Effect of black tea, garlic and onion on corn oil stability and fatty acid composition under accelerated oxidation
2006
Navas, Petra Beatriz | Carrasquero-Durán, Armando | Flores, Iraima
Fresh black tea, garlic bulbs and onion skin were macerated in refined corn oil to evaluate their antioxidant properties and the effect of heat on oil stability and fatty acid composition in accelerated oxidation experiments at 55 ° and 140 °C. At the lowest temperature control and onion treatments showed an induction time of 3 days with maximum peroxide values of 62 and 45 meq kg[superscript [-]1], respectively. Addition of black tea and garlic increased oil stability with peroxide values of 5 meq kg[superscript [-]1], without appreciable changes in the fatty acid composition. Heating at 140 °C for 48 h produced an accelerated deterioration of corn oil in all treatments. A reduction of polyunsaturated fatty acids of about 40% was observed, with high concentrations of non-eluted materials which contained thermo-oxidized substances. It was found that natural extract of black tea and garlic were effective to preserve corn oil under accelerated oxidation at 55 °C which simulates oil behaviour during storage, but cannot reduce the rate of oxidation at frying temperatures.
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