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Caffeine and Polyphenol Contents in Tea of Bangladesh and Its Nutritional Efficacy

M. Alamgir Choudhury
Biochemistry Division, Bangladesh Tea Research Institute, Srimangal; Moulvibazar

Abstract/ Executive Summary:

Among the constituents of tea, caffeine and polyphenol are the most significant, which make the best beverage. Tea contains 1-5% of caffeine and 15% of soluble polyphenols. The range of caffeine content in Bangladesh tea is 3.3 to 4.75% and that of polyphenol is 22 to 31 %. The caffeine composition of Bangladesh tea is above average but the polyphenol content is much higher than that of the most other countries.

Keywords: Tea, Polyphenol, Caffeine

Location: Srimangal, Moulvibazar

Start Date:

End Date:

Program Area: Quality and Nutrition

Commodity: Tea

Objectives:

To study the polyphenol and caffeine content in tea on free moisture basis

Methodology:

Tea of green leaves of different agrotypes and clones was manufactured separately in the miniature factory and a tea sample was collected from factory of large scale production. Estimation of theaflavin : 4.8 gm of black tea was extracted for eight minutes with 200 ml of boiling water in a 500 ml of vacuum flask with constant shaking. The mixture was filterred quickly through a cotton plugged funnel and under running tap water for cooling immediately. After cooling 10 ml of extract with 10 ml of isobutyl methyl ketone (IBMK) was shaken for 15 minutes and kept for some times to get the two layer's separation. Two ml of the IBMK extract of upper layer, 4 ml of ethanol and 2 ml of 2% ethanolic flavognost solution were added. After standing for 15 minutes the extinction of the extract was determined in a spectrophotometer at 625 mm. The concentration of theaflavin was calculated using the factor obtained by Hilton (Hilton 1972, Molla 1984). Determination of polyphenols : 100 mg of powdered tea sample was boiled in a water bath with 100 ml of water for 30 minutes and filtered. 0.2 ml of the sample solution and 5 ml of the regent (100 mg of FeS0₄ . 7H₂0 and 500 mg of Rochelle salt in 100 ml of water) were taken in a 25 ml volumetric flask and filled to the mark with Sorensen's phosphate buffer of pH 7.5. Then the absorbance was measured at 540 nm against a blank solution substituting water for the reagent and the amount of polyphenol was determined from the calibration curve (Molla 1984). Determination of caffeine : 5 gm of the oven-dry sample was taken in a weighed one liter Erlenmeyer flask. About 500 ml of water was added, swirled and heated to boiling. 10 gm of MgO was added and boiled gently over a low flame for 2 hours with occasional shaking. Water was added to prevent frothing and to wash down the sides of the flask and cooled. The extract was made to mass with water (tare mass + 510 gm + mass of the sample). It was filterred and 200 ml of clear filtrate (equivalent to 0.4 of the mass of the sample) was collected with 20 ml of H₂S0₄ (1 + 9 ml of water) and transferred to a 500 ml separator. It was shaken four times with chloroform, using 25,20, 15 and 10 ml portions. The combined extract was treated with 5 ml of 1 per cent potassium hydroxide solution, when the liquid was separated completely drained the chloroform layer into a kjeldahl flask. The alkaline solution into the separator was washed with two 10 ml portions of chloroform and combined the washing with the remaining bulk of the extract. It was evaporated or distilled the chloroform to complete dryness and weighed the dry caffeine (Institute, 1975).

Source of Information: Bangladesh J . Sci. Res. 11(1): 17-20, 1993 (June

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The caffeine content of tea of Bangladesh is above average but the polyphenols composition are higher than the other countries. Although no physiological disturbance should be observed in 5-6 cups of daily consumption of the Bangladesh tea, yet the nutritional and pharmacological effectiveness of the aforesaid constituents of tea for the people of Bangladesh will be accomplished by the Bangladesh Tea Research Institute, in collaboration with the Institute of Nutrition and Food Science, University of Dhaka, as soon as feasible

Knowledge Management: Journal