Study On Antioxidative Activities Of Aged Aroma Single Clump Tea From Lingtou

Lingtou single clump tea is the famous tea of oolong tea in Guangdong province.It has the characteristics of sweet aroma and great taste.Oolong tea has healthy and pharmacological effects on human body,such as lowering blood fat and cholesterol,anti-cancer and anti-oxidation.It was proved that the content and proportion of the main quality components in the process of storage are different,which directly affects the quality and healthy function of the tea.In this paper,the main quality indicators of two types of the teas which were Lanhua and Milan aromatic variety aged for 5,10,15,20 years and the control was processed in 2016 were determined,the sensory evaluation and the electric nose technology were combined to evaluate the effect of aging time on quality of Lingtou single clump teas.Furthermore,its antioxidative activities were measured in vitro by using the scavenging abilities of DPPH(1,1-bipheny l-2-picrylhy drazyl)radicals and hydroxylradicals,inhibiting ability of superoxide radicals and reducing power,and were analyzed by correlation with antioxidant components.The D-galactose aged model mice gavaged with teas extracts,The activities of superoxide dismutase(SOD)and glutathione and peroxidase(GSH-Px),the contents of total antioxidant capacity(T-AOC)and malondialdehyde(MDA)in serum,liver and brain tissue of mice were determined;Finally,the expression level of antioxidant related gene SOD₁m RNA,SOD₂m RNA,CAT m RNA and GSH-PX m RNA in the liver of mice gavaged with different aged teas extracts were tested by Real time-PCR.So as to provide theoretical basis for the storage,bioactivity and development of new products of Lingtou single clump tea,and as exploring the antioxidation mechanism of Lingtou single clump tea at molecular level.The results are as follows:(1)The storaged was advantaged for the accumulation of the tea polyphenol,soluble sugar,soluble protein,the flavonoids and catechins content,and was not advantaged for the accumulation of the free amino acid and caffeine content,and the theaflavins and the soluble amylogen content relatively stable in Milan aromatic variety.The storaged was advantaged for the accumulation of the free amino acid,soluble sugar soluble protein content,and the content of caffeine storagd at 5 and 15years,and was not advantaged for the accumulation of the catechins and theaflavins content,and the tea polyphenol,flavonoids and soluble amylogen content relatively stable in Lanhua aromatic variety.As the aged time increased,both the water extracts content and p H value reduced in two types of Lingtou single clump tea.(2)The results of sensory evaluation were found that the score was in the decreasing order,for Lanhua aromatic variety,20 years>10 years>15 years>the control>5 years.For Milan aromatic variety,15years>20 years=10 years>the control>5 years.The results determined by electronic nose and sensory evaluation were basically consistent.(3)It was observed that the antioxidant capacity by the APC was in the decreasing order,for Milan aromatic variety teas,aging for 20 years>10 years>15 years>5 years>the control,for Lanhua aromatic variety teas,aging for 5 years>20 years>10 years>15 years>the control.The correlation analysis revealed that the antioxidant capacity were different significantly positively correlated with the contents of tea polyphenols,flavonoids,catechin,caffeine and theaflavins for Lingtou single clump tea water extracts from different storage-time(P<0.05).(4)Compared to the D-galactose aging model mice,the activities of SOD and GSH-Px,the contents of T-AOC increased and MDA reduced to some extent.in serum,liver and brain tissue of mice gavaged with teas extracts from different aging teas.The experimental results showed that two types of teas have antioxidative effects on D-galactose aging model mice.The difference analysis was found that the antioxidant activity was in the decreasing order:for Milan aromatic variety teas,Vc>aging for 20 years>15 years>10 years>5 years>control,for Lanhua aromatic variety teas,Vc>aging for 5 years>10 years>20 years>15 years>control.(5)Compared to the aging model mice,the differences of up-regulated expression of GSH-PX m RNA in liver of contral group and aging for 15 years teas in Milan aromatic variety was not significant(p>0.05),and the differences of up-regulated expression of SOD₂m RNA in liver from contral group and aged for 10,15 and 20 years teas in Lanhua aromatic variety was not significant too(P>0.05).The up-regulated expression of SOD₁m RNA,SOD₂m RNA,CAT m RNA and GSH-PX m RNA were significantly higher(p<0.05)in liver of mice gavaged with teas extracts from others aging years,and enhance the antioxidation ability.