Bioethanol Production from Potato Peels (Solanum Tuberosum) as Sustainable Alternative for Urban Eco-Communities

Abstract

Potato cultivation in Colombia accounts for 1.4 % of the agricultural GDP, with potato peel waste (PPW) being the main byproduct. The valorization of agro-industrial waste has gained particular interest as a strategy for transitioning to a circular and sustainable economy. Eco-communities play an important role in utilizing this available residual biomass (collecting 126 kg of PPW per week). This study explored the development of a biotechnological process for obtaining bioethanol from PPW at a laboratory scale. The process began with the application of thermochemical (HCl 0.1 %v/v and NaOH 0.1 %v/v) and hydrothermal pretreatments to the PPW. Enzymatic hydrolysis was evaluated using Celluclast 1.5 L (700 EGU/g) and Amylase AG 300 L (260 AGU/g). The product was then fermented with Saccharomyces cerevisiae and subsequently distilled under reduced pressure. The hydrolysate with HCl 0.1 %v/v showed a higher sugar release (29.08 ± 0.04 g/L) and lower bioconversion (11.23 ± 0.37 g ethanol / 100 g dry peel) with an 8 %w/v PPW, compared to the hydrolysate with 0.1 %v/v NaOH under the same conditions (24.10 ± 0.07 g sugar/L), but the ethanol bioconversion was higher (12.14 ± 0.45 g ethanol / 100 g dry peel). This represents a transformation process applicable in eco-communities, where an estimated 3.15 L of alcohol al 70 – 80 % is projected to be produced per week.