ArticlePDF Available

COMPARISON OF THE COMPOSITION AND ANTIOXIDANT CAPACITIES OF GREEN TEAS PRODUCED FROM THE ASSAM AND THE CHINESE VARIETIES CULTIVATED IN THAILAND

Authors:

Abstract and Figures

Tea (Camellia sinensis L.) has attracted much attention due to the antioxidant capacities of bioactive compounds present in it, which are considered beneficial to consumer health. In Thailand, commercially cultivated teas are the Assam and the Chinese cultivars which both are processed as green teas. The aim of this study was to investigate the chemical composition and antioxidant capacities of these teas. Samples were collected from tea factories and analyzed for caffeine content (CF), total polyphenol content (TPC), total catechin content (TCC), (-)-gallocatechin (GC), (-)-epigallocatechin (EGC), (+)-catechin (C), (-)-epicatechin (EC), (-)-epigallocatechin gallate (EGCG), (-)-gallocatechin gallate (GCG), (-)-epicatechin gallate (ECG), (-)-catechin gallate (CG), the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity (DPPH-assay) and the ferric reducing antioxidant power (FRAP-assay). The results showed that green tea produced from the Assam cultivar was significantly higher in CF and TPC than the Chinese cultivar. There was no significant difference in the TCC. Both cultivars had the same level of radical scavenging capacity (DPPH). As opposed to the radical scavenging capacity, there was a significant difference in the reducing power capacity (FRAP). The FRAP of the Assam was significantly higher than that of the Chinese tea. There was a significant difference in the individual catechins; the Assam cultivar mainly contained ECG, EGCG, and EC, whereas the major catechins in the Chinese cultivar were EGCG and EGC. Results from this study suggest that the profiles of catechins in green teas manufactured in Thailand might contribute to the cultivars.
Content may be subject to copyright.
364
COMPARISON OF THE COMPOSITION AND ANTIOXIDANT CAPACITIES OF GREEN TEAS PRODUCED FROM
THE ASSAM AND THE CHINESE VARIETIES CULTIVATED IN THAILAND
Theerapong Theppakorn 1*, Atika Luthfiyyah 1 and Karnjana Ploysri 2
Address(es): Theerapong Theppakorn,
1 School of Agro-Industry, Mae Fah Luang University, Chiang Rai 57100, Thailand.
2 Tea Institute, Mae Fah Luang University, Chiang Rai 57100, Thailand.
*Corresponding author: theerapong@mfu.ac.th
ABSTRACT
Keywords: Antioxidant, caffeine, catechins, green tea, polyphenols
INTRODUCTION
Tea is made from the young tender shoots (flushes) of Camellia sinensis (L.) O.
Kuntze and it is the most widely consumed drink after water, due to its refreshing
and mildly stimulant effects. Freshly harvested tea leaves are processed
differently to produce specific types of tea (green, oolong, and black tea). Green
tea is heated to avoid enzymatic oxidation. Oolong tea is semi-fermented to
permit a moderate level of enzymatic oxidation during processing and then dried.
Black tea is the most thoroughly oxidized enzymatically. Approximately 76-78%
of the tea produced and consumed worldwide is black tea, 20-22% is green tea
and less than 2% is oolong tea (McKay and Blumberg 2002).
The predominant constituents of tea leaves, accounting for up to 30% of the dry
weight, are the polyphenols, which include flavonols, flavones, and flavan-3-ols.
Of these, 6080% are the flavan-3-ols commonly known as catechins. Some
studies support the idea that among all tea types, green teas contain the highest
amount of catechins (Lin et al., 2003). The catechins include (-)-gallocatechin
(GC), (-)-epigallocatechin (EGC), (+)-catechin (C), (-)-epicatechin (EC), (-)-
epigallocatechin gallate (EGCG), (-)-gallocatechin gallate (GCG), (-)-
epicatechin gallate (ECG) and (-)-catechin gallate (CG). These compounds are
primarily responsible for many of the health benefits, resulting from the
antioxidant properties. Antioxidative tea components are reported to have
beneficial protective effects against cancers (Trudel et al., 2012; Khan et al.,
2009; Shukla 2007), obesity (Li et al., 2013; Ueda and Ashida 2012),
cardiovascular disease (Yamada and Watanabe 2007) and diabetes (van
Woudenbergh et al., 2012; Fiorino et al., 2012). The radical-scavenging and
antioxidant properties of tea polyphenols are frequently cited as important
contributors to these beneficial effects (Higdon and Frei 2003). However,
studies have shown that the compounds having beneficial health effects in tea is
influenced by many factors such as the cultivars, harvest season, age of the plant,
climate, environmental conditions and processing conditions (Owuor et al.,
2008).
In Thailand, tea is cultivated in the north part of the country in the provinces of
Chiang Rai and Chiang Mai (accounting for 93% of tea production in Thailand).
About 30% of the production is commercialized in the domestic market, whereas
the remaining 70% is exported. Commercially grown teas in Thailand are the
Assam cultivar (Camellia sinensis var. assamica) and the Chinese cultivar
(Camellia sinensis var. sinensis). The Assam tea is usually used for green and
black tea production, while the Chinese tea is used for green and oolong tea
production. Green tea processing in Thailand occurs in five steps: harvesting,
roasting, rolling, drying and blending/packing. The amount of tea polyphenols
has been regarded as a quality indicator of tea (Owuor et al., 2006). Research
concerning the Thai tea has been conducted on the caffeine content
(Suteerapataranon et al., 2009) and volatile flavor constituents (Pripdeevech
and Machan 2011). Data based on chemical constituents are complementary
indicators of the quality of tea, regarding its biological activities. The growing
popularity of tea in recent years on the basis of beneficial health effects requires
additional data concerning its chemical constituents and biological activities. As
polyphenols are the most important group of tea leaf components, especially the
catechins, the objectives of this study were to investigate and compare the
chemical content and antioxidant capacities of green teas produced from C.
assamica and C. sinensis cultivated in Thailand. The contents of caffeine, total
polyphenols, total catechins and eight catechins (GC, EGC, C, EC, EGCG, GCG,
ECG and CG) together with the radical scavenging capacity and reducing power
capacity are also investigated.
MATERIAL AND METHODS
Green tea samples
A total of 13 green teas of 2 major cultivars, C. assamica and C. sinensis (cv.
oolong no.12) were collected from factories in Thailand from April to June 2013.
The samples were analyzed within 6 months of their production. For each
factory, three samples were sampled.
Chemicals and reagents
The standards , which include gallic acid (G, ≥ 99%), (-)-gallocatechin (GC,
98%), (-)-epigallocatechin (EGC, 98%), (+)-catechin (C, 98%), (-)-
epicatechin (EC, 90%), (-)-epigallocatechin gallate (EGCG, 95%), caffeine
(CF, ≥ 99%), (-)-gallocatechin gallate (GCG, ≥ 98%), (-)-epicatechin gallate
Tea (Camellia sinensis L.) has attracted much attention due to the antioxidant capacities of bioactive compounds present in it, which are
considered beneficial to consumer health. In Thailand, commercially cultivated teas are the Assam and the Chinese cultivars which both
are processed as green teas. The aim of this study was to investigate the chemical composition and antioxidant capacities of these teas.
Samples were collected from tea factories and analyzed for caffeine content (CF), total polyphenol content (TPC), total catechin content
(TCC), (-)-gallocatechin (GC), (-)-epigallocatechin (EGC), (+)-catechin (C), (-)-epicatechin (EC), (-)-epigallocatechin gallate (EGCG),
(-)-gallocatechin gallate (GCG), (-)-epicatechin gallate (ECG), (-)-catechin gallate (CG), the 2,2-diphenyl-1-picrylhydrazyl (DPPH)
radical-scavenging activity (DPPH-assay) and the ferric reducing antioxidant power (FRAP-assay). The results showed that green tea
produced from the Assam cultivar was significantly higher in CF and TPC than the Chinese cultivar. There was no significant difference
in the TCC. Both cultivars had the same level of radical scavenging capacity (DPPH). As opposed to the radical scavenging capacity,
there was a significant difference in the reducing power capacity (FRAP). The FRAP of the Assam was significantly higher than that of
the Chinese tea. There was a significant difference in the individual catechins; the Assam cultivar mainly contained ECG, EGCG, and
EC, whereas the major catechins in the Chinese cultivar were EGCG and EGC. Results from this study suggest that the profiles of
catechins in green teas manufactured in Thailand might contribute to the cultivars.
