Generation of Koku-Related Peptides Using Gamma-Glutamyl Transpeptidase Post-Treatment in Porcine Liver Hydrolyzates

The growing production volume of the meat industry has increased the need for revalorization of meat by-products to reduce economic and environmental impacts. Enzymatic hydrolysis of protein-rich meat by-products is an effective strategy for producing hydrolyzates with bioactive potential. Combining sequential enzymatic hydrolysis with γ-glutamyl transpeptidase activity can promote the formation of γ-glutamyl peptides associated with koku perception, a sensory attribute that increases taste intensity, continuity, and palatability. This study aimed to develop porcine liver hydrolyzates enriched in koku-related peptides through enzymatic hydrolysis followed by post-treatment with the transpeptidase Protana Uboost. Substrate specificity assays showed that a 0.2 U/mL enzyme concentration maximized γ-glutamyl dipeptide formation. Sequential hydrolysis using Alcalase and Protana Prime followed by Protana Uboost post-treatment generated the highest levels of koku-related peptides. Moreover, post-treatment significantly enhanced antioxidant capacity in the resulting hydrolyzates, supporting their potential as a functional ingredient.