Suppressive ability of defatted rice bran against lipid oxidation in cookies containing iron

Cookies containing iron, defatted rice bran, and several oils were prepared, and their oxidative stability evaluated. Oxidation was suppressed by the defatted rice bran, but a limit to the suppressive effect was observed. The maximum peroxide values obtained with defatted rice bran were low, and similar, regardless of the degree of unsaturation of the oils. A chemical analysis suggested that proteins and polyphenols in the defatted rice bran contributed to the suppressive effect. Cookies without the defatted rice bran showed decreasing maximum peroxide value as the relative humidity increased. No such dependence was observed for the cookies containing defatted rice bran. The water sorption isotherm of defatted rice bran indicated that the weak dependence was due to low water sorption.