Exopeptidases and their application to reduce bitterness in food: a review.

When exopeptidases catalyze hydrolysis of peptide bonds, the product(s) may have a less bitter taste, and the free amino acids or small peptides formed may function in food as pleasant-tasting flavor compounds or as flavor precursors. There are several classes of exopeptidase based on specificity for hydrolysis of synthetic substrates. Exopeptidases in food-stuff may be of natural origin or may be extrinsic, that is, produced by microorganisms or parasites. Exopeptidases used to modify foods are also becoming increasingly available in the industrial enzyme market. Exopeptidases contribute to a variety of quality changes in postharvest fruit, meats, and food fermentations. Foodstuff impacted by these enzymes during processing include cocoa, beer, aged and cured meat products, koji, fish sauce, ripened cheeses, and protein hydrolysates. An important role of exopeptidases in food is the hydrolysis of hydrophobic, bitter peptides. The relationship between peptide structure and sensory transduction/receptor models is discussed. Research on the use of exopeptidases to reduce bitterness is reviewed.