CASEIN IN MILK.

Otago Witness, Issue 2934, 8 June 1910, Page 8

CASEIN IN MILK.

AND ITS RELATION TO THE DAIRY INDUSTRY.

[ -.' By F. J." Heatley, M.A., M.Sc. It has been for Jong- a moot poi:;* with ' mrppliera of milk to cheese factories as to •. -whether the payment for milk on a fat fcasis. is a fair method. As a basis of payment for milk in butter-making there w, of course, no question, but in cheesemaking- it is considered that as the total solids in milk are fairly constant, a milk jpoor in fat is likely to be richer ia solids

fiot, fat—i.e., in casein, and therefore more valuable for cheese. On the other hand, there is a fairly general belief that fat and casein are present in constant proportions, and that, given the £*± percentage, the amount of casein can bfe "Calculated fey rule. This is fjpecially true of milks containing from 3 per cent, to 4£ per cent. of fat. The rule is given by Dr Van Slyke as-follows: —From the percentage of fat in ♦he milk subtract 3, multiply the result by A, and add this result to 2.1, and Is based on his investigations that milk testing 3 per cent, of fat aver»*yas 2.1 per cent, of casein,' and the caseia increases on an average A per cent., whew the percentage of fat increases 1 per cent, above B. For milks of upward of 4£ per cent. of fat the casein does not increase proportionately with the fat, and, further, it is * commonly-held belief that no cheddar cheese can hold more than about 3.8 per cent, of fat. Hence from a a&eese fac-tory-supplier's point of view were there tome quick and accurate method of determining casein the reasonable practice would be to pay out on the known content of fat and casein together. In view of the fact that Taranaki has many cheese factories, and the Stratford High School carries on a special rural course, Mr F. Heatley, who is <n charge pf the technical classes in dairy work, etc., has been in communication with some_ of the experimental stations in America. From the station in connection with the .University of Wisconsin, he received a. wood deal of information with regard to & simple test for casein likely to prove of interest and value to dairyman. The test ir&s invented' by Professor H?«s?i professor £f chemistry at the above univo? ftty, as the Iputoome of his investigations, and has been demonstrated at the dairy evening classes now current in Stratford to be a Wry quick and simple method. In the twenty-fourth annual report of she university Professor Hart reports that be., has thoroughly gone into the matter of Hie supposed definite quantitative relation between fat and casein. His results fro lo show.that to yedge the cas« < ontfnt of milk by its hi tfcwipnt : s :;, applicable to txiyiC miusx prccr -■ »j

' animals of high fat-producing.capacity. He ! goes on to say that " from the standpoint of the breeder of dairy cows andthecheesei maker, it would appear extremely lmportant to know whether or not animals pro-. ; ducing milks of 5 ner cent, to 6 per cent. j fat content are producing a definitely rei lated percentage of casein, and with animals I producing 3 per cent, to 5 per cent, of fat, ■whether the same relation, holds good. It it does not, then it would appear that here is important work for breeders of dairy cows "in the selection and production of ' animals producing milk more fitted for the 1 butter or the cheese industry, as the case j might be." tt 4. In summing up his report Professor Hart ! savs he has concluded that—" (1) The rei lation of casein to fat in cows milk is 1 a variable one. (2) One of the prime ! factors controlling the relation is the individuality of the cow. (3) The. relation : of casein to fat varies among ammaJs ot different breeds and amon? animals of the ! same breed. (4) Direct determination of i both fat and casein seems necessary in j determining the value of the milk in any I single cow for cheese production. I As a result of his investigation Professor : Hart has devised a simple mechanical i method for estimating casein—that is, in, I the words of Bulletin 156 of the university i received recently bv Mr Heatley, " opera--1 tive by the. unskilled, and can be used j with acuracy by anyon* when proper care is exercised." It is in most respects as ! simple as the Babcock tester, and m its use i especial care is to be given to the tem- | perature of acid and milk, the time of ; shaking to mix acid and milk and ohloro--1 form, and the -speed of the centrifugal. Should s.nyone feel sufficiently interested to write for details Mr Heatley will be pleased to supply them. The tester has not yet been introduced to this part of the Avorld, but doubtless when its value is demonstrated, as we hope shortly to do, some such tester will be an adjunct to most cheese factories. < Appended is a table of analysis of milk of the university herd, showing the percentage of fat and) casein, the amount calculated by Dr Van Slyke's rule, and also the relation of fat to casein and casein to fat. The calculations were made by the official agricultural chemists' method, the : only variation being; the use of the factor 6.38 instead of 6.25. The sample® were , from a mixture of night and morning's , milk. Fats were run by the Babcock, ' test from composite samples selected durj ing a period of a week in the usual way. > The samples for casein-testing were taken |'in the middle of the week, during which the fat samples were taken:

