Among the major microorganisms known for their ability to produce enzymes Neratinib cost that degrade the cell wall of plants, fungi comprise the most interesting group (Hegde, Kavitha, Varadaraj, & Muralikrishna, 2006). The genus Rhizopus is one of the most promising in this process because it has been shown that, besides the ability to increase the protein content of the raw materials of low nutritional value, these proteins possess functional activity and specific catalytic activity. Furthermore, the fungi of this genus are well indicated for not producing toxic substances ( Oliveira et al., 2010). The aim of this study was to determine the profile of
phenolic acids derived from solid state fermentation of rice bran with the fungus Rhizopus oryzae and evaluate the antioxidant capacity and inhibition of enzymes peroxidase and polyphenol oxidase by extracts containing these compounds. The fungus R. oryzae (CCT 1217), was obtained from the André Tosello Foundation (FAT), Campinas, Brazil. The cultures were maintained at 4 °C in slants of potato dextrose agar (PDA, Acumedia®). The spores were spread by adding 5 mL of an aqueous emulsion (Tween 80 at 0.2%v/v) and they were incubated for 7 days at 30 °C until a whole new sporulation of the fungus by adding 0.2 mL of the emulsion in Petri dishes containing potato dextrose agar. Spore suspension for fermentation was achieved by adding 10 mL of an aqueous emulsion of Tween 80 (0.2%)
to each plate. The release of spores was obtained by scraping Trametinib clinical trial the Branched chain aminotransferase plates with a Drigalski handle and the concentrated spores solution was estimated by enumeration in a Neubauer chamber (L. Opitik, Germany). The rice bran (rice variety BR-IRGA 417) used as substrate
in fermentation was provided by industries from Rio Grande do Sul, with their particles size standardised to particles smaller than 32 mesh, and packed in 100 g in tray bioreactors (12 × 8 × 4 cm3) arranged in 2 cm layers, covered with sterilized gauze and cotton to allow aeration and prevent external contamination. The reactors containing the substrate were added in a nutrient solution (2 g/L KH2PO4, 1 g/L MgSO4 and 8 g/L (NH4)2SO4 in 0.4 N HCl) sterilized by filtration in Millipore membrane of 0.45 μm (Oliveira et al., 2010). The spores solution of the fungus R. oryzae was added at an initial concentration of 4 × 106 spores/gbran. Distilled water was added to the medium in order to adjust the humidity to 50%. The bioreactors were placed in a fermentation chamber at 30 °C with controlled humidity. Upon expiry of the incubation time (0–120 h, with sampling every 24 h), the fermented biomass was stored at −18 °C. The biomass generated during the fermentation process was indirectly estimated by the glucosamine content (Aidoo, Henry, & Wood, 1981). The glucosamine content was estimated spectrophotometrically (Biospectro, Brazil) at 530 nm using a standard curve of glucosamine (Sigma, USA) in water (1–15 mg/mL).