Ultrasound-assisted acid and enzymatic hydrolysis of yam (Dioscorea sp.) for the production of fermentable sugars

This work focuses on the ultrasound-assisted hydrolysis of yam to obtain fermentable sugars using phosphoric acid or enzymes as catalysts. In the chemical and enzymatic hydrolyses the effects of temperature and catalyst concentration on the amount of fermentable sugar released were evaluated. The same experiment was carried out with and without ultrasound. For chemical hydrolyses, the maximum amounts of fermentable sugars obtained were 0.155 g sugar g−1 dry material and 0.205 g sugar g−1 dry material, whereas for enzymatic hydrolysis the maximum fermentable sugars obtained were 0.32 g sugar g−1 dry material and 0.42 g sugar g−1 dry material, without and with ultrasound, respectively. These experiments demonstrated that the amount of fermentable sugars differs according to the type of hydrolysis applied. In this work, ultrasound increased the yield for chemical and enzymatic hydrolysis, showing a promising technology to be used for hydrolysis.