Ultrasound-assisted enzymatic hydrolysis of cassava waste to obtain fermentable sugars

This work evaluates ultrasound-assisted enzymatic hydrolysis of cassava waste using α-amylase and amyloglucosidase to obtain fermentable sugars. The influence of solid to liquid ratio and the concentrations of α-amylase and amyloglucosidase on the amount of fermentable sugars released was assessed in the presence and absence of ultrasound irradiation by means of a central composite rotational design. The results showed that the concentration of fermentable sugars released ranged from 21.3 to 83.1 g l−1 and from 32.8 to 116.1 g l−1, in the absence and presence of ultrasound, respectively. The specific total reducing sugar (TRS) production (expressed as g of TRS per g of dry cassava waste) ranged from 0.18 to 0.27 for hydrolysis in the water bath and from 0.26 to 0.36 g g−1 in the ultrasound bath. The TRS concentration obtained using ultrasound for a sample with solid to liquid ratio of 0.16 was around 80 g l−1, and without ultrasound the similar concentration was only obtained for solid to liquid ratios higher than 0.34. This demonstrates that ultrasound technology can be useful for process intensification due to its positive effects on sugar yield.