J Microbiol Biotech Food Sci / Theppakorn et al. 2014 : 3 (5) 364-370
365
(ECG, ≥ 98%) and (-)-catechin gallate (CG, ≥ 98%), were purchased from
Sigma-Aldrich (St. Louis, Missouri, USA). Trolox ((±)-6-Hydroxy-2,5,7,8-
tetramethylchromane-2-carboxylic acid) and DPPH (2,2-diphenyl-1-
picryhydrazyl) were purchased from Aldrich (Steinheim, Germany). Folin
Ciocalteu’s phenol reagent, monosodium phosphate monohydrate, disodium
phosphate heptahydrate, acetonitrile, trifluoroacetic acid (TFA), trichloroacetic
acid (TCA) and methanol (HPLC-grade) were purchased from Fluka (Buchs,
Switzerland). Potassium hexacyanoferrate [K3Fe(CN)6] and anhydrous sodium
carbonate were purchased from Merck (Darmstadt, Germany). Ascorbic acid and
ferric chloride (FeCl3) were purchased from Ajax Finechem (Seven Hills,
Australia). Water was purified with a Milli-Q water purification system
(Millipore, Bedford, USA). All other chemicals and solvents in this study were
of analytical grade.
Sample extraction
Collected tea samples were ground and samples (5 g, weighed to the nearest
0.001g) were extracted with 100 mL of distilled water at 80 °C for 30 min
(Vuong et al., 2013). The extraction mixture was filtered through a filter paper
(Whatman No. 4). The residue was washed with distilled water (3x10mL). The
tea solution was cooled to room temperature and adjusted to 250 mL with
distilled water. All samples were extracted in triplicate.
Determination of moisture content
Tea samples, 5 g, weighed to the nearest 0.001g, were placed in a moisture can
and heated in an oven at 103±2C for at least 16 h to constant weight. The
percentage of moisture content (%MC) and dry matter (%DM) in the samples
were then calculated from the weight differences. All tests were performed in
triplicate.
Determination of total polyphenol content (TPC)
The total polyphenol content (TPC) was determined by spectrophotometry, using
gallic acid as a standard, according to the method described by the International
Organization for Standardization (ISO 145021, 2005). Sample extracts were
diluted 50-fold with distilled water and 1.0 mL portions of the diluted solution
were transferred in duplicate to separate tubes containing 5.0 mL of 10%v/v
dilution of Folin-Ciocalteu’s reagent in water. Then, 4.0 mL of sodium carbonate
solution (7.5% w/v) was added with mixing. The tubes were then left to stand at
room temperature for 60 min before absorbance at 765 nm was measured. The
concentration of polyphenols in samples was derived from a standard curve of
gallic acid ranging from 10-100 μg/mL. The TPC was expressed as gallic acid
equivalents (GAE), i.e. GAE g/100 g dry weight (DW).
Determination of individual catechins, total catechins and caffeine
Individual catechins, total catechins content (TCC) and caffeine (CF) were
determined by ISO method (ISO 145022, 2005) with slight modifications. The
individual standard solutions of GC, EGC, C, EC, EGCG, GCG, ECG, CG and
CF were prepared by dissolving them in methanol to generate a stock
concentration of 1,000 µg/mL. The mixed stock standard solution was prepared
by mixing an equal volume of each stock standard. Working standard solutions
were prepared by dilution of the mixed stock solution and then filtered through a
0.45 µm polytetrafluoroethylene (PTFE) filter (Millipore Ltd., Bedford, USA.
HPLC analysis of standards and samples was conducted on Water 966 high
performance liquid chromatography comprising vacuum degasser, quaternary
pump, auto-sampler, thermostatted column compartment and photo diode array
detector. The column used was a Platinum EPS C18 reversed phase, 3µm (53x7
mm) with the column temperature of 30°C. Mobile phase was water/acetonitrile
(87:13) containing 0.05% (v/v) trifluoroacetic acid (TFA) with the flow rate of 2
mL/min. The injection volume was 20 µL. Absorption wavelength was 210 nm.
Validation was carried out in compliance with the AOAC International guidelines
for single Lab. validation of chemical methods for dietary supplements and
botanicals (AOAC, 2002). Individual catechins and caffeine were identified by
comparing their retention times and UV spectra in the 190-400 nm range with
standards. Calibration graphs were constructed using nine levels of concentration
which covered the concentration ranges expected in the tea samples. The
characteristics of the calibration curves, including the regression equation,
correlation coefficient (r), range of linearity, limit of detection (LOD), limit of
quantitation (LOQ) were determined. The LOD and LOQ were based on a signal-
to-noise (S/N) ratio as 3:1 and 10:1, respectively. The linearity of the HPLC
method was checked for caffeine and individual catechins (0.10-51.9, 0.09-43.1,
0.20-100.0, 0.19-97.0, 0.16-80.0, 0.20-100.0, 0.11-52.9, 0.20-98.0, 0.09-44.1
µg/mL for GC, EGC, C, EC, EGCG, CF, GCG, ECG and CG, respectively. All
the analytes exhibited good linearity (r) over the range tested with correlation
coefficient from 0.9965 for GCG to 0.9997 for CF. Individual catechins and
caffeine were quantified using calibration curves. The results were expressed as
g/100 g DW. The total catechin content (TCC) as g/100 g DW was determined by
the summation of individual catechins (GC, EGC, C, EC, EGCG, GCG, ECG and
CG).
Determination of DPPH radical scavenging activity (DPPH assay)
Tea extract was diluted (50-fold) with distilled water. The diluted tea extract (50
µL) was mixed with an aliquot of 2,000 µL of 60 µM DPPH radical in methanol.
Distilled water was used as a control instead of the extract. The reaction mixture
was vortex-mixed and let to stand at 25C in the dark for 60 min. Absorbance at
517 nm was measured using methanol as a blank. The control and standard were
subjected to the same procedures as the sample except that, for the control, only
distilled water was added, and, for the standard, the extract was replaced with 0-
1,000 µM Trolox standard. The percentage inhibition values were calculated
from the absorbance of the control (Ac) and of the sample (As). The calibration
curve was plotted between Trolox concentration (µM) and % inhibition. The
DPPH radical scavenging activity of tea sample was expressed in terms of
millimole equivalents of Trolox (TE) per 100 grams of dry sample, i.e. mmol
TE/100 g DW) (Roy et al., 2010) .
Determination of ferric reducing antioxidant power activity (FRAP assay)
A 1-mL aliquot of each extract (50-fold dilution) was mixed with 2.5 mL of
phosphate buffer (0.2 M, pH 6.6) and 2.5 mL of a 1% aqueous potassium
hexacyanoferrate [K3Fe(CN)6] solution. After 30 min incubation at 50C, 2.5 mL
of 10% trichloroacetic acid were added, and the mixture was centrifuged for 10
min. A 2.5-mL aliquot of the upper layer was mixed with 2.5 mL of water and
0.5 mL of 0.1% aqueous FeCl3, and the absorbance was recorded at 700 nm. The
control and standard were subjected to the same procedures as the sample except
that, for the control, only distilled water was added, and, for the standard, the
extract was replaced with 0-1,000 µM ascorbic acid standard. The calibration
curve was plotted between ascorbic acid concentration (µM) and absorbance at
700 nm. Iron (III) reducing activity was determined as millimole equivalents of
ascorbic acid (AA) per 100 grams of dry sample, i.e. mmol AA/100 g DW)
(Hajimahmoodi et al., 2008).
Statistical analysis
Data were expressed as means ± standard deviation. The data were also subjected
to analysis of variance (ANOVA) and Duncan’s multiple range tests using SPSS
16.0 for Windows. The significance level of P<0.05 was considered significantly
different.
RESULTS AND DISCUSSION
Elution order of compounds analyzed by HPLC
The modification of the analytical method separated a mixture of standards of
caffeine (CF) and 8 catechins (GC, EGC, C, EC, EGCG, GCG, ECG and CG)
within 20 min. Typical chemical profiles identified by HPLC in green teas are
shown in Fig. 1. The elution order was GC, EGC, C, EC, EGCG, CF, GCG ECG
and CG (Fig. 1A). As can be seen from Fig. 1 (B and C), green teas from C.
assamica (Assam tea) and C. sinensis (Chinese tea) contained CF and 7 catechins
(GC, EGC, C, EC, EGCG, GCG and ECG), but CG was not detected in green
teas produced from either cultivars.The disappearance of CG in both varieties
might be related to the quality of tea grown in Thailand having soil and climatic
conditions different from other regions. Moreover, cultivation practices, post-
harvesting handling and processing techniques of Thai green teas may contribute
in this disappearance.
