Ferulic acid (FA) is the most abundant phenolic compound in wheat grain, mainly located in the bran. However, its bioaccessibility from the bran matrix is extremely low. Different bioprocessing techniques involving fermentation or enzymatic and fermentation treatments of wheat bran were developed aiming at improving the bioaccessibility of phenolic compounds in bran-containing breads. The bioaccessibility of ferulic acid, p-coumaric acid, and sinapic acid was assessed with an in vitro model of upper gastrointestinal tract (TIM-1). Colonic metabolism of the phenolic compounds in the nonbioaccessible fraction of the breads was studied with an in vitro model of human colon (TIM-2). The most effective treatment was the combination of enzymes and fermentation that increased the bioaccessibility of FA from 1.1% to 5.5%. The major colonic metabolites were 3-(3-hydroxyphenyl)propionic acid and 3-phenylpropionic acid. Bran bioprocessing increases the bioaccessibility of phenolic compounds as well as the colonic end metabolite 3-phenylpropionic acid.

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Grain is an important source of phytochemicals, which have potent antioxidant capacity. They have been implicated in the beneficial health effect of whole grains in reducing cardiovascular disease and type 2 diabetes. The aim of the present study was to identify the most important antioxidant fractions of wheat grain. It was found that the aleurone content of these fractions was highly correlated with the antioxidant capacity of the fractions (r = 0.96, p < 0.0001). Ferulic acid appeared to be the major contributor to the antioxidant capacity in fractions with higher antioxidant capacity. The contribution of protein was rather limited. It was concluded that the antioxidant potency of wheat grain fractions is predominantly determined by aleurone content, which can be attributed to the presence of relatively large amounts of phenolic compounds, primarily ferulic acid.

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