Anti-polymerization activity of tea and fruits extracts during rapeseed oil heating.

The aim of the study was to analyze the influence of natural antioxidants on polymerization of partially hydrogenated rapeseed oil heated in 170°C for 40h. In the research ethanolic extracts of green tea leaves (China Lung Ching), yellow tea leaves (China Kakecha), cranberry, blackberry, and lime were used. The yellow and green tea extracts were characterized by the highest content of total polyphenol and antioxidant activity. Polymers of triacylglycerols were found only in the polar fraction of heated oil. During heating, the increase of dimers, trimers, and oligomers was observed. However, it was dependent on the used additives and not directly related to the content of phenolic compounds and their antioxidant activity. The final content of polymers in oil samples increased in the fallowing order: green tea<yellow tea<blackberry<BHT<cranberry<lemon<oil without additives.