Synergistic Effects of Dual-Enzyme Hydrolysis on Flavor Enhancement and Umami Improvement in Tilapia Bone Byproducts.

Tilapia processing generates significant quantities of byproducts, such as fish bones, which can be converted into valuable protein hydrolysates through enzymatic hydrolysis. To overcome the limitations regarding efficiency and flavor profile associated with the use of flavorzyme alone, this study investigated a stepwise dual-enzyme hydrolysis strategy. Five commercial endopeptidases-bromelain, neutral protease, alkaline protease, papain, and trypsin-were evaluated in combination with flavorzyme to improve the physicochemical properties and flavor characteristics of tilapia bone hydrolysates. The trypsin-flavorzyme (TF) dual-enzyme system achieved a hydrolysis equivalent of 287.91 mmol/g (with 61.50% of peptides <0.5 kDa) and a free flavor-enhancing amino acid content of 150.0 mg/g, thereby improving the umami potential of the hydrolysate. Electronic sensor analysis revealed significant differences in the volatile odor profiles among the various dual-enzyme systems. GC-IMS and HS-GC-IMS analyses demonstrated that the TF system generated the highest concentrations of total aldehydes and alcohols and significantly increased the levels of key volatile compounds, including aldehydes (nonanal, octanal, hexanal), alcohols (1-octen-3-ol), ketones (1-hepten-3-one), and esters. These results indicate that this innovative dual-enzyme hydrolysis strategy enables the deep and efficient hydrolysis of proteins, transforming fish processing byproducts into high-value flavor enhancers; this approach not only significantly improves flavor quality and added value but also expands avenues for efficient utilization, thereby enhancing the fishery supply value chain.