Repressions of the toxic α, β-hydroxyaldehyde homologues, HHE, HOE, HNE and HDE formations by synthetic and natural antioxidants in commercial corn oil at frying temperature

Abstract

Commercial corn oil, which contains high level of linoleic acid (~60%) is widely available and is often used for frying food products. The α, β-unsaturated-4-hydroxyaldehydes, the toxic degradation products of lipid peroxidation is forming due to heat treatment at frying temperature in high PUFA vegetable oils containing high level of linoleic acid. The objective of present experiment was to find the suppressing effects of α, β-unsaturated-4-hydroxyaldehydes in the presence of synthetic and natural antioxidants.In the present experiments corn oil was heated for 0, 1, 2, 4, and 6 hours at 185°C in the presence and absence of synthetic and natural antioxidants to measure the formation of the four α, β-unsaturated-4-hydroxyaldehydes, especially the 4-hydroxy-2-trans-nonenal (HNE) which is known to be the most toxic product of the unsaturated fatty acids peroxidation process. In addition to HNE, 4-hydroxy-2-trans-hexenal (HHE), 4-hydroxy-2-trans-octenal (HOE) and 4-hydroxy-2-trans-decenal (HDE) were also existed in commercial heat treated corn oil at 185°C. The formation of HHE, HOE, HNE and HDE increased with the length of heating time. The combinations of 200ppm TBHQ+50ppm citric acid (CA)+100ppm ascorbyl palmitate (AP) and 50ppm or 100ppm rosemary extracts (RE) were selected to study the repressing effects on the oxidation retarding the α, β-unsaturated-4-hydroxyaldehydes formation in heat treated corn oil at 185°C.It was found that the oxidation process and the formation of HHE, HOE, HNE and HDE in corn oil were suppressed by the addition of synthetic antioxidants and also by a natural antioxidant at frying temperature of 185°C. 200ppm TBHQ+50ppm CA+100ppm AP suppressed the oxidation of corn oil at 185°C after 6 hours by 27% for HNE, 88% for HHE, 70% for HOE and 96% for HDE formation. 50ppm or 100ppm Rosemary extracts (RE) suppressed 29% HNE, 40% HHE, 48% HOE and 74% HDE formation in corn oil.