PROTECTIVE EFFECT OF Allium cepa L. ANTHOCYANIN EXTRACT ON THE OXIDATIVE STABILITY OF SUNFLOWER OIL

摘要

The paper describes the great potential of anthocyanin extracts from dry skins of red onions (Allium cepa L.) to stabilise sunflower oil in comparison to the effect generated by tocopherols mixture. Total phenolics content in the investigated red onion samples is 1346 mg GAE 100 g~(-1) fresh mass (FM), while total anthocyanins content is 99.66 mg 100 g~(-1) FM. The anthocyanin extract shows activity against Streptococcus pyogenes. The effectiveness of the natural antioxidant on the oxidative stability of sunflower oil was assessed by evaluation of primary and secondary oxidation products, using peroxide value and thiobarbituric acid reactive substances tests. Our results indicate that sunflower oil containing small amounts of red onion anthocyanin extract exhibits lower levels of lipid oxidation at 40°C during 10-day storage compared to control and samples containing tocopherols. Also, a significant decrease of thiobarbituric acid reactive substances (TBARS) values of sunflower oil treated with red onion anthocyanin extract was observed compared to the control sample. These results may contribute to the future consideration of anthocyanins from red onion by-products as economically advantageous sources of natural antioxidants and antimicrobials to be used in edible oils.