Ultrasound treatment of herbal extraction residue to enhance enzymatic saccharification

Abstract

The utilization of herbal extraction residues (HERs) for production of valuable products has gained significant momentum in recent years. In this study, Lianhua Qingwen residue (LQR) was selected as a representative HER for enzymatic saccharification. By subjecting starch-containing raw unpretreated LQR to direct hydrolysis using a combination of cellulolytic and amylolytic enzyme, a glucan conversion of around 60 % was achieved within 48 h. To further enhance the hydrolysis rate and yield, ultrasound treatment of LQR samples was conducted. Investigation into the effect of ultrasound treatment on subsequent enzymatic saccharification revealed a noteworthy acceleration in the saccharification rate of LQR, exceeding 20 % within 10 h of hydrolysis time. Notably, this enhancement was achieved even when the substrate concentration was high at 10 % under optimized conditions of 5 min of sonication at a power intensity of 1.20 kW/cm2 and a temperature of 50 °C. The improvement in efficiency can be attributed to the disruptive effect of ultrasound treatment on the structure of LQR, leading to a reduction in particle size. Consequently, the LQR particles exhibited better contact with the enzyme, promoting a more efficient saccharification process. These findings suggest that ultrasound technology holds considerable potential for enhancing the enzymatic saccharification of HERs.