J Microbiol Biotech Food Sci / Theppakorn et al. 2014 : 3 (5) 364-370
366
GC
A
B
C
EGC C
EC
EGCG
CF
GCG
ECG
CG
Figure 1 Typical chromatogram of standards (A), green teas from C. assamica
(B) and C. sinensis (C). Peak identification and approximate retention times in
minutes in parentheses are as follows: GC (1.25); EGC (1.59); C (1.88); EC
(2.56); EGCG (2.94); CF (3.40); GCG (4.36); ECG (5.81); and CG (8.71).
Chemical compositions and antioxidant capacities of green teas from C.
assamica
Data on the caffeine content, total polyphenol content, total catechin content and
antioxidant capacities (DPPH-assay and FRAP-assay) of the green teas produced
from C. assamica are presented in Table 1. The caffeine content ranged from
3.27 to 3.71 g/100 g DW, with a mean of 3.44±0.51 g/100 g DW. There was no
significant difference in caffeine content of all samples analyzed (P≥0.05). Total
polyphenol content varied slightly, ranging from 16.63 to 20.83 GAE g/100 g
DW with an average of 18.95±1.45 GAE g/100 g DW. Among these teas, A-GT-
004 taken from Ming Dee Tea had the highest concentrations of phenolic
substances, whereas A-GT-006 taken from Mae Ka Tea had the lowest
concentrations. Catechins are the main phenolic compounds and are present in
large amounts in green tea. In this study, total catechins varied slightly, ranging
from 9.02 to 14.08 g/100 g DW with an average of 12.42±2.41 g/100 g DW.
There was no significant difference in total catechins in all samples (P≥0.05).
Among the 6 tested samples, the DPPH values ranged from 132.32 to 247.11
mmol TE/100 g DW, with a mean value of 183.90±46.68 mmol TE/100 g DW.
A-GT-001 collected from Raming Tea had the highest DPPH value (247.11±2.02
mmol TE/100 g DW), followed by A-GT-002 (240.56±4.77 mmol TE/100 g
DW) collected from Choui Fong Tea. A-GT-006 collected from Mae Ka Tea had
the lowest DPPH value (132.32±0.89 mmol TE/100 g DW). The FRAP values
ranged from 1.22 to 2.13 mmol AA/100 g DW, with a mean value of 1.66±0.32
mmol AA/100 g DW. A-GT-004 collected from Ming Dee Tea had the highest
FRAP value (2.13±0.06 mmol TE/100 g DW).
Table 1 Mean values of caffeine, total polyphenol, total catechin content and antioxidant capacities of 6 green teas produced from C. assamica
No.
Code
Company
Caffeine ns
(g/100 g DW)
Total polyphenols
(GAE g/100 g DW)
Total catechins ns
(g/100 g DW)
Antioxidant capacities
DPPH
(mmol TE/100 g DW)
FRAP
(mmol AA/100 g DW)
1
A-GT-001
Raming Tea
3.71±0.21
19.69±0.62 ab
13.08±0.54
247.11±2.02 a
1.44±0.00 d
2
A-GT-002
Choui Fong Tea
3.43±0.05
18.27±0.25 c
12.87±0.32
240.56±4.77 a
1.22±0.01 e
3
A-GT-003
Thai Tea Suwirun
3.44±0.01
19.71±0.87 ab
13.51±0.21
150.69±3.20 c
1.91±0.05 b
4
A-GT-004
Ming Dee Tea
3.35±1.59
20.83±0.80 a
11.97±0.98
178.92±1.58 b
2.13±0.06 a
5
A-GT-005
Choui Fong Tea
3.27±0.04
18.57±0.06 bc
14.08±0.17
153.80±11.40 c
1.74±0.06 c
6
A-GT-006
Mae Ka Tea
3.45±0.23
16.63±0.07 d
9.02±0.29
132.32±0.89 d
1.53±0.08 d
Minimum
3.27
16.63
9.02
132.32
1.22
Maximum
3.71
20.83
14.08
247.11
2.13
Mean
3.44
18.95
12.42
183.90
1.66
Standard deviation
0.51
1.45
2.41
46.68
0.32
Values are expressed as means ± SD (n=3). Different letters in the same column indicate significant difference at p < 0.05.
ns = not significant.
Comparison of the individual catechins of 6 tea manufactures is shown in Table
2. Green teas produced from C. assamica contained GC, EGC, C, EC, EGCG,
GCG and ECG. Surprisingly, CG was not detected in all tested samples. Among
quantified catechins, ECG was predominant, ranging from 1.65 to 3.53 g/100 g
DW with an average of 2.94±0.78 g/100 g DW, followed by EGCG (ranging
from 1.16 to 3.69 with an average of 2.62±0.94 g/100 g DW), EC (ranging from
1.31 to 2.88 with an average of 2.23±0.60 g/100 g DW), EGC (ranging from 0.70
to 2.48 with an average of 1.77±0.61 g/100 g DW), C (ranging from 1.41 to 2.15
with an average of 1.65±0.38 g/100 g DW) and, to lesser extents, GC and GCG.
The tested samples possessed slightly varied quantities of individual catechins
depending on the tea company sources. A little variation in catechins composition
among samples may be the result of cultivation practice, postharvest handling
and processing techniques of each manufactures (Cooper et al., 2005).
However, our results indicate that the major catechins in C. assamica green teas
were ECG, EGCG and EC.
J Microbiol Biotech Food Sci / Theppakorn et al. 2014 : 3 (5) 364-370
367
Table 2 Mean values of individual catechins present in 6 green teas produced from C. assamica
No.
Code
Company
Individual catechins (g/100 g DW)
GC ns
EGC
C ns
EC
EGCG
GCG ns
ECG
1
A-GT-001
Raming Tea
0.77±0.06
1.60±0.36 c
1.70±0.04
2.88±0.16 a
2.20±0.61 cd
0.39±0.08
3.53±0.14 a
2
A-GT-002
Choui Fong Tea
1.01±0.02
1.95±0.01 bc
1.51±0.03
2.29±0.05 ab
2.74±0.05 abc
0.48±0.04
2.90±0.14 ab
3
A-GT-003
Thai Tea Suwirun
0.89±0.11
1.70±0.20 bc
2.15±0.13
2.62±0.04 ab
2.44±0.16 bc
0.25±0.02
3.45±0.00 a
4
A-GT-004
Ming Dee Tea
0.99±0.56
2.16±0.19 ab
1.41±0.95
1.31±0.91 c
3.69±0.92 a
0.76±0.58
1.65±1.41 b
5
A-GT-005
Choui Fong Tea
0.96±0.03
2.48±0.02 a
1.61±0.01
2.39±0.02 ab
3.47±0.06 ab
0.34±0.02
2.84±0.04 ab
6
A-GT-006
Mae Ka Tea
0.39±0.03
0.70±0.01 d
1.53±0.05
1.87±0.01 ab
1.16±0.02 d
0.10±0.14
3.24±0.10 a
Minimum
0.39
0.70
1.41
1.31
1.16
0.10
1.65
Maximum
1.01
2.48
2.15
2.88
3.69
0.76
3.53
Mean
0.84
1.77
1.65
2.23
2.62
0.39
2.94
Standard deviation
0.28
0.61
0.38
0.60
0.94
0.28
0.78
Values are expressed as means ± SD (n=3). Different letters in the same column indicate significant difference at p < 0.05.
CG was not detected in any sample. ns = not significant.
Chemical compositions and antioxidant capacities of green tea from C.
sinensis
Results of the caffeine content, total polyphenol content, total catechin content
and antioxidant capacities of the green teas from C. sinensis are presented in
Table 3. The caffeine ranged between 1.69 to 3.51 g/100 g DW with a mean of
2.50±0.71 g/100 g DW. This mean value was significantly lower than in
C.assamica samples (P<0.05). Among 7 samples analyzed, O12-GT-007 taken
from Doi Chang Tea had the highest concentrations of caffeine, whereas O12-
GT-004 taken from Sing Long Shop had the lowest concentrations than other
samples. Total polyphenols varied from 11.52 to 17.34 GAE g/100 g DW with an
average of 14.58±1.87 GAE g/100 g DW. This value was significantly lower than
in C.assamica samples (P<0.05). Total catechins ranged from 8.32 to 13.20 g/100
g DW with an average of 10.86±1.47 g/100 g DW. This value was not
significantly different from C.assamica samples (P≥0.05). Among 7 samples
analyzed, there were significant differences in total polyphenols and total
catechins (P<0.05), in which the highest total polyphenols (17.34±0.29 GAE
g/100 g DW) and total catechins (13.19±0.32 g/100 g DW) were found in the
OT-GT-003 sample taken from Jing Jing Tea shop. Among the tested samples,
the DPPH values ranged from 80.08 to 241.39 mmol TE/100 g DW, with a mean
value of 146.97±56.40 mmol TE/100 g DW. O12-GT-007 collected from Doi
Chang Tea had the highest DPPH value (241.39±0.71 mmol TE/100 g DW). The
FRAP values ranged from 0.61 to 1.08 mmol AA/100 g DW, with a mean value
of 0.85±0.16 mmol AA/100 g DW. O12-GT-003 collected from Jing Jing Tea
shop had the highest FRAP value (1.08±0.17 mmol AA/100 g DW).
