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Ten different brewing methods of green tea: comparative antioxidant study

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In this study, three brands of green tea collected from different markets of Rawalpindi, Pakistan were screened to identify best brewing method for green tea preparation and characterize their antioxidant potential. Brand A, brand B and non-branded green tea were examined for antioxidant potential by DPPH (1,1-Diphenyl-2-picrylhydrazyl) radical scavenging assay and reducing power method. Samples were prepared by ten different recipes used in different cultures. Distilled water and ethanol were used as solvent. Three brewing methods with highest, lowest and moderate antioxidant activities were identified and analyzed for phytochemical constituents such as phenolic compounds, flavonoids, tannins, saponins, proteins, alkaloids and steroids. Cold cocktail showed highest antioxidant activity (85.9%), soft infusion showed moderate (70.6%) while hard infusion indicated lowest antioxidant potential (59.9%)amongst all the green tea brands tested. Phenolic compounds, tannins and proteins were found in all tea types with varying strength due to different brewing method. Alkaloids were not present in any type of green tea while steroids were found in brand A and B.
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Journal of Applied Biology & Biotechnology Vol. 4 (03), pp. 033-040, May-June, 2016
Available online at http://www.jabonline.in
DOI: 10.7324/JABB.2016.40306
Ten different brewing methods of green tea: comparative antioxidant
study
Naila Safdar*, Amina Sarfaraz, Zehra Kazmi, Azra Yasmin
Microbiology and Biotechnology Research Lab, Department of Environmental Sciences, Fatima Jinnah Women University, Rawalpindi, Pakistan.
ARTICLE INFO
ABSTRACT
Article history:
Received on: 18/11/2015
Revised on: 30/01/2016
Accepted on: 26/03/2016
Available online: 21/06/2016
In this study, three brands of green tea collected from different markets of Rawalpindi, Pakistan were screened to
identify best brewing method for green tea preparation and characterize their antioxidant potential. Brand A,
brand B and non-branded green tea were examined for antioxidant potential by DPPH (1,1-Diphenyl-2-
picrylhydrazyl) radical scavenging assay and reducing power method. Samples were prepared by ten different
recipes used in different cultures. Distilled water and ethanol were used as solvent. Three brewing methods with
highest, lowest and moderate antioxidant activities were identified and analyzed for phytochemical constituents
such as phenolic compounds, flavonoids, tannins, saponins, proteins, alkaloids and steroids. Cold cocktail
showed highest antioxidant activity (85.9%), soft infusion showed moderate (70.6%) while hard infusion
indicated lowest antioxidant potential (59.9%)amongst all the green tea brands tested. Phenolic compounds,
tannins and proteins were found in all tea types with varying strength due to different brewing method. Alkaloids
were not present in any type of green tea while steroids were found in brand A and B.
Key words:
Camellia sinensis;
phytoconstituents;
antioxidant assay; brewing
methods; Cold Cocktail.
1. INTRODUCTION
Tea is the nature’s wealth to human. In the world, the
second mainly consumed drink is tea, next to water. It is an
infusion that is prepared by steeping fermented leaves and twigs
of a plant, Camellia sinensis, in water or other solvents [1].
Twigs, buds and leaves of Camellia sinensis are used to generate
tea [2]. Camellia sinensis, tea plant is aboriginal to Southeast
Asia but now a days it is harvested in approximately more than
thirty nations of the world. Shen Nung, a Chinese emperor,
discovered tea accidentally in 2737 BC while boiling water and
some leaves fell into it, producing an apparent aroma and taste.
Emperor named it as, ‘heaven sent’. The variation in the
tea aroma, color, name and flavor depends upon how the tea
leaves are manufactured [3]. Asia has a great contribution to
every green tea importing market in the world. In Japan,
consumption of green tea is about 100,000 tons per annum, out
of which 90,000 tons are produced domestically. Other green tea
. .
* Corresponding Author
Naila Safdar, Microbiology and Biotechnology Research lab,
Department of Environmental Sciences, Fatima Jinnah Women
University, Rawalpindi, Pakistan. Email: naila_bch@yahoo.com
producing countries are Kenya, Taiwan, Korea, Sri Lanka, India,
Vietnam, Bolivia & Hawaii [4]. Free radicals, which are produced
in body by several biochemical reactions, have been concerned as
mediators of many diseases, including atherosclerosis, cancer and
heart diseases [5]. Antioxidants can efficiently neutralize the free
radicals by safely cooperating with free radicals and ceasing the
chain reaction before vital molecules get damaged. Antioxidants in
blood, tissue and cells play a significant role in neutralizing the
typical level of oxidative damage caused by these free radicals.
