Improving Complexation of Puerarin with Kudzu Starch by Various Ultrasonic Pretreatment: Interaction Mechanism Analysis

Abstract

The industrial preparation of kudzu starch (KS) significantly reduces the remaining of flavonoids like puerarin (PU) in the product, weakening its biological activity and making pre-treatments on kudzu crucial. Ultrasonic technique, widely used for modifying biomolecules, can enhance nutrient interactions like those between starch and polyphenols in foods. Thus, a puerarin-kudzu starch (PKS) complex was prepared with the introduction of ultrasonic pretreatment. The results indicated that sonication increased the binding of PU to KS from 0.399 ± 0.01 to 0.609 ± 0.05 mg/g. Particle size analysis and SEM revealed that the particles of the ultrasonic puerarin-kudzu starch complex (UPKS) were larger than those of the untreated complexes. XRD, UV-vis, and FT-IR spectroscopic analysis demonstrated that the interaction between PU and KS was predominantly governed by hydrogen bonding. Moreover, the addition of PU reduced the orderliness of the starch structure, while the ultrasonic treatment disrupted the helical structure of the straight-chain starch and reformed it into a new ordered structure through the generation of new hydrogen bonds. Additionally, gels formed from UPKS exhibited higher viscosity, elasticity, and shear stress, suggesting that ultrasound significantly altered the intermolecular interactions between PKS. In conclusion, ultrasound effectively prepares PKS complexes, showing significant potential for high value-added kudzu products.

Keywords: Kudzu starch, Puerarin, Complexation, Ultrasonic treatment, Identification