Effects of ultrasound-assisted H 2 O 2 on the solubilization and antioxidant activity of yeast β-glucan

Yeast β-glucan (YG) possess an extensive range of biological activities, such as the inhibition of oxidation, but the poor water solubility of macromolecular YG limits its application. In this study, through the combined degradation of ultrasonic waves and H 2 O 2, and the optimization of the main process parameters for solubilizing YG by response surface methodology (RSM), a new product of YG UH was generated. The molecular weight, structural characteristics and degradation kinetics before and after solubilization were evaluated. The results showed that the optimal solubilization conditions were reaction time: 4 h, ultrasonic power: 3 W/mL, H 2 O 2 concentration: 24 %. Under these conditions, ultrasound-assisted H 2 O 2 increased the solubility (from 13.60 % to 70.00 %) and reduced molecular weight (from 6.73 × 10 6 Da to 1.22 × 10 6 Da). Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), Congo red (CR), scanning electron microscopy (SEM) revealed that ultrasound-assisted H 2 O 2 increased the conformation's flexibility greatly, without changing the main structure of YG. More importantly, solubilization of YG improved free radical scavenging activity with YG UH exhibiting the highest levels of DPPH and ABTS + free radical scavenging activity. These results revealed that ultrasound-assisted H 2 O 2 degradation could be a suitable way to increase the solubility of YG for producing value-added YG.