Current progress in kokumi-active peptides, evaluation and preparation methods: a review

Kokumi is a complex sensation characterized by thickness, mouthfulness and continuity. Kokumi-active peptides, which are distributed in many kinds of food, induce a rich and long-lasting mouthfeel of food. Aimed to provide a comprehensive overview of kokumi peptides, this review covers the aspects of preparation and evaluation methods for kokumi peptides, kokumi receptor calcium-sensing receptor (CaSR), as well as structural features of kokumi peptides and derivatives. Apart from extraction and separation from natural and fermented food, preparation of kokumi peptides can be effectively obtained from enzymatic generation. Kokumi peptides are perceived by CaSR in taste cells and the proposed transduction pathway has been described. The evaluation on kokumi-inducing effect of peptides has employed a combination of sensory assessment and CaSR method. The discovered kokumi peptides mainly comprise glutamyl peptides, leucyl peptides and other peptides without specific features. Derivatives of amino acids and peptides including sulphur-containing amino acids, N-acyl-Tyr derivatives, N-acetylated amino acids and Maillard reaction products (MRPs) also work as kokumi enhancers. Based on the summarized developments, great sensory properties and bioactivities enable kokumi peptides as promising protein ingredients in future application.