LAUSR

Abstract Dual- and triple-frequency ultrasonic processing features advantages such as uniform energy distribution and the ease of resonance within the extracted raw material, which attenuates the directional effect of single frequency ultrasonic treatment. In this study, the effects of dual-frequency and triple-frequency ultrasound extraction were evaluated based on the physicochemical properties, structural characteristics, and biological activities of polysaccharides from ginger stems and leaves (GSLPs). Triple-frequency ultrasound extraction was found to obtain higher polysaccharide yield (10.50 ± 0.20%) than dual-frequency ultrasound extraction (9.74 ± 0.30%). Moreover, the former possessed higher contents of total sugar, uronic acid, and sulfate radicals, but lower molecular weight. Both types of polysaccharides exhibited intact helical structure, similar thermal properties, and clumpy structures with porous surfaces. More importantly, the polysaccharides extracted by triple-frequency ultrasound extraction showed stronger antioxidant activity and better functional properties, while those extracted by dual-frequency extraction exhibited superior rheological properties due to larger molecular weight. The latter also demonstrated better glucose entrapment and α-glucosidase inhibitory activity. In conclusion, dual- and triple-frequency ultrasound treatment may enable a greater range of GSLP applications in functional foods.