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T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
is still further oxidized and does not show up in the final reaction with the fuchsine bisulfite reagent. I n the presence of formaldehyde, therefore, i t appears necessary t o proceed somewhat as follows: Determine the amount of formaldehyde in the solution colorimetrically by means of the fuchsine bisulfite reagent and a suitable series of standards containing known amounts of formaldehyde. Then make up the methyl alcohol standards so t h a t they will also contain formaldehyde in the same concentration as t h a t in the solution t o be examined. After this has been done, the procedure referred t o above for estimating the methyl alcohol may be followed and the figures fm methyl alcohol obtained directly by comparison with these modified standards. HYGIEXIC LABORATORY,
u. s.
%'ASHINGTON,
PUBLIC
D.
c.
297
mained except t o consult actual analytical figures. We were able to obtain the figures of herd milk and of t h a t of a large number of individual cows of known purity in papers by Lythgoel and Sherman* and from our own work. The results of all three of these sources, about 1,600 samples, were separately plotted. Using the fats as ordinates and the solids-not-fat as abscissae, curves of the same general shape but on different portions of the chart were obtained. The making of a zone with the extreme curves as boundaries suggested itself t o Mr. Ekroth, giving the interior zone bounded by the lines K - K and P-P as shown in Fig. I herewith. 6.1
HEALTH SERVICE
55 RELATION OF THE FAT IN MILK TO THE SOLIDS-NOT-FAT By LUCIUSP . BROWNAND CLARENCE V. EKROTH
5.0
Received December 1, 1 9 1 6
I n the year 1910the New York State standard for the chemical composition of milk was placed by the 4.5 Legislature a t its present figures, t o wit: 3 per cent No standard for fat and 11.j per cent total solids. solids-not-fat was mixed. In making municipal standards the City of New 4.1 York was empowered under the law t o enact additional legislation but could enact no legislation conflicting with t h a t of the State. I n endeavoring t o secure a good milk supply for t h e city and, a t the same time, 3.5 to make figures which would be useful in the detection of adulteration, the only additional legislation which the city could enact was t o set a standard for solidsnot-fat, which was accordingly placed a t the difference 3.0 between the State's standards for fat a n d total solids, namely 8. j per cent. When a rigid enforcement of this standard was attempted it was objected by dealers t h a t the standard was an impossible one and t h a t the 2.5 ;D cattle in the city's milk shed could not supply it. 6 An investigation was, therefore, set on foot t o deP E R C€NT SOLJDS N O T FAT termine whether these claims were justified. I n the I 1 2.0 ccurse of this some very interesting facts developed. 8.0 6.5 9.0 < 1 1 I n looking into the experiences of the several states FIQ. I as (presumably) set forth in legislation, it developed t h a t apparently the standards for t h e different states This seemed promising but it was recognized t h a t with had been made entirely without system. For instance, such a small number of samples the influence of the one state requires a minimum of 1 2 per cent total many factors of variation in the composition of the solids, but only 2.5 per cent of this need be fat. milk might not be eliminated, these factors being: difWhether any normal cow could be found in t h a t state ference in breeds, the season of the year, feeding (or anywhere else) giving milk containing 9.5 per cent practice in different sections of the country and in solids-not-fat and 2 . 5 per cent butter-fat is not only different countries, etc. The available literature open t o a t least a reasonable doubt but i t is quite cerfurnished a large number of analyses of milk, the tain t h a t no unadulterated herd milk would even apsources drawn upon being Richmond, Leach, Haecker, proach such figures. Another state requires 9.75 Woodward and Lee, and others. Altogether the per cent solids-not-fat. We venture t o say t h a t a figures from over 200,000 samples, including approxiliteral enforcement of this standard would leave the mately 40,000 New York City samples (unpublished), state without a milk supply. were used. We exercised our best judgment in elimiThe legal standards furnishing no help, nothing re1
I
Ccnlr. Bakt. Parasitcnk.. I I Ab;.. 86, 4 9 1 .
