Effect of Reducing Sugar Type on Structure and Flavor Characteristics of Maillard Reaction Products from Enzymatically Hydrolyzed Soybean Meal

The effects of xylose, ribose, glucose, fructose, and galactose on the structural and flavor properties of Maillard reaction products (MRPs) derived from enzymatically hydrolyzed soybean meal were investigated. The extent of browning and ultraviolet (UV) spectroscopy analysis indicated that pentose exhibited higher reactivity than hexose, and aldose demonstrated greater reactivity than ketoses. Fluorescence spectroscopy analysis revealed an increase in the fluorescence intensity of MRPs, while infrared spectroscopy indicated alterations in absorption peak intensities of MRPs, compared with soybean meal hydrolysate. The molecular masses of MRPs were mainly distributed in the ranges of 128-500 and 500-1000 Da. In addition, the contents of bitter amino acids and umami amino acids in ribose-derived MRPs (R-MRPs) were relatively high, at 9.29 and 3.60 mg/g, respectively. Pentose-derived MRPs exhibited superior umami value, richness value and lower bitterness compared with hexose-derived MRPs. Furans, pyrazines, ketones, and aldehydes were the most abundant volatile substance in R-MRPs, presenting stronger caramel, nutty and grilled meat-like aromas. Furthermore, strong-flavored soybean oil was successfully prepared using the ribose-soybean meal hydrolysate (SBMH) system, indicating that while the system imparted a rich flavor to the oil, the fatty acid composition and physicochemical indices of the oil remained stable and safe.