Bioavailability of acetylated derivatives of methionine, threonine, and lysine

Supplementation of vegetable proteins with various essential amino acids is an effective means of improving proteins quality. Unfortunately, simple amino acid additions to foods which must be heat processed and cooked is not without consequences. Under these conditions, methionine interacts with reducing sugars yielding methional through the Strecker degradation reaction. This generation of methional during heat treatment imparts undesirable sulfur odors and flavors to the food rendering it organoleptically unacceptable. Similarly, threonine and lysine are also susceptible to interaction with reducing sugars rendering them nutritionally unavailable. Acetylated derivatives of methionine, threonine and lysine have been studied to determine their utility in overcoming the inherent problems associated with each amino acid. To this end, N-acetyl-L-methionine and N-acetyl-L-threonine were found to be fully available to promote growth of rats. To the contrary, neither the alpha nor the epsilon, monoacetylated derivative of L-Lysine nor the alpha, epsilon diacetyl derivative of L-Lysine were effective in significantly promoting the growth of rats. Utilization of N-acetyl-L-methionine by humans has also been studied and shown to be as effective as methionine in improving the quality of vegetable proteins deficient in sulfur amino acids.