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

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1. The biological value of proteins at an 8% level of protein intake measured on rats by the method of Mitchell (7, 10) was 52 for white bread of 73% extraction, 76 for Cheddar cheese, 75 for a mixture of both foods when each supplied 50% of the protein, and 67 when the two sources of protein were given on alternate days. The true digestibilities were, respectively, 99, 100, 98 and 99.2. Similar experiments with dried skim milk and dried cooked potatoes yielded biological values of 71 for potato, 89 for milk, 86 for the mixture and 81 for the substances fed separately on alternate days. The true digestibilities were, respectively, 82, 90, 82 and 87.3. An attempt to carry out experiments of the same type with dried whey and dried potato failed because of deaths of some rats receiving the whey diet, probably because of its high content of lactose. A biological value of 76 was obtained for the potato proteins and of 70 for a mixture of whey and potato in which whey supplied 25% of the protein. The true digestibilities were, respectively, 82 and 68.4. The biological value and the true digestibility of the proteins of a sample of edible soya-bean flour were, respectively, 73 and 90.5. It is concluded that there is a marked supplementary relationship between the proteins of milk and potato and those of bread and cheese when the members of each pair supply equal amounts of protein and when they are given together. No supplementary relationship is exhibited when the sources of protein are given separately on alternate days.

Section: Resultscontrasting

confidence: 65%

Section: Resultsmentioning

confidence: 57%

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337. The supplementary relationships between the proteins of dairy products and those of bread and potato as affected by the method of feeding. With a note on the value of soya-bean protein

Henry

Kon

1946

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“…Two types of bread were made, a national wheatmeal loaf and a milk-wheatmeal loaf in which roller-dried skim milk supplied about 20 % of the total protein in the bread; this higher level was chosen as it was felt that it would allow a supplementary effect to become evident (3). Actually the milk supplied 23% of the total nitrogen.…”

Section: Exp 1 Experiments With Young and Older Rats On The Effect mentioning

confidence: 99%

343. Studies of the Biological Value of the Proteins (Nitrogen) of Dried Skim Milk: Value As An Addition to Bread; Tests With Young and Olderrats; Effects of Storage

Henry

Rowland

1946

A considerable amount of work has been done in recent years on the improvement of the nutritive value of bread by the addition of small amounts of dried skim milk to the flour (i, 2, 3, 4, 5). It is generally agreed that this improvement is largely due to the protein, calcium and riboflavin supplied by the milk. The experiments now to be described deal further with the protein side of the problem.Our earlier experiments (3) showed that the addition of 2 or 6 % milk to white bread resulted in an increase in the biological value of the proteins of the mixture, but no evidence was obtained that, at these levels of feeding, the milk proteins exerted a supplementary effect on those of bread. At the time it was not feasible to make a simultaneous determination on the milk itself. It was suggested that this lack of a supplementary effect was probably due to the relatively low level of the milk additions. At the same time it was pointed out that, during the baking of bread, the proteins in the crust suffer some injury (6, 7), and that it was possible that the milk proteins might be similarly affected by baking to a degree sufficient to inhibit any supplementary effect. To test this point an experiment was planned in which milk was added to bread either before or after baking.We thought that it might be opportune to inquire at the same time into the effect of age of the rat on the assessment of the biological value of proteins, a problem on which the literature is far from unanimous. French & Mattill(8), for example, have reported biological values for white bread, containing an unstated quantity of milk, of 74 and 83 for young and mature rats respectively. Sumner(9), on the other hand, obtained lower values for dried milk and dried whole egg with 12-months old rats than with rats 40-50 days old.We decided to carry out the present experiment according to our normal procedure with young actively growing rats and to repeat it with the same animals when active growth had ceased. As a result of the findings of this experiment certain other problems arose, and the results of tests to solve some of them are also included in this report. The term 'biological value of the protein' recurs frequently throughout this paper and to economize space the abbreviation b.v. will be used. EXPERIMENTAL National wheatmeal bread made from 85 % extraction flour was used in the experiments described below. In all experiments the diets were made to contain about 8 % protein; the b.v. and true digestibility of the proteins were determined on rats by the method of Mitchell & Carman(io,11). In each experiment three litters of four female rats were used; they were 24-29 days old and weighed 49-68 g. at the beginning of the tests. The cages

“…Improvements in the nutritive value of white bread following the addition of whey to flour are described by Henry et al (322). Improvements in the nutritive value of white bread following the addition of whey to flour are described by Henry et al (322).…”

Section: (Ii) Wheymentioning

confidence: 99%

Section D. The Nutritional Value of Milk and Milk Products

Kon

1943

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Reviews of the progress of dairy science Thompson (30). Simple rapid methods for the measurement of the yellow colour of milk by means of a 'lactochrometer'(3i) and of carotene in butter fat by visual comparison with potassium bichromate standards (32) have been described. Effern(33) has applied the reaction of Rosenthal & Erdely(34) to the photometric estimation of vitamin A in butter, but the value of this method is not proven and the calculations are open to criticism.In previous reviews (35,36,37) papers dealing with the apparently abnormal behaviour of vitamin A and carotene in butter were discussed, but evidence is now growing that the vitamin A . activity of milk or butter calculated from proper chemical and physical measurements of vitamin A and carotene agrees with results of biological assay (25,38). The recent results of Fraps et al. {39) correcting their earlier findings also point in the same direction, while Shrewsbury & Kraybill(40) now report that carotene dissolved in butter fat devoid of vitamin A activity has the same availability for rats as when dissolved in cotton-seed or maize oil. On the other hand, Koehn(27,28) is still of the opinion that the factor for converting colorimetric readings into international units of vitamin A is appreciably higher for milk than for cod-liver oil.Normally the fat-soluble pigment of milk consists mostly of /? carotene and the ratio of 94 % j8 carotene and 6 % xanthophylls put forward by Gillam(4i) has been generally accepted. It has been known, however, for some time that the exact proportions vary according to the composition of the carotenoids in the fodder of the cow(37). More recent work in which the analysis was done by chromatography instead of by phase separation indicates that even in normal milk the contribution of /3 carotene may be smaller than hitherto believed, while special feeding of the cow may result in the appearance in the milk of much inactive carotenoid. Thus Johnson et al. (42,43) found in the butter of cows receiving molasses lucerne silage only 68 % of the total carotenoids in the form of /} carotene, the rest consisting of xanthophylls, 24 %, and 'acidformed' pigments(44), 8 %. Phosphoric acid lucerne silage yielded 65 % ft carotene and a higher proportion, 12 %, of pigments formed by the action of acid. Even pasture butter had 20 % of xanthophyllic pigments, but artefacts were absent and carotene amounted to 80 % (42,43). Similar values for pasture butters are reported by Thompson et aZ.(45) who also observed that Guernsey cows are less selective than Shorthorns and pass into their milk under comparable conditions a larger proportion of inactive carotenoids. This is doubtless another expression of the known peculiarities of carotenoid metabolism of the Channel Island cattle. There are further examples of these peculiarities. Thus, Gillam & Kon(46) showed that the Shorthorn cow effectively excludes lycopene, an isomer of carotene, from her milk, even when large quantities of it are fed in the form of tomato puree. Under similar...