Plants are a prosperous source of polyphenolic compounds which
are efficient antioxidants [6].
The main antioxidants in tea are catechins, flavonols,
tannins and phenolic compounds. Green tea is the most powerful
antioxidant tea among all tea types. The antioxidant properties of
green tea polyphenols and the pro oxidant effects of these
compounds have been recommended as potential candidates for
cancer prevention [7]. The tea plant has shown the antimicrobial
efficiency against a variety of pathogenic microorganisms and
beneficial effects of tea have been attributed to its strong
antioxidant activity which in turn is due to the phenolic compounds
[8]. The carotenoids, tocotrienols, flavonoids, cinnamic acid,
benzonic acid, ascorbic acid, folic acid, tocopherols are some
antioxidants generated by the plants [9].
Safdar et al. / Journal of Applied Biology & Biotechnology 4 (03); 2016: 033-040
Active constituents of green tea possess many medicinal
benefits, theanine has potential role in reducing stress, catechins
promote weight loss and has antiviral, anti-inflammatory and anti-
carcinogenic effects while theaflavins are associated with
decreased cardiovascular risk [10].
The side effects of nervous system stimulants and tea
may include anxiety, nervousness, and irritation of the gastric
mucosa, heart irregularities, tremors, headaches, hypertension,
insomnia, restlessness, daytime irritability and dieresis. These
effects are normally for relatively high dosages and are not linked
with the ingestion of rational amounts of tea (e.g., 1 to10 cups per
day) [11].
Methods of preparing green tea infusion vary all over the
world, as in China, tea leaves are steeped in hot water having
temperature of 70°C to 80°C for 20 to 40 seconds, and the same
tea leaves are usually steeped repeatedly for about seven times.
Recently, in Taiwan, particularly in summer seasons, steeping in
cold water with the temperature of 4 or 25ºC is a new popular
method for making tea. While in Pakistan, two different methods
of green tea preparation are used either adding green tea in boiling
water (100°C) or steeping green tea in warm water (70-80°C)like
Chinese tradition [12]. Different phytochemicals present in green
tea are associated with prevention of specific diseases; therefore it
is important to consider the preparation method of green tea which
generates highest amount of phytochemicals.
Pakistan is the second largest importer of both processed
and raw tea from abroad after United Kingdom and the total per
capita tea consumption is one kg. There are different kinds of tea
and brands of tea offered in the markets of Pakistan having
great distinction in their quality, composition and characteristics
[13]. In this project, three different brands of green tea which
differ greatly in their market prices were selected and analyzed for
their antioxidant effects. To the best of our knowledge, no work
has been reported in literature where ten different brewing
methods of green tea are compared and analyzed. This is the first
novel report where different tea brands available in Pakistan have
been compared in terms of difference in price and respective
health benefits (antioxidants). This project also spots the best
green tea (on the basis of price, brewing method and antioxidant
potential) among different types of green tea highly consumed in
Pakistan.
2. MATERIALS AND METHODS
Different types of green tea with two different batches
(consignment produced by industries at two different durations)
were collected from different markets of Rawalpindi, Pakistan.
Green tea of international brand twining of London (ToL - Brand
A) was purchased from Cosmo Jinnah Park Rawalpindi. Lipton
(Brand B) green tea was collected from Central Store Department
Rawalpindi and, low-priced, non-branded open green tea imported
from China named as ‘China Plando’ was collected from Raja
bazaar Rawalpindi. Three samples from each batch were prepared
by ten different recipes and were analyzed for antioxidant
potential.
2.1. Green Tea Sample Preparation Recipes
In order to find out the best brewing method, we
prepared green tea infusions by ten different recipes. These recipes
are used in different cultures throughout the world [11].
2.1.1. Soft infusion
In this preparation method, a tea bag was dipped in warm
water having the temperature of 75-85 °C for 3 to 5 minutes. This
method is used by Chinese people for tea preparation.
2.1.2. Hard infusion
In this brewing method, a tea bag was infused in distilled
warm water having the temperature of 75-85 °C for 25 to 30
minutes.
2.1.3. Ambient infusion
This method involves dipping of tea bags in distilled
water at room temperature 25 ±2 °C for 30 to 40 minutes.
2.1.4. Cold infusion
In this method, tea bags were infused in distilled water
and maintained at room temperature for 15 minutes. After that, the
prepared infusion was refrigerated for an hour.
2.1.5. Decoction method
In this recipe, tea bags or tea leaves are placed in distilled
water and boiled for 3 to 5 minutes. The above mentioned five
methods are predominantly used in Asian cultures as in Pakistan,
China, India and Bangladesh.