1
Lythgoe, THIS JOURNAL, 6 (1914), 899. Sherman, J. A m . Chem. Soc., 26 (1903). 132.
298
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
nating samples apparently adulterated and it is our belief that the influence of adulteration in the large number of samples examined is negligible. T h e result was the zone, bounded b y the lines A - A a n d B-B, of the greater area as shown. It is significant t h a t in no portion of its boundaries does this zone exclude the smaller one. It is believed t h a t this larger zone offers a practical means of determining, a t least presumptively, whether or not a given sample of herd milk or other mixed milk is adulterated. Thus, if a given milk in its fat and solids-not-fat falls within the zone i t can, in the absence of other facts, be fairly considered t o be unadulterated but if the junction line of these two constituents falls outside the zone the milk is a t ieast suspicious a n d the burden of proof is then to show t h a t it is unadulterated. There will, of course, be individual animals whose milk a t times or continuously will not show the composition herein indicated, but inasmuch as milk supplies are made up of t h e milk of a number of individuals, i t is believed t h a t this chart will be of value not only t o governmental milk controls but t o dealers as well. T h e curve C-C shown about the middle of the larger zone represents a smoothed curve obtained from 1,000 analyses of individual cows made by Dr. Lythgoe a n d placed by him in 1 2 groups according t o the total solids. I n plotting this curve, however, total solids were disregarded by us a n d were separated into fat and solidsnot-f at. At the time this paper was read no method of treatment of the chemical composition of milk, having to do with the limiting values of unadulterated milk, had been found by either of the authors in the literature but we have since seen Dr. A. G. Woodman’s table on page 135 of his work on “Food Analysis,” published in 1915. While t h e two methods are not strictly comparable, Dr. Woodman’s idea of limiting values is t h a t which we had already adopted independently in this treatment of the subject. It will be noted, however, t h a t Woodman’s table referred t o is calculated from certain assumptions and analyses while we have endeavored t o confine ourselves only to published tables. Inasmuch as this represents a somewhat considerable departure from ordinary methods of treating the matter, we do not wish t o be considered as suggesting t h a t the zone in its present form represents absolutely true conditions but we present i t in the hope that i t may be tested out by workers interested in these lines t o t h e end that, if possible, a graph may be finally obtained which may be used t o give US absolute results in testing the composition of a n y sample of milk. It is hoped, in addition t o the use above suggested, t h a t this figure may serve as a guide t o our law-making bodies so t h a t they shall not make the impossible standards we have noted above. I n making this chart we attempted t o use analytical results from some 5,000 samples of milk produced in New York State as cheese factory supplies, but the average composition of these milks, when plotted according t o the solids-not-fat, gave the curve D - D in Fig. I, of a n entirely different form from any normal
Vol. 9, No. 3
milk curve which we have been able t o obtain, being convex t o the ordinate. T h e conclusion is irresistible t h a t a considerable portion of these samples had been skimmed. A study of the proportions of the two milk constituents mentioned, as indicated by this figure, shows some very interesting inter-relations. I n order t o bring this out more clearly, Tables I and I1 have been made. In. making both these tables, t h e fat has been used as TABLEI FAT Per cent 3.00 3.25 3.50 4.00 4.50 5.00 5.50 6.00
SOLIDS-NOT-FAT Av. 8.05 8.30 8.55 8.90 9.20 9.35 9.50 9.60
(PER CENT) Extremes 7.75-8.35 8.05-8.65 8.20-8.90 8.55-9.25 8.85-9.50 9.05-9.65 9.20-9.80 9.30-9.90
TOTAL SOLIDS Per cent 11.05 11.55 12.05 12.90 13.70 14.35 15.00 15.60
