Conclusion
The obtained extracts of green tea were very effective to prevent of the primary and secondary oxidation products in the studied canola oil. Green tea extract both free and incorporated in liposome showed a good antioxidant activity. The 600 mg/L concentration of green tea extract had stronger antioxidant properties than BHT and other green tea concentrations that its reason can be extract polyphenols. In addition to, the results determined green tea extract liposomes possessed powerful antioxidant activity that showed liposome structure caused to improve the stability of tea polyphenol. The increasing storage time caused to upward trend of canola oil oxidation. While the increasing green tea extract concentration from 200 to 600 mg/L had a significant impact in preventing of oxidation process (P≤0.05) but green tea extract in concentration of 1000 mg/L did not show any strong antioxidant activity and causing delay in canola oil oxidation. This study determined natural antioxidants such as green tea extract can be a good alternative instead of synthetic antioxidants.