2.1.6. Chilled green tea
In this type of preparation, tea bags were infused into
distilled boiling water for 3 to 5 minutes and after that the infusion
was refrigerated for an hour.
2.1.7. Cold cocktail
In this alcoholic infusion, distilled water and ethanol was
used with the ratio of 60 to 40%. Tea bags were infused in
alcoholic solution for 15 minutes and then removed, after which
the infusion was refrigerated for an hour.
2.1.8. Hot Cocktail
Tea bags were infused in alcoholic solution for 15
minutes followed by heating up to 52 °C. Hot and CCs are
commonly used in Western cultures and in some Asian countries
like China and India.
2.1.9. Puree
In this recipe, the tea was grounded into fine powder and
blended into warm water having the temperature of 70 to 80 °C for
4 to 5 minutes. The puree obtained was filtered and analysed
Safdar et al. / Journal of Applied Biology & Biotechnology 4 (03); 2016: 033-040 035
immediately for antioxidant activity. This type of preparation
method is mostly used in Japan.
2.1.10. Sun green tea
In this method, tea bags are infused in distilled water and
put into direct sun light for 3 to 4 hours. This brewing method is
most common in United States.
All Green tea samples were prepared in glass beakers of
250ml. Infusions were prepared in distilled water and ethanol.
Composition of all tea infusions include one tea bag (1.265g of
tea) in 100 ml of distilled water.
2.3. Antioxidant assays
2.3.1. DPPH(1,1-Diphenyl-2-picrylhydrazyl) radical scavenging
assay As reported [14], reaction mixture consisted of 3 ml of
methanol, 0.5ml of tea infusion, and 0.3ml of DPPH (1,1-
Diphenyl-2-picrylhydrazyl) solution (0.5mM) in methanol.
Reaction mixture was incubated for 45 minutes, after which
absorbance was determined by spectrophotometer at 517nm.
Ascorbic acid (100µg/ml) was used as positive control. Blank
sample was methanol and mixture of methanol (3ml) and DPPH
solution (0.3ml) was taken as negative control. The experiment
was performed in triplicates. Percentage of inhibition was
determined by using the formula.
Inhibition % = Ac - As / Ac × 100
Where Ac = Absorbance of the control
As = Absorbance of the sample
2.3.2. Reducing power Assay
As reported [15] 2.5 ml of tea infusions was mixed with
phosphate buffer of 2.5ml (pH 6.6, 0.2 M) and 2.5 ml of one
percent potassium ferricyanide. The reaction mixture was
incubated for about twenty minute at 50°C. After that, 2.5 ml of
ten percent trichloro acetic acid was introduced. 2.5 ml of the
reaction mixture was mixed with 2.5ml of distilled water and
0.5ml of ferric chloride (0.1%). Reaction mixture without tea
infusions was used as negative control. Ascorbic acid (1%) was
used as positive control. The absorbance of solution was
measured at 700 nm. The experiment was performed in triplicates.
2.3.3. Phytochemical Analysis
Qualitative phytochemical examinations were carried out
as per the standard methods [16][8].
2.4. Hager’s reagent test
Infusions were mixed separately into hydrochloric acid
(dilute) followed by filtration. After that Hager’s reagent test was
performed in which filtrates were mixed with Hager’s reagent
which is the saturated picric acid solution. Existence of alkaloids
was indicated by the development of yellow coloured precipitate.
2.5. Detection of flavonoids
Infusions were treated by few drops of lead acetate
solution. Configuration of yellow colour precipitate showed the
existence of flavonoids.
2.6. Xanthoproteic test
In this test the extracts were treated with few drops of
concentrated nitric acid. Presence of yellow colour indicated the
occurrence of proteins.
2.7. Salkowski’s test
Here infusions were mixed with chloroform and filtered.
Then the filtrates were mixed with few drops of concentrated
sulphuric acid, shaken and allowed to stand. Appearance of golden
yellow colour showed the presence of steroids.
2.8. Gallic tannin test
In this test 0.5ml of tea infusion was dissolved in 1 ml of
water, mixed uniformly and then 2 drops of ferric chloride solution
were added. Appearance of blue colour indicated the presence of
Gallic tannin.
2.9. Catecholic tannin test
0.5 ml of tea extract was dissolved in 1 ml of water,
treated consistently then 2 drops of solution of ferric chloride were
added. Green black colour was appeared for presence of catecholic
tannin.
