CARBODIIMIDE-MEDIATED COVALENT ATTACHMENT OF LYSINE TO WHEAT GLUTEN AND ITS APPARENT DIGESTIBILITY BY PENAEID SHRIMP

Carbodiimide-mediated covalent attachment of lysine to wheat gluten was evaluated with respect to its availability to penaeid shrimp. Normality of acid hydrolysis and carbodiimide reaction criteria (levels of carbodiimide and L-lysine hydrochloride) were optimized, and the resultant lysine-enriched samples were evaluated for extent of isopeptide bonding. In vivo apparent digestibilities of both enriched and unenriched glutens to shrimp were compared. Large-scale lysine enrichment of wheat gluten yielded a 590% increase in lysine content of wheat gluten. Only an additional 6% of the lysine present was attached by isopeptide bonding. In vivo apparent dry matter digestibility, protein digestibility, and lysine availability of both the enriched and unreacted glutens were similar, confirming suitability of reaction criteria. The ability of shrimp to hydrolyze isopeptide-bound lysine was indicated by similarities in apparent digestibility of lysine in enriched and unenriched glutens.