Bicarbonates and carbonates as antioxidants in vegetable oils at frying temperatures.

Antioxidant activity of bicarbonates and carbonates including NaHCO 3 , Na 2 CO 3 , KHCO 3 , and K 2 CO 3 was evaluated in soybean oil (SBO) at 180°C. KHCO 3 and K 2 CO 3 had stronger activity than NaHCO 3 and Na 2 CO 3 . KHCO 3 (5.5 mEq/L, 0.060 wt.%) and K 2 CO 3 (5.5 mEq/L, 0.041 wt.%) were more effective than 0.02 wt.% tert-butylhydroquinone (TBHQ) in preventing oxidation of SBO. While the antioxidant activity of KHCO 3 and K 2 CO 3 increased with increasing their concentrations up to 5.5 mEq/L, it decreased at 11 mEq/L. KHCO 3 and K 2 CO 3 were also effective in preventing oxidation of other vegetable oils including avocado, canola, corn, high oleic soybean, and olive oils. Correlation tests conducted with the results from the six oils showed that KHCO 3 and K 2 CO 3 had weak to moderate positive correlations with γ- and δ-tocopherols. In a separate study in stripped SBO, it was found that KHCO 3 had a synergistic effect with α-tocopherol, but not with γ- and δ-tocopherols. KHCO 3 had additive or synergistic effect with rosemary extract, epigallocatechin gallate, ascorbic acid, and ascorbyl palmitate. Antioxidant activity of KHCO 3 was confirmed in frying of potato cubes in SBO and canola oil. Although more studies should be conducted for better understanding of the mechanisms and factors affecting the antioxidant activity of bicarbonates and carbonates, this study demonstrated that they could serve as antioxidants or co-antioxidants of other antioxidants in frying. PRACTICAL APPLICATION: Inorganic salts including NaHCO 3 , KHCO 3 , Na 2 CO 3 , and K 2 CO 3 hadstrong antioxidant activity in vegetable oils at frying temperatures when they wereadded as powder. Antioxidant activity of 0.06 wt.% KHCO 3 was higherthan that of 0.02 wt.% TBHQ in soybean oil and canola oil during frying potato. KHCO 3 had additive orsynergistic effect with rosemary extract, epigallocatechin gallate, ascorbicacid, and ascorbyl palmitate indicating that these inorganic salts can be usedas co-antioxidants to enhance the antioxidant activity of existing antioxidantswhile they can be used alone as well.