2.10. Saponins Test
Tea infusions (5ml) were shaken strongly in the company
of distilled water (5ml) in a test tube. The development of steady
foam was indicated as a sign of the occurrence of saponins.
2.11. Detection of Phenols
Ferric Chloride Test: Tea infusions were mixed with 3-4
drops of ferric chloride solution. Creation of bluish black colour
indicated the presence of phenols.
2.12. Statistical analysis:
All the experiments were carried out in triplicates. The
values were expressed as the means ± standard deviation (S.D.) of
three observations in each group. Two-way ANOVA tests were
performed using data analysis tools in excel for calculating P
value. P value less than or equal to 0.05 was considered to be
significant.
3. RESULTS
Antioxidant potential of three different types of green tea
Brand A, Band non-branded green tea according to ten different
brewing methods was successfully screened. The antioxidant
potential of different green tea varies and variation occurred from
batch to batch of same green tea with the change of brewing
.
Safdar et al. / Journal of Applied Biology & Biotechnology 4 (03); 2016: 033-040
methods and type of tea. All brewing methods showed
considerable percentage inhibition ranging from 58 to 85% in
brand B green tea. Cold cocktail showed maximum percentage
inhibition (85.5% ±0.22) while minimum percentage inhibition
(58.4% ±1.19) was shown by hard infusion method just like Brand
A. Percentage inhibition of brand B green tea varies with brewing
method in the following order as; cold cocktail > hard cocktail >
sun green tea > cold infusion > Ambient > Puree > Chilled > soft
infusion > decoction > hard infusion. The antioxidant activities
alter between two batches of brand B green tea in all the brewing
methods and this fluctuation in percentage inhibition ranges from
1 to 5%. In case of Brand A, all brewing methods of the selected
Brand A showed significant percentage inhibition ranging from 59
to 85%. Cold cocktail showed maximum percentage inhibition
(85.9% ±1.1) while minimum percentage inhibition (59.9% ±5.1)
was shown by hard infusion method. Antioxidant potential of
Brand A green tea varies with brewing method in the following
order cold cocktail>hard cocktail>ambient infusion>sun green
tea> puree > cold infusion > chilled >decoction >soft
infusion>hard infusion. Antioxidant variations were also observed
between two batches of green tea in all the brewing
methods and this fluctuation in percentage inhibition ranges from
1 to 4%.
Non-branded green tea brewing methods also showed
significant percentage inhibition ranging from 66 to 84%. Cold
cocktail showed maximum percentage inhibition (84.4% ±0.42)
while minimum percentage inhibition (66.6%±0.3) was shown by
hard infusion method. Percentage inhibition of Non-branded green
tea varies with brewing method in the following order as; cold
cocktail > hot cocktail > cold infusion > Ambient > sun green tea
> Puree > soft infusion > decoction > chilled > hard infusion. All
the Percentage inhibitions of green tea infusions calculated by
DPPH assay are shown in table 1. Significant difference (<0.05)
was found to be present amongst the tea samples, tea brewing
methods and interaction between tea samples and brewing
methods as shown in table 4 (a). Reducing power method was also
used for measuring antioxidant activities of the tea samples as
shown in table 2. Data obtained from reducing power collaborated
with the DPPH assay. Higher absorbance values indicate higher
reducing ability. Reducing power showed reducing ability of
different tea brands with identifying the best brewing method as
the cold cocktail (3.885 ± 0.19 as highest absorbance value) and
hard infusion method (2.890 ± 0.1 lowest absorbance value) as the
lowest brewing method. Two-way ANOVA depicted significant
difference (< 0.05) amongst tea brewing method as shown in table
4 (b).
Table 1: DPPH free radical scavenging assay for different brands and preparation methods of green tea.
Brewing
method
Tea
types
Scavenging activity (%) of different preparation methods of green tea
Soft
infusion
Hard
infusion
Ambient
infusion
Cold
infusion
Decoction
Chilled
green tea
Cold
cocktail
Hot
cocktail
Puree
Sun green
tea
Brand B
Batch-1
70.59±3.56
60.29±0.3
79.945±0.39
82.52±1.73
67.225±3.05
68.9 ±6.09
85.24 ±0.14
85.24±2.98
75.62 ±0.70
83.965 ±1.52
Brand B
Batch-2
70.59±2.38
58.40±1.19
82.115±1.53
81.30±0
69.615±1.01
72.725±2.03
85.845± 0.29
84.84±0.71
80.04±1.34
85.95±0.35
Brand A
Batch-1
67.22±2.08
62.82±0.90
85.01±0.76
80.625±0.57
68.42±-3.38
68.66±1.70
85.94± 1.27
85.04±1.27
80.995±0.23
82.27±0.65
Brand A
Batch-2
66.39±2.38
59.87±5.06
82.385±2.68
80.76±1.15
66.985±0.67
67.94±0
85.945±0.86
82.43±1.56
81.695±0.53
83.18 ±3.68
Non-branded
tea
68.07±0.29
66.60±0.3
79.675±2.3
81.3±0.76
66.025±2.03
66.51±4.74
84.44±0.42
83.835±2.98
76.365±1.17
78.43± 6.08
Ascorbic
Acid
95.25±2.6
Bold values indicates the highest antioxidant activity obtained among different types of tea, while underlined values shows lowest antioxidant acti vity among the
tea samples.
