Optimization study of bioethanol production from sponge gourd (Luffa cylindrica)

Abstract

Luffa cylindrica also known as sponge gourd (SG), is a non-edible feedstock that is readily available and under-utilized. In this study, SG as a potential source for production of ethanol was studied under statistically optimized conditions. SG was collected, peeled, dried, milled and sieved (1mm). Several pretreatment methods were employed on SG namely: steam explosion, alkaline, combination of alkaline and steam explosion, zinc chloride and sodium sulphite. Central Composite Design (CCD) of Response Surface Methodology (RSM) was used to design and determine the optimum parameters for glucose yield as well as the fermentation for bioethanol production. The best pretreatment method for sponge gourd was investigated to be sodium sulphite pretreatment with a glucose yield of 6.65 kgm−3. The sodium sulphite pretreated SG was modelled, optimized and validated with R2 of 0.9974 at p < 0.05. Glucose production was optimal at conditions: sodium sulphite (9% w/w), temperature (100 °C) and reaction time (60 min) resulting in glucose yield of 6.673 kgm−3. From the CCD, the factors that gave the highest ethanol concentration of 6.84kgm−3 were inoculum size (7.5 v/v), fermentation time (24 h) and nitrogen source (inorganic). The study concluded that sponge gourd could be a potential feedstock for bioethanol production and would prevent under-utilized agro-waste materials.