Tea Leaf Qualities In Different Periods Studies Of Hilly Pear Jujube

Pear jujube(Zizyphus jujube Mill.cv.Lizao)which is also called Cuizao or Dalingzao,is a rare excellent fresh jujube.In recent years,dwarfing and high-density culture pear jujube orchards were established with modern drip irrigation technology in Loess plateau area of northern Shaanxi,meanwhile great economic and ecology benefits were gained.To promote flower and bud differentiation,picking heart is very important.Which requires a lot of work and time,but the sporting most is discarded,which is wasteful.The study researched the changing patterns of sensorial quality of flavor,color and et al,and nutritional quality character,as while as the antioxidant content,composition and activity with the change of different growing stages.In addition,the study discussed the best best extraction technology of total saponins of pear-jujube,and the antioxidant capacity and bacteriostatic ability.Main results obtained were as follows:(1)Significant difference was found in the content of soluble sugar,amino acids,tea polyphenol and ascorbic acid.The tea in May possessed tight and thin strip,vivid green color,clear soup,fresh and pure taste with the best overall quality.The leaves for tea making were best in May,and jujube leaf tea is with great potential of new tea development with rich content of minerals and Vitamins,and no content of caffeine.(2)The antioxidant performance of pear jujube leaf tea harvested in summer were better than in spring,and rutin was the main composition of the phenolic compounds.The content of total phenolics,total flavonoid and vitamin C significantly varied among stages(P<0.05),and respectively changed from 29.94±0.28 mg GAE/g FW to 42.65±0.56 mg GAE/g FW,16.61±0.39 mg RE/g FW to 25.21±1.53mg RE/g FW and 136.5 mg/100 g～324.6 mg/100 g.(3)Gallic acid,catechin,rutin and quercetin were main detected phenolics,and the content had significant differences among stages(P<0.05),especially the rutin content was the most,and the maximum was 60.11 mg/100 g.Oxidation resistance were significantly correlated with total phenolics(P<0.05)and total flavonoid(P<0.05),but neither with vitamin C content.(4)The best extraction technology of total saponins was:1:40 ratio of material liquid,the extraction temperature was 70℃,the extraction time was 75 min.In which process,the average total saponins extraction rate can reach 1.40%.(5)The total saponins of pear jujube leaf tea had antioxidant ability,in removing DPPH·free radicals and the determination of the total reducing power,the antioxidant activity of total saponins were superior to ascorbic acid,so which can be as a good antioxidant.(6)The total saponins of pear jujube leaf tea had good inhibition effect on antimicrobial,the MIC of Escherichia coli,Staphylococcus aureus and Salmonella were MIC were 0.64 mg/mL,0.64 mg/mL and 0.32 mg/mL,and the MBC all were 2.55 mg/mL.