results reveals many inter-esting facts. Thus, only two of the foods show a specificgravity at all analogous to that which is usually takenas the average for mothers’ milk ; and these two foodscontain an amount of solid matter not far removed fromthat of mothers’ milk. The others have a comparativelylow density in harmony with their smaller proportion ofsolid matter, two, as the table shows, having but aboutfifty-four per cent, and one sixty-three per cent, of thesolid matter present in mothers’ milk. Hence, whateverthe character of this solid matter, these three foods arefar weaker fluids than ordinary breast milk.

* According to Leeds. tBy direct determination.

Mothers’ Malted Nestld’s Imperial Mellin’s Peptoge-milk.* milk. milk food. granum. food. powder.

Specific gravity.... 1031 1025 x 024 1025 1031 1032Water 86.73 92.47 92.76 91-53 88.00 86.03Total solid matter f 13.26 7-43 7.24 8.47 12.CO 13-97Inorganic salts .... 0.20 0.29 0.13 0.34 0.47 0.26Total albuminoids. 2.00 1. 15 0.81 2.15 2.62 2.09Soluble albuminoids 2.00 1.15 0.36 1.67 2.62 2.09Insoluble albumi-

O trace 0.450.360.84

0.48i-542.71

0 OFat 4-13

6-930.68 2.89

3-2f4-38j.261.18

O O 2.57trace

0 0 00 3.28

0.920

trace 2.2c 0DextrinSoluble starch.....

00 [ O.44 [ 0 -58 0.53

000

0 O I.99alkaline

1.22 0 Oalkaline alkaline alkaline alkaline alkaline

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The very great difference in the physical properties ofthese foods should be mentioned, especially in view ofthe fact that some of the foods when warm are compara-tively fluid and become quite thick or gelatinous uponcooling.

Just here, it is well to remember that the solubility ofthe constituents of milk does not depend upon tempera-ture. Lactose, mineral salts, and maltose are readilysoluble in cold milk as well as in cold water ; so thatcows’ milk, or a properly modified milk, is not noticeablythinner when warm than when cold. When, however,fresh milk has been evaporated to dryness, the solidmatter so obtained is not soluble or readily diffusible inwater, owing to the incorporation of hard casein and fat.In Nestle’s milk food, for instance, there is a very rapidseparation of the milk mixture into two distinct layers—-viz., an upper thin layer, and a heavier layer containingconsiderable insoluble albuminoid and starch.

The thickness of a food such as Nestle’s and imperialgranum particularly is undoubtedly due to the presenceof starch, which thus shows its characteristic behaviorupon mixing with water and boiling.

With regard to the amount of mineral matter, twocontain approximately the same percentage as mothers’milk, while the others have either an excess or deficiencyof these important elements, the excess being in all casesdue chiefly to alkaline carbonates. Although the pro-portion of inorganic salts present in milk is small, theimportance of mineral matters in the nutrition of the in-fant is not to be ignored or lightly passed over. Thegrowing infant must have a bony framework to supportits rapidly developing tissue, and if the necessary ele-ments are not contained in its daily food, how are theyobtained ?

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The albuminoids which are so essential for the growthand well-being of the animal organism, whether youngor old, are seen to vary in these foods from 0.81 to 2.62per cent. Compared with mothers’ milk, all but twoshow wide variations. Imperial granum and milk modi-fied by peptogenic milk powder, however, contain prac-tically the same amount of albuminoids as average breastmilk. Mellin’s food, on the other hand, contains thirty-one per cent, more albuminoids than mothers’ milk itself ;

malted milk has fifty-seven per cent, and Nestle’s foodforty per cent, of the albuminoids present in mothers’milk.

It is to be noted, further, that differences exist in thecharacter of thealbuminoids present, as indicated by thefact that in some of the foods a certain proportion of thealbuminoids is in an insoluble form. Thus, in imperialgranum, more than one fourth of the total albuminoidsare insoluble. In Nestle’s food more than one half ofthe albuminoids are in an insoluble form.

There are still other differences, not shown in the an-alyses, that need to be considered in connection with thealbuminoidal matter of these foods. Thus it is a well-known fact that the albuminoids of human milk differ ina number of ways from the corresponding bodies incows’ milk. Leaving differences in chemical composi-tion, etc., out of consideration, we may merely call at-tention to the way in which casein behaves when freshcows’ milk is mixed with dilute acid, as the hydrochloricacid of the gastric juice. Woman’s milk, when mixed withdilute acid, such as i-per-cent. acetic acid, or 0.2-per-cent. hydrochloric acid, yields a soft, flocculent precipi-tate of albuminoid, which is very different from thetough and solid curd formed in cows’ milk. The dif-ference is not due merely to difference in the proportion

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of albuminoid contained in the two milks, but rather tothe nature of the substance itself. Simple dilution ofcows’ milk with water is without avail in obviating thistendency of the milk to form tough and more or lessindigestible curds. It is obvious, therefore, that anymethod of modifying cows’ milk that aims to producea product analogous to mothers’ milk must take intoaccount this radical difference in the nature of the twocaseins.

