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
Apr 21, 2023 2
Course grading Seminar: 30% Midterm exam/Lab. Report/assignment: 20% Final exam: 50%
Apr 21, 2023 3
Contents
- General introduction of tea
- Flavonoids and other components of tea
- Technology of tea products (Green, black, Oolong,…teas)
Apr 21, 2023 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
Apr 21, 2023 5
Countries grow tea plant
World tea market share in 2009
Apr 21, 2023 6Courtesy: http://www.vietnam-tea.com/overview.html
Apr 21, 2023 7
Tea growing areas of Vietnam
Fig. 2 Vietnam and its location
Hà Giang,Tuyên Quang, Cao Bằng, Lạng SơnVĩnh Phúc, Phú Thọ, Sơn La, Hòa Bình, Bắc Thái
Nghệ An, Hà Tĩnh, Thanh Hóa
Lâm Đồng, Gia Lai, Kon-tum
Apr 21, 2023 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
Apr 21, 2023 9
Flavonoids and other components in tea
Apr 21, 2023 10
O
OHOH
R1
OR2OH
HO
OH
OH
OH
C
O
X =
Forms of Catechin
(-)-Catechin: R1 = R2 = H
(-)-Gallocatechin: R1 = OH, R2 = H
(-)-Catechin gallate: R1 = H, R2 = X
(-)-Gallocatechin gallate: R1 = OH, R2 = X
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O
OHOH
R1
OR2OH
HO
OH
OH
OH
C
O
X =
(-)-Epi form
(-)-Epicatechin: R1 = R2 = H
(-)-Epigallocatechin: R1 = OH, R2 = H
(-)-Epicatechin gallate: R1 = H, R2 = X
(-)-Epigallocatechin gallate: R1 = OH, R2 = X
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Technology of tea products
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Plucking
Preservation
Processing
Core stages
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Plucking of T-leaves and flushes
Courtesy: http://tea-plucking.blogspot.com/
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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
Apr 21, 2023 19
Courtesy: http://greentealovers.com/greenteatypeschina.htm
Apr 21, 2023 20
Courtesy: http://www.cookscorner.net/Tea/Antioxidants.html
Apr 21, 2023 21
Green tea processing
Tea leaves and flushes
Green tea productSteaming/Panning
Rolling Packaging
ClassificationDrying
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Oolong tea processing
Tea leaves and flushes Oolong tea product
Sunned withering
Indoor withering Drying
Special rollingPanning
Packaging
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OTD - Black tea processing
Tea leaves and flushes Black tea products
PackagingWithering
Rolling Classification
DryingFermentation
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Dried scented tea processing
Tea panning(MC = 1.5 – 2%wb)
Additive preparing(Drying, grinding)
Blending(15 min.)
Scented incubation(Temp. = 80 - 85 oC)
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Tea blending with fresh flowers
Tea
Mixing
Flower
Turning Screening
DryingNatural cooling
Flower mixing Flower screening
‘Fresh flower scented tea’
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Soluble powder tea processing
Tea leaves and flushes Rolling/Grinding
Extraction Drying/steaming
Aroma strippingFiltration
Freeze drying Concentration
Spray dryingSoluble tea powder
Packaging
aroma aro
ma
Apr 21, 2023 27
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
Apr 21, 2023 28
Tea material
Develop new T-productsStudy on bioactivity
In vitro
Study on animal
Sample
Blingding
Commercial T-refine
Products from T-catechins
Study on human beings
mechanism, toxic, digest, dose,…
Trends in studying and developing new products from tea
Apr 21, 2023 29
T-preservation
RH of air (%) 30 45 60 62 70 80 85 96
EMC of tea(%)
5,8 6,7 8,7 9,0 10,4 12,2 14,8 20,5
Table 1. Relationship between equilibrium MC of tea and RH of air
Apr 21, 2023 30
T-preservationTable 2. The effect of packaging vs. MC of tea
Types of packagingMC of tea (%)
0 After 30 days
Glass flask with head-pin 7,5 7,5
Tin box 7,5 7,5
Wrap by hands, 2 layers of paper 7,5 12,8
Carton box with T-paper wrapping 7,5 13,8
Carton box with anti-humidity paper 7,5 12,7
Control (T without-package) 7,5 14,0
Apr 21, 2023 31
T-packaging
Apr 21, 2023 32
End of lecture, continuing slides for reference
Free glutamate in foods
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Gre
en t
ea
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O
OHOH
H
OHOH
HO
(-)-Catechin
Apr 21, 2023 35
O
OHOH
OH
OHOH
HO
(-)-Gallocatechin
Apr 21, 2023 36
O
OHOH
H
OOH
HO
OH
OH
OH
C
O
(-)-Catechin gallate
Apr 21, 2023 37
O
OHOH
OH
OOH
HO
OH
OH
OH
C
O
(-)-Gallocatechin gallate
Apr 21, 2023 38
O
OHOH
R1
OR2OH
HO
OH
OH
OH
C
O
X =
Các dạng (-)-Catechin
(-)-Catechin: R1 = R2 = H
(-)-Gallocatechin: R1 = OH, R2 = H
(-)-Catechin gallate: R1 = H, R2 = X
(-)-Gallocatechin gallate: R1 = OH, R2 = X
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Aroma bamboo rotationer
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Flavonoids in tea
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Green T. Black T
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Apr 21, 2023 50Department of Food Engineering, FST, NLU