Increased protein digestibility of beef with aging in an infant in vitro digestion model

This study investigated the protein digestibility of aged beef using an infant in vitro digestion model. Semitendinosus muscles were vacuum-packed and aged for 0, 7, and 14 days at 4°C. Malondialdehyde content of raw and cooked beef increased with aging (P < .05). However, no changes in carbonyl content were observed for aged raw and cooked beef samples. The α-amino group content and myofibrillar fragmentation index of beef increased with aging (P < .05). The α-amino group content of cooked beef digesta increased upon aging (P < .05). Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed the decrease in band intensities of actin in the digesta of aged beef. These results highlight the improvement in the protein digestibility of beef aged for 7 and 14 days. Therefore, aged beef is more desirable as complementary food owing to increased protein digestibility.