Table 3 Mean values of caffeine, total polyphenol and total catechin content and antioxidant capacities of 7 green teas produced from C. sinensis
No.
Code
Company
Caffeine
(g/100 g DW)
Total polyphenols
(GAE g/100 g DW)
Total catechins
(g/100 g DW)
Antioxidant capacities
DPPH
(mmol TE/100 g DW)
DPPH
(mmol TE/100 g DW)
1
O12-GT-001
Rai Boon Rawd
2.54±0.11 c
14.31±0.23 d
10.97±1.08 ab
119.35±3.52 d
0.79±0.08 cd
2
O12-GT-002
Wong Pud Tan Tea
2.81±0.27 bc
15.09±0.11 c
10.91±0.78 ab
116.18±1.19 de
0.89±0.02 abc
3
O12-GT-003
Jing Jing Tea Shop
3.17±0.08 ab
17.34±0.29 a
13.19±0.32 a
147.34±1.03 c
1.08±0.17 a
4
O12-GT-004
Sing Long Shop
1.69±0.10 d
13.71±0.37 d
10.29±1.26 bc
111.80±0.56 e
0.82±0.00 bcd
5
O12-GT-005
Thai Sanguan Tea
1.93±0.36 d
11.52±0.09 e
8.32±1.62 c
80.08±2.19 f
0.61±0.04 d
6
O12-GT-006
Yao Sing Shop
1.82±0.03 d
13.91±0.23 d
10.52±0.53 bc
212.64±5.73 b
0.78±0.07 cd
7
O12-GT-007
Doi Chang Tea
3.51±0.07 a
16.14±0.44 b
11.66±0.35 ab
241.39±0.71 a
1.00±0.09 ab
Minimum
1.69
11.52
8.32
80.08
0.61
Maximum
3.51
17.34
13.20
241.39
1.08
Mean
2.50
14.58
10.86
146.97
0.85
Standard deviation
0.71
1.87
1.47
56.40
0.16
Values are expressed as means ± SD (n=3). Different letters in the same column indicate significant difference at p < 0.05.
ns = not significant.
Comparison of the individual catechins of 7 tea manufactures is shown in Table
4. Green teas produced from C. sinensis contained 7 catechins as found in C.
assamica. CG was again not detected in any sample. Among quantified catechins,
the most abundant catechin was EGCG. The EGCG ranged from 2.75 to 5.49
with an average of 3.99±0.92 g/100 g DW, Among samples analyzed, O12 -GT-
003 taken from Jing Jing Tea Shop had the highest concentrations of EGCG
(5.49±0.29 g/100 g DW), followed by O12-GT-007 taken from Doi Chang Tea
(4.62±0.30 g/100 g DW). The second most abundant catechin was EGC, ranging
from 2.17 to 3.18 with an average of 2.75±0.48 g/100 g DW. There was no
significant difference in EGC among samples analyzed. The remaining catechins,
GC (0.94±0.14 g/100 g DW), C (0.83±0.17 g/100 g DW), EC (0.92±0.14 g/100 g
DW), GCG (0.65±0.23 g/100 g DW), and ECG (0.77±0.29 g/100 g DW), were
found in small amount when compared to EGCG and EGC. These results
demonstrate that the two major catechins in C.sinensis green teas were EGCG
and EGC.
J Microbiol Biotech Food Sci / Theppakorn et al. 2014 : 3 (5) 364-370
368
Table 4 Mean values of individual catechins present in 7 green teas produced from C. sinensis
No.
Code
Company
Individual catechins (g/100 g DW)
GC
EGC ns
C
EC
EGCG
GCG
ECG
1
O12-GT-001
Rai Boon Rawd
1.13±0.04 a
2.87±0.41
0.90±0.02 ab
0.95±0.07 b
3.74±0.61 bc
0.76±0.18 b
0.63±0.01 c
2
O12-GT-002
Wong Pud Tan Tea
0.91±0.04 bc
2.95±0.18
0.87±0.14 bc
0.91±0.08 bc
4.01±0.27 bc
0.51±0.10 bc
0.78±0.06 b
3
O12-GT-003
Jing Jing Tea Shop
0.91±0.03 bc
2.41±0.13
1.04±0.01 a
1.09±0.01 a
5.49±0.29 a
1.06±0.11 a
1.19±0.04 a
4
O12-GT-004
Sing Long Shop
1.08±0.05 a
3.18±0.56
0.64±0.03 d
0.80±0.01 cd
3.50±0.63 bc
0.60±0.12 bc
0.52±0.03 cd
5
O12-GT-005
Thai Sanguan Tea
0.99±0.05 ab
2.17±0.63
0.64±0.01 d
0.70±0.01 d
2.75±0.85 c
0.66±0.10 b
0.41±0.06 d
6
O12-GT-006
Yao Sing Shop
0.80±0.01 cd
3.16±0.22
0.72±0.04 cd
0.91±0.04 bc
3.83±0.34 bc
0.36±0.06 c
0.76±0.01 b
7
O12-GT-007
Doi Chang Tea
0.74±0.14 d
2.50±0.40
1.03±0.07 a
1.09±0.08 a
4.62±0.30 ab
0.58±0.01 bc
1.12±0.06 a
Minimum
0.74
2.17
0.64
0.70
2.75
0.36
0.41
Maximum
1.13
3.18
1.04
1.09
5.49
1.06
1.19
Mean
0.94
2.75
0.83
0.92
3.99
0.65
0.77
Standard deviation
0.14
0.48
0.17
0.14
0.92
0.23
0.29
Values are expressed as means ± SD (n=3). Different letters in the same column indicate significant difference at p < 0.05.
CG was not detected in any sample. ns = not significant.
Comparison of green teas from C. assamica and C. sinensis
The chemical compositions and antioxidant capacities of green teas produced
from C. assamica and C.sinensis are shown in Table 5. The caffeine of the
Assam cultivar (3.44±0.51 g/100 g DW) was significantly higher than the
Chinese cultivar (2.50 ±0.71 g/100 g DW). Obuchowicz et al (Obuchowicz et
al., 2011) reported that caffeine content in green tea was 1.44-4.03 g/100 g DW
(average 2.60, n=287). Our values are in the range of previous reports. The
comparison between the Assam and the Chinese cultivars indicated that cultivars
affected the level of caffeine in green teas. However, there have been reports that
there was no significant difference in the caffeine contents of tea infusions
brewed from these two varieties (Suteerapataranon et al., 2009). This might be
because this study used only one tea sample and taken from a manufacturer who
cultivated the variety assamica in the area near to the variety sinensis, indicating
that cultivation areas may also affect the caffeine content. It is suggested that the
determinations of the chemical profile of teas should follow sampling protocols
that include tea samples from various sources and manufacturers.
Phenolic compounds are a class of chemical constituents containing one or more
hydroxyl residues attached to an aromatic (phenyl) ring. They are one of the most
effective antioxidative constituents that contribute to the antioxidant capacities of
teas. Hence, it is important to quantify phenolic content and to assess its
contribution to antioxidant activity. Green tea from the Assam cultivar
(18.95±1.45 GAE g/100 g DW) had levels of total polyphenols significantly
(p<0.05) higher than the Chinese cultivar (14.58±1.87 GAE g/100 g DW). This
result is in agreement with Jin et al. (Jin et al., 2005) who reported that the
Assam cultivar had significantly higher polyphenols content than the Chinese
cultivar. Previous reports have stated that the total polyphenols in green tea was
9.95-25.79 GAE g/100 g DW (average 16.35, n=347) (Obuchowicz et al., 2011),
10.10-22.20 GAE g/100 g DW (average 17.00, n=51) (Engelhardt 2005), 8.70-
10.60 GAE g/100 g DW (average 8.63, n=3) (Khokhar and Magnusdottir
2002). Our results are in reasonable agreement with these previous reports.
