The Uv Vis Spectrometric Technique Biology Essay

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For this study, the mean total polyphenol content in green tea produced in Asia and Europe were 33.84 mg/g tea leaves and 39.05 mg/g tea leaves respectively. There was no significant difference (p>0.05) between the polyphenol content in green tea produced in Asia and Europe.

According to Figure 4.1(b), Ahmad Tea London: Original Green tea (91.8038 mg/serving) which produced in one of the Asia countries have higher total polyphenol content compare to other tea used in this study. Alternatively, TenRenTea: Fresh Green Tea (44.3021 mg/serving) has the lowest total polyphenol content compare to the tea samples used in this study.

When assessed as mg/g tea leaves, the highest total polyphenol content no longer is Ahmad Tea London: Original Green tea, however, BOH: Green Tea has highest total polyphenol content (54.1076 mg/g tea leaves) compare to other brands of tea used in this study. In contrast, the lowest total polyphenol content for this study is TenRenTea: Fresh Green Tea (11.0755mg/d tea leaves). The ascending order of total polyphenol in tea was as follows: TenRenTea: Fresh Green Tea (11.0755 mg/g tea leaves), Duchy Originals from Waitrose: Organic Green Tea (29.2039 mg/g tea leaves), Teekanne: Finest Green Tea (32.2013 mg/g tea leaves), TeaZen:First Flush Pure Green Tea (33.3152 mg/g tea leaves), Dilmah: Special Green Tea (34.7328 mg/g tea leaves), Japanese Green Tea Sencha (36.8593 mg/g tea leaves ), Lipton: Clear Green (37.5682 mg/g tea leaves), Ahmad Tea London: Original Green tea (45.9019 mg/g tea leaves), BOH: Green Tea (54.1076 mg/g tea leaves).

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According to Belde and Zoerb (2011), the deviation of polyphenol content in tea might due to type, selection, post harvest technique, processing technique, age and cultivation between commercial tea brands. Besides, environment factors for instance room temperature and extraction technique also the reason that lead to deviation of polyphenol content in tea samples.

The study carried out by Kafley (2008) shown that total polyphenol content of caffeinated green tea ranged from 52.4 mg/serving to 239 mg/serving. In this study, the total polyphenol content ranged from 44.3021 mg/serving to 91.8038 mg/ serving and the average is 70.1756 mg/ serving. The difference might cause by the age of tea, soil, season of havesting, period of storage, processing, species (Belde and Zoerb, 2011; Zuo, Chen and Deng, 2002).

According to Yao, teas came from Indian or Sri Lanka varieties have higher polyphenol contents as compare to those originating from China variety. In current study, Dilmah: Special Green Tea (34.7328mg/g tea leaves) originated from Sri Lanka have higher polyphenol contents compare to Duchy Originals from Waitrose: Organic Green Tea (29.2039 mg/g tea leaves) which came from China.

Total Flavonoid Content Assay

In this study, the average total flavonoid content in green tea produced in Asia was 25.8662 mg/ g tea leaves while green tea produced in Europe was 29.62 mg/g tea leaves. There was no significant difference (p>0.05) between the flavonoid content in green tea produced in Asia and Europe.

As seen in Figure 4.1(c), total flavonoids in TenRenTea: Fresh Green Tea (23.9273 mg/ serving) was the lowest while Japanese Green Tea Sencha (71.4898 mg/serving) was the highest among the tea samples for this study.

Same tea samples which were TenRenTea: Fresh Green Tea (5.98183mg/g tea leaves) and Japanese Green Tea Sencha (35.7449 mg/g tea leaves) possess the highest and lowest total flavonoids respectively when evaluated as mg/(g tea leaves). The increasing order of total flavonoid in tea samples was as follows: TenRenTea: Fresh Green Tea (5.98183 mg/g tea leaves), Duchy Originals from Waitrose: Organic Green Tea (21.6033 mg/g tea leaves), Dilmah: Special Green Tea (22.7939 mg/g tea leaves), Lipton: Clear Green (29.4684 mg/g tea leaves), Ahmad Tea London: Original Green tea (29.4684 mg/g tea leaves), Teekanne: Finest Green Tea (29.7717 mg/g tea leaves), TeaZen:First Flush Pure Green Tea (30.0981 mg/g tea leaves), BOH: Green Tea (35.3733 mg/g tea leaves), Japanese Green Tea Sencha (35.7449 mg/g tea leaves). The reasons that can cause the deviation of total flavonoids are temperature on the extraction, extraction time, ratio on the extraction of flavonoids, effect of extracting agent and number of extractions (Sathishkumar, et al., 2008). Besides, environmental factors such as temperature of surrounding environment and purity of the water used for extraction also the factors that cause deviation of total flavonoids content in the tea samples. On the other hand, the current study shown that total flavonoid content ranged from 23.9273 to 71.4898 mg/serving and the average is 53.1382 mg/serving.

