Effects Of Altitude On Quality And Oxidative Damage Repair Of Alpine Green Tea

The growth of tea trees is easily affected by environmental factors,such as light,soil,temperature and humidity,so the quality of tea leaves is significantly different under different planting conditions.Among them,the altitude has a significant effect on the quality of tea.With the increase of altitude,the temperature variation between day and night is obvious,so the organic substances are gradually enriched.At the same time,the content of some nitrogenous and aromatic substances also increases during this process.At present,although there are many studies about the effect of altitude on tea quality,few of them reported on the effect of altitude on mountain green tea made by different processing techniques and classified at different grades.In order to further study the influence of altitude on the quality of high mountain tea,Yunfeng and Longjing of high mountains tea at altitudes of 500 m and 900 m and four grades high mountain Longjing teas were selected as test objects to study the influence of altitude on their physical and chemical properties and their oxidative damage repair properties.The main results are as follows:1.Between the altitude of 500 m and 900 m,the water content of Longjing and Yunfeng had the opposite change tendency,but thier Vitamin C content increased,the contents of Vitamin C in Longjing and Yunfeng at 900 m were 3.39 mg/g and 4.33 mg/g respectively,which were significantly higher than 1.62 mg/g and 2.28 mg/g at 500 altitude,phenol ammonia ratio dropped significantly,the content of polyphenol in Longjing tea decreased from 20.51% to 16.17%,and that in Yunfeng tea decreased from 19.31% to 15.87%,water extract and total flavonoids,theanine and catechin had no significant difference.The aroma quantity and content,sensory taste score rose,which shew that with the increase of altitude,the variation trend of different teas was obviously different,but their quality and taste shew an upward trend.2.At the altitude of 500 m,there were no significant differences in water content,water extract and flavonoid content among different grades of Longjing tea.At 500 m altitude,grades 1 to 4 the contents of theophylline were 34.68 mg/g,33.71 mg/g,32.66 mg/g,28.37 mg/g,and the contents of tea polyphenols were 20.51%,19.70%,19.98%,19.87%,900 m,the contents of theophylline were36.51 mg/g,33.71 mg/g,32.66 mg/g,28.37 mg/g,and the contents of tea polyphenols were 16.17%,16.24%,16.35%,16.16%,respectively,With the increase of altitude,the tea quality changed significantly among different grades,but it didn’t have obvious correlation between altitude and different grades when the tea was from high altitude.3.Under the condition of different altitudes,the effects of tea extract on PC-12 cell activity shew that different tea extracts can maintain the cell normal form,protect its nucleus,hold the function of mitochondria,increase the intracellular contents of glutathione and other antioxidants,and activate the antioxidant enzymes’ activity to protect cells against the oxidative stress.Especially,compared with tea extract at 500 m,the tea extract at 900 m altitude had better effect on alleviating oxidative stress induced by hydrogen peroxide in PC-12 cells.