the fixed point and the solids-not-fat and total solids corresponding thereto have been sought. For the lower percentages, fat has been selected in differences of l / 4 of I per cent. The zone shows t h a t corresponding t o 3 per cent of fat, there may be from 7 . 7 5 to 8.35 per cent solids-not-fat. The average of these gives the figure in Col. 2 , Table I, while the total solids are, of course, the sum of this average and the fat. The limiting figure in this table should be of value t o legislators. I n Table I1 the difference apparent by a n examination of the chart in the increment of fat and solids-notf a t is reduced to figures. Thus, it will be seen t h a t in t h e lower ranges the average fat increments are about the same as those for the solids-not-fat but with about 3.5 per cent of fat the increment of t h e solids-not-fat begins t o decrease until on reaching the higher figures for fat the latter increment is less than one-third t h a t of the fat. T h e difference between extremes, as shown by Cols. 7 and 8 of Table 11, is also of interest, showing TABLEI1
DIFFERENCE BETWEEN
PER CENT FAT Approx. AverExtremes ages 3.00 2.85-3.30 2.95-3.60 3.25 3.15-3.95 3.50 3.50-4.65 4.00 3.90-5.40 4.50 4.20-6.25 5.00 4.50-? 5.50 4.75-1 6.00
INCREMENTS EXTREMES PER CENT Per cent Per cent SOLIDS-NOT-FAT Per Per Solids SolidsAverApprox. cent cent NotNotFat Fat ages Extremes Fat Fat 0 0 0.45 0.60 8.05 7.75-8.35 0.25 0.65 0.60 8.30 8.05-8.65 0.25 8.20-8.90 0.25 0.25 0 . 8 0 0.70 8.55 8.90 a. 55-9.25 0 . 5 0 0.35 1 . 1 5 0.70 1.50 0.65 0.30 8.85-9.50 0.50 9.20 0.50 2.05 0.60 9.35 0.15 9.05-9.65 0.50 ? 0.60 9.50 9.20-9.80 0.15 0.50 ? 0.60 9.60 9.30-9.90 0.10
the fat t o be much the more variable constituent. For a n y given average percentage of fat, it will be noted t h a t the maxima a n d minima of the corresponding figures for solids-not-fat have a comparatively limited range, these figures in no case being more t h a n 0.7 nor less t h a n 0.6 of I per cent. For the higher average percentages of fat, on the contrary, the difference between maxima a n d minima may be over 2 per cent. It will be apparent from these facts t h a t standard requirements embracing only fat a n d solids are illogical because it is possible so t o water or skim a milk with high fat as t o benefit considerably the dealer and, a t the same time, leave the milk well within t h e requirements of the legal standard for both fat a n d total solids. Table I1 likewise seems t o show t h a t the practice of paying for milk on the fat percentage basis will,
Mar., 1917
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
when t h e cattle predominating in any given milk supply are of breeds or strains having a comparatively low percentage of fat, probably have t h e effect of markedly raising t h e “solids-not-fat” b u t t h a t this effect will not be so marked with percentages of fat above about 4.50. Inasmuch as possibly most city milk supplies in t h e United States are now furnished b y cattle having milk of low fat percentages, this method of payment is t o be commended if a milk of given moderate nutritive value is desired; but, as has been pointed out b y others, this method of payment is unfair t o the man furnishing a low or medium grade milk, in t h a t his cattle produce relatively higher total solids t h a n cattle with a high fat content. It will further appear, from an examination of t h e tables and figures, t h a t in legislating, unless due regard is had t o t h e inter-relations of t h e constituents of t h e milk, legislators will make trouble for administrators by suggesting such a composition for milk as is not normally produced b y the cows themselves. Thus, for a standard of 3 per cent fat a n average of 8 per cent solids-not-fat would be proper and for 8. j per cent solidsnot-fat, the fat should be placed at 3. j per cent. It is t h u s seen t h a t t h e standard proposed by t h e Federal Government and in use b y them of 3.25 per cent fat and 8.5 per cent solids-not-fat is open t o criticism, t h e corresponding figure as shown by this curve being 8.3 per cent solids-not-fat as a n average and t h e same thing is apparently true of the standards of most of t h e states. It is worth while here t o note Fig. I1 of our accompanying paper on t h e “Chemical Quality of New York City Market Milk.” This figure shows t h e percentage of t h e samples in certain groups of known purity milk, arranged according t o t h e same scheme of percentages as indicated b y t h e tables in this paper. It will be noted b y reference t o t h a t paper t h a t t h e groups of t h e higher fat content and of t h e corresponding solids-not-fat show a marked parallelism, tending t o show the accuracy of t h e relationship indicated b y t h e zone chart presented herein. This is further indicated b y Fig. I11 of t h a t paper. SUMMARY
