Improvement of adzuki bean paste quality by Flavourzyme-mediated enzymatic hydrolysis

Abstract

The primary aim of this study was to investigate the changes in the quality and flavor profiles of adzuki bean paste hydrolyzed by Flavourzyme. The texture analyzer and gas chromatography-mass spectrometry were used to evaluate the texture, and volatile organic compounds of adzuki bean paste. At the same time, rheometer, high-performance liquid chromatography (HPLC), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and size-exclusion chromatography (SEC) were used to evaluate the changes of adzuki bean paste viscoelasticity, free amino acids and protein. The results demonstrated that the appropriate amount (0.3%, adzuki bean basis) of Flavourzyme enhanced the quality of bean paste, resulting in denser taste and reduced hardness by 51.94% (from 2097.30 g to 1007.79 g). Flavourzyme had an obvious hydrolysis effect on the protein of adzuki bean. The results of SDS-PAGE indicated that low molecular weight proteins increased significantly with higher amount of Flavourzyme addition, which is consistent with the conclusions of SEC (≤12 kDa, increased from 26.12% to 88.65% with 0.3% Flavourzyme). The hydrolysis of protein might contribute to the reduced viscoelasticity and softer texture of adzuki bean paste. Furthermore, the addition of Flavourzyme produced more small peptides and amino acids. It could promote the Maillard reaction during bean paste frying. Thus Maillard-reaction-derived volatile compounds (furfural, maltol, 2-pentylfuran, etc.) were enhanced to improve the flavor of bean paste. The positive effects of appropriate amount of Flavourzyme on adzuki bean paste properties indicated the potential application of Flavourzyme on bean paste.