The levels of total catechins in the Assam and the Chinese cultivars were
12.42±2.41 g/100 g DW and 10.86±1.47 g/100 g DW, respectively. This result is
in accordance with mean values obtained in previous studies, 6.57-21.38 g/100 g
DW (average 11.70, n=358) (Obuchowicz et al., 2011), 8.50-20.60 g/100 g DW
(average 15.10, n=51) (Engelhardt 2005) and 2.80-22.80 g/100 g DW (average
10.90, n=18) (Unachukwu et al., 2010). There were no significant differences in
total catechins of green teas from these two varieties. Among 8 catechins
analyzed in two varieties, CG was not detected and GC was in a similar level in
both tea types. The levels of the EGC, C, EC, EGCG, GCG and ECG showed
apparently significant differences (p<0.05). The ECG (2.94±0.78 g/100 g DW),
EGCG (2.62±0.94 g/100 g DW), and EC (2.23±0.60 g/100 g DW), were the 3
predominant catechins in the Assam cultivar, whereas the EGCG (3.99±0.92
g/100 g DW), and EGC (2.75±0.48 g/100 g DW), were the 2 predominant
catechins in the Chinese cultivar. The four major catechins present in green tea
were reported as EGCG, EGC, ECG, and EC (Peterson et al., 2005; Ananingsih
et al., 2013; Obuchowicz et al., 2011). According to the study by Obuchowicz
et al., (2011), the greatest amount of individual catechins in green teas was
EGCG followed by EGC, which is similar to our result with the Chinese cultivar.
Most studies of individual catechins in green teas have been carried out on the
Chinese tea. This may be because the Chinese tea is usually used to produce
green teas. There are a few countries that grow both the Assam and the Chinese
tea in order to process as the green tea. Therefore, most data on individual
catechins in green teas is obtained from the Chinese cultivar. Khokhar and
Magnusdottir (2002) had cited variations in the abundance of compounds in
teas as being dependent on sample tea subtypes and the different subtypes result
from different tea processing protocols, horticultural practices, and geographic
settings (Sultana et al., 2008).
The radical scavenging capacity and reducing power capacity of a sample is
regarded as a significant indicator of its potential antioxidant activity. FRAP
measures the ability of compounds to act as an electron donor while DPPH
measures their ability to act as hydrogen donors. In DPPH assays, the antioxidant
capacity of the Assam cultivar was slightly higher than the Chinese cultivar.
However, no significant differences between cultivars were found with the
Duncan test. Although the Assam cultivar had the total polyphenols significantly
higher than the Chinese cultivar, both cultivars had the same level of radical
scavenging capacity (DPPH). This is likely due to the presence of different
antioxidant compounds in green teas. As opposed to the radical scavenging
capacity, there was a significant difference in the reducing power capacity
(FRAP) (P<0.05). The FRAP of the Assam was substantially higher than the
Chinese (P<0.05). According to a study by Stewart et al., (2005), the greatest
antioxidant contribution to green tea comes from catechins. The different result in
the DPPH and the FRAP found in this study can be demonstrated by the
difference in mechanisms between the scavenging and chelating for measuring
the antioxidant capacity. The antioxidant capacity of tea may not be determined
by one or few phytochemical compounds, but is widely distributed among a
range of phenolic compounds including catechins (Horzic et al., 2009) and
additional antioxidant compounds such as glycosylated flavonols,
proanthocyanidins, and phenolic acids and their derivatives (Lin et al., 2008) in
green tea as evidenced by higher TPC levels in the Assam tea.
Table 5 Comparison of green teas produced from C. assamica and C. sinensis
Specifications
C. assamica
C. sinensis
Caffeine content
3.44±0.51 a
2.50±0.71 b
Total polyphenol content
18.95±1.45 a
14.58±1.87 b
Total catechin content
12.42±2.41
10.86±1.47
GC
0.84±0.28
0.94±0.14
EGC
1.77±0.61 b
2.75±0.48 a
C
1.65±0.38 a
0.83±0.17 b
EC
2.23±0.60 a
0.92±0.14 b
EGCG
2.62±0.94 b
3.99±0.92 a
GCG
0.39±0.28 b
0.65±0.23 a
ECG
2.94±0.78 a
0.77±0.29 b
CG
nd
nd
DPPH assay
183.90±46.68
146.97±56.40
FRAP assay
1.66±0.32 a
0.85±0.16 b
Values are expressed as means ± SD.
Different letters in the same row indicate significant difference at p < 0.05.
nd = not detected.
J Microbiol Biotech Food Sci / Theppakorn et al. 2014 : 3 (5) 364-370
369
As found in this study, the difference in chemical constituents and antioxidant
capacities might be related to the cultivars. Thus our hypothesis is that the pattern
displayed by catechins enables and observer who is given a tea extract, but is not
told from which tea species the extract was prepared, to determine this with
reasonable confidence purely from analyzing the pattern displayed by these
compounds. At present, the data do not enable a decision as to whether this is just
true for the region where the work was performed, or if is generally applicable.
The challenge is therefore to tea scientists in other geographical regions where
teas are produced comparable to those studied here, to determine if their regional
products are classifiable by the same criteria, and by their results to verify or
falsify this hypothesis as something processing general applicability.
It also should be noted that these differences could be related to the quality of tea
grown in different regions having their soil and climatic conditions different,
cultivation practices, post-harvesting handling and processing techniques by
different manufacturers. Because health effects may depend on the tea consumed
and because there is a lack of composition data on tea produced in different parts
of the world, there is a need to know the compositions. Our results provide
information that the consumer may be able to select green teas containing high
levels of beneficial compounds and avoid those containing low amounts of these
compounds.
CONCLUSION
This study provides evidence of the dependability of amounts of compounds and
antioxidant capacities in green tea manufactured in Thailand. Present findings
show that green tea from the Assam cultivar had caffeine and total polyphenols
levels significantly higher than the Chinese cultivar. The ECG, EGCG and EC
were the 3 predominant catechins in the Assam cultivar, whereas the EGCG and
EGC were the 2 predominant catechins in the Chinese cultivar. The difference in
catechins found in this study might be related to the cultivars used to produce
green teas. The results reported here were derived from the analysis of samples
collected from representative tea manufacturing establishments in Thailand. It is
well recognized that uncontrolled variables, such as the geography, climates,
season, cultivation practice, postharvest handling and processing techniques may
affect the chemical composition and antioxidant capacities of green teas.
However, this investigation provides basic information on important chemical
compounds present in Thai green tea, which can be added to the national and
regional databases. The data can also be used as a guideline for establishing tea
standards and for further detailed studies.
Acknowledgments: The authors warmly thank Mae Fah Luang University for a
support.
REFERENCES
ANANINGSIH, V. K., SHARMA, A., ZHOU, W. 2013. Green tea catechins
during food processing and storage: A review on stability and detection. Food
Research International, 50(2), 469-479.
AOAC. (2002). Guidelines for single laboratory validation of chemical methods
for dietary supplements and botanicals. Gaithersburg, Md.: AOAC Int. Available
from: http://swww.aoac.org/dietsupp6/Dietary-Supplement-web-
site/slv_guidelines.pdf. Accessed Nov 30, 2011.
COOPER, R., MORRE, J., MORRE, D. M. 2005. Medicinal benefits of green
tea: Part II. Review of anticancer properties. Journal of Alternative and
Complementary Medicine, 11(4), 639-652.
ENGELHARDT, U. H. 2005. Authenticity of tea (C. sinensis) and tea products.
Abstracts of Papers of the American Chemical Society, 229, U40-U40.
FIORINO, P., EVANGELISTA, F. S., SANTOS, F., MAGRI, F. M. M.,
Delorenzi, J. C. M. O. B., Ginoza, M., Farah, V. 2012. The Effects of Green Tea
Consumption on Cardiometabolic Alterations Induced by Experimental Diabetes.
Experimental Diabetes Research.
HAJIMAHMOODI, M., HANIFEH, M., OVEISI, M. R., SADEHHI, N., Jannat,
B. 2008. Determination of total antioxidant capacity of green teas by the ferric
reducing/antioxidant power assay. Iranian Journal of Environmental Health
Science & Engineering, 5(3), 167-172.
HIGDON, J. V., FREI, B. 2003. Tea catechins and polyphenols: Health effects,
metabolism, and antioxidant functions. Critical Reviews in Food Science and
Nutrition, 43(1), 89-143.
HORZIC, D., KOME, D., BELSCAK, A., GANIC, K. K., IVEKOVIC, D.,
KARLOVIC, D. 2009. The composition of polyphenols and methylxanthines in
teas and herbal infusions. Food Chemistry, 115(2), 441-448.
ISO 145021. 2005. Tea; Methods for determination of substances characteristic
of green and black tea. Part 1, Content of total polyphenols in tea: colorimetric
method using FolinCiocalteu reagent.
ISO 145022. 2005. Tea; Methods for determination of substances characteristic
of green and black tea. Part 2. Contents of catechins in green tea: method using
High Performance Liquid Chromatography.
