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Processing technology of tea

Processing technology of tea. Quang H. Luong, MSc. Department of Food Engineering Faculty of Food Science and Technology Nong Lam University – Ho Chi Minh City. Course grading. Seminar: 30% Midterm exam/Lab. Report/assignment: 20% Final exam: 50%. Contents. - General introduction of tea.

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Processing technology of tea

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  1. Processing technology of tea Quang H. Luong, MSc. Department of Food Engineering Faculty of Food Science and Technology Nong Lam University – Ho Chi Minh City

  2. Course grading • Seminar: 30% • Midterm exam/Lab. Report/assignment: 20% • Final exam: 50%

  3. Contents - General introduction of tea - Flavonoids and other components of tea - Technology of tea products (Green, black, Oolong,…teas)

  4. History of tea • Reading of reference materials • Since 1690, E. Kaempfer named the bush “Thea” sinensis • In 1753, C. Linné named Camellia sinensis • Camellia sinensis (L.) O. Kuntze

  5. Countries grow tea plant

  6. World tea market share in 2009 Courtesy: http://www.vietnam-tea.com/overview.html

  7. Fig. 2 Vietnam and its location Tea growing areas of Vietnam Hà Giang,Tuyên Quang, Cao Bằng, Lạng Sơn Vĩnh Phúc, Phú Thọ, Sơn La, Hòa Bình, Bắc Thái Nghệ An, Hà Tĩnh, Thanh Hóa Lâm Đồng, Gia Lai, Kon-tum

  8. Teas and health benefits • Tea as a panacea • Anti-carcinogenic activity • Lung cancer, prostate cancer, breast cancer, skin cancer; stomach, pancreatic, oesophageal, and colon cancers • Anti-inflammatory and anti-microbial properties • Dental and oral diseases • AIDS • Cardioprotective and neuroprotective properties • Heart disease • Parkinson’s and Alzheimer’s diseases

  9. Flavonoids and other components in tea

  10. Forms of Catechin OH OH O OH HO O R1 OH X = C OH OR2 OH (-)-Catechin: R1 = R2 = H (-)-Gallocatechin: R1 = OH, R2 = H (-)-Catechin gallate: R1 = H, R2 = X (-)-Gallocatechin gallate: R1 = OH, R2 = X

  11. (-)-Epi form OH OH O OH HO O R1 OH X = C OH OR2 OH (-)-Epicatechin: R1 = R2 = H (-)-Epigallocatechin: R1 = OH, R2 = H (-)-Epicatechin gallate: R1 = H, R2 = X (-)-Epigallocatechin gallate: R1 = OH, R2 = X

  12. Technology of tea products

  13. Core stages Plucking Preservation Processing

  14. Plucking of T-leaves and flushes Courtesy: http://tea-plucking.blogspot.com/

  15. Categories of tea • Based on fermentation level • Unfermented tea (Green tea) • Full fermented tea (Black tea) • Partly fermented tea (Oolong tea, Pouchong tea) • Based on tea-shape • Loose, compressed form (tea brick), and powder teas • Based on processing-method • Raw and scented teas

  16. Courtesy: http://greentealovers.com/greenteatypeschina.htm

  17. Courtesy: http://www.cookscorner.net/Tea/Antioxidants.html

  18. Green tea processing Tea leaves and flushes Steaming/Panning Green tea product Rolling Packaging Drying Classification

  19. Oolong tea processing Tea leaves and flushes Oolong tea product Sunned withering Packaging Indoor withering Drying Panning Special rolling

  20. OTD - Black tea processing Tea leaves and flushes Black tea products Withering Packaging Rolling Classification Fermentation Drying

  21. Dried scented tea processing Tea panning (MC = 1.5 – 2%wb) Additive preparing (Drying, grinding) Blending (15 min.) Scented incubation (Temp. = 80 - 85 oC)

  22. Tea blending with fresh flowers Tea Flower Mixing Turning Screening Natural cooling Drying Flower mixing Flower screening ‘Fresh flower scented tea’

  23. Soluble powder tea processing Tea leaves and flushes Rolling/Grinding Extraction Drying/steaming Filtration Aroma stripping aroma aroma Freeze drying Concentration Soluble tea powder Spray drying Packaging

  24. Tea extracts and their applications • Strong infusions • Strong infusion are made by soaking tea leaves in alcohol/water mixtures (the catechin content is about 2% w/v) • Soft extracts • Soft extract are made by concentrating the strong infusion to a water content of 20-25% (the catechin content is about 20% w/w) • Dry extracts • Dry extract are made by spray drying the strong infusion after they have been concentrated to 40-50% solids (Catechin ~ 25% w/w) • Partly purified extracts • Purified catechins

  25. Trends in studying and developing new products from tea Tea material Study on bioactivity Develop new T-products In vitro Sample Study on animal Commercial T-refine mechanism, toxic, digest, dose,… Blingding Study on human beings Products from T-catechins

  26. T-preservation Table 1. Relationship between equilibrium MC of tea and RH of air

  27. T-preservation Table 2. The effect of packaging vs. MC of tea

  28. T-packaging

  29. End of lecture, continuing slides for reference

  30. Free glutamate in foods Green tea

  31. (-)-Catechin OH OH HO O H OH OH

  32. (-)-Gallocatechin OH OH HO O OH OH OH

  33. (-)-Catechin gallate OH OH HO O H O OH O C OH OH OH

  34. (-)-Gallocatechin gallate OH OH HO O OH O OH O C OH OH OH

  35. Các dạng (-)-Catechin OH OH O OH HO O R1 OH X = C OH OR2 OH (-)-Catechin: R1 = R2 = H (-)-Gallocatechin: R1 = OH, R2 = H (-)-Catechin gallate: R1 = H, R2 = X (-)-Gallocatechin gallate: R1 = OH, R2 = X

  36. Aroma bamboo rotationer

  37. Flavonoids in tea Green T. Black T

  38. Department of Food Engineering, FST, NLU

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