I-The zone chart devised appears to show t h e approximate chemical composition of normal milk. 11-This chart appears t o be capable of use as a guide in fixing legal standards. 111-It appears also t o be capable of use as a guide in detecting adulterated milk. IV-A milk standard having regard only for t h e total solids is illogical. V-Most of t h e legal milk standards in force in t h e several states of t h e Union as well as t h a t of t h e Federal Government are unbalanced and, therefore, incapable of enforcement. We desire t o acknowledge our indebtedness t o t h e sources of reference given herewith and t o Dr. L. L. Van Slyke, J. B. Newman, Assistant Food Commissioner of Illinois, and others for valuable information furnished in private communications. BUREAUOB FOOD AND DRUGS DEPARTMENT OB HEALTH. NEW Y O R K
CITY
299
CHEMICAL QUALITY OF NEW YORK CITY MARKET MILK B y LUCIUSP. BROWNAND CLARENCE V. EKROTA Received December 1 , 1916
The size of t h e problem presented in an endeavor t o control t h e quality of milk supplied t o New York City is one which is, of course, equalled nowhere else in t h e United States and probably in only one other city of t h e world. The population of t h e city is j,joo,ooo. It consumes daily about 2,000,000 quarts of fluid milk and as much or a little more milk in other forms. The fluid milk is collected at about 1 2 0 0 country creameries and pasteurizing plants a n d supplied b y some 4 j,ooo dairy farms located in 7 different states and in Canada. When i t arrives in t h e city, i t is distributed by about 600 dealers using more than 7,000 delivery wagons and b y 1 2 , 0 0 0 retail stores. It is axiomatic t h a t t h e cow producing t h e largest flow of milk will be the one favored b y t h e dairyman dealing with a city milk supply, other thingsbeingequal. Unfortunately, this tendency can be pushed t o extremes and i t is conceivable t h a t cattle may be so bred, with a n eye single t o the flow of milk, as t o reduce greatly and injuriously t h e food-value of this milk. For t h e past t e n years t h e chief efforts of the New York City Health Department have been devoted t o securing a safe milk supply rather t h a n one furnishing a maximum of nutrients. It is obvious t h a t t h e tendency t o reduce t h e quality of the milk supply must have limits set t o i t lest t h e community suffer from too great a reduction in the actual amount of food furnished b y it. I n a n attempt t o get together, in a n easily demonstrable form, information gathered during t h e past 40 years, we have made an exhaustive analysis of certain available data, hoping i t may be of use t o other food officials. Space, obviously, will not permit of detailed presentation of many of the facts which could be brought out. I n t h e years 1904 and 1905 this Department conducted a survey of the country creameries supplying t h e city, which resulted in t h e establishment in 1906 of a regular country inspection service. These investigations indicated t h a t a considerable amount of skimming had been practiced in t h e country. A comparison of inspections in 1909 with those of I g o j showed t h a t there had resulted, as the effect of closer supervision, a marked increase in t h e content of both fat and solids-not-fat, as shown by Charts a , b , c and d of Fig. I and as further indicated by Fig. 111. Up t o t h a t time the standard for total solids of New York State milk had been 12 per cent. The Legislature of 1901 reduced this t o 11.j per cent, t h e fat being left unchanged at 3 per cent. Inasmuch as a certain proportion of t h e milk supply had been running below the standard for a number of years prior t o this time, no marked change is indicated by Charts e and I, Fig. I, for 1912, except a slight drop of fat content; this is significant, however, only because t h e figures for 191j , when t h e lower solids requirement had been in effect for j years, indicated a still further lowering of t h e content of this constituent, very notable as
