Enhancing Reducing Sugar Yield from Fruit Peel Waste via Optimized Microwave Pretreatment

Abstract

Fruit peel waste (FPW) is a renewable and cheaper source of fermentable sugars for biofuel production. In this research, three types of FPW which are banana peel, orange peel, and pineapple peel were investigated for reducing sugar generation using microwave pretreatment. Pineapple peel waste was found to produce the highest yield of total reducing sugar compared to banana peel and orange peel, with the value of 10.58 g/L. The optimization condition for microwave pretreatment was studied by using the Central Composite Design under Response Surface Methodology. Microwave power (180 – 450 watt), time (3 – 7 minutes) and biomass loading (5 -15 % w/v) were the parameters used to optimize the reducing sugar yield from pineapple peel. The optimum condition for microwave pretreatment was found at biomass loading of pineapple peel of 15% (w/v), power of 450 watt with 5 minutes of treatment time with the concentration of 12.52 g/L. It was apparent that the structure of hemicellulose, cellulose, and lignin of the pineapple peel was affected by the microwave pretreatment condition based on Fourier Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscope (SEM) analysis. FTIR showed alteration in a functional group while the SEM micrographs showed a marked change on the pretreated sample when compared with the untreated sample. In conclusion, microwave pretreatment is a promising approach for reducing sugar production from the agricultural residue such as FPW.