Quality of frozen porcine Longissimus lumborum muscles injected with L-arginine and L-lysine solution

This study investigated the effects of L-arginine and L-lysine on the water holding capacity, shear force, color, and protein denaturation of frozen porcine Longissimus lumborum. Four batches were prepared, each corresponding to samples of an experimental treatment: without a cryoprotective solution, injecting a 0.3% sodium tripolyphosphate and 0.5% NaCl solution, a 0.5% L-arginine solution, or a 0.5% L-lysine solution. The results showed that both L-arginine and L-lysine decreased thawing loss, cooking loss, shear force, L* values, b* values, and surface hydrophobicity, but they increased pH values, a* values, percentages of peak areas for T21 relaxation times, and Ca2+-ATPase activity. Additionally, both histological and transmission electron microscopy images showed that L-lysine, and especially L-arginine could inhibit the formation of gaps between fiber bundles, alleviate the disruption of intracellular spaces, and maintain the structural integrity of sarcomeres. Overall, the results showed that both L-arginine and L-lysine hindered the structural damage of muscle fibers during freezing and protected myofibrillar proteins from denaturation, ultimately contributing to superior quality attributes.