Effect of Dhool Temperature on Quality of Orthodox Rotorvane Tea and Its Grade Outturn Percentage Manufactured using Two End-Attachments in Different Degrees of Wither

다국어 초록 (Multilingual Abstract)

Total antioxidant capacities of green tea, oolong tea and black tea processed from the leaves of four selected tea cultivars i.e. TRI 2025, TRI 777, CY 9 and DT 1 were measured by DPPH assay. Colorimetric Folin-Ciocalteu method was used to determine total phenolics. Catechins and caffeine were identified by HPLC. Significantly higher total phenolic contents and catechins were found in green tea produced from all selected cultivars. Green tea and oolong tea had significantly higher total antioxidant capacities than black tea in all selected cultivars except TRI 777 with highest total antioxidant capacity in green tea. In black tea and oolong tea, cultivar TRI 777 showed significant lowest antioxidant capacity when compared to other selected cultivars. The total antioxidant capacity values were positively correlated with the total phenolics (R2 = 0.78), ECG% (R2 = 0.86), EGC% (R2 = 0.71) and EGCG% (R2 = 0.79). Our results indicate that green tea contains higher amounts of total phenolics, catechins (ECG, EGC, and EGCG) and total antioxidant capacities than oolong and black tea produced from all selected cultivars. Phenolics constituents in made tea are the major contributors to the total antioxidant capacity and made tea with high catechins are good sources of dietary antioxidants.

참고문헌 (Reference)

1 Anon, "What does a tea leaf contain?"

2 Brand-Williams W., "Use of free radical method to evaluate antioxidant activity. Leben-Smittel" 28 : 25-30, 1995

3 Anon, "The suitability of tea clones for the different regions" Tea Research Institute of Sri Lanka 2002

4 Anon, "Test method for substances characteristics of green tea and black tea. Part 2 : Determination of catechins in green and black tea. Method using high performance liquid chromatography" 8 : 5-7, 2004

5 Modder WWD., "Tea and Health" The Tea Research Institute of Sri Lanka 2002

6 Liu RH, "Supplement quick fix fails to deliver" 1 : 71-72, 2002

7 Cos P., "Structure-activity relationship and classification of flavonoids as inhibitors of xanthine oxidase and superoxide scavengers" 61 : 71-76, 1998

8 Sanderson GW, "Structural and Functional Aspects of Phytochemistry" Academic Press 1972

9 Liu RH, "Potential synergy of phytochemicals in cancer prevention: Mechanism of action" 134 : 3479s-3485s, 2004

10 Benzie IF., "Consumption of green tea causes rapid increase in plasma antioxidant power in humans" 34 : 83-87, 1999

11 Willett WC, "Balancing life-style and genomics research for disease prevention" 296 : 695-698, 2002

12 Temple NJ, "Antioxidants and disease : More questions than answers" 20 : 449-459, 2000

13 Cao G., "Antioxidant and prooxidant behavior of flavonoids : Structure-activity relationships" 22 : 749-760, 1997

14 Thompson LU, "Antioxidant and hormone-mediated health benefits of whole grains" 34 : 473-497, 1994

15 Yen GC., "Antioxidant activity of various tea extracts in relation to their antimutagenecity" 43 : 27-32, 1995

16 Singleton VL., "Analysis of total phenolics and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent" 299 : 152-178, 1999