Assessment of microwave-assisted alkali pretreatment for the production of sugars from banana fruit peel waste

Abstract

The current investigation deals with the application of microwave energy to facilitate alkali (NaOH) pretreatment on banana peel waste (BPW) to achieve optimal reducing sugar. We studied the effect of microwave power (100 to 600 W) and irradiating time (1 to 6 min) on composition and reducing sugar content of BPW. The enzymatic hydrolysis of microwave-assisted alkali-pretreated BPW at 600 W for 2 min gave the maximum reducing sugar (0.561 g/g) of dry biomass waste. Atomic force microscopy revealed that the surface of all BPW was changed noticeably when microwave-assisted alkali pretreatment was employed. X-ray diffraction study revealed a 5-fold increment in the degree of crystallinity in optimal microwave alkali-treated samples (54.45%) as compared to the untreated sample (10.55%). Overall, the microwave-assisted alkali pretreatment removed a significant amount of hemicelluloses and lignin and led to a high amount of sugar production, suggesting microwave heating pretreatment as a potential alternative to conventional methods to achieve maximal reducing sugars.