22 BULLETIN 342, U. S. DEPARTMENT OF AGRICULTURE. 



pasteurized at 145 F. for 30 minutes does not undergo any appreci- 

 able chemical change. He found that soluble phosphates do not 

 become insoluble, that the albumin does not coagulate, and that when 

 higher temperatures are used chemical changes do occur. He also 

 developed the fact that 5 per cent of the albumin is rendered insoluble 

 in milk heated for 30 minutes at 150 F., while at 160 F. 30.78 per 

 cent of the albumin is coagulated. Further evidences that low-tem- 

 perature pasteurization does not injure the digestibility and nutritive 

 value of milk are shown by the results of feeding experiments with 

 babies. According to Weld (31), a number of babies that were fed 

 raw milk and pasteurized milk showed only a slight difference in 

 the average net daily gain in weight during the feeding period. The 

 slight difference was in favor of pasteurized milk. Hess (21), how- 

 ever, has found that milk pasteurized for 30 minutes at 145 F. may 

 cause, in infants, a mild form of scurvy, which yields readily to so 

 simple a remedy as orange juice. 



High-temperature pasteurization of earlier days must not be con- 

 fused with low -temperature pasteurization of the present day. Many 

 of the objections which have been raised to pasteurization have been 

 founded on the observation of milk heated to high temperatures. 

 The fallacy of the objections to pasteurization have been shown, 

 however, through scientific research in the last few years, and as a 

 result the value of the process has been firmly established. 



PASTEURIZATION AND VITAMINS. 



The discovery of vitamins within recent years has shown how im- 

 possible it is to estimate nutritive requirements solely in terms of 

 digestible protein, carbohydrate, fat, and inorganic salts. But little 

 is known of the real chemical nature of vitamins, except that they are 

 necessary for normal growth and health. Three vitamins are now 

 recognized, known as vitamin A (soluble in fat) and vitamins B 

 and C (soluble in water). Most authorities now agree that fat- 

 soluble A and water-soluble B are essential for growth, and water- 

 soluble C, the antiscorbutic vitamin, may also play a part in this 

 relation. 



Because of the limited character of the infant's diet the vitamin 

 content of its food is more important than that of the adult's, as the 

 latter has a great variety of foods. Fortunately, milk has been 

 found to be a food containing the three vitamins and the effect of 

 pasteurization on the vitamin content is of importance. 



Fat-soluble A and water-soluble fe have been found to be quite 

 resistant to heat, and it is agreed that pasteurization has little or 

 no effect upon them. The antiscorbutic vitamin C, however, is quite 

 sensitive to heat above 122 F. While the destruction of this vita- 



