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Aims: The aim of the present study was to evaluate the protective effect of Deoiled seed cakes extracts of Simarouba glauca and Radermachera xylocarpa toward oxidation of soybean oil during accelerated storage.
Study Design: Seeds harvesting, oil extraction, natural antioxidants extraction from deoiled cakes, supplementation of soybean oil with the extract and evaluation of its oil stability during accelerated storages.
Place and Duration of Study: Council for Scientific and Industrial Research-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad, India, from July 2015 to December 2015.
Methodology: Oils were extracted from the seeds on a Soxhlet apparatus. Deoiled cakes were then extracted with methanol. The obtained extract was used for phytochemical analysis, by colorimetry and high performance liquid chromatography (HPLC). After preliminary antioxidant tests, the extracts were respectively added in soybean oil at concentrations 200-1800 ppm. Oil containing butylated hydroxytoluene (BHT) and oil without antioxidants served as positive and negative controls respectively. The oxidative stability of these oil samples was evaluated by Rancimat and Schaal oven tests under forced storage conditions and measurement of oxidation parameters.
Results: The outcomes showed the total phenolic contents to be 19.22 and 9.87 mg GAE/g for Simarouba glauca (SG) and Radermachera xylocarpa (RX) respectively. Quercetine, Vanillic, caffeic, ferulic acids were the phenolic antioxidants detected in RX, while gallic acid and vanillic acid were those detected in SG. The induction times of soybean oil supplemented with the extracts of SG and RX were found to be in the range of 5.08-6.28 and 5.87-6.55 h respectively. Those of oil without antioxidant and oil supplemented with BHT were 4.84±0.03 and 6.42±0.12 h respectively. The extracts, at all concentrations, were efficient like BHT in delaying soybean oil oxidation during 21 days of storage at 65°C.
Conclusion: These extracts are viable sources of natural antioxidants for stabilization of soybean oil.