High value-added products from the orange juice industry waste

An underutilized residue called Citrus Pulp of Floater (CPF), which causes problems during the industrial process of manufacturing of orange juice, was explored for the production of high value-added products. Mixed, first (1G) and second generation (2G) ethanol, a clean and renewable biofuel, was obtained after an enzyme cocktail isolated from the Xanthomonas axonopodis pv. citri (Xac) was applied in hydrolysis of this biomass. Then, mono- and co-culture fermentations were performed using the yeast Saccharomyces cerevisiae and two Candida strains (Candida parapsilosis IFM 48375 and NRRL Y-12969), where the last two were isolated from the orange bagasse in natura. After the enzymatic hydrolysis step, sugars obtained were converted to ethanol achieving a yield of almost 100% after co-fermentation. Hesperidin, a flavonoid widely used for its antimicrobial and/or antioxidant activities, was also extracted from CPF by liquid-solid extraction and precipitation, with the yield of 1.2% and 92.6% pure. Finally, nanocellulose was produced through processes such as extraction, bleaching and nanonization with the yield of 1.4% and over 98% of purity. These products - ethanol, hesperidin and nanocellulose were obtained from three independent processes: (1) after an enzyme-based hydrolysis of CPF, liquid part was used for ethanol production, and solid was preserved; (2) hesperidin was isolated from a dry CPF, and solid residue was preserved; and (3) nanocellulose was obtained from the solid residues after processes cited in 1 and 2.