Approximately 30.1 million tons of oranges are processed to produce juices, essential oils and other by-products. A large quantity of citrus processing wastes will be eliminated every year. Thus, in recent decades, the interest in research on alternative ways to use these wastes, such as production of phenolic compounds has increased. Biotechnological process is a promising technology for food, pharmaceutical and chemical industries. Flavanones in citrus are molecules that play an important role in antioxidant activities in nutraceutical products, with potential for therapy on carcinoids. Nevertheless, they are produced by extraction of citrus wich are very scarce and limited sources. The aim of this study was to evaluate naringenin, a scarce sources of flavanones, obtainment by solid-state fermentation using Brazilian orange pomace. Kinetic studies and design experimental tests were performed to define the time profile of naringenin production. The results showed higher concentration of naringenin, increasing of 15 times. Tannase was supposed to be, partially, responsible for biotransformation of the naringin into naringenin. To verify these hypotheses, naringin was reacted with tannase from Paecilomyces variotii and the product was assayed for its antioxidant capacity. The product of the tannase biotransformation of the naringin standard, by the ORAC and DPPH assays, presented up to 1.3 and 6.4 times the antioxidant capacity of the original compound, respectively. These results suggest that this fermentation process may be a viable alternative for the production of a functional and nutraceutical potential phenolic compound, such as naringenin, for industrial application.