Natural antioxidants from agro-wastes enhanced the oxidative stability of soybean oil during deep-frying

Abstract

Plant leaves are an abundant natural antioxidant source that could effectively alternate synthetic antioxidants. Here, we investigated the effect of the lyophilized pomegranate/orange/beetroot leaves extract (POB) (1:1:1), as a natural antioxidant, in retarding the thermo-oxidative degradation of the soybean oil during the deep-frying. To achieve this, we examined the effect of the POB extract at 200, 400, and 800 μg/ml and the potentiated effect of POB-400 μg/ml on butylated hydroxytoluene (BHT) at 100 μg/ml versus that of BHT-200 μg/ml. The extract at 200 and 400 μg/ml weakly retarded the oxidation. Whereas POB-800 μg/ml and POB/BHT (400/100 μg/ml) inhibited the oil oxidation at the early stages, the peroxide value was <10 meq O2/kg. POB-800 μg/ml and POB/BHT reduced the total oxidation (TOTOX) by 55% and 64%, respectively, compared to the raw oil, and decreased the formation of the malondialdehyde by nearly 80%. Besides, the gas chromatography results proved that the POB extract efficiently retarded the oxidation process during discontinuous frying. Consequently, the POB extract could be a promising alternative to BHT in inhibiting the thermo-oxidative degradation of the soybean oil during the frying up to 50 frying batches.