HPLC analysis

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Figure 4.3(a to g) shows the chromatograms of standard solutions used to identify the retention time of each of the analytes. In Table 4.3(a), the retention time for Gallic acid at 3.6401 minutes, second was Theobromine at 6.5788 minute, third was catechin at 11.3382 minute, fourth was caffeine at 12.38 minute, fifth was Epicatechin-3-gallate at 14.994 minute, sixth was Theaflavin-3-gallic at 18.9623 minute and finally was theaflavin at 18.984 minute. The peak area represents the concentration in a particular solution.

The standard linear curves obtained from concentrations of standards and peak areas at the wavelength of 280nm were shows in Figure 4.3(h to j). The concentration of each polyphenolic and methylxanthine present in each tea samples under analysis was determined by using the calibration curve of each component. Subsequently, the amounts of polyphenol, theobromine and caffeine in tea samples were analyzed to determine the amount of respective tea components per serving and per gram of tea leaves. The results are shown in Table 4.3(h to j). Theaflavin and theaflavin-3-gallate which were the main components in black tea, however, both of these components cannot be found in the tea samples that used in this study.

The ascending order of components in the tea-samples produced in Asia countries was as following: gallic acid (0.0385 mM), catechin (0.0408 mM), theobromine (0.0537 mM), E3G (0.9112 mM), caffeine (1.2518 mM). Meanwhile, the increasing order of components present in the tea-samples produced in Europe countries was as following: gallic acid (0.0548mM), theobromine (0.0554mM), catechin (0.0696mM), E3G (0.7572mM), caffeine (1.2717mM). There was no significant difference (p>0.05) between components present in green teas produced in Asia and Europe. Based on the analysis, the main component in green tea produced in Asia and Europe that used in this study was Caffeine with the average concentration of 1.2518 mM and 1.2717 mM respectively.

Table 4.3(h) shows that Ahmad Tea London: Original Green tea (0.0983 mM) produced in London (Europe) and TenRenTea: Fresh Green Tea (0.0825 mM) produced in Taiwan (Asia) possesses the largest Catechin concentration compare to other tea samples under analysis. The component of gallic acid ranged from Japanese Green Tea Sencha (0.0121 mM) to Duchy Originals from Waitrose: Organic Green Tea (0.0887 mM). Alternatively, the concentration of theobromine ranged from BOH: Green Tea (0.0917 mM) to Japanese Green Tea Sencha (0.0325 mM). Duchy Originals from Waitrose: Organic Green Tea possesses the highest concentration of Caffeine (2.3429 mM) as well as E3G (1.5930 mM) compare to other tea samples under analysis. Meanwhile, TeaZen:First Flush Pure Green Tea have lowest concentration of Caffeine (0.5304 mM), Catechin (0.0275 mM) and E3G (0.135 mM) in this study. The reasons that lead to the deviation of gallic acid, polyphenols and methylxanthines in commercial green tea were species, season, horticultural conditions and degree of fermentation in manufacturing process (Zuo, Chen and Deng 2002).

When evaluate as mg/serving, the increasing order of tea component in tea samples produced in Asia and Europe countries under analysis was not similar as the mean concentration of tea components. The increasing order of components in the tea-samples produced in Asia countries under analysis when evaluated as mg/serving was as following: Gallic acid (1.6392 mg/serving), Theobromine (2.4192 mg/serving), Catechin (3.358 mg/serving), Caffeine (60.774 mg/serving), E3G (67.714 mg/serving). Alternatively, the ascending order of components in tea-samples produced in Europe countries in this study was as following: Gallic acid (2.3321 mg/serving), Theobromine (2.4961 mg/serving), Catechin (5.3626 mg/serving), caffeine (61.743 mg/serving), E3G (86.776 mg/serving). There was no significant difference (p>0.05) between components present in green teas produced in Asia and Europe countries. In this study, E3G was the main component per serving in five out of nine tested samples produced in Asia and Europe countries. Caffeine was the major component another four tested samples.

