Introduction Green tea has become a very popular drink worldwide because of its health benefits...
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Transcript of Introduction Green tea has become a very popular drink worldwide because of its health benefits...
Introduction Green tea has become a very popular drink worldwide because of its health
benefits attributed to high polyphenol (~30 %) and l-theanine content (~1-2 %). Green tea extracts are usually spray dried and further processed into Ready-To-
Drink (RTD) green tea beverages. Response surface methodology was employed to optimize thermal extraction of
green tea by controlling 3 key parameters namely, water-to-tea ratio (WTR), temperature and time. Important organoleptic characteristics concerned with quality of RTD beverage such as tea cream (%), colour of extract and turbidity were measured.
Chemical quality parameters were introduced for assessing green tea extracts
Materials and Methods
Conclusion
Made green tea (Tata Tea, India) Extracts were prepared from green tea with 3 different WTR (30:1, 45:1, 60:1; v:w)
over 3 extraction periods viz. 20, 40 and 60 min at 3 different temperatures of 70°C, 80°C and 90°C. Tea cream contents and turbidity were measured at beverage strength (0.29 % w/v).
Analyses Total soluble solids (TSS) and yield - Nagalakshmi et al., 1984 Total polyphenols - International Standard (ISO ⁄CD, 2005) L-theanine - Chen et al., 2008
Results and Discussion
Optimized conditions Recovery/Yield, g/g-GT
Response parameter WTR Temperature
(C)
Time
(min)
Extract Infusion
Specific
condition
Common
condition*
ESY 44:1 90 44 0.288 0.287 0.226
PP Recovery 43:1 90 50 0.173 0.173 0.108
L-T Recovery 50:1 90 45 0.0117 0.0116 0.007
Sample PES (g/g) TES (mg/g)
Tea Solids (mg/ml)
Turbidity (NTU)
Colour
L a b
Infusion 0.465 33.5 2.66 47.2 56.04 -1 6.73
Extract 0.602 40.4 2.94 122.5 51.41 -1.92 26.78
Effect of temperature and time on PP recovery
70
80
9020
30
40
50
60
0.12
0.13
0.14
0.15
0.16
0.17
0.18
0.136
0.145
0.155
0.164
0.173Optimum - 0.173 g/g Infusion - 0.108 g/g
45:1
7075
8085
902030
4050
60
10
10.5
11
11.5
Temperature (°C)Time (min)
L-Th
eani
ne re
cove
ry (m
g/g)
11.3
11.6
11.0
10.6
10.3
Optimum – 11.7 (mg/g)
Infusion – 7.57 (mg/g)
45:1
Effect of temperature and time on L-Theanine RecoveryEffect of temperature and WTR on ESY
3035
40
45
50
55
60 70
75
80
85
90
0.25
0.26
0.27
0.28
0.29
0.263
0.271
0.255
0.286
0.278
50 min
Optimum - 0.288 g/g
Infusion – 0.226 g/g
3035
4045
5055
60 70
75
80
85
90
0.12
0.13
0.14
0.15
0.16
0.17
0.18
Water-to-tea ratio
Temperature (°C)
PP R
ecov
ery
(g/g
)
0.144
0.153
0.162
0.172
0.135
Effect of temperature and WTR on PP recovery
50 min
Optimum - 0.173 g/g
Infusion – 0.108g/g
3035
4045
5055
60
7075
8085
90
10
10.5
11
11.5
Water-to-tea ratio
Temperature (°C)
L-Th
eani
ne R
ecov
ery
(mg/
g)
11.3
10.2
10.6
10.9
11.6
Effect of Temperature and WTR on L-Theanine recovery
Optimum – 11.7 mg/g
Infusion – 7.57 mg/g
50 min
10 20 30 40 50 600.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
ESY (0.278-0.302) g/g
PP recovery (0.149-0.193) g/g
L-Theanine recovery (10.8-12.8) mg/g
Turbidity (94-122.5) NTU
Tea Cream (2.8-7.9) %
Time (min)
Nor
mal
ized
Val
ue
Effect of time on tea quality parameters
65 70 75 80 85 90 95 1000.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
ESY (0.252-0.302) g/g
PP Recovery (0.136-0.193) g/g
L-Theanine Recovery (11.9-12.8) mg/g
Turbidity (111-122.5) NTU
Temperature C
Nor
mal
ized
Val
ue
Effect of temperature on tea quality parameters
Acknowledgement
Optimizing yield and quality of green tea extractSamriddh Mudgala,c, C.S. Murugesha, L. Jaganmohan Raob, B. Manohara, R. Subramaniana
aDepartment of Food EngineeringbDepartment of Plantation Products, Spices and Flavour Technology
Central Food Technological Research Institute (CSIR), Mysore 570 020, IndiacDepartment of Biotechnology, National Institute of Technology, Warangal 506 004, India
Email: [email protected]
The extraction conditions were optimized with equal focus on polyphenols
recovery and l-theanine recovery
The conditions standardized also co-extracted other tea components
responsible for tea cream formation which could be addressed by an effective
clarification process
Chemical quality parameters PES and TES were introduced for assessing the
green tea extracts which could be used as benchmark quality parameters in
the user industry
Box-Behnken Design explained the extraction phenomena and the model
obtained provided close fit to the experimental results
The work demonstrated an optimization approach for obtaining the extract with
greater solids yield rich in polyphenols and l-theanine having significant
practical applications
Samriddh Mudgal is thankful to Director, CFTRI for providing the opportunity and Chandini S. Kumar for valuable suggestions.
Table 1: Tea solids, polyphenols and l-theanine recovery under specific and common optimized extraction conditions
Table 2: Comparison of infusion and extract* quality
ESYMaximum ESY of 28.8% was achieved at 44 min of extraction at 90C which is 27.4% higher than the recovery obtained under normal brewing conditions (100:1 WTR; 75C and 5 min).
PP RecoveryMaximum PP recovery recorded was 0.173 g/g for 50 min of extraction which was 60.2% higher than normal brew.
L-Theanine RecoveryL-theanine recovery increased up to 44 min of extraction and maximum recovery achieved was 54.5% higher than the normal brew.
Effect of temperature and time on ESY
70
75
80
85
90 20
30
40
50
60
0.265
0.27
0.275
0.28
0.285
0.29
0.287
0.279
0.283
0.283
0.276
0.269
0.272
Optimum - 0.288 g/gInfusion - 0.226 g/g
45:1
* Obtained under optimized conditions
*Common optimized conditions - 45:1; 50 min; 90ºC