210 THE VITAMINS 



for a year during which time there was no appreciable variation in 

 the vitamin C content of the milk. MacLeod concludes that by including 

 good quaUty silage in the ration of stall-fed cows it is possible to pre- 

 vent seasonal variations in the antiscorbutic value of milk. 



Milk scalded by being heated rapidly to the boiling point over a 

 gas burner and then quickly cooled was found by Barnes and Hume 

 (1919) to retain about one-half of its original antiscorbutic value. Hart, 

 Steenbock and Smith (1919) reported that milk sterilized for 10 minutes 

 at 120° C, commercial evaporated milk and commercial milk powder did 

 not show antiscorbutic properties when fed in amounts corresponding 

 to protective doses of the raw milk. Hess (1920) stated that in his 

 own experience in infant feeding "dried milk not only does not lead 

 to scurvy but may contain sufficient antiscorbutic vitamin to cure this 

 disorder." He attributed the unfavorable results obtained by Hart, 

 Steenbock and Smith with dried milk to lack of uniformity in the prod- 

 uct and suggested that "For milk to retain its antiscorbutic value, not- 

 withstanding drying, it must have been rich in the vitamin before 

 desiccation, it must have been dried quickly, and packed within the 

 shortest possible interval in air-tight, preferably hermetically sealed, 

 containers. As in relation to the heating of milk so in regard to its 

 drying it is not the degree of heat to which it is subjected which is all 

 important but rather the associated conditions. The merits of each 

 process will have to be tested individually and perhaps even each 

 particular brand of milk." 



We have seen that foods of high initial acidity such as tomatoes 

 and orange and lemon juice can be dried and still retain marked anti- 

 scorbutic value, while attempts to conserve vitamin C during the drying 

 of less acid foods, and for those of less favorable oxidation-reduction 

 potential, such as cabbage and potatoes have been less successful. The 

 drying of milk is perhaps more highly developed from the mechanical 

 standpoint than that of any other food and since it is nearly neutral in 

 reaction and largely used in infant feeding, special interest attaches 

 to the question of retention of the antiscorbutic value of milk during 

 drying. In view of the fact that the initial concentration of vitamin 

 C in milk may vary widely the actual destruction of the vitamin can 

 be measured quantitatively only by determining the vitamin C content 

 of the raw milk employed as well as of dried product. Such an investi- 

 gation was undertaken by Cavanaugh, Dutcher and Hall (1923). The 

 milk was taken from the mixed milk of 175 dairies, representing 1,276 

 cows. The samples to be used raw were cooled and shipped to the lab- 

 oratory in sterilized vacuum bottles, while more from the same lot 



