Sustentabilidade e inovação: estratégias para a produção de bioprodutos industriais a partir do pré-tratamento de resíduos de cana-de-açúcar

Abstract

Sugarcane straw and bagasse are waste products generated in large volumes by the sugar and ethanol industry. Straw is the fibrous material discarded during harvesting, while bagasse is the solid residue remaining after juice extraction. Both have great potential for the production of biofuels and bioactive compounds, adding value to these byproducts. This thesis investigated three distinct routes for valorizing lignocellulosic residues, focusing on the production of enzymes, second-generation ethanol, hyaluronic acid, and phenolic compounds. In the first stage, the fungus Penicillium sp. FSDE15 was used for the production of xylanase by solid-state fermentation (SSF), using wheat bran, either pure or combined with sisal fiber. The enzyme performed well in the hydrolysis of lignocellulosic substrates and released xylooligosaccharides, including X2, despite some limitations in thermal stability. In the second stage, sugarcane straw underwent organosolv pretreatment with glycerol, followed by semi-simultaneous hydrolysis and fermentation. Up to 31.12 g/L of ethanol, 1.72 g/L of hyaluronic acid, and 4,645 mg/100 g of phenolic compounds, such as p-coumaric and ferulic acids, were obtained from the residual liquor. In the third stage, the sugarcane bagasse was treated with KOH/urea, increasing the cellulose content and reducing lignin, which favored enzymatic conversion and resulted in the production of 19.83 g/L of ethanol. The pretreatment liquor was used to extract phenolic compounds with high antioxidant, hypoglycemic, and antibacterial activity, especially after extraction at pH 3 with 8% Triton X-114. These results demonstrate the viability of integrated routes for the complete use of sugarcane residues, contributing to the transition towards sustainable biorefineries and the circular economy.