The East African Tea Trade Association & The Uganda Tea Association, The Serena Hotel

1. The East African Tea Trade Association & The Uganda Tea Association, The Serena Hotel Kampala, Uganda 26th – 28thJune, 2019.

2. Enhancing Tea Quality Standards Prof Philip Okinda Owuor, PhD, FKNAS, FAAS Department of Chemistry, Maseno University P.O. Box 333 – 40105 Maseno Kenya Email: pokindao@gmail.com or okindaowuor@maseno.ac.ke

3. Quality Definition • In tea trade the definition of quality is ambiguous and shifts with roles of individuals in the business. • Producers = tea whose sale leads to higher income. • Tea traders = tea as that gives maximum profit • Consumers = tea which can be obtained at reasonable price but has desirable taste, aroma, appearance and class. 

4. Reality of Tea Prices • The prices of black tea are dictated by supply and demand, factors that usually have nothing to do with quality (Biswas; Biswas & SarkarJ. Sci. Food Agric, 22, 191-198 (1971); Biswas; Sarkar; Biswas J. Sci. Food Agric., 24, 1457-1477. (1973)) • When supply is less than demand all teas are bought with less choice and prices tend to be higher than usual. • When supply is more than demand all tea is bought on basis of quality as defined by some chemical composition. • However, for sustainable tea business, consumer satisfaction is key

5. Need for Tea Standards • Internationalstandardsarevital tofacilitateinternationaltrade • Toensureconsumerexpectationsaremet • Toprovideguidanceandcommonunderstandingof Good Manufacturingpracticesviacompositionalspecifications • Toprovidevalidatedmethodsof analysis

6. InternationalStandards forTea 1970’s-TeaCommitteebecameISOWorkingGroup8 -ISOTechnicalCommittee34Sub-committee8–Tea 1977-ISO3720Black teastandard 8testingmethodstomeasurebasicteaparameters 1980 - ISO1839Sampling tea 1980 - ISO3103Preparationof liquor for sensory analysis 1982 - Glossaryofterms 1990 - Instantteastandard 4 supporting testmethods

7. ISOBLACK TEASPECIFICATION-ISO37201977(Firstedition): The Quality Parameters Contentsofcaffeineandpolyphenolicconstituents are important chemicalcharacteristicsof black tea,(but not included in the specification) For caffeine agreementhasnotyetbeenreachedona standardmethodforthe determination. For polyphenolicconstituents, knowledgeabout testmethodswas notsufficientlydevelopedto justifythe standardizationof any one ofthe methods inexistence Also informationonthecontentsofthese constituents was only availablefora few typesof tea. 7

8. Measurements of Tea Caffeine and polyphenolic constituents Contents • 1995 - Measurementofcaffeineinteaandinstant tea • Measurementofcaffeineintea,instanttea and decaffeinatedtea • 2005 – Measurement of total polyphenols in tea • 2005 - Measurement of catechins in green and black tea 8

9. Minimum export standardIn early 1980s, UNCTAD commissioned a consultant to formulate Minimum Export Standard for black tea be adopted for use to regulate black tea trade. The requirements of the Minimum Export Standard Minimum level of theaflavins in tea 8 µmoles/gm (dry weight) Crude fibre 16% Moisture content 6% Purpose of standard To remove low quality and sub-standard black teas from the market. To improve the image of black tea as a beverage thereby, leading to increasing consumption And creating an upward surge in black tea prices for the benefit of the producers.

10. Towards Quality Black Tea Enhancing Quality Standard :- • Through Agronomic Practices • Optimising Processing Conditions • Managing Post processing quality deteriorations

11. Agronomic Practices • The condition of the leaf • Plucking standard • Uniformity of the leaf (Influence of pruning and leaf handling) • Origin (Geographical area of production) • Harvest date (Further away from the equator)6. Cultivar • Management of pests and diseases

12. Optimising Processing Conditions • Tea maker • Processing • Withering • Maceration • Fermentation • Drying • Sorting

13. Managing Post Processing Quality Deteriorations • Percentage of moisture remaining in the tea • Colour • Conservation of Aroma • Taste • Contamination

15. Variations in the Chemical Composition of Black Tea Due to Plucking Standards • Plucking standards • Bud 1 & 2 & 3 & 4 & 5 & Mean CV (%) • bud bud bud bud bud • Caffeine (%) 3.89 3.42 2.11 1.56 1.29 1.22 2.25 50.7 • Theaflavins • (μM/g) 23.21 33.43 34.71 29.99 27.33 22.42 28.52 18.0 • Thearubigins • (%) 8.26 12.93 17.91 18.19 18.99 16.68 15.49 26.7 • GP I VFC 3.61 4.47 4.63 4.86 5.23 5.74 4.76 15.13 • GP II VFC 8.18 8.30 6.94 5.50 5.06 4.54 6.45 25.89 • F.I. 2.26 1.86 1.50 1.13 0.97 0.79 1.43 40.56

16. Clonal Variations in Quality in Different Tea Cultivars Due to Plucking Standards

17. Clonal Variations in Quality in Different Tea Cultivars Due to Plucking Standards

18. Changes in Quality Parameters and Sensory Evaluation of Black Tea Due to Plucking Intervals. • Plucking Theaflavins Thearubigins Caffeine Flavour Tasters evaluations • interval μM/g) (%) (%) index A B C • 6 days 38.79 16.103.622.74 40 36 95 • 10 days 37.52 16.393.60 2.67 39 37 89 • 14 days 35.76 15.60 3.57 2.36 39 36 85 • 18 days 35.17 17.043.58 2.10 41 37 81 • 22 days 33.79 15.383.53 1.99 40 37 79 • CV (%) 3.00 8.980.41 - 12.66 1.00 4.78 • LSD, • P=0.05 2.05 NS0.03 - NS NS 7.71