The very first step in the process of digestion is theprecipitation of the casein in the stomach by the com-bined action of the acid of the gastric juice and the ren-net ferment, and with a weak stomach the form in whichthe casein is precipitated is a matter of some moment.As to how far this difference has been taken into accountin the preparation of the foods under consideration, wecan in a measure judge from the behavior of the severalfoods toward dilute acid.

This may be readily ascertained by placing a givenamount, say five cubic centimetres of o. 2-per-cent, hydro-chloric acid, on a watch glass, and then allowing the foodto fall, drop by drop, upon the acid.

A simple and suggestive method is also to take somebulk, say two ounces of the warm food, in a glass andadd the acid little by little, stirring gently. Tested bythese methods, it will be found that malted milk andNestle’s food both yield a fine, flocculent precipitate onthe addition of acid. Of malted milk it is stated that thecasein of the milk of this food is altered by the actionof plant pepsin, as a part of the process of manufacture.The incorporation of fresh, unaltered cows’ milk withsaccharine and farinaceous matters, and concentrationand reduction to a dry pulverulent form, must resultin a food containing casein in fine, hard, granular par-

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tides, and this may account for the fact that a dried milkfood like Nestle’s, when diluted and prepared withwater, does not behave at all like fresh milk caseinto dilute acid.

We have a striking illustration of this in the behaviorof Mellin’s food with the acid. Here the casein sepa-rates in flocks or curds when the dilute acid is added tothe prepared food, thus showing that the addition ofsoluble maltose and dextrin to fresh milk does not ofitself noticeably modify the character of the casein.

In milk modified by the imperial granum, the addi-tion of acid causes a very thick separation of the casein,and the separated casein appears gelatinous rather thancurdy, due probably to its intimate mixture with thestarch paste of the imperial granum. The lack of thetrue casein curd common to cows’ milk upon the addi-tion of acid is not due in this case to solubility of thecasein. It is the result evidently of mechanical mixtureof farinaceous matter with the casein, by which theprecipitated proteid is kept more finely divided. Fur-ther, it must not be overlooked that this result is accom-plished by the addition of a substance wholly foreign tothe natural food of an infant, and it may well be ques-tioned whether such a mixture is well adapted to itsnormal digestive functions.

In milk modified by the peptogenic powder, thespecific statement is made that the albuminoids of themilk are truly modified by the process to which they areexposed when the diluted milk and cream are warmedwith a specified amount of the powder. In conformitywith this statement it is found that the precipitate pro-duced by acid, while naturally bulky from the dueamount of albuminoids present, is composed of soft,non-adherent coagula. It is further evident, from the

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bulk of this precipitate, that the proteolytic action madeuse of in the preparation of the milk for the bottle hasby no means resulted in the complete digestion of theproteids of the milk, the transformation resulting sim-ply in a modification of the casein, with solution of asmall amount of proteid, so that the precipitate pro-duced by acid is much less bulky and less coherent thanthat from similarly diluted cows’ milk, to which has beenmerely added maltose or lactose. So far as our resultsshow, cows’ milk, modified by peptogenic milk powder, isnot to be classed with predigested foods, for the reasonthat the proteids of the milk are so altered as to renderthem closely analogous to the proteids of mothers’milk without converting them wholly into soluble albu-moses and peptone.

These observations naturally raise the question ofwhether any of these foods, when made ready for thenursing-bottle, contain active forms of enzymes of anysort, particularly proteolytic or amylolytic. So far as wecan find, the answer to this question is entirely in thenegative. None of these foods when prepared for usecontain any active enzyme capable of converting eitherstarch or proteid.

The enzyme of the peptogenic milk powder is ob-viously destroyed in the boiling to which the fluid issubjected during the preparation of the food. Hencethe conclusion that all of these foods when prepared forthe nursing-bottle are to be judged solely on the basis oftheir food value, since none of them possess any recog-nizable digestive power.