JIN, C., WANG, P. S., XIA, Y. M., XU, M., PEI, S. J.. 2005. Genetic diversity
and differentiation of Camellia sinensis L. (cultivated tea) and its wild relatives in
Yunnan province of China, revealed by morphology, biochemistry and allozyme
studies. Genetic Resources and Crop Evolution, 52(1), 41-52.
KHAN, N., ADHAMI, V. M., MUKHTAR, H. 2009. Review: Green Tea
Polyphenols in Chemoprevention of Prostate Cancer: Preclinical and Clinical
Studies. Nutrition and Cancer-an International Journal, 61(6), 836-841.
KHOKHAR, S., MAGNUSDOTTIR, S. G. M. 2002. Total phenol, catechin, and
caffeine contents of teas commonly consumed in the United Kingdom. Journal of
Agricultural and Food Chemistry, 50(3), 565-570.
LI, Q., LIU, Z. H., HUANG, J. A., LUO, G. A., LIAN, Q. L., WANG, D., YE, X.
Y., WU, C. B., WANG, L. L., HU, J. H. 2013. Anti-obesity and hypolipidemic
effects of Fuzhuan brick tea water extract in high-fat diet-induced obese rats.
Journal of the Science of Food and Agriculture, 93(6), 1310-1316.
LIN, L. Z., CHEN, P., HARNLY, J. M. 2008. New phenolic components and
chromatographic profiles of green and fermented teas. Journal of Agricultural
and Food Chemistry, 56(17), 8130-8140.
LIN, Y. S., TSAI, Y. J., TSAY, J. S., Lin, J. K. 2003. Factors affecting the levels
of tea polyphenols and caffeine in tea leaves. Journal of Agricultural and Food
Chemistry, 51(7), 1864-1873.
MCKAY, D. L., BLUMBERG, J. B. 2002. The role of tea in human health: An
update. Journal of the American College of Nutrition, 21(1), 1-13.
OBUCHOWICZ, J., ENGELHARDT, U. H., DONNELLY, K. 2011. Flavanol
database for green and black teas utilising ISO 14502-1 and ISO 14502-2 as
analytical tools. Journal of Food Composition and Analysis, 24(3), 411-417.
OWUOR, P. O.,OBANDA, M., NYRENDA, H. E., MANDALA, W. L. 2008.
Influence of region of production on clonal black tea chemical characteristics.
Food Chemistry, 108(1), 263-271.
OWUOR, P. O., OBANDA, M., NYRENDA, H. E., MPHANGWE, N. I. K.,
WRIGHT, L. P., APOSTOLIDE, Z. 2006. The relationship between some
chemical parameters and sensory evaluations for plain black tea (Camellia
sinensis) produced in Kenya and comparison with similar teas from Malawi and
South Africa. Food Chemistry, 97(4), 644-653.
PETERSON, J., DWYER, J., BHAGWAT, S., HAYTOWITZ, D., HOLDEN, J.,
ELDRIDGE, A. L., BEECHER, G., Aladesanmi, J.. 2005. Major flavonoids in
dry tea. Journal of Food Composition and Analysis, 18(6), 487-501.
PRIPDEEVECH, P., MACHAN, T. 2011. Fingerprint of volatile flavour
constituents and antioxidant activities of teas from Thailand. Food Chemistry,
125(2), 797-802.
ROY, M. K., KOIDE M., RAO, T. P., OKUBO, T., OGASAWARA, Y., JUNEJ,
L. R.. 2010. ORAC and DPPH assay comparison to assess antioxidant capacity of
tea infusions: Relationship between total polyphenol and individual catechin
content. International Journal of Food Sciences and Nutrition, 61(2), 109-124.
SHUKLA, Y. 2007. Tea and cancer chemoprevention: A comprehensive review.
Asian Pacific Journal of Cancer Prevention, 8(2), 155-166.
STEWART, A. J., MULLEN, W., CROZIER, A. 2005. On-line high-
performance liquid chromatography analysis of the antioxidant activity of
phenolic compounds in green and black tea. Molecular Nutrition & Food
Research, 49(1), 52-60.
SULTANA, T., STECHER, G., MAYER, R., TROJER, L., QURESHI, M. N.,
ABEL, G., POPP, M., BONN, G. K.. 2008. Quality assessment and quantitative
analysis of flavonoids from tea samples of different origins by HPLC-DAD-ESI-
MS. Journal of Agricultural and Food Chemistry, 56(10), 3444-3453.
SUTEERAPATARANON, S., BUTSOONGNERN, J., PUNTURAT, P.,
JORPALIT, W., THANOMSIL, C. 2009. Caffeine in Chiang Rai tea infusions:
Effects of tea variety, type, leaf form, and infusion conditions. Food Chemistry,
114(4), 1335-1338.
TRUDEL, D., LABVBE, D. P., BAIRATI, I., FRADET, V., BAZINET,
L.,TETU, B. 2012. Green tea for ovarian cancer prevention and treatment: A
systematic review of the in vitro, in vivo and epidemiological studies.
Gynecologic Oncology, 126(3), 491-498.
UEDA, M., ASHIDA, H. 2012. Green Tea Prevents Obesity by Increasing
Expression of Insulin-like Growth Factor Binding Protein-1 in Adipose Tissue of
High-Fat Diet-Fed Mice. Journal of Agricultural and Food Chemistry, 60(36),
8917-8923.
UNACHUKWU, U. J., AHMED, S., KAVALIER, A., LYLES J. T.,
KENNELLY, E. J. 2010. White and Green Teas (Camellia sinensis var. sinensis):
Variation in Phenolic, Methylxanthine, and Antioxidant Profiles. Journal of Food
Science, 75(6), C541-C548.
VAN WOUDENBERGH, G. J., KUIJSTEN, A., DROGAN, D., VAN DER A,
D. L., ROMAGUERA, D., ARDANAZ, E., AMIANO, P., BARRICARTE, A.,
BEULEN, J. W. J., BOEING, H., BUENO-DE-MESQUITA, H. B., DAHM, C.
C., CHIRLAQUE, M. D., CLAVEL, F. C., CROWE, F. L., EOMOIS, P. P.,
FAGHER-AZZI, G., FRANKS, P. W., HALKJAER, J., KHAW, K. T.,
MASALA, G., MATTIELLO, A., NILSSON, P., OVERVAD, K., QUIROS, J.
R., ROLANSDDON, O., ROMEIU, I., SACERDOTE, C., SANCHEZ, M. J.,
SCHULZE, M. B., SLIMANI, N., SLUIJS, I., SPIJKERMAN, A. M. W.,
TAGLIABUE, G., TEUCHER, B., TJONNELAND, A., TUMINO, R.,
FOROUHI, N. G., SHARP, S., LANGENBERG, C., FESKENS, E. J. M.,
RIBOLI, E., WAREHAM, N. J., 2012. Tea Consumption and Incidence of Type
2 Diabetes in Europe: The EPIC-InterAct Case-Cohort Study. Plos One, 7(5).
J Microbiol Biotech Food Sci / Theppakorn et al. 2014 : 3 (5) 364-370
370
VUONG, Q. V., GOLDING, J. B., STATHOPOULOS, C. E., Roach, P. D. 2013.
Effects of aqueous brewing solution pH on the extraction of the major green tea
constituents. Food Research International, 53(2), 713-719.
YAMADA, H.,WATANABE, H. 2007. Tea polyphenols in preventing
cardiovascular diseases. Cardiovascular Research, 73(2), 439-440.
... In Indonesia, green tea is generally made from the Assam variety and produced using the panning method (Prawira-Atmaja et al., 2019). Tea from the Assam variety has a higher polyphenol content than tea from the Sinensis variety (Theppakorn et al., 2014). The panning system has weaknesses, including the fixation temperature that is not controlled and unstable to inactivate the PPO enzyme so that enzymatic oxidation still occurs in the following process. ...
... assamica ranging from 16.63-20.83 g GAE/100 g D.W. (Theppakorn et al., 2014). Another result study by Yadav et al. (2020) showed that green tea from various clones had a total flavonoid content of 200-350 mg QE/g. ...
