Health Care Efficiency Of Puer Tea Compared With Other Teas And Of The Relation To Storage Time

ObjectiveCompared with DianGong tea (black tea), longjing (green tea) and tieguanyin, the puer tea regards theanine, EGCG and caffeine as anti-fatigue ingredients for functional component index, and the puer tea was evaluated in anti-fatigue effect by anti-fatigue classical experimental criterion in mice. At the same time, the relation between the anti-fatigue effect and the storage time was also studied.As the feasible analytical methods of anti-fatigue ingredients of teas, a high-performance liquid chromatography (HPLC) method was developed for the determination of theanine in puer tea without derivatization, and the other HPLC method for determination of EGCG, and caffeine without gradient elution system was put forward as well.Methods1. The method of determinating theanine, EGCG and caffeine in teas1.1 The method of extracting theanine, EGCG and caffeine from teaAfter smashed, the tea samples went through 80 mesh screen. Then theanine was extracted with water for 30 min at 70℃twice from tea; EGCG and caffeine were extracted with 50% ethanol for 30 min at 70℃twice.1.2 Chromatographic conditionsThe extract was analyzed by HPLC- PDAD with an Inertsil ODS-C18 column and at the flow rate lml/min. The content of theanine was determinated with H3PO4(0.1%)-acetonitrile(50%) mobile phase system(95:5, v/v), and EGCG and caffeine with 0.15mmol/l KH2PO4-methonal mobile phase system(75:25, v/v).2. The comparative study among anti-fatigue effect of DianGong tea (black tea), longjing (green tea), tieguanyin and puer teaHealthy male mice,18～22g, were divided into four batches. Each batch was randomly divided into 5 groups, four experimental groups and one control. Each experimental group had ten rats respectively, and they were orally given extraction liquid of DianGong tea, longjing, tieguanyin and puer tea made in 2008 at the dose of 1.34 g/kg·bw. The control group was given distilled water. After 30d the first batch was used for swimming experiment, the second batch was used for serum urea nitrogen determination, the third batch was used for glycogen and Cu, Zn, Fe trace elements determination in liver and the fourth batch was used for blood lactic acid measurement.3. The study among the anti-fatigue effect of puer teas produced in 1996, 2000,2004 and 2008.Healthy male mice,18～22g, were divided into two batches. Each batch was randomly divided into 5 groups, four experimental groups and one control. Each group had ten rats respectively, and they were orally given extraction liquid of puer teas produced in 1996,2000,2004 and 2008 at the dose of 1.34 g/kg·bw. The control group was given distilled water. After 30d the first batch was used for swimming experiment and the second batch was used for serum urea nitrogen determination.Results1. The levels of theanine, EGCG and caffeine in teasIn 10～300μg/ml range, the peak area of the various components and correspo-nding concentration are in good linear relationship, r>0.999. The recovery range is 85%～110%. The RSD varied from 0.42% to 5.87%. The theanine contents of DianGong tea, longjing, tieguanyin are 5.11±0.21,14.43±0.65,5.93±0.32 mg/g respectively; The theanine content of puer tea produced in 1996,2000,2004 and 2008 are 3.86±0.15,2.55±0.17,6.10±0.11,9.76±0.21 mg/g respectively; The EGCG contents of DianGong tea, longjing, tieguanyin are 13.41±2.35,64.60±3.38, 49.85±7.76 mg/g; The EGCG contents of puer tea made in 1996,2000,2004 and 2008 are₃6.88±5.66,28.82±4.07,41.80±5.40,51.79±6.30 mg/g; The caffeine contents of DianGong tea, longjing, tieguanyin are 27.72±0.67,24.19±2.21,18.28±0.36 mg/g; The caffeine contents of puer tea produced in 1996,2000,2004 and 2008 are 27.75±1.10,29.48±2.74,24.58±0.61,27.11±0.92mg/g.2. The anti-fatigue effects of DianGong tea, longjing, tieguanyin and puer teasIn the test, the black tea was represented by Diangong tea, and the green tea was represented by longjing. By comparison, the difference of swimming time between black tea group and controls was statistically nonsense(P>0.05), and swimming times of the other three groups were longer than the control group(P< 0.05). The sequence was as follows:green tea> tieguanyin> puer tea>black tea; The serum urea nitrogen levels of four experimental groups were lower than that of the controls(P<0.05), and that of green tea group was the lowest. The difference among the serum urea nitrogen levels of the other three experimental groups was not statistically significant(P>0.05). The difference of glycogen content between black tea group and control group was not statistically significant(P>0.05), but the glycogen content of the other three experimental group was higher than that of control group. The sequence was as follows:puer tea> green tea> tieguanyin>black tea. The level difference of trace elements Cu, Fe and Zn in liver between experimental groups and control group was not statistically significant(P>0.05). The area under blood lactic acid curve of green tea group was lower than that of control group(P<0.05), but the differences between every other three experimental group and control group were not statistically significant(P> 0.05).3. The anti-fatigue effects of puer teas produced in 1996,2000,2004 and 2008.The swimming times of four experimental groups were shorter than that of control group(P<0.05). But the difference among four experimental groups was not statistically significant(P>0.05). Compared with control group, the serum urea nitrogen levels of four experimental groups are lower(P<0.05). The serum urea nitrogen levels of puer tea group produced in 2004 and 2008 were lower than that of puer teas produced in 1996 and 2000.Conclusion1. In this paper, among four teas, the contents of theanine, EGCG and caffeine of longjing(green tea) are the most, and the theanine, EGCG and caffeine contents of puer tea produced in 2008 were lower than those of longjing(green tea). The contents of those in DianGong tea(black tea) were the lowest. According to "Evaluation Procedures and Inspection Method of Health food " promulgated in 2003, longjing (green tea), tieguanyin, puer tea produced in 2008 have the anti-fatigue effects at the same dose. Among four teas, the anti-fatigue effect of longjing(green tea) was the best, while that of DianGong tea was uncertain. The differences among the anti-fatigue effects of four kinds of teas were mostly correlated with theanine, EGCG and caffeine contents.2. By swimming and serum urea nitrogen experiments, the anti- fatigue effects of puer teas produced in 2004 and 2008 was better than that of puer teas produced in 1996 and 2000. The experiments manifest that the anti-fatigue effect of puer tea was declining with the storage time, reversing the claims that the longer the storage time of puer tea, the better the health care.3. The trace element determination results showed that in the experiment the Zn, Cu, Fe levels in mouse liver were not siginificantly changed.Generally, although puer tea has anti-fatigue effect, it is lower than that of green tea. The longer the storage time of puer tea, the lower health care of it.