Neither is any one particularly or unduly digestibleas compared with mothers’ milk. Their utilization bythe system depends wholly upon the digestive power ofthe infant’s own secretions,

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With reference to the quantity of fat contained inthe several foods when prepared for use, only one con-tainsany approach whatever to the amount characteristicof mothers’ milk. In the food prepared by the pepto-genic milk powder the natural deficiency of fat whichresults from the dilution of cows’ milk has been over-come by the addition of a certain amount of cream, anaddition which, as the analyses show, is fully competentto attain the end in view. In all the other foods the de-ficiency of fat is marked, as the table of analyses shows.The necessity and importance of adding cream or fat tofresh cows’ milk, in order to bring the proportion of fatup to that of mothers’ milk, is here well illustrated, whilethe deficiency of fat in the foods prepared with the driedmilk products is extreme—very far below that of moth-ers’ milk.

The carbohydrate material of mothers’ milk, as wellas of cows’ milk, is composed solely of milk sugar. Inhuman milk the average amount, according to Leeds, is6.93, while in cows’ milk the percentage of the sugaris nearer 4.5. In malted milk and in Mellin’s food thetotal carbohydrate matter, represented by milk sugar,maltose, and dextrin, is not widely divergent from thatof breast milk. It is to be remembered, however, thatmaltose and dextrin are foreign substances, not con-tained either in cows’ milk or human milk, and, whileboth are undoubtedly possessed of high food value, yet itis equally evident that Nature gives preference to milksugar or lactose as the proper form of carbohydrates forthe nutrition of an infant.

As soon as the growing infant acquires the ability tosubsist upon solid foods the farinaceous matters naturallyconsumed are converted into dextrins and maltose bythe enzymes of the several digestive juices. But, prior to

this period, the food provided by Nature for the sus-tenance of the young is characterized by the completeabsence of every form of carbohydrate matter exceptmilk sugar. It may be said that infants thrive as wellupon maltose or sucrose as lactose, but in the writer’sjudgment there is no good ground for such an assertion.It may be true, but positive proof is wanting. However,at the present time, the writer’s purpose is to simply callattention to certain facts bearing upon the chemicalcomposition of infant foods in their relation to mothers’milk ; and, limiting ourselves to this point, we see onreference to the table, that only one product compareswith breast milk in the kind and proportion of sugarpresent. All the others contain more or less milk sugar;but in addition to this carbohydrate they are character-ized by thepresence of variable amounts of maltose, dex-trin, cane sugar, soluble starch, or starch, all of whichare foreign to natural milk.

The writer would not be understood as speaking ina derogatory way of any of these food products, or aseulogizing one product at the expense of another. Theyare all, no doubt, of value and useful, but with one ex-ception, when prepared for use, they show wide varia-tion from the composition of human breast milk. Itmay, perhaps, be a matter of opinion as to what consti-tutes the best diet for a young infant; but if we are toadopt mothers’ milk as the standard, then it is well forus to consider how far and in what respect the infantfoods widely used differ from this standard.

Cows’ milk is without question the best materialavailable for the nutrition of the infant when the latteris deprived of its natural food, and any modification thatwill render this fluid more closely analogous to breastmilk is certainly to be recommended on physiological

grounds. That there is no special difficulty in modify-ing cows’ milk so that it will resemble mothers’ milk,both qualitatively and quantitatively, is clearly appar-ent from the analytical results shown in the table.Cows’ milk, modified by the addition of water, cream,and peptogenic milk powder, offers a product contain-ing to the full extent all of the proximate principlespresent in human breast milk and wholly free from ex-traneous admixtures. The proportion of solid matter,fat, albuminoids, carbohydrate, and inorganic salts cor-responds as closely as one could ask with what is consid-ered as the average chemical composition of mothers’milk, and in this respect the product differs notablyfrom all of the other products examined. Further, theprocess of modification takes into account the radicaldifference between cows’ casein and human casein, andaffords a method by which the former can be modifiedto a closer resemblance to the latter without the additionof any substance that will permanently interfere withthe purity of the final product.

The general resemblance of milk modified by thepeptogenic milk powder to the infant’s natural supplyis a very striking one. The logical outcome of the pres-ent scientific attitudes must ultimately place infant feed-ing on a practical, exact basis, which will supersede theempiricism which has too long prevailed. In the con-sistent pursuit of this scientific attitude lies the onlyhope of any real progress.

THE DEFICIENCY OF FAT IN DRY MILK-FOODS FOR INFANTS.

R. H. CHITTENDEN, Ph.D.,PROFESSOR OF PHYSIOLOGICAL CHEMISTRY IN YALE UNIVERSITY,

Reprinted from The Dietetic and Hygienic Gazette, October, 1895.