Full-text available
Article
Fixation is essential in green tea processing to inactivate the polyphenol oxidase enzyme. In Indonesia, green tea is made from the Assam variety and produced using the panning method. Few studies are reported on green tea made from Indonesian clones of the Sinensis variety. This study aims to identify chemical characteristics, antioxidant activity, and sensory evaluation of green tea from local clones of the Sinensis variety (GMBS 2, GMBS 4, and GMBS 5) with different fixation methods (panning and steaming). The results show that the caffeine content of green tea products ranged from 2.51-2.59% and 2.67-2.74% for panning and steaming methods. The panning method produced green tea with higher total polyphenol and flavonoid content than the steaming method. Green tea with the panning method has an IC50 value of 14.45; 14.41; and 17.41 mg/L for GMBS 2, GMBS 4, and GMBS 5, respectively. The panning method resulted in a smaller IC50 value than the steaming method for GMBS 2 and GMBS 4 clones. The steaming method produced green tea with a higher taste, aroma, and total score than those the panning method. However, different fixation methods did not significantly affect the appearance, liquor color, and leaf infusion. In conclusion, different fixation methods on GMBS 2, GMB 4, and GMB 5 produced green tea products that met the Indonesian National Standard 3945:2016. Further research is needed to determine the role of the plucking period/season and the characteristics of volatile compounds of green tea from GMBS clones with different fixation methods.
... Commercially tea products in Thailand are obtained from both Assam and Chinese cultivar. About 30% of tea products are commercialized in the domestic market, whereas 70% is exported (Theppakorn et al., 2014). In Thailand, Assam tea is cultivated in a larger planting area than Chinese tea (Theppakorn et al., 2014). ...
... About 30% of tea products are commercialized in the domestic market, whereas 70% is exported (Theppakorn et al., 2014). In Thailand, Assam tea is cultivated in a larger planting area than Chinese tea (Theppakorn et al., 2014). It is mainly used to produce Miang or fermented tea . ...
Article
Tea is considered as the most consumed drink in the world containing high antioxidant capacity. In this study, the volatile compounds, the phenolic content, catechins and caffeine including antioxidant activities of 22 Camellia sinensis var. assamica (Assam tea) cultivars were investigated. The volatile compounds were investigated by GC-MS. At least forty-five volatile compounds representing 94.99-99.65% of all cultivars were identified. Limonene, trans-linalool oxide, cis-linalool oxide, linalool, and furfural were detected as the major components among these cultivars. Varied ranges were found in all Assam tea cultivars for the contents of phenolics (113.45-245.55 mg gallic acid/g dry weight), total catechins (170.03-355.59 mg/g dry weight), caffeine (0.92-3.40 mg/g dry weight), and antioxidant activities (1418.68-2728.46 µmol Trolox/g dry weight and 1448.98-2864.17 µmol Trolox/g dry weight for DPPH and ABTS assay, respectively). The antioxidant activity was correlated with phenolic compounds such as epigallocatechin gallate, epicatechin gallate, and catechin gallate. The specific differences among Assam tea cultivars are dependent on the tea cultivar and altitude which may play a significant role in breeding Assam tea cultivars in Thailand for providing its potential health benefits.
... sinensis) and Assam (C. assamica) green tea in the current study were similar to those reported by Theppakorn et al. (2014). ...
Article
The sensory profiles were investigated of drinking Chinese green tea (Ch) and Assam green tea (As) processed for different durations of pan-firing (4 levels; 0 min, 5 min, 10 min and 15 min) and rolling (3 levels; 0 min, 2 min and 4 min) based on 24 samples. In total, 33 attributes from all tea samples were evaluated using generic descriptive analysis according to a tea cupping standard, followed by classification using principal component analysis. Based on the results, all the tea samples could be divided into three groups. The first group was influenced by the duration of the pan-firing and rolling processes used with Ch that contributed to the ‘Green’ and ‘Seaweed’ attributes. The second group, also Ch, had a positive correlation only to rolling duration that contributed to ‘Bitter aromatic’, ‘Tobacco’, ‘Brown’, ‘Dark Brown’, ‘Sweet aromatic’, ‘Floral’ and ‘Spice’ attributes. The third group associated with all the As samples was influenced by the duration of both pan-firing and rolling that contributed to ‘Dark green’, ‘Tea ID’ and ‘Ashtray’ attributes. The results revealed that aroma and flavor are important attributes that could be used to categorize the green tea samples into three groups depending on processing duration and the green tea variety. Therefore, the findings regarding green tea attributes could be utilized in tea processing development, especially regarding the pan-firing and rolling process conditions. Copyright © 2020. This is an open access article, production and hosting by Kasetsart University of Research and Development institute on behalf of Kasetsart University.
Article
Assam green tea possesses health benefits and aromatic compounds in the tea leaves. Effects of pan‐firing time (0, 5, and 10 min) and rolling time (0, 2, and 4 min) on chemical and antioxidant properties and sensory descriptive analysis of Assam green tea were investigated. Increasing pan‐firing time increased total phenolic content (TPC), total catechin content, and antioxidant activity (2,2‐diphenyl‐1‐picprylhydrazyl (DPPH), (2,2′‐azinobis)‐3‐ethylbenzothiazoline‐6‐sulphonic acid (ABTS), and ferric ion reducing antioxidant power (FRAP)) values, whereas increasing rolling time tended to decrease such chemical properties. There were four categories of volatile functional groups analysed by gas chromatography‐mass spectrometry (GC‐MS) during green tea preparation, including aldehyde, alcohol, furan, and ether. A sensory lexicon consisting of ten attributes developed by trained descriptive panellists showed a significant relationship with chemical properties. The green tea under pan‐firing process expressed bitter taste, total catechin, TPC, and antioxidant activity. These active chemical compounds and critical sensory attributes of drinking green tea could potentially be beneficial for healthy beverage production. Principal component analysis (PCA) of Assam green tea samples (As‐1 to As‐9) from different pan‐firing and rolling treatments in the process duration and their chemical properties, volatile compound and sensory attributes (flavour (F) and taste (T)). Tea leaves with no pan‐firing before rolling for 0, 2, and 4 min were designated as As‐1, As‐2, and As‐3, respectively. Tea leaves which were pan‐fired for 5 min and then rolled for 0, 2, and 4 min were designated as As‐4, As‐5, and As‐6, respectively. Tea leaves which were pan‐fired at 10 min and then rolled for 0, 2, and 4 min were designated as As‐7, As‐8, and As‐9, respectively.
Full-text available
Article
Polyphenols are natural substances that have been shown to provide various health benefits. Antioxidant, anti-inflammatory, and anti-carcinogenic effects have been described. At the same time, they inhibit the actions of bacteria, viruses, and fungi. Thus, studies have also examined their effects within the oral cavity. This review provides an overview on the different polyphenols, and their structure and interactions with the tooth surface and the pellicle. In particular, the effects of various tea polyphenols on bioadhesion and erosion have been reviewed. The current research confirms that polyphenols can reduce the growth of cariogenic bacteria. Furthermore, they can decrease the adherence of bacteria to the tooth surface and improve the erosion-protective properties of the acquired enamel pellicle. Tea polyphenols, especially, have the potential to contribute to an oral health-related diet. However, in vitro studies have mainly been conducted. In situ studies and clinical studies need to be extended and supplemented in order to significantly contribute to additive prevention measures in caries prophylaxis.
Full-text available
Article
Production of black tea from the same vegetatively propagated (VP) cultivars, in Kenya and Malawi, shows variations in both chemical composition and quality. Whereas it is possible to produce black teas with similar total theaflavins and individual theaflavins, brightness and total colour levels, black teas from Kenya generally have higher thearubigins, total volatile flavour compounds and flavour index. The black tea fermentation process is much faster in Malawi compared to that in Kenya, as evidenced by faster production of plain black tea chemical parameters, especially theaflavins. Consequently, in Malawi the maximum amount of theaflavins formation takes a shorter fermentation duration than in Kenya. Given ample fermentation duration, fermentation in Kenya produces a similar amount of theaflavins. This makes it necessary to optimise fermentation time, in different geographical regions even when the same cultivar is being processed. The other plain black tea quality parameters (thearubigins, brightness and total colour) were higher in black tea which was processed in Kenya than those processed in Malawi. However, the pattern in the changes in the individual theaflavins or theaflavins digallate equivalent followed that of total (Flavognost) theaflavins, suggesting that the flavan-3-ols patterns in tea leaf might not have been affected by the geographical area of production. The total volatile flavour compounds (VFC), Group I and II VFC and the flavour index were higher in black teas processed in Kenya, further demonstrating the fact that high grown Kenyan teas are more flavoury. In both Kenya and Malawi black teas, aroma quality declined with a long duration of fermentation. Short fermentation time is therefore a method of producing more aromatic black teas. The variations in black tea quality between Malawi and Kenya were possibly due to difference in environmental conditions, leading to different shoot growth rates and biochemical composition in the shoots.
