Relationship between total antioxidant capacities of cereals measured before and after in vitro digestion

Total antioxidant capacity (TAC), which is the cumulative capacity of different antioxidants to reduce oxidative stress, proved to be very useful to correlate the antioxidant capacity of the diet with the incidence of some disease or with modification of disease biomarkers. Therefore, it is important to estimate the real antioxidant potential of cereals. Most methods are based mainly on extractive methods which may largely underestimate the TAC of cereals. Several recent articles have reported a direct approach, the Quencher procedure, which produces a higher TAC compared to extractive methods. However, both the extractive methods and the Quencher procedure are performed prior to digestion. In this article, an in vitro approach using enzymatic digestion, designed to mimic digestion in the gastrointestinal tract (physiological conditions), had been used to release antioxidants from cereals. Seven whole cereals were employed for the determination of DPPH as well as ABTS radical scavenging activity before and after simulated digestion. The objective was to compare the in vitro procedure of antioxidant extraction with the Quencher procedure and water extraction. The values of the TAC's from the cereal grains obtained from the in vitro procedure were 1.8-10.3 times higher than the Quencher procedure and 3.5-10.5 times higher than water extraction. Correlation between the results of the TAC obtained using the three different procedures was also investigated. The in vitro gastrointestinal digestion procedure is more useful in the screening of grains, assessing their beneficial health effects compared to the Quencher procedure or water extraction.