Effect of solid medium fermentation on total phenol content and antioxidant of maize

Maize contains a large number of antioxidant compounds. However, many of them are not in free form, as they are bound to components of the cell wall of maize kernels. For this reason, the use of treatments is required to release them, such as the use of enzymes or fermentation processes. Fermentation in solid medium (FMS) with Rhizopus oryzae has been applied to increase the antioxidant capacity (AC) and phenolic content in cereals and legumes. The objective of the present work was to evaluate the effect of FMS with R. oryzae on AC and total phenolic content (TPC) of maize. Fermentation on solid medium was carried out in zip-lock bags (25 cm2) at 30 degrees C for 72 h, with an inoculum of 1 x 106 spores/g. Samples were taken every 12 h, the extract was recovered with 80% ethanol, and used to determine TPC and AC (ABTS+, DPPH and FRAP essay). The highest values were obtained at 60 h of culture, with a TPC of 1.92 mg/gram dry metter (gdm) and an AC of 1.47 mg TE/gmd, 1.27 mg TE/gdm and 5.8 mg Fe+2/gdm for the ABTS+, DPPH and FRAP assays, respectively. The use of FMS allowed to increase up to 0.83 and 1.25 times the CFT and CA of corn, with respect to time zero. Corn fermented with R. oryzae showed potential to be used as a raw material for the development of functional foods, by increase its AC through a bioprocess.