Molecular mechanisms underlying species-dependent differences in heat-induced gel properties of fish maw.

Fish maw, a fish-processing byproduct, is a collagen-rich marine protein resource for gel-based foods. To elucidate species-dependent gelation, this study examined how structural characteristics and cross-linking regulate imino acid release, heat-induced protein remodeling, and gel network formation in slate cod croaker fish maw (SFM), basa fish maw (BFM), and cod fish maw (CFM). Slate cod croaker fish maw gel (SFMG) exhibited the highest gel strength (41.05 g), whereas basa fish maw gel (BFMG) was weaker (22.51 g) and cod fish maw gel (CFMG) failed to gel. The lower cross-linking degree of SFM than BFM favored collagen unwinding and imino acid release, promoting network formation. In contrast, higher cross-linking in BFM restricted effective imino acid release, while the low initial imino acid content of CFM led to limited release after heating. Protein abundance analysis showed enrichment of type I collagen α chains, myosin heavy chain, and tropomyosin in SFMG, a lack of substantial enrichment of highly abundant type I collagen α chains in BFMG, and downregulation of cross-linking- and scaffold-related proteins in CFMG.