Study on the ultrasonic treatment of black rice dietary fiber and its effect on anthocyanin adsorption

This study investigated the interaction between ultrasonic-treated black rice insoluble dietary fiber (UBIDF) and Aronia melanocarpa anthocyanins (AMA) and the effect on anthocyanins stability. The results showed that the maximum adsorption of AMA by UBIDF with optimal ultrasonication conditions (300 W, 54 °C, 31 min, and a liquid-to-solid ratio of 38:1, v/w) and optimal adsorption parameters (95 min, 37 °C, 3 mg/mL, pH 5) was 46.54 ± 0.87 mg/g. Structural analysis revealed that the interaction between UBIDF and AMA was related to hydrogen bonding, which effectively inhibited crystallization. The non-covalent binding between UBIDF and AMA enhanced the thermal stability of UBIDF-AMA complexes. Compared to BIDF-AMA, the particle size of UBIDF-AMA decreased, while the specific surface area increased, which was consistent with the results of increasing in water-holding capacity, oil-holding capacity, and swelling capacity. The stability test results demonstrated that UBIDF significantly improved the environmental stability of AMA, with a retention rate as high as 94.30 %. Additionally, the non-covalent binding between UBIDF and AMA effectively enhanced the bio-accessibility and antioxidant activity of AMA. This study reveals the potential of ultrasonic-treated dietary fiber in adsorbing anthocyanins and provides a theoretical basis for dietary fiber-polyphenol complexes development.