Effect of carbohydrate type on the structural and functional properties of Maillard‐reacted black bean protein

Protein from black beans (Phaseolus vulgaris L.) has good solubility, emulsification, and antioxidant properties, with significant potential applications in the food industry. Maillard-reaction-mediated dry-heat glycosylation is a relatively safe modification method to improve the functional properties of black bean protein (BBP). Here, Maillard-reacted conjugates were prepared by applying 24-h dry-heating to induce a reaction between BBP and one of three carbohydrates (dextran, chitosan, and sodium alginate) at 70°C and 79% relative humidity. The resulting Maillard conjugates were designated as BBP-Dex, BBP-Ch, and BBP-SA, respectively. The formation of each Maillard conjugate was characterized by analyzing the grafting degree, free sulfhydryl (SH) groups content, and surface hydrophobicity, as well as the results of Fourier-transform infrared (FTIR) spectroscopy and fluorescence spectroscopy. The FTIR and fluorescence spectroscopy results provided information on the formation of the Maillard conjugates. The BBP-SA conjugate had a higher grafting degree and SH group content than the other two conjugates. The solubility, emulsifying properties, and antioxidant properties of the BBP were significantly improved after the Maillard reaction (p < 0.05). Moreover, the physicochemical and functional properties of the conjugates were superior to those of the BBP-carbohydrate mixtures, indicating that covalent interactions may be stronger than noncovalent interactions. This study provides theoretical guidance for future research on protein-carbohydrate conjugates. PRACTICAL APPLICATION: This study has great potential applications in the development of new multi-functional food ingredients and the realization of functional factor homeostasis, and provides scientific and theoretical bases for the application of protein-carbohydrate conjugate in the field of functional food.