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Production of ethanol from two varieties of potato peel waste through cellulolytic and amylolytic enzymes

Abstract:

Organic waste are a potential source of biofuels. Around 10 tons/day of potato peel waste are generated in the world, which could be used for bioethanol production, due to a high content of sugars and carbohydrates in them. Ecuador has a great diversity of potatoes with more than 550 varieties, and potato peel waste generation of 20% of its production, these waste not valued are usually deposited in landfills or used for cattle feed, generating pollution problems. The aim of this work was to determine the yield of bioethanol, obtained from potato peel waste of two varieties with great participation in the Ecuadorian market - chola and blanca - through thermal and enzymatic hydrolysis (EH), using two enzymes: alpha amylase and cellulase. For that, we considered the following parameters for the initial characterization of potato peels: moisture (%), ash (%), fat (%w/v), protein (%w/v), reducing sugars (RS) (%w/w), and carbohydrates (%w/w), also reducing sugars after fermentation. On average, 11.50 g/L of ethanol and 24.10 g/100 g of dry substrate of reducing sugars were obtained for the chola variety; with the blanca variety, 11.90 g/L and 30.10 g/100 g of ethanol and dry substrate, of reducing sugars were obtained, respectively. The control samples (without addition of enzymes) showed amounts of reducing sugars similar to samples subjected to enzymatic hydrolysis with 21.20 g/100 g of dry substrate, but the ethanol content was the lowest with 0.30 g/L. The results showed that among the varieties tested, there were no significant differences in reducing sugars and ethanol parameters: however, the blanca variety exceeds the chola one with the highest concentration of ethanol and reducing sugars after the enzymatic hydrolysis, surpassing the chola veriety with 24.90% of RS and 3.48% of ethanol.