In the May number of The Gazette we called attentionin a general way to the desirability of pure foods for bothadults and infants, and suggested a possible remedy forexisting evils. We must admit, however, that perhapsthe best remedy at present lies in the education of thepeople, so that they may have an adequate understandingof the dangers, both positive and negative, attending theuse of impure foods. With proper enlightenment on thispoint more strict enforcement of existing laws will natur-ally be called for, and we may then look for greater free-dom from foods of questionable purity. With this endin view, we desire in the present article to call specialattention to what seems to the writer a serious evil inconnection with a certain class of infant foods.

Among the various foods offered for the use of invalidsand young infants none appeal to the physician and tothe public more strongly than the so-called dry milk-foods prepared by the evaporation of fresh milk, becauseof the natural inference that such foods must necessarilyconstitute a model diet, especially for infants wheremothers’ milk is unavailable. Purity and concentrationboth seem assured, and the purchaser of such foods

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naturally assumes that he is obtaining an article theequivalent in every sense of pure, fresh milk. Chemists,indeed, have long sought to make a dry milk whichwould satisfactorily take the place of fresh milk, but sofar as the writer is aware a product which strictly fulfilsall the requirements has not yet been made. Condensedmilk still remains the chief reliance for dietetic purposesin all situations where fresh milk is not obtainable, butthe physician well knows that for the nutrition of the in-fant condensed milk is far from being an ideal food.The process of condensation as ordinarily conductedenables us to so concentrate the milk that approximatelytwo-thirds of the water can be removed and the constitu-ents of the milk preserved in their original condition.This process, however, entails the addition of cane sugarto such an extent that the finished product containsabout 40 per cent, of the sugar, thus making up about 55per cent, of the total solid matter. If now such a con-densed milk is diluted with water so as to bring thealbuminoids and fats to a correspondence with the origi-nal cows’ milk, it will contain approximately 16 to 17 percent, of cane sugar, and be altogether too sweet for use

as an infant food, to say nothing of the danger attendingthe introduction of such a large amount of easily fer-mentable sugar into the gastro-intestinal tract of a younginfant. If, on the other hand, the condensed milk be sodiluted with water that the sweetness is made comparableto that of fresh milk, either human or cows’, then theproduct becomes greatly deficient in fats, albuminoids,and salts ; i.e., its nutritive value falls far below that offresh milk. For these reasons condensed milk can

hardly be recommended as an ideal food for infants, al-though there may be times and places where its usebecomes necessary.

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The suggestion naturally presents itself in this con-nection, why not condense milk without the addition ofcane sugar ? Theoretically, this seems quite simple, butin reality the carrying out of the process is liable to beattended with certain undesirable results. Thus, if puremilk is evaporated to a density approaching that of thesweetened product the milk sugar crystallizes out, and ifnot concentrated very densely the cream separates andthe product does not keep well when once opened.Practically, then, unsweetened condensed milk is lesslikely to be successful commercially.

To one unfamiliar with the action of heat, long con-tinued, on milk, the thought might naturally present it-self, why not simply evaporatepure milk to a dry powder ?

If this could be accomplished in such a manner that theresultant product would dissolve in water and yield afluid really milk, it would be a satisfactory solution ofthe problem ; but this cannot at present be done. Inorder to thoroughly understand the problem, consider fora moment the chemical composition of pure cows’ milk.It contains, on an average, 87 per cent, of water and 13per cent, of solid matter, of which nearly one-third isfat. Now, on the evaporation of this fluid to dryness, soas to remove the 87 per cent, of water, there will obvi-ously remain a solid residue, of which 30 per cent., oreven more in the case of a rich country milk, will becomposed of fat ; i.e., it will be so rich in fat as to con-stitute an entirely impracticable product. Further, thedrying necessary to accomplish this result has a markedeffect on the fat; it loses its peculiar emulsified conditionand cannot now be diffused or suspended in water, as inthe original milk. Moreover, it acquires a brownishcolor, and is very prone to become rancid. Butter fat,as is well known, melts at a comparatively low tempera-

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ture, and a dry product containing 30 per cent, or moreof such a fat must necessarily be very unstable and proneto become rancid, especially when exposed to the air inwarm weather. Again, the process of drying has amarked influence upon the casein of the milk, renderingit hard and insoluble, so that it will not dissolve in waterand regain its characteristic condition. These difficultiesmay be overcome somewhat by the incorporation ofcane sugar and lactose, but this does not protect the fatfrom change, and the addition of these sugars naturallydefeats the object in view, since the product is not thena pure dried milk.

