Detection And Application Of Tea Polyphenol In Tea Seed Oil

Tea seed oil is a edible vegetable oil made from tea seed,a by-product of tea planting.It contains rich unsaturated fatty acids,in addition,it also contains bioactive ingredients such as sterols,enols,tocopherols,squalene and so on.So it is a nutritious but easily oxidized edible vegetable oil.Tea polyphenols are polyphenols extracted from tea as raw materials,which have antioxidant capacity.The existence of tea polyphenols in tea seed oil is controversial,and there is no corresponding standard for the determination of tea polyphenols in tea seed oil.This paper focuses on the determination methods of tea polyphenols,catechins and caffeine in tea seed oil,explores the loss of tea polyphenols in tea seed oil refining,and adds tea polyphenols to tea seed oil as antioxidants.The research results are as follows:?1?Referring to GB/T 31740.2-2015 Appendix A Folin-phenol method for determination of tea polyphenol and Appendix B HPLC for determination of catechins and caffeine,the raw material pretreatment and determination conditions were improved to adopt the experimental requirements.Under the determination by HPLC,the total content of catechins in tea seed hull was 1516.27¹606.55 mg·kg^-1 and the content of caffeine was 2601.33²713.43 mg·kg^-1,the total content of catechins in tea seed kernel was 1275.91¹302.19 mg·kg^-1 and the content of caffeine was1270.35¹305.18 mg·kg^-1,the total content of catechins in tea seed oil was 0.07¹.38mg·kg^-1 and the content of caffeine was 0.08⁴3.48 mg·kg^-1,the total content of catechins in tea seed oil cake was 1335.39¹602.21 mg·kg^-1 and the content of caffeine was 1415.48¹635.11 mg·kg^-1.The EGCG and ECG with ester bond structure in catechins were more likely brought in tea seed oil,and caffeine was more likely brought in tea seed oil than catechins.The content of tea polyphenol in tea seed oil was1.66¹9.84 mg·kg^-1 determined by Folin-phenol method.It was analyzed that the fat-soluble substances with phenolic hydroxyl group such as vitamin E in tea seed oil would interfere with the determination of tea polyphenol in oil by Folin-phenol method.Therefore,the determination of tea polyphenol in oil and oilseed should be based on the total content of catechins by HPLC.?2?In the laboratory simulation of tea seed oil refining,the catechins loss rate of tea seed oil was 95.13%⁹5.72%.the ECG in catechins could only be detected in refined tea seed oil.The caffeine loss rate of tea seed oil was over 99%and the content of caffeine in refining oil was 0.079⁰.083 mg·kg^-1.Tea seed oil will not cause excessive caffeine intake.?3?Ethanol was used as a solvent to adding polyphenols into refined tea seed oil,and a kind of colloid was prepared.The appearance of the tea polyphenol colloid did not change and the tea polyphenols in the sample did not change chemically.The residual ethanol of tea polyphenol colloid was 0.295¹.567 g·kg^-1.Tea polyphenols were easy to precipitate under centrifugal force and heating conditions,and the greater the amount of tea polyphenols added,the worse the stability.Under the condition of accelerated oxidation at 60?in air oven,The antioxidant ability in oil was shown as follows:tea polyphenol colloid>tea polyphenol palmitate>TBHQ>BHA>BHT.The optimum addition range of tea polyphenol in refined tea seed oil was 0.1⁰.2 g·kg^-1.?4?A kind of vacuum frying equipment was designed preliminarily.In this equipment,tea polyphenols could be added to oil as antioxidant,which could increase the durability of oil and improve the shelf life and quality of products.The determination method of tea polyphenols in the product was determined.