Potential of some tuber peels in bioethanol production using Candida tropicalis

Abstract

Cassava and sweet potato peels are two potential agro-wastes with high possibility for biofuel production due to the possession of high polysaccharides. Studies were conducted to evaluate the chemical compositions of these wastes as well as determine their potential as feedstock for bioethanol production using indigenously sourced yeast strain; Candida tropicalis (IMI 398401). Cashew nut shell extract was used to hydrolyze and saccharify the gelatinized mashed agro-waste. The results indicates that moisture content (14.16 %), ash content (2.25 %), fibre (5.10 %) and cellulose (734 mg/g) were higher in cassava peels and lower; 13.04 %, 1.12 %, 1.81 % and 498 mg/g respectively in sweet potato peels. Pretreatment of the peels with organic acid extract of Anacardium occidentale nut shell showed maximum reducing sugar yield of 300 mg/g and 471 mg/g in sweet potato peel and cassava peel. The amount of bioethanol (g/L) produced after 72 h of fermentation was higher; 23.90 ± 0.60 in sweet potato peel. The study shows that these peels may be useful for biofuel production after a proper pretreatment.

Keywords: Bioethanol; Candida tropicalis; Pretreatment; Proximate composition; Tuber peels