It is thus manifest from the foregoing statements thatit is practically impossible to prepare a pure dry milkwhich by the mere addition of water will yield a fluid atall analogous to fresh milk, and yet dried milk-foods arewidely used in the nourishment of infants. That theyare so used is due no doubt to the supposition on thepart of the purchaser that the foods are made from purefresh milk, and that they are in many respects more de-sirable than ordinary milk. Indeed, the specific claim ismade by some of these foods that they are superior toordinary milk, especially in the fact that they are com-posed of “ pure, rich cows’ milk,” combined with othersubstances designed to make the product “ resemble veryclosely the infant’s natural supply.”

We may thus properly inquire whether these dry milkfoods fairly represent average milk in the percentage ofone of its most important elements, viz.: the fat? Dothey, when prepared for the bottle, afford an equivalentto ordinary fresh milk-foods in the percentage of cream,and do they resemble very closely mothers’ milk in theircontent of fat ? The dry milk-foods most commonlyused are of two distinct kinds —one, milk concentrated

to dryness with malted cereals ; the other, milk evapora-ted to dryness with baked farinaceous substances and canesugar. A sample of “malted milk ” recently analyzedby the writer was found to contain 1.94 per cent, of fat.Assuming malted milk to be made by the concentrationof pure, whole milk of average richness, the above per-centage of fat would indicate that the actual milk solidshad been incorporated with say fifteen times their weightof other solids—of the dried malt. If such is the case,this dry milk-food contains a very small proportion ofmilk. Far more plausible is the supposition that thefood in question is prepared not from whole milk, butfrom skimmed milk, or from milk from which a portionof the cream had been removed. The correctness of thissupposition is indeed indicatedby the relative proportionof albuminoids, fat, and malt derivatives contained in theproduct. The actual fat present in dry malted milk is alittle more than half that ordinarily present in goodcows’ milk and about one-fifteenth that present in puredry milk.

“ Malted milk‘” when prepared with the maximumamount of water directed for an infant under threemonths contains 0.12 per cent, of fat. Prepared withthe minimum amount of water directed for infants fromsix to twelve months, it contains 0.21 per cent, of fat.Hence the young infant fed solely on such a diet willhave a food containing in the first instance only one-thirty-fourth, and in the second case only one-twentieththe amount of fat present in mothers’ milk—mothers’milk containing 4 per cent, of fat.

As a sample of the other class of dry milk-foods, we

may mention “ Lacteous Farina,” which contains from ananalysis recently made, 4.91 per cent, of fat. Here theamount of fat is greater than in the preceding prepara

tion, but is less than one-sixth the amount contained inpure, dry cows’ milk. If “ Lacteous Farina” is pre-pared for the feeding-bottle as directed for an infant ofthree months old, the mixture will contain 0.29 per cent,of fat, while for a child six months old the proportionof dry food and water called for in the directions willmake a mixture containing 0.38 per cent, of fat. Hencea young infant limited to such a diet will have a foodcontaining only one-thirteenth the amount of fat presentin mothers’ milk.

These facts certainly raise the question whether theadvantages connected with the use of these dry milk-foods are sufficient to compensate for the practical de-privation of cream which the infant fed upon such foodsmust endure. In the increasing scientific tendency ofinfant feeding, and in the widely recognized practice ofmodifying cows’ milk to a correspondence with humanmilk, the importance of cream as an element of the in-fant’s food is almost universally recognized. Yet, as we

have seen, these so-called milk-foods are wofully de-ficient in this important element. The addition of freshcream is evidently more essential in the use of thesefoods than it is with ordinary fresh milk, as commonlydiluted and prepared.

If we give due weight to the chemical composition ofthese dried milk-foods, and especially to their low con-tent of fat, we are at once confronted with the sugges-tion that the foods in question are manufactured fromskimmed milk, not for the sake of economy, but simplybecause the fat, if retained, would tend to spoil the food,for reasons already mentioned, and ultimately render itunsalable. There seems no plausible explanation of thecomposition of these foods other than the one just given,unless we suppose that the amount of whole milk used

in the preparation of the food is very small, in whichcase there is no justification for the use of the name“ milk-food.”

Apart from the consideration of these dry milk-foodsas representing cows’ milk in chemical composition andnutritive value, the question may be raised as to whetherthey are not amenable to the laws by which the sale ofmilk and food is regulated. By the laws of the State ofNew York, for instance, a food is defined as adulterated,first, “ if its strength or purity falls below the professedstandard under which it is sold.” Third, “if any valuableconstituent of the article has been wholly or in part ab-stracted.” So far as we are aware there is no intimationthat in the manufacture of these foods any portion of thefat of the milk has been removed. On the contrary, onthe circular accompanying one food of this class is thestatement that the basis of the food is “choice milk fromSwiss cows, concentrated in vacuo at a low temperature,so as to preserve its original valuable qualities un-changed.” The sale of skimmed milk is properly pro-hibited by law, and there would seem to be no reasonwhy’a dry milk-food for infants should not be amenableto the same law, especially when it is remembered thatthe chief arguments for the regulation of the milk sup-ply are found in its large use as a food for infants andyoung children. So long as these foods are sold withthe claim that they represent pure, fresh milk, or thatthey “ show a close resemblance to mothers’ milk,” theyare certainly open to criticism, for at the present day,when the tendency in infant feeding is toward as closean approach as possible to mothers’ milk, the markeddeficiency in fat in the above foods cannot be over-looked. Fat is an essential element in the nutrition ofthe infant, as well as of the adult, and its place cannot

