Comparative Evaluation of Pretreatment Strategies on Enzymatic Saccharification of Hylocereus polyrhizus’s Pericarps for Bioethanol Production

In order to evaluate the possibility of bioethanol production from an indigenous fruit waste - pericaps of dragon fruit, the efficacy of several pretreatment methods on enzymatic digestibility of pericarps were investigated. Following that, the simultaneous saccharification and fermentation (SSaF) of pretreated pericarps to ethanol was conducted by using instant dry yeast. From our study, it was observed that the total sugar yields obtained after enzymatic hydrolysis of thermally pretreated pericarps (0.6 g/g) were higher than untreated pericarps powders (0.28 g/g). By using thermally pretreated pericarps as biomass resource, ethanol concentration of 1.5 g/L was achieved after 80 h of cultivation process. The ethanol yield of 27% (% w/w initial dry weight of biomass) as recorded from the present study is lower compared to the theoretical yield of ethanol from pure glucose solution (51% w/w glucose). Nevertheless, these results indicate that by applying thermal pretreatment, the pericarps of dragon fruit could be considered as an economically viable lignocellulosic material for production of fermentable sugars related to bioethanol production.