Optimization of reaction conditions for the design of cereal-based dietary fibers with high antioxidant capacity.

Abstract

Bound antioxidants are distinguished by their strong potential to defend the body against oxidative stress. Cereal bran fractions contain antioxidant compounds bound to dietary fiber, but this only occurs to a limited extent. Increasing the quantity of bound antioxidant compounds using soluble phenolic compounds is thought to be a possible method for designing cereal-based dietary fibers with high antioxidant potential. Certain cereal bran samples (wheat, oat, rye, and rice) were reacted with different concentrations of beverages (green tea infusion, black tea infusion, espresso, and red wine), rich in various soluble phenolic compounds. The interactive effects of parameters (time, temperature, and pH) and the optimum conditions for the reaction were determined using response surface methodology. Green tea infusion (30 g·L-1 ) was found to be the most effective beverage. The pH rather than the time and temperature had significant (O p< 0.0001) effects on the reaction. Neutral or slightly alkaline conditions (pH7.0-7.9) and mild temperatures (at about 50 °C) were found to be optimum to increase the antioxidant capacity of cereal bran samples. The total antioxidant capacity of oat bran treated with green tea infusion under optimum conditions (53.3°C, pH7.4, 60.0min) reached 226.42 ± 0.88 mmol Trolox equivalent·kg-1 . The free amino groups in cereal bran were also found to decrease (32-95%) after treatment. It is possible to design functional cereal-based dietary fibers, rich in bound antioxidant compounds through treatment with green tea infusion under optimum conditions. © 2022 Society of Chemical Industry.