Biochemical properties of proteolytic extracts from different Zingiber officinale varieties and their catalytic role in myofibrillar degradation: Effect on beef tenderness

This study explores the proteolytic activity and meat-tenderizing potential of crude enzyme extracts obtained from the rhizomes of two Zingiber officinale varieties, Roscoe (ZR) and var. rubrum (Zr), tested at different concentrations. The proteolytic activity of all extracts was characterized by using azocasein as a model substrate. Among all tested conditions, the Z. officinale Roscoe sample at an extraction ratio of 0.2 g_FW/mL (ZR_0.2) exhibited the highest catalytic efficiency (V_max/K_M = 129.79), while Zr extracts exhibited lower turnover rates but higher substrate affinity (K_M was down to 0.007 mM). These kinetic results guided the selection of the optimal ginger extract and the most suitable enzyme-to-substrate ratio for meat tenderization. To better understand substrate specificity and hydrolytic efficiency on muscle tissue, the proteolytic kinetics of the selected extract (ZR_0.2) were further assessed using myofibrillar proteins isolated from the Biceps femoris muscle. ZR_0.2 demonstrated superior activity compared to commercial proteases (papain, bromelain), with enhanced degradation of structural proteins and a higher myofibrillar fragmentation index. Marination trials with beef cubes confirmed these results, showing significant improvements in technological parameters such as cooking yield (>90%) and water-holding capacity, while maintaining pH stability. Color analysis revealed greater redness (a* values) in treated samples, both raw and cooked, suggesting a possible antioxidant effect. Sensory evaluation confirmed increased tenderness, juiciness, and chewiness in ZR_0.2-treated meat. Overall, these findings support the use of Z. officinale extracts, specifically ZR_0.2, as selective and multifunctional agents for clean-label meat tenderization, with promising applications for improving the quality and value of beef cuts.