Abstract: Maillard reaction products (MRPs) derived from Sipunculus nudus enzymatic hydrolysates (SEH) and different saccharides (glucose, maltose, xylose and gum acacia) were characterized by the measurement of absorbance at 420 nm and 294 nm, pH, color difference, total and free amino acids (TAA/FAA) and fluorescence intensity, combined with electro-nose to analyze their changes in volatile flavor compounds. The results obtained suggested that SEH conjugated with saccharides caused the browning degree to increase and pH to decrease, with yellow enhancing and luminosity darkling. Additionally, 17 FAA and TAA of MRPs were significantly reduced, especially for 8 kinds of bitter amino acids, as compared with SEH, which improved the bitter of SEH. The fluorescence spectra results revealed that the fluorescence intensity of MRPs was significantly reduced and slightly red-shifted as compared to that of SEH, leading to the changes in the tertiary structure of SEH. On the basis of the above results, the reaction degree of SEH conjugated with different saccharides highlighted the declining order: xylose > gum acacia > glucose > maltose. Electronic-nose can distinguish the flavor characteristics of SEH and MRPs, with the LDA having higher distinguish ability than PCA. Loadings analysis showed that 2 and 7 sensors contributed greatly to the first principal components, and 6 and 9 sensors contributed greatly to the second principal components, thus the flavor components including ammonia oxides, methane and sulfides were the difference between SEH and MRPs. The flavor and reaction characteristics of MRPs were significantly affected by the saccharide types, according to which an appropriate saccharide type was chosen for technological demands.

Key words: Sipunculus Nudus, hydrolysates, different saccharides, Maillard reaction, electronic-nose