Microbial Production of Potent Phenolic-Antioxidants Through Solid State Fermentation Silvia Martins, Diego Mercado, Marco Mata-Gómez, Luis Rodriguez, Antonio Aguilera-Carbo, Raul Rodriguez, and Cristóbal N. Aguilar Abstract The agroindustrial residues including plant tissues rich in polyphenols were explored for microbial production of potent phenolics under solid state fer- mentation processes. The fungal strains capable of hydrolyzing tannin-rich materials were isolated from Mexican semidesert zones. These microorganisms have been employed to release potent phenolic antioxidants during the solid state fermentation of different materials (pomegranate peels, pecan nut shells, creosote bush and tar bush). This chapter includes the critical parameters for antioxidants production from selective microbes. Technical aspects of the microbial fermentation of antioxidants have also been discussed. Keywords Phenolic antioxidants · Solid-state fermentation · Gallic acid · Ellagic acid · Nordihydroguayaretic acid 1 Introduction Antioxidants are bioactive compounds capable of slowing or preventing the oxida- tion of other molecules. This process is a chemical reaction that transfers electrons from a compound to an oxidizing agent. Free radicals are generally produced in the oxidation reactions, which start the chain reactions that damage cells. Chemically, antioxidants act modifying this chain of reaction removing free radical intermedi- ates and inhibit other oxidation reactions by being oxidized themselves. As a result, antioxidants are often reducing agents such as polyphenols, which are natural com- pounds present in numerous plants, located in fruits, flowers, cases, ferns, crusts, wood, etc. The distribution of these compounds in plant cells varies depending on the vegetal [1]. Polyphenols, constitute an important kind of chemical substances, C.N. Aguilar (B ) Department of Food Science and Technology, School of Chemistry, Universidad Autonoma de Coahuila, Saltillo, Coahuila, México e-mail: cag13761@mail.uadec.mx 229 O.V. Singh, S.P.Harvey (eds.), Sustainable Biotechnology, DOI 10.1007/978-90-481-3295-9_12, C  Springer Science+Business Media B.V. 2010