Chapter
This paper deals with the following aspects of tea authentication: (I) the differentiation of green and black tea can be achieved using ratios of different polypenolic compounds, e.g. catechins vs. total phenolics or catechins vs theaflavins. The concept of the ratio of total phenolics to total catechins is currently established by accumulation of more data. (II) To detect the geographic origin the flavonol glycosides ratios seem to be promising, but there is still a lack of data. (Ill) White teas are increasingly sold but there are not many data available on the constituents. It is currently impossible to asure the authenticity of white teas, especially of instant products. The ratio total polyphenols vs catechins is similar to green teas. (IV) The use and the amount of (instant) tea in RTD beverages such as ice tea is not always easy to detect depending on the process used to produce a cold water soluble tea. The authenticity can be checked using the flavonol pattern, in case of a harsh treatment by flavone C glycosides. Theanine could possibly be used as a marker in tea products. Methods are available for the determination and for the separation of D- and L-theanine. However, not much is known about the fate of theanine during the extraction and drying process.
Article
Reliable and accurately measurable chemical parameters that can be used to estimate black tea quality are desirable in trade, research and breeding programmes. Using plain Kenyan black tea from 11 cultivars, which gave some significant differences in their plain black tea quality parameters, the individual theaflavins composition, total theaflavins, thearubigins, theaflavin digallate equivalent, total colour and brightness were determined. The parameters were regressed against sensory evaluation scores of two tasters A and B. The theaflavin digallate equivalent (TDE) showed the strongest relationship (r = 0.71 (P ⩽ 0.01) and r = 0.80 (P ⩽ 0.001)) for A and B′, respectively. The simple (non gallated) theaflavin and thearubigins did not show significant relationships with sensory evaluation. Of the liquor characteristics, there were significant relationships between liquor brightness and sensory evaluation by A and B (r = 0.58 (P ⩽ 0.06) and r = 0.59 (P ⩽ 0.05)), respectively. In consequence, TDE and brightness can be used in tea breeding programmes as quality indicators or to estimate plain black tea quality potential in the tea trade. Optimising their levels can also help to produce good quality Kenyan black teas during processing. Comparison of these results with work published earlier indicates that, of the individual theaflavins, theaflavin-3,3′-digallate correlates best with tea taster scores for the 11 Kenyan cultivars, whereas the simple theaflavin correlates best with tea tasters’ scores for 40 Malawian cultivars. However, the derived parameter, TDE correlates very well with tea tasters’ scores for all of the above cultivars.
Article
Background: Fuzhuan brick tea is a kind of microbial fermented tea, which has received increasing attention in recent years owing to its benefits for human health. In this study, the anti-obesity and hypolipidemic effects of Fuzhuan brick tea water extracts (FTEs) were investigated. Results: FTEs consisted of 204.07 ± 3.38 mg g(-1) polyphenol, 109.20 ± 1.36 mg g(-1) flavonoids, and others. The FTEs significantly suppressed the increase of body weight and accumulation of adipose tissue, and reduced the level of serum triacylglycerol, total cholesterol and low-density lipoprotein (LDL) cholesterol in obese rats fed a high-fat diet. Moreover, FTEs attenuated the gene expression of sterol regulatory element binding protein-1c, fatty acid synthase and CCAAT/enhancer binding protein α, which is related to lipogenic metabolism. In contrast, the gene expressions of enzymes involved in energy expenditure and lipodieresis including hepatic peroxisome proliferator-activated receptor α, carnitine palmitoyltransferase 1a and LDL receptor gene expression were increased by FTE treatment. Conclusions: Our study demonstrates that FTEs have anti-obesity and hypolipidemic functions, suggesting that it might be effective for treatment of obesity and hyperlipemia.
Article
A worldwide data collection was undertaken using the validated ISO methods ISO 14502 parts 1 and 2, with 17 laboratories participating worldwide. This is the largest tea database worldwide, containing 295 black- and 358 green-origin teas. We found it quite easy to differentiate most green and black teas by the type of analysis presented in this study. The geographic spread gave a good representation of the vast majority of the producing countries. The production figures of the countries and the proportion of teas in the database are very similar. There are only a few origins which are not easy to differentiate, e.g. Darjeeling samples fall into the area of green teas. Other types of tea, e.g. Oolong or white teas, are currently not in the database. In the future other standardized methods for tea phenolics, such as theaflavins or flavonol glycosides, might become available. Additional data will certainly contribute to an even more robust discrimination between the types of tea.
Article
Green tea catechins can undergo degradation, oxidation, epimerization and polymerization during food processing. Many factors could contribute to the chemical changes of green tea catechins, such as temperature, pH of the system, oxygen availability, the presence of metal ions as well as the ingredients added. Several detection methods have been developed for tea catechin analysis, which are largely based on liquid chromatography (LC) and capillary electrophoresis (CE) methods for getting a good separation, identification and quantification of the catechins. Stability of green tea catechins is also influenced by storage conditions such as temperature and relative humidity. The stability of each catechin varies in different food systems and products. Pseudo first-order kinetic model has been developed and validated for the epimerization and degradation of tea catechins in several food systems, whereas the rate constant of reaction kinetics followed Arrhenius equation.
Article
The volatile flavour components of different teas growing in Thailand were extracted using the simultaneous distillation and extraction (SDE) technique. These volatiles were investigated by GC–MS. At least 54 components representing 76.51–83.32% of all samples were identified. Hotrienol, geraniol and linalool were found to be the major components in Green Oolong tea. Green Assam tea contained linalool, geraniol and α-terpineol as the key flavour constituents. Chin Shin Oolong tea was dominated by linalool, indole and cis-jasmone whilst the major flavour volatiles of Chin Hsuan Oolong tea were trans-nerolidol, cis-jasmone and geraniol. Indole, geraniol and cis-jasmone were detected as the main constituents in Four Season tea. Change of quality and quantity of volatile flavour components was related to fermentation methods that increased volatiles were illustrated by the semi-fermented tea processing method. Green Assam tea infusion extract was evaluated to have the strongest antioxidant activities with the highest amount of phenol content followed by Four Season tea, Chin Shin Oolong tea, Chin Hsuan Oolong tea and Green Oolong tea, respectively.
Article
a b s t r a c t Caffeine in Chiang Rai tea infusions was found to be dependent on infusion conditions (water tempera-ture and infusion time), and leaf form (non-ground or ground) but independent of tea variety and type. For non-ground leaf samples, the higher the water temperature and the longer the infusion time, the higher the caffeine concentrations in tea infusions. After infusing for longer than 15 min, the dissolution rate of caffeine became slower and the concentration was essentially constant. For ground leaves, the caf-feine content was not influenced by infusion time. Caffeine concentrations in tea infusions from Camellia sinensis var. sinensis (26.8 ± 0.81 and 22.3 ± 5.55 mg/100 ml for ground and non-ground samples, respec-tively) were not significantly different from that of Camellia sinensis var. assamica (24.4 ± 0.66 and 20.3 ± 5.07 mg/100 ml for ground and non-ground samples, respectively). The difference in caffeine con-centration between green tea (28.1 ± 8.19 mg/100 ml) and oolong tea (20.3 ± 1.52 mg/100 ml) was not statistically significant.
Article
We evaluated morphological, isozyme and biochemical diversity of a total of 87 accessions in the genus Camellia [Camellia sinensis var. sinensis (10), C. talinensis (7), C. sinensis var. dehungensis (3), C. crassicolumna (3) and C. sinensis var. assamica (64)]. Great variation of morphological characters was apparent within each taxa. Across the five taxa, all leaf and most flower quantitative characters showed significant differences while all fruit quantitative characters measured did not differ significantly, and, seven (i.e., life form, bud color, petal texture, pubescence on ovary, style number, stamen location and locule per fruit) of the 33 qualitative characters yield significant differences. As a whole, caffeine content had the highest variation with CV of 22.7%, water extract solid showed the least variation (13.4%) and content of polyphenols (20.0%) and free amino acids (18.8%) showed intermediate variations. Camellia taliensis and C. sinensis var. assamica had significantly higher content of polyphenols and water extract solid than in the other three taxa, while no significant differences were detected for the content of caffeine and free amino acids. For allozyme study, 14 loci presented good resolution, among which, nine loci (64%) were polymorphic in each taxon (AAT-3, FUM-1, 6PDG-1, G6PDH-1, G3PDH-1, ME-1, PGM-1, PGM-2 and SKD-1). The percentage of polymorphic loci (P) for each taxon was 21.4–50.0%. Mean heterozygosity per locus (H e ) varied 0.114–0.218. F ST value indicated that only 4.6% of the variations could be ascribable to genetic differences among taxa. Genetic relationships among the five taxa revealed by allozymes, were also exposed by the result of clustering of the morphological and biochemical characters.