Dilute acid hydrolysis of wastes of fruits from Amazon for ethanol production

This study carried out the screening of wastes from Amazon plants to produce hydrolysates with a high monosaccharides content for ethanol production. Initially, we hydrolyzed (diluted acid) Amazon wastes (peel from the fruit of Astrocaryum aculeatum Meyer, peel from the fruit of Bactris gasipaes Kunth, straw obtained from endocarp of the fruit of Euterpe oleracea Mart., peel from the fruit of Theobroma grandiflorum Schumann and peel from the root of Manihot esculenta Crant) to obtain hydrolysates with the high content of fermentable sugars. Then, we investigated by 2³ factorial design the influence of the factors: a) hydrolysis time (min); b) H₂SO₄-to-waste ratio (g/g) and c) solid-to-liquid ratio (g/mL) in the variables reducing sugars and furans. The hydrolysis of the peel of the fruit of Bactris gasipaes resulted in the highest concentration of reducing sugars (23.7 g/L). After detoxification and concentration process, the Bactris gasipaes hydrolysate results in 96.7 g/L of reducing sugars largely fermentable (90%) by Saccharomyces cerevisiae PE-2. The experimental design demonstrated that the factors H₂SO₄-to-waste ratio (g/g) and solid-to-liquid ratio (g/mL) were the most significant affecting the final content of reducing sugars and furans in the hydrolysate of the peel of Bactris gasipaes. Hydrolysis time of 4.4 min, H₂SO₄-to-waste ratio of 0.63 g/g, and the solid-to-liquid ratio of 0.17 g/mL resulted in the concentration of reducing sugars of 49 g/L. This study shows the potential of peels from the fruit of Bactris gasipaes to produce ethanol.