226. The effect of commercial drying and evaporation on the nutritive properties of milk

Abstract

1. Spray-dried (Kestner process), roller-dried and evaporated milks were prepared commercially from one batch of raw milk.2. The biological value of the proteins (nitrogen), vitamin B1and the growth-promoting properties of the milks were measured by tests on rats.3. Vitamin A and carotene, riboflavin and vitamin C were measured by physical and chemical methods at intervals in the course of storage for a year.4. No significant difference was found between the biological values of the proteins (nitrogen) of the processed milks. The values ranged from 80 for evaporated milk to 84 for spray-dried milk.5. The proteins (nitrogen) of evaporated milk were significantly less digestible (true digestibility 91) than those of spray-dried milk (true digestibility 94). The difference between either of those and roller-dried milk (true digestibility 93) was not significant.