J. Houston

The Vitamin B1 and Riboflavin of Milk. Part II. The Different Forms of Vitamin B1 in 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.

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.

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.

315. The effects of commercial processing and of storage on some nutritive properties of milk. Comparison of full-cream sweetened condensed milk and of evaporated milk with the original raw milk

1. Full-cream unsweetened condensed milk (evaporated milk) and full-cream sweetened condensed milk (condensed milk) were prepared simultaneously on several occasions each time from a common bulk of raw milk. Heat treatment in the preparation of evaporated milk is, of course, much more severe than with condensed milk. (a) There was no loss of vitamin A, carotene or riboflavin in either of the processes. (b) The mean loss of vitamin C as compared with the raw milk was 10% for condensed and 60% for evaporated milk. (c) The vitamin B 1 losses were 3·5 and 27% respectively. (d) Tests on rats showed that the biological values and true digestibilities of the proteins of the raw, condensed and evaporated milks were respectively 85·6 and 94·2, 84·6 and 98·8, 84·1 and 93·7. The differences in biological value are without statistical significance but the digestibility of the condensed milk was significantly higher than that of the other two milks.

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.

284. The effects of additions of dried skim milk and dried whey on the baking quality and nutritive properties of white bread

Experiments were carried out to study the effects on the quality and nutritive value of bread of the addition to white flour of roller-dried skim milk and roller-dried whey. Both samples were typical commercial products. Additions of 2% of the dried milk could be made without any marked effect on loaf quality or on flavour. The addition of 4% or more definitely lowered the quality of the bread, the volume being smaller and the crumb more rubbery. As the content of milk was increased above 2% the flavour of the bread became increasingly distinctive and departed from the normal neutral flavour of water bread. Up to 5% of dried whey could be added to the flour without any marked deterioration in the crumb of the bread, although with one flour this quantity decreased the volume by 16%. At this level, however, the whey imparted a distinct cheesy flavour to the bread. Attention is drawn to the fact that the effects produced by the addition of dried milk or whey to bread can only be considered in relation to the particular sample used, since other workers have found that modifications in the method of manufacture considerably alter the value of the product as far as its use in bread is concerned. For this reason improved types of dried milk or whey might well lead to their greater use by the baking industry.

The Vitamin B1 and Riboflavin of Milk. Part III. Effect of Stage of Lactation and of Season on the Vitamin B1 and Riboflavin Content 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.

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.

The Vitamin B1 and Riboflavin of Milk. Part I. The Application of Jansen's Thioehrome Test to the Estimation of Vitamin B1 in 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.

The vitamin Br and riboflavin of milk. Part III. Effect of stage of lactation and of season on the vitamin BI and riboflavin content 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.