Production of Ethanol from Apple Peels using Acid Hydrolysis and Fermentation

Abstract

Ethanol is produced from sugar and starchy material like sugarcane, sugar beet, corn, and wheat. More dependence on these crops leads to the global food crisis. Around 6.96 million tons of fresh fruits are produced in Pakistan, including 0.54 million tons of apples annually. As a result, a massive amount of fruit waste is generated, whose open discard leads to adverse environmental impacts. This work subjected apple peels to acid hydrolysis and fermentation for ethanol production. The parameters of acid hydrolysis such as particle sizes (149, 210, 297, 590, and 2000 µm), solid loadings (3, 6, 9, 12, and 15 grams (gm)), acid concentrations (4, 8, 12, 16 and 20%), and the hydrolysis time (1, 2, 3, 4 and 5 hours) were investigated. The results showed that the maximum sugar of 15.4˚ Brix was obtained at 9 gm per 50 mL of solid loading with a particle size of 297 µm at a 12% acid concentration in 2 hours of incubation time. The fermentation of apple peels hydrolysate yielded 2.0% (v/v) ethanol. Thus, the results suggested that apple fruit waste can be the potential feedstock for ethanol production. Furthermore, it indicated that bioethanol could be produced from a waste resource, which can help to meet the current energy demands and reduce environmental pollution.