Mechanisms of volatile production from sulfur-containing amino acids by irradiation

• Radiolysis of amino acid side chains were the major cause of volatile production.
• The Strecker degradation were involved in the production from sulfur amino acids.
• Odor of the irradiated sulfur amino acids were similar to that of irradiated meat.
• Methionine was the major amino acid in the production of irradiation off-odor.

Sulfur-containing amino acids were used to study the mechanisms of off-odor production in meat by irradiation. Irradiation not only increased the amounts of volatiles but also produced many new volatiles from sulfur-containing amino acid monomers. We speculate that the majority of the volatiles were the direct radiolytic products of the side chains, but Strecker degradation as well as deamination and decarboxylation of radiolytic products were also involved in the production of volatile compounds from sulfur amino acids. The volatile compounds produced in amino acids were not only the primary products of irradiation, but also the products of secondary chemical reactions after the primary compounds were produced. Cysteine and methionine produced odor characteristics similar to that of the irradiated meat, but the amounts of sulfur volatiles from methionine were far greater than that of cysteine. Although the present study was carried out using an amino acid model system, the information can be applied to the quality indexes of irradiated meats as well as other food products.