Under this study, TeaZen: First Flush Pure Green Tea possesses the smallest amount in all the tested components per serving which were gallic acid (0.3457 mg/serving), Theobromine (1.3573 mg/serving), Caffeine (25.749 mg/serving), Catechin (2.1194 mg/serving) and E3G (15.471 mg/serving) as compare to other brands of tea. The selected green teas produced in Asia countries in this study have the highest amount of all the tea components per serving except catechin. The green tea involved was Duchy Originals from Waitrose: Organic Green Tea which has 3.7724 mg/serving for gallic acid, 113.75 mg/serving from Caffeine and 182.56 mg/serving for E3G. In addition, Boh: Green Tea has the largest amount of theobromine in a serving (4.1289 mg/serving) among the tea samples under analysis. Alternatively, Ahmad Tea London: Original Green tea has the largest amount of catechin per serving (7.5783 mg/serving). It was approximately two to three times higher than other brands of teas in this study.

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When assessed as mg/g, the increasing order of tea component in selected tea samples was similar as mg/serving. The ascending order of tea components in green tea produced in Asia countries under analysis when assessed as mg per gram tea leaves as following: Gallic acid (0.7254 mg/g tea leaves), Theobromine (1.1591 mg/g tea leaves), Catechin (1.5427 mg/g tea leaves), Caffeine (27.234 mg/g tea leaves), E3G (29.508 mg/g tea leaves). In contrast, tea-samples produced in Europe countries under analysis has lowest amount of Gallic acid at 1.2277 mg/g tea leaves, followed by Theobromine at 1.3218mg/g tea leaves, catechin at 2.7937 mg/g tea leaves, caffeine at 32.819mg/g tea leaves and E3G at 47.117 mg/g tea leaves. There was no significant difference (p>0.05) between components present in green teas produced in Asia and Europe countries. In this study, E3G was the main component for five out of nine selected tea samples. Caffeine was the major components for another four selected tea samples.

The selected green teas produced in Asia countries in this study have the lowest amount of all the tea components. The tea samples involved were TeaZen:First Flush Pure Green Tea, TenRenTea: Fresh Green Tea and Duchy Originals from Waitrose: Organic Green Tea. TeaZen:First Flush Pure Green Tea have lowest amount in three out of five tested components per gram of tea leaves. The components involved were gallic acid (0.1729 mg/g tea leaves), caffeine (12.875 mg/g tea leaves) and E3G (7.7355 mg/g tea leaves). In addition, TenRenTea: Fresh Green Tea has lowest amount of theobromine (0.6663 mg/g tea leaves) and Duchy Originals from Waitrose: Organic Green Tea has the lowest amount of catechin (0.9248 mg/g tea leaves). Alternatively, the highest amount of all tea components can found in tea-sample produced in Asia countries under analysis except catechin. It comprise of Duchy Originals from Waitrose: Organic Green Tea have greatest amount of Gallic acid (1.509 mg/g tea leaves), Caffeine (45.498 mg/g tea leaves) and E3G (73.025 mg/g tea leaves). Besides, BOH: Green Tea has the highest amount of theobromine (2.7526 mg/g tea leaves) as compare to brands of tea that used in this study. Alternatively, the amount of catechin in Ahmad Tea London: Original Green tea was almost three times more than other brands of green teas under analysis. Horzic et al. (2009) reported that the catechin content in teas fluctuate based on the tea variety, origin, season of harvest and sun exposure. In addition, Kumamotot and Sonda (1998) stated that catechin content increase with the intensive of sun exposure. This can explain that Ahmad Tea London: Original Green tea which has the largest amount of catechin when evaluate as mg/g as well as mg/serving.

Friedman et al. (2005) concluded from their researches that the extracted caffeine content was ten times more than extracted theobromine content. When evaluated as mg/serving and mg/g the ratio of extracted theobromine content to extracted caffeine amounts in this study was ranged from 0.0284 to 0.0804. Conversely, the ratio ranged from 0.0306 to 0.0866 when assessed as mean concentration. The factors contribute to the difference were the type of solvent used, temperature applied, extraction technique, environment condition and time of extraction.

According to Liang et al. (2007), caffeine was more readily diffuse and dissolves into water as compare to catechins due to its small molecule size and higher water solubility. In this study, when evaluated as mean concentration, the ratio of catechin to caffeine was ranged from 0.0128 to 0.0692. Alternatively, the ratio ranged from 0.0203 to 0.1099 when assessed as mg/g and mg/serving.

When assessed as mean concentration, the methylxanthine which consists of caffeine and theobromine ranged from 0.5605 mM to 2.4262 mM. However, it ranged from 27.1063 mg/serving to 117.5035 mg/serving when evaluated as mg/serving. In this study, the maximum and minimum amount of methylxanthine was 46.9994 mg/g tea leaves and 13.5536 mg/g tea leaves respectively. The reasons that lead to the variation of methylxanthine among the tea samples under analysis for instance climate, origin (Roberts and Barone 1983) and age of the tea leaves (Ashihara and Kubota 1986).