Table 2: Reducing power assay for different brands and preparation methods of green tea.
Brewing
Methods
Type Of
Tea
Absorbance values of different type of Green Tea
Soft
infusion
Hard
infusion
Ambient
infusion
Cold
infusion
Decoction
Chilled
green tea
Cold
cocktail
Hot cocktail
Green tea
purree
Sun green
tea
Brand B
Batch-1
3.725±0.39
2.890±0.1
3.742±0.030
3.154±0.004
3.597±0.076
3.715±0.005
3.885±0.19
3.757±0.008
3.489±0.029
3.603±0.06
Brand B
Batch-2
3.765±0.018
2.960±0.027
3.661±0.05
3.059±0.03
3.583±0.027
3.690±0.06
3.830±0.018
3.789±0.07
3.375±0.033
3.593±0.011
Brand A
Batch-1
3.70±0.042
3.022±0.032
3.601±0.028
3.125±0.011
3.636±0.008
3.728±0.04
3.808±0.020
3.75±0.011
3.579±0.02
3.586±0.008
Brand A
Batch-2
3.721±0.036
2.991±0.097
3.695±0.015
3.133±0.02
3.661±0.030
3.639±0.09
3.852±0.35
3.725±0.016
3.429±0.03
3.599±0.04
Non-branded
tea
3.453±0.23
2.978±0.07
3.630±0.0035
3.08±0.046
3.635±0.028
3.747±0.042
3.794±0.017
3.7440.014
3.488±0.064
3.556±0.2
Ascorbic
Acid
4 ± 0.12
Bold values indicates the highest Absorbance value obtained among different types of tea, while underlined values shows lowest absorbance.
Safdar et al. / Journal of Applied Biology & Biotechnology 4 (03); 2016: 033-040 037
3.1. Effect of temperature on Green Tea
Temperature had a significant effect on antioxidant
activities of green tea. In present research, different brewing
methods were investigated out of which three infusion methods
were prepared at colder temperatures in the range of 2 to -4°C.
Other infusions were prepared at ambient, warm and hot
temperatures with different ranges. Different brewing methods at
ambient and warm temperature showed good antioxidant activities
e.g. The antioxidant potential of ambient infusion ranged from 80
to 85 % with sound antioxidant affects in hot cocktail(85%) and
sun green tea (84.9%).
Warm and ambient temperatures are the suitable
temperatures identified for extracting antioxidants in green tea by
different brewing methods (fig 1).
Table 3: Phytochemical Analysis of different types of green tea.
Type of tea
Phytochemicals
Best brewing Method
Moderate brewing method
Lowest Brewing method
Cold cocktail
Soft infusion
Puree
Hard infusion
Brand B
Brand A
Non-branded Tea
Brand B
Brand A
Non-branded tea
Brand B
Brand A
Non-branded
tea
Steriods
++
+
_
++
++
_
++
++
_
Flavonoids
++
++
+
+++
++
++
+++
++
++
Proteins
+++
++
+
-
-
-
++
+
+
Catecholictanin
+++
++
+
+
+
++
+++
++
++
Gallic Tanin
_
_
_
_
_
_
_
_
_
Saponin
_
_
_
++
+++
++++
_
+++
+++
Alkoloids
_
_
_
_
_
_
_
_
_
Phenols
++++
+++
+++
+++
+
++
++
+
+
Key: Strongly present (++++), Moderate (+++), Normal (++) Low (+), Not Present ( -).
Table 4: Statistical analysis. A-Two-Way ANOVA for Dpph free radical scavenging assay.
