Desenvolvimento de processo integrado utilizando resíduos de frutas para produção de d-limoneno e etanol de segunda geração

Abstract

Around 14% of the world's fruits and vegetables produced annually are discarded, including waste such as peels and seeds. These residues, rich in cellulose, pectin, and soluble sugars, are considered a promising biomass for the integrated production of ethanol and D-limonene. However, their lignocellulosic structures require pretreatments to simplify the conversion of sugars into ethanol, making it necessary to deal with specific challenges, such as D-limonene, a possible inhibitor of alcoholic fermentation. In this study, a mixture of fruit waste (MRF) was investigated concerning the chemical composition of the waste, highlighting the presence of pectin. An alternative process of enzymatic hydrolysis of waste was used, with emphasis on the production of an enzymatic cocktail by the fungus Aspergillus niger. Furthermore, a D-limonene removal step was carried out using the Soxhlet extractor, and the juice extracted from the fruit mixture resulting from the enzymatic hydrolysis and extraction process was used as a fermentative medium for the production of bioethanol using Wickerhamomyces sp. UFFS-CE-3.1.2 fermentation. Enzymatic hydrolysis carried out using the enzyme cocktail produced by the microorganism Aspergillus niger proved to be satisfactory, indicating the action of enzymes in the MRF, since after 120 hours, 23.30±0.09 g/L of fermentable sugars was obtained. The extraction of D-limonene proved to be an efficient process, resulting in 15 mg/L of oil. During the alcoholic fermentation process, the presence of high levels of citric acid impacted bioethanol production levels. Effective removal of D-limonene and adequate pretreatment to reduce citric acid is essential to improve ethanol production from these residues.