Overall, the two beverages fermented with L. plantarum LP09 had a lighter color compared to the non-fermented control. Probably, this was due to the effect of the acidity towards phenolic compounds. Oat contains appreciable concentration of anthocyanins, whose color depends on the value of pH. Polyphenols deserve an increasing interest for their antioxidant and anti-inflammatory properties. The beverages made with oat flakes contained appreciable levels of polyphenols. The highest concentration was found in fermented beverages, especially when enzymes were added. It was shown that lactic acidification improved the extraction of phenols, especially fromflour containing bran fractions. The combined activity of hydrolytic enzymes andmicrobial fermentation further promoted the release of phenolic acids and increased their free fraction in cereal doughs. The ferulic acid esterase activity of Depol 740 L allowed the release of ferulic acid from wheat bran, and the efficiency increased when combined with cell-wall degrading enzymes, especially xilanases. As estimated towards DPPH radical, the antioxidant activity of the methanolic extracts from beverages was in agreement with the concentration of total polyphenols.