ANOVA
Source of Variation
SS
df
MS
F
P-value
F crit
Tea Sample
73.5976
4
18.3994
3.499607
0.010203
2.462615
Brewing methods
9902.76
9
1100.307
209.2808
0.000000
1.974829
Interaction
451.7109
36
12.54752
2.386567
0.000367
1.535138
B-Two-Way ANOVA for reducing power assay
ANOVA
Source of Variation
SS
df
MS
F
P-value
F crit
Tea Sample
0.045433
4
0.011358
1.285606
0.280768
2.462615
Brewing methods
10.72578
9
1.191753
134.8921
0.000000
1.974829
Interaction
0.357083
36
0.009919
1.12271
0.320495
1.535138
Fig.1: Effect of temperature on antioxidant activity of green tea infusions.
0
10
20
30
40
50
60
70
80
90
Cold
infusion
Chilled
Cold
cocktail
Ambient
infusion
Puree
Hot
cocktail
Sun green
tea
Decoction
Soft
infusion
Hard
infusion
(2 to -4°C ± 2)
(25 °C ± 2)
(40-50°C ± 2)
(100°C ± 2)
Cold
Ambient
Warm
Hot
percentage inhibition %
Temperature
Safdar et al. / Journal of Applied Biology & Biotechnology 4 (03); 2016: 033-040
3.2. Phytochemical Investigation
Three different brewing methods with highest (cold
cocktail), lowest (hard infusion) and moderate antioxidant
activities (soft infusion and puree) were selected and analyzed for
phytochemicals (table 3).
3.3. Correlation between antioxidant capacity and tea
phytoconstituents
Different brewing methods had different antioxidant
properties. The difference in antioxidant properties was due to the
difference in phytochemicals released in infusion. The difference
in the presence of phytochemical in different brewing methods
depends upon steeping time of the infusion, type of tea, type of
solvent and temperature. Steeping time of soft infusion was short
(3-7minutes) but time of hard infusion was long (30-40 minutes)
while temperature and solvent was same in soft and hard infusion.
Cold cocktail has low temperature, alcoholic solvent and long
steeping time (1 hour). When comparing these three infusions in
brand B green tea, we find increased release of phytochemicals in
cold cocktail as compared to other counter parts. Similarly, when
comparing different tea infusions of Brand A, increased
phytochemicals were detected in hard infusion. Non-branded green
tea also showed similar results as those of Brand A. Strength of
phytochemicals also varies in types of tea and different brewing
methods (fig 2).
4. DISCUSSION
In Pakistan, due to the numerous medicinal properties of
green tea, it is used in all the segments of the society. There are so
many brands and types of green tea available in the markets of
Pakistan. Out of them, some are imported in raw form and then
processed and purchased, like brand B, while some are imported in
its final product form and distributed, like Brand A. In this project,
we selected three different commonly used brands (with varying
prices) of green tea. Brand A is imported through a well-known
multinational company (5800 rupees per kg), Brand B (2500
rupees per kg) is manufactured and distributed by Unilever
Pakistan while non-branded green tea (280 rupees per kg) is
imported from China and distributed in unwrap form. Usage of
different types of green varies between different classes of the
society based on the prices of green tea. Due to high price, Brand
A green tea is used by elate class while Brand B and open non-
branded green tea are mostly used by middle and lower class
people of Pakistan. Present research project showed that the
difference between antioxidant potential of above mentioned green
tea types was very low though they differ greatly in their prices.
Green tea is well known for those individuals that have
increased oxidative stress and decreased insulin sensitivity, such as
those with the type II diabetes or metabolic syndrome [17]. The
opposite association among various serum markers and
consumption of green tea indicates that green tea may perform
protectively against disorders of the liver and cardiovascular
disease and exert protective effects against oxidative stress and
cancer[18]. Due to the antioxidant properties of green tea,
infusions can be used as defensive method for carcinogenic
processes, prostate cancer, liver or renal diseases and many other
oxidative damages [19]. Catechins are antioxidants found in green
tea that scavenge free radicals [20].
Fig. 2: Phytochemicals of different types of tea in best moderate and lowest brewing Method.
Key * 0 = (-), 1 = (+), 2 = (++), 3 = (+++), 4 = (++++)
Safdar et al. / Journal of Applied Biology & Biotechnology 4 (03); 2016: 033-040 039
Methods of preparing green tea infusion vary all over the
world. Iced tea is greatly consumed by Americans who prepare it
from hot tea and then cooled with ice. The Japanese frequently
make green tea by steeping tea leaves in hot water for about 2
minutes and using them for 2 to 3 times. Actually, tea prepared
using cold water contains lower quantity of caffeine, higher aroma
and reduced bitterness. For its preparation, tea leaves are steeped
in water at 25 ºC for at least 2 hours. Difference is reported
between antioxidant activities of tea prepared by different steeping
method. Stimulant action of tea is strongest when allowed to steep
for 2 to 5 minutes as caffeine dissolves quickly in hot water.
