The Chelating Effect of Black Tea Extract on Metals

The oxidation process in oils and fats and the speed of oxidation to some extent depends on the presence of prooxidants namely metals. The application of chelatingagents namely citric acid among others can retard this process. In this study the chelating effect of tea extract, tannic acid and citric acid are evaluated and compared to each other.
Copper in the organic form at the concentration of 0.1 ppm were added to tallow, sunflower seed, canola and olive oils and then by the addition of 0.01% citric acid, 0.01% tannic acid and 0.1% tea extract the effect of chelation concerned with each oil has been evaluated.
The results indicated that all the chemicals (citric and tannic acids) and tea extract added have chelating effect on copper and increased the induction period of the oils concerned.
It was concluded that tannic acid followed by tea extract and citric acid had the best chelating effect on copper.