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

<abstract> <p>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 <italic>Astrocaryum aculeatum</italic> Meyer, peel from the fruit of <italic>Bactris gasipaes</italic> Kunth, straw obtained from endocarp of the fruit of <italic>Euterpe oleracea</italic> Mart., peel from the fruit of <italic>Theobroma grandiflorum</italic> Schumann and peel from the root of <italic>Manihot esculenta</italic> 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 <italic>Bactris gasipaes</italic> resulted in the highest concentration of reducing sugars (23.7 g/L). After detoxification and concentration process, the <italic>Bactris gasipaes</italic> hydrolysate results in 96.7 g/L of reducing sugars largely fermentable (90%) by <italic>Saccharomyces cerevisiae</italic> 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 <italic>Bactris gasipaes</italic>. 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 <italic>Bactris gasipaes</italic> to produce ethanol.</p> </abstract>