Longer steeping of about 10 to20 minutes decreases the stimulant
effect and increases the catechin yield as the polyphenols bind the
caffeine [11]. Our results also suggest the cold solvent as the best
medium for extracting increased antioxidant from green tea.
Longer steeping time had no effect on increased antioxidant
potential of green tea as indicated in our experiments.
Polyphenolic compounds present in tea vary significantly with the
source of tea, the production location, the season of tea production,
and tea processing, ultimately affecting the antioxidant properties
of tea [21]. So, we can say that different brewing methods can also
alter the concentration of tea phytochemicals in a ready to drink
cup of tea. Green tea of different brand showed higher antioxidant
properties in alcoholic cold beverage and lower antioxidant
property in hot water (30 to 40 minutes steeping). This is in
contrast to the report oriented by some researchers [22] who found
higher antioxidant activity for hot water extract of different
caffeine products than those of cold extracts and this activity were
time and concentration dependent. He found a positive correlation
between the antioxidant and reducing compounds presented in
water extracts of different caffeine products.
In a comparative research of Korean green tea and
traditional fermented Korean tea (TFKT), it was shown that TFKT
contains high amount of bioactive compounds and have high
antioxidant activity in methanol [23]. In present research, alcoholic
brewing method containing 40 percent ethanol also showed higher
antioxidant affect than any other type of preparatory method.
Moreover, in present study all types of tea showed significant
antioxidant properties and content of bioactive compounds so they
all could be suggested as a source of bioactive compounds. Herbal
infusions of Argentina have been studied for their antioxidant and
phenolic content. The elevated correlation between antioxidant
capacities of herbal infusions and total phenolic contents suggested
that phenolic compounds are the main contributors of antioxidant
properties [24]. In our research project, differences between
antioxidant properties of various brewing methods were also based
on the presence of phenolic compounds. Cold cocktail with highest
antioxidant property had higher content of phenols in all three
types of tea studied than the other two brewing methods which
showed moderate and lowest antioxidant properties. Reduced
phenols were detected in the later brewing methods. It was
reported that green, black and white tea products that was
processed from Japanese and Chinese tea cultivars, had
significantly lower antioxidant activity than green tea which was
processed from Kenyan tea cultivars [25]. Tea used in present
research was purchased from Pakistani markets but they had
different origins like China, Kenya, India and Vietnam and were
imported to Pakistan. This could be one of the reasons of our
selected green tea brands showing different antioxidant potential in
different brewing methods.
5. CONCLUSIONS
Green tea of three different types used in Pakistan had
significant antioxidant potential with Brand A and Brand B almost
showing similar performance followed by non-branded green tea.
Best brewing recipe was found to be cold cocktail with highest
(85%) antioxidant potential followed by soft infusion and hard
infusion methods which showed moderate (70%) and lowest
(60%) antioxidant effects respectively. Phytochemical
investigation showed that Brand B tea infusions had higher
amount of flavonoids, phenols and Catecholic tannin than Brand A
and non-branded green tea. The difference between antioxidant
activities of different types of green tea was very slight but the
variation in their price was very high. In Pakistan, there is a
narrow research related to quality of tea importing from different
nations, as the tea consumption is very high, therefore, research
should be done related to quality of different types of tea available
in markets. Elevated import cost of tea for developing country like
Pakistan is very critical; hence there is a need of hour to work on
tea to minimize the burden on economy.
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How to cite this article:
Safdar N, Sarfaraz A, Kazmi Z, Yasmin A. Ten different brewing
methods of green tea: comparative antioxidant study. J App Biol
Biotech. 2016; 4 (03): 033-040. DOI: 10.7324/JABB.2016.40306
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Book
While there have been many claims of the benefits of teas through the years, and while there is nearly universal agreement that drinking tea can benefit health, there is still a concern over whether the lab-generated results are representative of real-life benefit, what the risk of toxicity might be, and what the effective-level thresholds are for various purposes. Clearly there are still questions about the efficacy and use of tea for health benefit. This book presents a comprehensive look at the compounds in black, green, and white teas, their reported benefits (or toxicity risks) and also explores them on a health-condition specific level, providing researchers and academics with a single-volume resource to help in identifying potential treatment uses. No other book on the market considers all the varieties of teas in one volume, or takes the disease-focused approach that will assist in directing further research and studies. * Interdisciplinary presentation of material assists in identifying potential cross-over benefits and similarities between tea sources and diseases * Assists in identifying therapeutic benefits for new product development *Includes coverage and comparison of the most important types of tea - green, black and white.
