Abstract: Headspace-solid phase micro-extraction coupled with gas chromatography-mass spectrometry and descriptive sensory analysis were conducted to investigate the changes in volatile compounds and sensory characteristics of the Maillard reaction products (MRPs) prepared from enzymatically hydrolyzed Sipunculus nudus protein with different saccharides (glucose, maltose, xylose and gum acacia) at 120 ℃ for 120 min. Principal component analysis (PCA), hierarchical cluster analysis and partial least squares regression were applied to explore the correlation of main volatile compounds with different MRPs and sensory characteristics. The results indicated that saccharide type affected the kinds and concentrations of volatile compounds, including aldehydes, alcohols and ketones. The Maillard reaction reduced the bitter and earthy taste of S. nudus enzymatic hydrolysate (SEH) and enhanced the aroma and caramel flavor; the reaction with xylose could significantly increase the kinds and concentrations of aldehydes improving the flavor characteristics. Further analysis suggested that the flavor characteristics of MRPs from SEH with glucose, maltose and gum acacia were not significantly different from each other, which were correlated with hexanal, hexadecanal and decene; MRPs from SEH with xylose were positively correlated with aldehydes, including 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, hexanal, heptaldehyde, methylthiopropanal, furfural, benzaldehyde, undecanal, phenylacetaldehyde, tridecanal, dodecanal, tetradecanal and pentadecal. Nevertheless, SEH showed positive correlations with 4-terpenol, 1-nonanol, 2-pentylfuran, 6-methyl-5-hepten-2-one, octyl formate and 2-acetylthiazole. Moreover, methylthiopropanal, phenylacetaldehyde, n-octanol and 2-pentylfuran were the main volatile compounds that contributed to the aroma and caramel flavor, while 4-terpenol, 2-pentylfuran and 6-methyl-5-hepten-2-one affected the formation of earthy taste. Different saccharides, therefore, remarkably affected the volatile compounds and sensory characteristics, where xylose indicated optimal improvement in the flavor and sensory characteristics. This study provides a theoretical basis for selecting better saccharides to improve the flavor and sensory characteristics of SEH.

Key words: Sipunculus nudus, enzymatic hydrolysates, different saccharides, Maillard reaction, volatile compounds