Abstract: Umami peptide was prepared by microwave-assisted sequential enzymatic hydrolysis of perilla seed meal protein with alcalase followed by flavorzyme. Optimization of the hydrolysis conditions was performed using an orthogonal array design. Sephadex G-15 gel permeation chromatography, reversed phase-high performance liquid chromatography (RP-HPLC) and electronic tongue were applied to characterize the changes in peptide composition and umami taste during the hydrolysis process. The results showed that the optimum conditions for alcalase hydrolysis were as follows: microwave power, 400 W; enzyme dosage, 1 600 U/g; pH, 10.0; temperature, 60 ℃; and hydrolysis time, 35 min, and the optimum conditions for flavorzyme hydrolysis were as follows: enzyme dosage, 1 600 U/g; pH, 6.5; temperature, 65 ℃; and hydrolysis time, 40 min. A degree of hydrolysis of 44.86% was obtained under the optimized conditions. Compared with single enzymatic hydrolysis, the microwave-assisted stepwise enzymatic hydrolysis was quicker and more efficient and showed improved taste.

Key words: step-wise enzymatic hydrolysis, microwave, gel permeation chromatography, RP-HPLC, electronic tongue, umami peptide