Book
Presenting both the concerns and problems of beer consumption as well as the emerging evidence of benefit, Handbook of Beer Health and Disease Prevention offers a balanced view of todays findings and the potential of tomorrows research. From a beverage of warriors to a cheap and affordable commodity, beer has been a part of our consumption for nearly 8000 years. Like most alcoholic drinks it has been prone to abuse and in some counties the per capita consumption of beer has led to considerable health risks. However, just as wine in moderation has been proposed to promote health, research is showing that beer -- and the ingredients in beer -- can have similar impact on improving health, and in some instances preventing disease. For example, some cancers like bladder cancers and the incidence of cardiovascular disease are reported to be lower in moderate beer drinkers. Furthermore there is a considerable body of emerging evidence to show that the anti-oxidant capacity of beers is high. It has been argued by some that the total antioxidants ingested in some beer drinkers equates that consumed by red wine drinkers. The key to this, of course, is understanding and this volume presents a collection of the most current writings on the subject of beer and its potential in health.
Article
The aim of the present study was to study the phytochemical composition and antioxidant potential of the Ficus benjamina. Antioxidant activity of the methanolic extracts of F. benjamina was screened by 2, 2-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging assay, total antioxidant activity, iron chelating activity and reducing power assay. In addition to antioxidant activity, extract was also evaluated for cytotoxic activity brine brine shrimp lethality assay. Estimation of total phenolic content was performed by Folin-Ciocalteau reagent method and estimation of total flavonoid content was performed by aluminium chloride method. During preliminary phytochemical analysis, F. benjamina showed the presence of carbohydrates, phenolic compounds, oil and fats, saponins, flavonoids, alkaloids, proteins and tannins as major phytochemical groups. Methanolic extract of F. benjamina exhibited significant antioxidant activity in DPPH radical scavenging assay, total antioxidant activity, iron chelating activity and reducing power assay. Phytochemical screening of methanolic extract of F. benjamina showed the presence of high levels of phenolic (4.006 mg gallic acid equivalence/gm) and flavonoids (16.005 mg quercetin acid equivalence/gm) compounds which could be responsible for its antioxidant potential. Extract also resulted in significant cytotoxic activity towards brine shrimp nauplii. The obtained results emphasize the antioxidant activity of F. benjamina and provided the scientific basis for the traditional use in prevention and therapies of diseases.
Article
Medicinal plants possess an important source of pharmacological effects that acts as new anti-infections, antioxidant and anti-cancer agents. The most important bioactive constituents of plants are steroids, terpenoids, carotenoids, flavonoids, alkaloids, tannins and glycosides which serve a valuable starting material for drug development. Tea (Camellia sinensis) is consumed worldwide and is second only to water in its popularity as a beverage. It has ascribed many health benefits viz reduction of cholesterol, protection against cardio – vascular diseases and cancer. By concerning all these studies, we have traced out the presence of phytochemical in Camellia sinensis leave. The phytochemical analysis showed the presence alkaloids, flavonoids, steroids and tannins by changing the colour of medium when treated with respective reagents. One gram of Camellia sinensis leaves extract contained 0.7 grams of phenolic compounds. While flavonoid content was 14 mg/gram of Camellia sinensis leave extract. one gram of leaf extracts contained 0.11 gram of reducing power. The methanolic extract of Camellia sinensis showed the presence of various functional groups when run through Fourier transforms infrared spectroscopy. The methanolic extract of Camellia sinensis showed the antimicrobial activity against Bacillus subtilis, and Enterococcus sp. It reveals the highest zone of inhibition around the bacterial colonies when compared with standard antibiotics Erythromycin, Tetracycline and Ampicillin.
Article
Green tea has always been considered by the Chinese and the Japanese as a potent medicine for the maintenance of health, endowed with the power to prolong life. The health-promoting properties of the tea plant are often attributed to the active ingredients that include polyphenols. Ultimate antioxidative and bioactive potential of green tea in vivo is dependent on the absorption, distribution, metabolism, and excretion (ADME) properties of the catechins within the body after ingestion and the reducing properties of the resulting metabolites. It has antibacterial, antifungal, anticancerous, anticaries, antiperiodontitis properties; is effective for weight loss; and also arrests the exacerbation of pulpitis. Clinical applications of these potential benefits warrant further investigation through scientifically sound research prior to any definitive statements. The article was aimed to review the dental benefits of green tea as very few articles are documented. The literature was searched through Google search engine, EBSCOhost, and PubMed Central. Data were collected and the articles pertaining to dental implications were selected for this article.