Enzymatic hydrolysis of porcine fibrinogen by trypsin and flavourzyme: structural characterization and functional properties of low-molecular-weight peptides

This study investigated the enzymatic hydrolysis of porcine fibrinogen using trypsin, flavourzyme, and their sequential combination to clarify how hydrolysis conditions influence hydrolysates’ structural and functional properties. The dual-enzyme treatment (trypsin followed by flavourzyme) produced the highest degree of hydrolysis (21.64%) and soluble protein recovery efficiency. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel permeation chromatography revealed extensive cleavage of the α-, β-, and γ-chains and a marked shift toward low-molecular-weight peptides, with fragments below 1.5 kDa comprising the majority of the hydrolysate. Amino acid analysis showed that the resulting peptide fraction of dual-enzyme treatment contained 31.39% essential amino acids and a higher cysteine content than single-enzyme hydrolysates. Moreover, enzymatic hydrolysis by complex proteases significantly increased surface hydrophobicity and reactive sulfhydryl group content, indicating greater exposure of nonpolar residues and active thiols that may favor disulfide bond formation during gelation. Overall, the improved structural and functional characteristics of dual-enzyme fibrinogen hydrolysates may provide a theoretical basis for their potential use in the development of gel-based foods.