Amino Acid Impairment in Casein Heated With Glucose

Abstract

Vitamin Test Casein (G.B.I.), free of di-alyzable N, was refluxed for 24 hrs. in a 5%, N-free, glucose soln. at 96.5[degree]C. Aliquots subsequently freed of the glucose were used for comparison with untreated casein, both the untreated and treated samples being hydrolyzed by refluxing them for 30 hrs. in 6 N HC1. For assaying tryptophan, the samples were digested with pepsin, papain and Taka-diastase, and with trypsin. Nine essential amino acids were detd. on the hydrolysates by the use of Streptococcus faecalis R. Of these 9, only lysine, arginine, and tryptophan were inactivated appreciably by the heat-treatment. Heat processing in the presence of reducing sugar seems therefore to produce partial inactivation of at least 3 of the essential amino acids.