S. K. Kon

252. The effect of commercial pasteurization and sterilization on the vitamin B 1 and riboflavin content of milk as measured by chemical methods

1. Fluorimetric tests applied to commercially pasteurized and commercially sterilized milk showed that in the former some 10% and in the latter up to 50% of vitamin B 1 was destroyed in the course of the heat treatment. 2. Riboflavin withstood both treatments without loss. 3. These findings are in satisfactory agreement with the results of earlier biological tests.

170. The effect of commercial sterilization on the nutritive value of milk

We have dealt in a previous communication (1) with the effects-of commercial pasteurization on the nutritive value of milk. We present here the results of an enquiry into the nutritional effects of the more drastic heat treatment to which milk is subjected during commercial sterilization. There is no legal definition of either sterilized milk or of the process of sterilization, but in commerce it is customary to apply the term to milk which has been heated to at least 212° F. for varying lengths of time.

The vitamin A and carotene content of Shorthorn colostrum.

1. The concentration of carotene and of vitamin A in colostrum and colostral fat and the total daily yield of these substances in successive milkings has been studied for four shorthorn cows and nine heifers. 2. The concentration of vitamin A in the first colostrum ranged from 8160 to 820 Moore blue units per 100 g. and that of carotene from 2026 to 411 Moore yellow units per 100 g. 3. The highest and lowest concentrations and yields of vitamin A and carotene respectively in samples of colostrum and later milk were in the ratios: per g. of colostrum (milk) 35:1 and 65:1; per g. of fat 27:1 and 34:1; calculated on daily yield 31:1 and 65:1. This last calculation favours colostrum. 4. Access to pasture before calving appeared to have no effect on the secretion of vitamin A in colostrum but increased the output of carotene. Our best thanks are due to Mr A. G. Cotton who supervised the collection of the samples of colostrum and to Miss D. V. Dearden for churning the butters.

Reproduction and lactation in the rat on highly purified diets.

During recent years much work has been carried out to determine what vitamins and other nutritional factors are necessary for successful reproduction and lactation in rats and mice. Earlier work in this field has been reviewed by Folley, Ikin, Kon & Watson (1938) and by Foster, Jones, Dorfman & Kobler (1943). Nakahara and his co-workers (Nakahara & Inukai, 1933; Nakahara, Inukai & Kato, 1934; Nakahara, Inukai, Kato & Ugami, 1936) have described a diet on which rats would reproduce, but on which successful lactation could only be obtained by the addition of factors L, and L, which were present in liver and yeast respectively. Folley et al. (1938), using an apparently similar diet, failed to confirm these findings; they found that this basal diet was comparable with their stock diet as regards reproduction and lactation, and that consequently the addition of yeast or liver to the experimental diet had little or no effect. Later Nakahara, Inukai & Ugami (1939) pointed out that they had used a special type of baker’s yeast deficient in factors L, and L, and suggested that the brewer’s ygast used by Folley et al. (1938) had presumably contained both these factors. Experiments have been in progress here for over five years in which reproduction and lactation have been studied with rats receiving a basal diet of purified foodstuffs and supplemented with the known vitamins alone or with various other additions. A preliminary report of some of these experiments has been published elsewhere (Folley, Henry & Kon, 1942). A full account of the findings is given in the present communication.

258. The Vitamin B 1 and Riboflavin of Milk

Part I 1. A method for the estimation of vitamin B 1 in milk by a modified Jansen test involving takaphosphatase treatment is described in detail. Part II 2. It is shown by ultra-filtration experiments, by treatment with pepsin and takaphosphatase, with trichloroacetic acid and with fullers earth that vitamin Bx is present in milk unesterified and phosphorylated and that both forms may be freely diffusible or combined with protein either loosely or by firmer bonds. Part III 3. The effect of the stage of lactation on the amounts and partition of vitamin B 1 in milk has been studied. Samples of colostrum and early milk were found to contain large amounts of cocarboxylase (up to 80 % of the total). Hardly any cocarboxylase was present in mid or late lactation milks. The total vitamin B 1 content was 60–100μg./100 ml. for colostrum, up to 60μg./100 ml. for early milk and 30–40μg./100 ml. for mid and late lactation. 4. A marked negative correlation exists between the cocarboxylase content of cows and goats milk and their alkaline phosphomonoesterase titre. As this enzyme cannot dephosphorylate cocarboxylase it is probably accompanied in milk by other enzymes more suited to this process. 5. The suggestion is put forward that the vitamin B 1 of milk is mostly derived not directly from the blood but from the secretory cells of the mammary gland.

173. The effect of commercial sterilization on the nutritive value of milk. III. Effect on the vitamin A and carotene content of milk

1. The vitamin A and carotene content of raw milk have been compared with that of milk from the same bulk after it had been commercially sterilized. 2. For this purpose the fat was obtained by ether extraction from eleven samples of raw milk and from eleven corresponding samples of sterilized milk. As the sterilized milk had been previously homogenized it was not possible to churn it. 3. The vitamin A and carotene content was estimated by colorimetric (Lovibond tintometer) and by spectrophotometric tests. 3. The vitamin A and carotene content was estimated by colorimetric (Lovibond tintometer) and by spectrophotometric tests. 4. The results showed that the efiect of the heat treatment was negligible, neither method demonstrating a loss in vitamin A, while for carotene only the colorimetric method indicated a loss of about 2 %. 5. The vitamin A and carotene contents of sterilized milk were not decreased after storage for several weeks in a cool dark place.

196. The influence of various fodder supplements on the production and the nutritive value of winter milk

1. An experiment is described in which comparisons were made between the effect of (a) mangels (control feeding), (b) artificially dried grass, (c) sprouted maize, and (d) kale used as dietary supplements on the production and nutritive properties of the milk of dairy cows. 2. No significant differences were found between any of the foods in their effect on yield of milk, or its content of fat or solids-not-fat. 3. The feeding of kale and of artificially dried grass markedly increased the colour and vitamin A content of the milk, but sprouted maize had no more effect in this respect than mangels. 4. As compared with the feeding of mangels, sprouted maize and artificially dried grass had no measurable effect on the vitamin B complex level of the milk. 5. The vitamin B2 (complex) level was more variable and was lowest in the milk from the sprouted maize cows. It is not known, however, whether the difference was due to the feeding or to differences in the cows themselves. 6.The same statement applies to figures for the vitamin C level which was highest in the sprouted maize milk. 7. The growth-promoting properties of the milks produced on mangels, artificially dried grass and sprouted maize were compared. The milks were fed, supplemented either with minerals alone, or with minerals plus sugar as a source of energy. In one series of experiments the milks were given adlibitum , in another the intake was “equalized.” No differences were found and it is concluded that under English conditions, this technique does not disclose the presence in milk of a new essential factor.

240. The effect of light on the vitamin C of milk in different containers

The destruction of vitamin C in milk under the action of light was studied in different containers. Brown glass bottles showed little destruction, green glass bottles considerably more, and wax impregnated cartons still more. Nevertheless, in the latter, twice as much vitamin C survived as in clear glass bottles.