19. Impact of Nitrogen and Plucking Frequency on Black Tea Quality • Parameter Plucking Rates of nitrogen (kg N ha-1 year-1) Mean • intervals plucking • (Days) 100 200 300 400 500 600 intervals • 7 12.80 13.32 11.75 11.21 10.84 12.32 12.04 • Theaflavins 14 11.67 10.79 10.53 9.74 9.51 9.87 10.35 • (μmol/g) 21 10.39 10.03 9.26 9.52 8.59 8.69 9.41 • Mean rates 11.62 11.38 10.51 10.16 9.64 10.29 • C.V. (%) 5.84 7.95 • LSD (P=0.05) 1.62 0.49 • 7 19.03 17.26 16.39 14.93 15.18 17.98 16.79 • Brightness 14 16.87 14.74 14.59 14.01 14.43 16.60 15.21 • (%) 21 14.23 13.53 12.96 13.68 12.87 14.53 13.64 • Mean rates 16.71 15.19 14.64 14.20 14.16 16.37 • C.V. (%) 6.19 7.34 • LSD (P=0.05) NS 0.65

20. Impact of Nitrogen and Plucking Frequency on Black Tea Quality • Parameter Plucking Rates of nitrogen (kg N ha-1 year-1) Mean • intervals plucking • (Days) 100 200 300 400 500 600 intervals • 7 14.43 14.49 13.87 14.34 13.39 12.97 13.94 • Thearu- 14 15.22 15.22 14.37 15.07 14.31 14.89 14.85 • bigins (%) 21 17.24 16.60 15.90 16.03 14.77 15.61 16.03 • Mean rates 15.63 15.44 14.71 15.16 14.19 14.19 • C.V. (%) 4.37 5.28 • LSD (P=0.05) NS 0.46 • 7 3.03 2.69 2.95 2.91 2.71 2.94 2.87 • Total 14 3.48 3.23 3.21 3.34 3.20 3.46 3.32 • colour 21 3.68 3.39 3.39 3.56 3.57 3.59 3.53 • (%) Mean rates 3.39 3.10 3.18 3.27 3.16 3.33 • C.V. (%) 4.53 7.73 • LSD (P=0.05) NS 0.15

21. Nitrogen and Plucking Frequency Effects on Black Tea quality Aroma and Pricing**  Parameter Plucking Rates of nitrogen (kg N ha-1 year-1) Mean • intervals plucking • (Days) 100 200 300 400 500 600 intervals • Flavour 7 1.13 0.99 0.89 0.80 0.77 0.73 0.89 • Index 14 0.91 0.75 0.72 0.67 0.64 0.61 0.72 • 21 0.77 0.66 0.66 0.59 0.57 0.53 0.63 • Mean rates0.94 0.80 0.76 0.69 0.66 0.62 • C.V. (%) 4.67 8.42 • LSD (P=0.05) 0.11 0.04 • Prices** 7 92 91 89 87 84 78 87 • (164) (162) (159) (155) (150) (139) (155) • ()*** 14 87 85 83 81 80 76 82 • (155) (152) (148) (145) (143) (136) (146) • 21 85 81 76 74 70 69 76 • (152) (145) (136) (132) (125) (123) (136) • Mean rates 88 86 83 81 78 74 • (157) (153) (148) (145) (139) (132) • C.V. (%) 10.74 12.8 • LSD (P=0.05) 6 9 • (11) (16)

22. Changes in Sensory Evaluation* of Black Tea Due to Nitrogen Fertilizer and Plucking Intervals Evaluation Plucking Rates of nitrogen (kg N ha-1 year-1) Mean • Method intervals plucking • (Days) intervals • 100 200 300 400 500 600 • Taster A 7 44 43 42 40 39 38 41 • 14 40 38 37 36 35 36 36 • 21 37 32 33 31 33 33 33 • Mean rates 40 38 37 36 36 34 • C.V. (%) 1.77 8.80 • LSD (P=0.05) 2 2 • Taster B 7 140 126 99 91 92 72 103 • 14 121 101 89 81 44 82 86 • 21 79 65 62 60 48 39 59 • Mean rates 113 97 83 78 61 64 • C.V. (%) 19.71 31.66 • LSD (P=0.05) NS 15

23. Yield Response to Rates of NKPS 25:5:5:5 and Plucking Rounds

24. Response of Clonal Black Tea Total Theaflavins (µ mol/g) and Relative Ranking Based on Theaflavins Levels to Growing Environment

25. Response of Clonal Black Tea to Taster A Sensory Evaluation and Their Relative Ranking in Different Growing Environments

26. Response of Clonal Black Tea to Taster B Sensory Evaluation and Their Relative Ranking in Different Growing Environments

27. Effects of Geographical Area of Production

28. Effects of Geographical Area of Production (Aroma)

29. Processing Conditions Withering process

30. Withering Effects

31. Effects on Withering Temperature On Tea Quality (MPU)

32. Withering Temperature Control in Commercial Factory

33. Changes in Tea Quality Parameters Due to Withering Temperature and Fermentation Duration

34. Delayed Withering and Fermentation (90 Min)

35. Delayed Withering and Sensory Evaluation

36. Maceration

37. CTC vs. Orthodox Manufacture

38. Colour change during fermentation

39. Changes in TFMT, ILTF and Tasters’ Evaluation with Fermentation Time

40. Effects of Fermentation Temperatures

41. Conclusion Enhance Tea Quality Standard: • Agronomic and Cultural Practices • Optimising Processing Conditions • Managing Post processing quality deteriorations

42. ACKNOWLEDGEMENT The Organisers of the 4th African Tea Convention and Exhibition for the Invitation THANK YOU