Production of Taste Enhancers from Protein Hydrolysates of Porcine Hemoglobin and Meat Using Bacillus amyloliquefaciens γ-glutamyltranspeptidase.

To improve the flavor of hydrolysates from porcine hemoglobin and meat, gamma-glutamyltranspeptidase (GGT) from Bacillus amyloliquefaciens was added to catalyze the formation of kokumi gamma-glutamyl peptides via a gamma-glutamyl transfer reaction. Quantitation of free amino acids and gamma-glutamyl dipeptides was carried out in combination with sensory analysis. Sensory perception, especially the thick, complex, continuous, and overall kokumi sensation of both hemoglobin and meat hydrolysates, was greatly enhanced by gamma-glutamylation. Due to the higher amount of glutamine present in meat hydrolysates, gamma-glutamylated hydrolysates from meat contained higher concentrations of gamma-glutamyl dipeptides and showed stronger kokumi sensation than the hemoglobin counterpart without the addition of glutamine. For hydrolysates from both raw materials, extra addition of glutamine (10 and 20 mM) was beneficial for obtaining higher concentrations of gamma-glutamyl dipeptides but contributed little to the kokumi sensation. This study revealed that the kokumi sensation of protein hydrolysates could be intensified by a gamma-glutamyl transfer reaction, and the enhanced kokumi sensation could be related to the generation of gamma-glutamyl peptides.