Valorization from Cacao Pod Husk to Bio-ethanol: A Sustainable Source for Renewable Biochemicals

Abstract

Ethanol is a versatile compound used as an antiseptic or disinfectant, a primary ingredient in alcoholic beverages, and fuel additive in biodiesel. Given the growing demands for alternatives, researchers are increasingly exploring sustainable and eco-friendly sources of raw materials and processes of ethanol synthesis for a better bio-ethanol recovery from waste. This study aims to synthesize bio-ethanol from cacao pod husk. The method includes eco-friendly and non-toxic processes, including a 10-day delignification, acid-hydrolysis and fermentation. These processes were applied to determine the optimal precursor amounts to maximize the synthesis of bio-ethanol. Delignification yielded the highest amount of removed lignin at day 5, 6 and 7; 13.13, 13.00 and 13.13 milligrams, respectively. For acid-hydrolysis, 1 millimolar of sulfuric acid is sufficient to digest the delignified pod husk producing 50 mL of cacao pod hydrolysate containing fermentable sugars. Further, 10 mg of baker’s yeast yielded the highest ethanol concentration from 50 mL of cacao pod husk, 1.02 ± 1.2 (% w/v). This three-pronged synthesis efficiently maximized the synthesis of bio-ethanol from cacao pod husk. This study establishes a framework for bio-ethanol production from cacao pod husk. Future research should focus on improving natural delignification duration, optimizing the conditions in acid hydrolysis, refining for yeast selection, and assessing the process feasibility for commercialization of bio-ethanol from waste.