Extraction of Caffeine from Thea sinensis
Extraction of Caffeine from Thea sinensis main objective is to isolate, purify characterized caffeine from tea leaves. Sublimation technique was used to get the % yield which is 0.07%. The melting point of the standard caffeine with the sublimate is 229°C.
The active ingredient that makes tea and coffee valuable to humans is caffeine. Caffeine is an alkaloid; a class of naturally occurring compounds containing nitrogen and having the properties of an organic amine base.
Caffeine is a naturally occurring alkaloid found in over 60 plant species. Caffeine belongs to a family of naturally occurring compounds known as xanthines. The xanthines, which come from plants, are possibly the oldest known stimulants. Caffeine is the most powerful xanthine in its ability to increase alertness, put off sleep and to increase ones capacity for thinking.
Caffeine is a vasodilator (relaxes the blood vessels) as well as a diuretic (increases urination). Caffeine does not exist alone in tealeaves; the leaves are mainly cellulose, pigments and chlorophylls, and tannins. Tannins are phenolic compounds of high molecular weight that have certain properties in common.
Some of the better-known plant sources are coffee and cocoa beans, tealeaves, and kola nuts. While coffee and tea are both popular products containing caffeine, the amounts vary widely in a single serving. To further confuse the matter, coffee beans contain less caffeine than tea leaves when measured dry. However, a serving of coffee contains roughly twice the caffeine of tea. Much of the flavor of coffee and tea comes from tannins and other flavoring agents.
Caffeine has a slightly bitter flavor. As a result, decaffeinating coffee beans and tea leaves will leave the flavor slightly changed even if no other compounds are lost. Beverage Caffeine (mg)/cup Coffee 80 – 125; Coffee, decaffeinated 2 - 4;Tea 30 – 75; Chocolate milk/cocoa 3 – 30; Soft drink 20 – 50
Several health concerns have been raised over the consumption of caffeine. The Food and Drug Administration (FDA) has extensively studied the consumption of caffeine and its health effects. In 1987 the FDA concluded that normal caffeine consumption does not increase risk to health. These studies included cancer risk, coronary heart disease, osteoporosis, reproductive function, birth defects, and behavior of children.
Many consumers prefer to avoid caffeine partially or altogether due to its stimulant effects and others still have health concerns. This makes decaffeinating coffee and tea an important industrial process. Decaffeination is also significant for the world’s economy; approximately eight billion pounds of coffee are grown a year making it second only to oil as an international commodity. It should be noted that decaffeinated coffee and tea are not caffeine free. These products can be labeled decaffeinated as long as 97% of the caffeine has been removed.
Results and Discussion
For isolation of bioactive molecules found in the tea bags, two extraction set-ups were used; the solid-solid extraction and liquid-liquid extraction. 250 ml beaker with 100 ml water
3 tea bags
Figure 1 Solid-Liquid Extraction Set-up
Figure 2 Liquid- Liquid Extraction Set-ups
The sample Thea sinensis (tea leaves) weighs 6.4448 g. The dry tea leaves were extracted (Figure 1). The water extract was transferred into the separatory flask with CH2Cl2. The purpose of dichloromethane is to remove all impurities that the mixture is dissolved in a suitable solvent such as poured into a separatory funnel (Figure 2). An aqueous solution of the acid or base is added, and the pH of the aqueous phase is adjusted to bring the compound of interest into its required form. After shaking and allowing for phase separation, the phase containing the compound of interest is...
References:  (n.d.). Retrieved July 13, 2011, from http://spot.pcc.edu/~chandy/241/CaffeineExtractionCH2CCl2.pdf
 (n.d.). Retrieved July 13, 2011, from http://en.wikipedia.org/wiki/Caffeine
Murray, S. D., & Hansen, P. J. (1995). The Extraction of Caffeine from Tea. Journal of Chemical Education , 851-852.
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