be wholly taken by carbohydrates. It would seem wisestto follow nature’s leading, and when the infant is de-prived of its natural nourishment to supply a food whichapproximates as closely as possible to mothers’ milk,and if we are to adopt this law, due weight must begiven to the fat or cream, which is such a conspicuouselement. It is, therefore, very questionable whether themanufacturing necessity of leaving out the cream, inpart at least, in making a commercial milk product, issufficient justification for the use of foods so deficientin one of the chief elements of “pure, rich milk.”

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THE CONTENT OF FAT IN DRY MILK-FOOD FOR INFANTS.

R. H. CHITTENDEN, Ph.D.,PROFESSOR OF PHYSIOLOGICAL CHEMISTRY IN YALE UNIVERSITY.

Reprinted from The Dieteticand Hygienic Gazette, January, 1896.

In the October number of The Gazette(1895) attentionwas called to the deficiency of fat in dry milk-foods forinfants as compared with mothers’ milk, and emphasiswas laid upon the practical impossibility of manufactur-ing successfully a dry food by the evaporation of purecows’ milk, which on solution in water would yield afluid resembling or analogous to mothers’ milk, espe-cially in its content of fat. Further, in this connectionanalytical results were given showing that at least twowidely used dry milk-foods, when prepared for thenursing-bottle as directed, contained a very muchsmaller amount of fat than human breast milk. Sincethe above paper was written, however, certain facts havecome to the writer’s notice which have necessitated a re-

consideration of this question, and although the work wehave done in this direction has not led to any materialmodification of our views upon the main subject, it hasemphasized the importance of carefully considering themethods now in use for the determination of fat in dryfood-products, and rendered necessary a modification orcorrection of some of our previous statements.

The analytical chemist, whose work lies mainly in the

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domain of organic or physiological chemistry, wouldprobably consider a determination of the amount of fatin a dry and finely pulverized substance as a simpleoperation. The conventional method, in use now formany years, consists merely in thoroughly extracting aweighed amount of the powder with warm anhydrousether—preferably in some form of extraction-apparatus,such as Soxhlet’s—and weighing the fat so abstracted,after suitable drying at ioo° C. This is the methoduniversally used, and so far as I am aware it has neverbeen the subject of any decided criticism. By such amethod as this the writer found on analysis of a sampleof “ malted milk ”

1.94 per cent, of fat, the duplicate de-terminations agreeing so closely that the possibility oferror was obviously not to be considered. Shortly afterthe publication of the above article a paper was receivedfrom the physiological institute at Bonn,* calling atten-tion to the fact that dry, finely pulverized musculartissue—freed from all visible fat—gives up its containedfat to ether very slowly and incompletely. Indeed, Dor-meyer states that even after 100 hours’ continuous ex-traction with anhydrous ether in a Soxhlet apparatusonly of the contained fat can be removed, eventhough the material be brought to the finest state ofdivision. The full complement of fat was obtained onlyby digesting the muscle-tissue with active gastric juiceand then extracting the resultant solution with ether.The fat was found to be ordinary neutral fat, readilysaponifiable by alkali. At about this same time thewriter received a letter from Dr. R. C. Hindley, chemistto the “malted milk ” company, stating that the amount

* Die quantitative Bestimmung von Fett in thierischen Organen.Vorlaufige Mittheilung von Dr. Phil. C. Dorraeyer, FJliigers Archiyf. Physiol.., Baud 6x, p. 341,

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of fat contained in this product was much greater thanhad been reported.

These facts naturally led to a reconsideration of thematter ; analysis of the product was repeated, and tomake the trial as thorough as possible two determina-tions were made upon widely different amounts ofmaterial. The extraction with anhydrous ether wasmade in an ordinary Soxhlet apparatus, and was con-tinued for eight hours with the following results :

Especially noticeable is the close agreement of thesetwo results ; an agreement which, taken in connectionwith the wide difference in the amount of substanceemployed, gives an air of accuracy quite convincing.Indeed, it is very plain that the dry powder containsonly 2 per cent, of fat capable of being extracted byether, and yet these figures represent only about one-

fourth of the total amount of fat actually present in thepreparation. In other words, the ordinary method ofextracting fat from a dry and finely divided powder willnot remove from the “ malted milk ” powder more thanone-fourth of the contained fat.

