Ultrasound–accelerated Maillard reaction to improve functional and antioxidant properties of hemp protein–carboxymethyl chitosan conjugates as a future food ingredient

This study investigates the functional and antioxidant properties of hemp protein–carboxymethyl chitosan (HP–CMCH) conjugates under the effect of conventional wet heating (non–UMR, 12 h heated) and ultrasonic–accelerated Maillard reaction (UMR). The results indicate that UMR at 70 °C for 2 h achieved the optimal balancing of functional and antioxidant properties. This highlights that effective Maillard conjugation can be achieved at lower temperatures and shorter times than conventional methods. Under this optimal condition, solubility increased from 40-50 % (native and untreated) to 88.37 %, while emulsifying activity index (EAI) and emulsion stability index (ESI) improved to 29.67 m²/g and 33.46 min, respectively. Similarly, foaming capacity and foaming stability reached 70.11 % and 68.64 %, while water–holding capacity (WHC) and oil–holding capacity (OHC) increased to 85.16 % and 60.76 %, respectively. Antioxidant activity, assessed using DPPH, ABTS, and FRAP assays, was significantly enhanced, with values of 28.46 %, 27.89 %, and 24.02 μmol FeSO₄/g, respectively. Therefore, UMR at 70 °C for 2 h is a highly efficient approach for accelerating protein unfolding and formation of Maillard reaction products and improving the functionality and bioactivity of HP–CMCH conjugates, presenting valuable applications in food, nutraceutical, and biomaterial industries as sustainable bio-based ingredients.