j A careful perusal of the above table will show that in many cases the rule for calculating casein holds good, but also that, as Dr Van Slyke pointed out, for high fat .' milks the agreement is not very close, and that actual casein determination alone • will give the true casein content. The table also shows that among breeds the Holsteins, brown Swiss, and Ayrshireshave a higher relative proportion of casein to j fat than do the Jerseys and Guerneeys, , and, further, that some individuals among , the latter show, as high a relation of casein |to fat as do certain individuals among other breeds. | As to what method on which payment should be made on a joint fat and casein basis it is not for me to lay down rules—that should be decided between the suppliers and factory associations, but something like the following may be here suggested. Instead of the fat or casein alone, suppose the payment was made in. some such way as adding the percentage of casein to that of fat and dividing by 2 as the average. Thus a cow higher in casein but poorer in fat than another would i receive duo consideration for hei cheese- [ producing quantities. To take instances from the above table: —Jewelletta: Casein 2.92 per cent., fat 6.02 per cent. ;—average, I 4.47 pere cent, (nearer the cheese fat content). Muriel: 2.03 per cent, casein, 6.04 per cent, fat; —average, 4.03 per cent. Marie: 2.15 per cent, casein, 3.03 per cent, fat;—average, 2.59 per cent. In this way a cow with good casein per cent, and fair fat per cent, would not be penalised, nor would a cow with a poor casein per cent., but high fat, receive as much advantage over a good cheese cow_ as she does now. However the payment is made is for others to say, but the fact remains that we have now a rapid way for estimating casein available.

TABLE OP ANALYSIS' OP MILK OP UNIVERSITY HEED, •n-a ° § c5 *3 1 $ *S 8 *5.5 -*> a (H Breed and a o a °'S , Name of S 1 Pk g 8.9 S .5 i oil Cow. P4 S SM ft 43 tl _ "S _ Jersey— Laura .. 2.45 2.60 . 4.27 1.74 : 1 .57 : 1 Double Time .. .. 3.11 2.83 4.83 155 : 1 .64 : 1 Macella .. .. 3.31 3.38 5.95 1.79 : 1 .55 : 1 Just in Time .. .. 3.65 3.24 5.85 1.60 ; 1 .62 : 1 Sadie .. .. 2.81 4.79 1.59 : 1 .62 : 1 Juvelletta .. 2.92 3.30 6.02 2.06 : 1 .48 : 1 Guernsey— .56 : 1 Cozie .. .. .. 3.S0 3.38 6.21 1.77 : 1 Floradora .. 2.77 3.30 6.01 2.16 : 1 .46 : 1 Queen .. .. 3.02 5.31 1.71 : 1 .58 : 1 Mollie .. .. 3.08 5.46 1.75 : 1 .57 : 1 Hannah. .. 2.91 2.85 4.89 1.67 : 1 .59 t 1 Countess .. 2.94 5.11 1.96 ; 1 .50 ; 1 Dorine ., .. 2.47 3.05 5.37 2.17 : 1 .46 : 1 Muriel ... .. .. 2.98 3.31 6.04 2.03 : 1 .49 : 1 Holstein— Alma 2.17 2.90 1.41 : 1 .70 ; 1 Joe .. 2.13 2.17 3.19 1.49 ; 1 .66 : 1 Maggie .. .. 2.27 3.44 1.37 : 1 .72 ; 1 Johanna .. .. 2.32 3.56 1.55 ; 1 .60 : 1 Maxie .. 1.88 2.17 3 18 1.52 : 1 .65 : 1 Marie , .. ... Brown Swiss — 2.11 3.04 1.40 : 1 ,70 : 1 .61 : 1 Irma 2.61 4.29 1.61 : 1 . Merney ... .. .. 2.70 2.49 3.99 1.51 : 1 .66 : 1 Ayrshire— 3.61 .70 ; 1 Priscilla .. .. .. 2.56 2.34 1.41 : 1 Christina .. 2.14 2.87 4.93 1.57 : 1 .63 : 1 Adelaide ... .. .. 2.47 2.28 3.47 1.40 : 1 .71 : 1 Jeanette .. 2.32 3,57 1.35 ; 1 .73 : 1 . , The data here given does not deny that a higher fat-holding nmlc means an increased casein-holding miik, but it does deny that'the increase is in a fixed proportionate rate*