Physical pretreatment and algal enzyme hydrolysis of dried low-grade and waste longan fruits to enhance its fermentable sugar production

Abstract

© 2020, Springer-Verlag GmbH Germany, part of Springer Nature. Fruit production in Thailand has been increasing due to the practical farmers’ knowledge of agroecology and sustainable farming. Thailand is one of the productions of the most massive fruit in southeast Asian countries. On the other hand, the status of fruit waste, which becomes stuck previous to landfills, is concerned by researchers over the years. Low-grade and waste longan fruits are also no exceptions that are feedstock material for bioethanol production. Accordingly, this study aims to evaluate bioethanol production from dried low-grade and waste longan fruits by using physical pretreatment (boiling and autoclave) and blue-green algal enzymes for hydrolysis. After pretreatment, total and reducing sugar was 227.63 ± 2.63 g/L and 89.26 ± 1.70 g/L, respectively. Algal enzymes were added at a pH of 7.0 in the hydrolysis process; subsequently, total and reducing sugar were achieved 348.68 ± 3.95 g/L and 183.33 ± 14.70 g/L, respectively. The present study shows that using algal enzymes in the hydrolysis process improves fermentable sugar production and applicable for bioethanol production.