That this preparation contains a farlarger amount offat than was at first reported we have been able todemonstrate by the following method : Dissolve, say 0.8gram of the powder in about 8 c. c. of warm water, andallow the fluid to be absorbed by a fairly large bulk offreshly ignited asbestos-wool contained in a Schleicherand Schlill paper cylinder (such as is used for fat ex-

tractions), using 1-2 c. c. of distilled water to transfer

“Malted milk” Amount of Percentageemployed. fat found. of fat.

(A) 2.1401 grams. 0,0425 gram. I.98(B) 5-6738 “ 0.1105 “

I.94

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the fluid wholly to the asbestos. By this method thefat-containing fluid is distributed over a large surface,after which the paper cylinder with its contents is driedin an air-bath at about so°-6o° C. for some hours, andfinally for about two hours at ioo° C. The cylinder isthen introduced into a Soxhlet tube, and extracted withether for 7-8 hours, etc. The following figures obtainedwith the sample of “ malted milk ” previously analyzedmay be quoted as showing the character of the resultsyielded by this method :

Especially noteworthy is the fact that the yield of fatby this method is just about four times the amountobtainable by direct extraction of the dry powder withether, thus agreeing with Dormeyer’s statement con-

cerning dry and finely pulverized muscle-tissue. Theseresults certainly raise a doubt concerning the reliabilityof the ordinary method for the determination of fat insuch products, and render it necessary for the carefulchemist to consider this possible source of error.Whether this danger is widespread, or whether it islimited to certain peculiar or specific mixtures or prod-ucts, the writer does not know. At first glance it mightbe assumed that this difficulty of completely extractingthe fat with ether is purely a mechanical one, dependentupon the possible lack of fine division of the particles,

“Malted milk”employed.

Amount offat found.

Percentageof fat.

(A) 0.8079 gram. 0.0642 gram. 7-94(B) 0.8079 “ 0.0635 “ 7.85(C) O.8333 “ 0.0659 “ 7-9° 9

(D) O.8333 “ 0.0658 “ 7.89(E) O.8333 “ 0.0665 “ 7.98(F) O.8333 “ 0.0670 “ 8.04

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or to the compact packing of the powder in the ex-tractor. These suggestions, however, are quickly nega-tived by the fact that several products resembling“ malted milk ” in their physical properties, recentlyanalyzed by the writer, yield their contained fat readilyand completely to ether by the ordinary method of ex-traction. Again, the close agreement in the results ob-tained with such widely different amounts of “ maltedmilk ” powder as 2.1 grams and 5.6 grams, otherwiseunder like conditions, suggests that a certain proportionof the fat—one-fourth—exists free, while the remainingthree-fourths exist in some loose combination with thecarbohydrate or albuminous matter of the compound ;

and in this connection the close analogy of these resultswith the results reported by Dormeyer in the analysis ofmuscle-tissue is quite striking and suggestive. Unlesswe accept some such explanation as the above, it isdifficult to understand why the fat in “ malted milk ”

should not be as readily dissolved by ether as that con-tained in similar products. Several hours’ continuousextraction with ether would seemingly be sufficient toentirely remove the fat present, no matter how closelyit may be blended, or how intimately it may be mixedwith the saccharine and other soluble constituents of themalted cereals used in the preparation of “ malted milk,”assuming no chemical combination to exist.

Whatever the true explanation may be, it is very plainthat the sample of “ malted milk ” examined by thewriter contains at least 8 per cent, of available fatAccording to Dr. Hindley, “malted milk” is intendedto contain on an average 8.5 per cent, of fat. This state-ment the writer is quite willing to accept, although inthis particular sample he has not been able to obtainevidence of more than 8.04 per cent. Dr. Hindley also

2 5

states that he likewise “ finds it impossible to extractfrom the powder much more than 2 per cent, of fat bythe ordinary method.” He employs a method for deter-mining the fat similar to that used by the writer, and helays special stress upon the necessity of drying theaqueous solution of the powder at a low temperature soas to prevent “ caking ” of the product.

