In vitro bioaccessibility of phenolic compounds and antioxidant activity in biofortified cowpea cultivars

Abstract

ABSTRACT The present work aimed to evaluate the contents of total phenolic compounds, total flavonoids and antioxidant activity, as well as to identify and quantify phenolic acids before and after simulated gastrointestinal digestion in vitro, in raw and cooked cowpea grains, of biofortified cultivars BRS Aracê and BRS Tumucumaque. The raw grains were analyzed as flour and the cooked grains were analyzed after maceration, before and after cooking and in the stages of the digestive process. The contents of total phenolic compounds were analyzed by the spectrophotometric method, using the reagent Folin-Ciocalteu, and total flavonoids using a spectrophotometric method with quercetin as standard. The antioxidant activity was evaluated using the free radical capture method ABTS (2,2'-azino-bis (3-ethylbenzothiazolino-6-sulfonic acid) and FRAP (Ferric Reducing Antioxidant Power). Eight phenolic acids were investigated, and the identification and quantification was performed by high performance liquid chromatography (HPLC), the content of total phenolic compounds and the antioxidant activity were reduced during cooking, but increased with simulated digestion in vitro, due to the release of bound forms. action of digestive enzymes, there was a difference in the behavior of the raw and cooked cultivars.The phenolic acids suffered degradation under gastrointestinal conditions, but the cultivars analyzed maintained compounds with relevant bioactivity (raw grain - gallic, caffeic and p-cumáric acids; cooked grain - acids and caffeine) and antioxidant activity, which can help protect against chronic non-communicable diseases, demonstrating that cowpea is a common food bioaccessible natural antioxidants.

Keywords

• Vigna unguiculata
• Thermal processing
• Bioactive compounds
• In vitro digestion