Goufo, P.Pereira, J.Figueiredo, N.Oliveira, M.Carranca, C.Rosa, E.Trindade, H.2014-01-102014-01-102014Goufo, P., Pereira, J, Figueiredo, N., Oliveira, M.B.P.P., Carranca, C., Rosa, E.A.S., Trindade, H., 2014. Effect of elevated carbon dioxide (CO2) on phenolic acids, flavonoids, tocopherols, tocotrienols, γ-oryzanol and antioxidant capacities of rice (Oryza sativa L.). Journal of Cereal Science 59 (1), 15-24.http://hdl.handle.net/10400.19/1961There have been no studies conducted with the objective of investigating the effect of elevated CO2 concentrations ([CO2]) on antioxidants in grains. Therefore, a two-year field experiment was conducted using open-top chambers with two levels of atmospheric CO2 (375 and 550 mmol/mol) to evaluate their effects on rice grain antioxidants. Following exposure to high [CO2], the total phenolic content of all rice milling fractions decreased (3%e18%), with the highest reduction in the brown rice for sinapic acid (167%), and in the white rice for p-hydroxybenzoic acid (100%). The total flavonoid content also decreased under elevated [CO2] in all rice milling fractions (8%e14%), with apigenin (25%) being highly affected in the white rice, and tricin (12%) in the bran. The same trend was found for g-oryzanol, with decreases of 35%, 32%, 25%, and 2% in the white rice, brown rice, husk, and bran, respectively. In the white and brown rices, tocopherols and tocotrienols were all lower under elevated [CO2], with reductions larger for a-tocotrienol (69%), g-tocotrienol (46%), and a-tocopherol (38%). Good correlations between antioxidant contents and DPPH radical scavenging capacities indicated that these decreases may be meaningful in the preventive ability of rice against free radical-mediated degenerative diseasesengElevated carbon dioxideVitamin EPhenolic compoundsBrown riceWhite riceHuskBranjournal article