We regret exceedingly the publication of any state-ment not strictly accurate, and consequently take pleas-ure in making the above correction. At the same time,candor compels us to express the opinion that the respon-sibility for this misstatement rests mainly with the manu-facturers of this food-product. The product is issuedwithout statement as to its chemical composition otherthan that it is “ composed of pure, rich cow’s milk com-bined with an extract of malted grain,” and that “ itschemical, physical, and physiological properties resem-ble very closely the infant’s natural supply.” The fat ofmothers’ milk offers no such difficulty in its extractionwith ether, and hence the chemist unfamiliar with theproduct would have no cause to suspect the inadequacyof the ordinary methods of analysis. The manufac-turers, however, being well aware that only one-fourth ofthe contained fat could be detected by the ordinarymethod of extraction, have, it seems to the writer, volun-tarily put themselves in a position where their productmight be misjudged.

However this may be, it is obviously necessary, inview of the facts, that some of the statements made inthe preceding paper upon this subject should be modi-fied. Thus, “malted milk,” assuming a content of 8.5per cent, of fat, when prepared for the nursing-bottlewith the maximum amount of water directed for aninfant from three to six months would contain about 0,48

26

per cent, of fat, /.<?., one-eighth the amount of fat presentin mother’s milk—mother’s milk containing 4 per cent,of fat. Prepared as indicated for infants of six months,the mixture would contain 0.64 per cent, of fat, whilewith the minimum amount of water specified for infantsfrom six to twelve months the prepared food would con-tain about 0.93 per cent, of fat. Hence, the younginfant fed solely upon such a diet will in the two lastinstances have a food with about one-sixth to one-fourththe amount of fat contained in mother’s milk. Our in-quiry was originally intended to call attention simply tothe deficiency of fat in dry milk-foods for infants ascompared with mother’s milk, believing as we do thatthe best and most natural food for the infant is thatwhich approximates most closely to the infant’s naturalsupply. The corrections we have made in regard to thefat content of “malted milk ” plainly show that thisdeficiency of fat is not as great as was originally stated,but it is equally evident that a deficiency exists, and toa very noticeable degree, in comparison with mother’smilk. We can therefore make no exception to the gen-eral statement previously made that in the use of drymilk-foods the addition of fresh cream is as essential ormore so than it is with ordinary fresh milk as commonlydiluted and prepared. We are well aware that the foodin question contains considerable dextrin as well asmaltose, but we do not believe that these are perfectsubstitutes for the deficient fat. An infant, no doubtmay manufacture fat from carbohydrates, but natureevidently has some reason for supplying the young infantwith the large amount of fat contained in mother’s milk,and there would seem to be no justification for the claimthat dry milk-foods resemble very closely in chemicaland physiological properties the infant’s natural supply,

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when there is this marked deficiency of fat, and a largesubstitution of maltose and dextrin, both of which areabsent from human milk.

Malted milk as well as other dry milk-foods are nodoubt possessed of high nutritive value, but there shouldbe a clear recognition of the fact that such foods whencontrasted with mother’s milk, are greatly deficient inthe fat which is so characteristic of the latter fluid.

Again, in our previous paper upon this subject thesuggestion was made that the comparatively small amountof fat contained in ordinary dry milk-foods might be ex-plained on the assumption that the foods in questionwere manufactured with milk from which a portion ofthe cream had been removed, or else that the amount ofwhole milk employed was small in proportion to theother constituents used in the preparation of the product.Pure cow’s milk contains on an average 13 per cent, ofsolid matter, of which nearly one-third is fat. Hence,the evaporation of pure rich cow’s milk to dryness wouldresult in a residue containing approximately 33 per cent,of fat. It is thus evident that a dry “ milk-food ” con-taining 8.0-8.5 per cent, of fat, if manufactured fromwhole milk rich in fat, must have considerable materialother than milk added to it ; indeed, the above figureswould suggest in the finished product a mixture of ap-proximately one-fourth whole milk solids and three-fourths of some other material, assuming the latter to bewholly free from fat.

We believe there is wisdom in the modern tendencyin infant feeding to approach as closely as possible tomother’s milk. Granting this, due weight must be givento the fat or cream which is such a conspicuous elementin breast milk. To make good this deficiency by additionof carbohydrates of various kinds can hardly be expected

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to give as satisfactory results as addition of fat, for fat isplainly an essential element in the nutrition of the infantas well as of the adult, and its place cannot be whollytaken by carbohydrates. It would be folly in infantfeeding to attempt any positive statements on generalprinciples as to how much fat or how much carbohydratethe infant should have. We can simply look to mother’smilk, and, taking that for our standard, rest assured thatin following nature’s leading we cannot greatly err.

REPRINTED FROM

New York Medical Journal, July iBih, iBg6.

Dietetic 6° Hygienic Gazette , October,

Dietetic 6° Hygienic Gazette, January, zYpd

FAIRCHILD BROS. & FOSTER,NEW YORK.