The Effect of Radiation Sterilization on the Nutritive Value of Foods I. Biological Value of Milk and Beef Proteins

Abstract
The effect of irradiation sterilization and of heat sterilization on the nutritive value of milk proteins and beef proteins has been studied by the Thomas-Mitchell method. A 3 million rep gamma irradiation was used to sterilize the frozen milk and beef. The ground beef was vacuum packed during irradiation treatment and milk was conventionally canned. Upon irradiation milk developed a reddish tinge, and the proteins had coagulated; the beef looked somewhat darkened. Irradiation did not produce pronounced off-flavors and odors in beef or milk. The irradiated beef when incorporated into a balanced diet was found completely acceptable to the rat while the diet containing irradiated milk was consumed reluctantly. Irradiation sterilization did not affect the apparent or true digestibility of the beef (100%) or of the milk protein (98%). The biological value of the beef protein (78%) also was not affected upon irradiation but the biological value of the milk proteins (90%) was reduced by 8% upon irradiation as compared to a reduction of 6% due to heat sterilization. The possibility of irradiation damage to the sulfur amino acids is discussed.