Extraction Of Caffeine From Tea Waste And Its Benefits
Introduction
Tea has been a part of the beverage world for centuries. Not only because of its sensory and potential health benefits, but also because of the stimulating properties of caffeine which is a major component in the tea leaves. Caffeine acts as a stimulant for the heart, respiratory and the central nervous system, and is a vasodilator (relaxes the blood vessels) as well as a diuretic (increases urination). Caffeine, aside from the usual beverage and chocolate industries, finds widespread applications in agriculture, in avian repellency, in military, as CNS stimulant and as a diuretic. In the current timeline, there are various means by which caffeine is being extracted. It can be extracted from tea leaves, coffee and cocoa beans, guarana berries, kola nuts, the leaves of Yerba mate, in the bark of Yoco, guayusa, the yaupon holly, etc. Aside from various natural variants, synthetic caffeine has become extremely popular among the food and beverage industries. It even extends as far as water, gum and personal hygiene products. But the main method of extraction of caffeine is from tea leaves and coffee beans. The extraction from tea leaves can particularly be a difficult task. This is because caffeine does not occur alone in tea leaves, but is accompanied by other natural substances like cellulose, tannins, flavonoid pigments and chlorophyll. Separation of these substances from each other can prove to be a costly affair due to the various chemicals and sophisticated apparatus used.
According to new and ongoing researches, the waste tea or the residue left behind after the preparation of the tea can be used to recover a significant amount of caffeine. Tea waste can include discarded tea leaves, buds, tender stems of tea plants, etc. Instead of improper disposal of the tea waste, it can be efficiently used for the recovery of residual caffeine.
Method of extraction
The extraction of caffeine is carried out in a multi-stage counter-current extraction process which can be broadly divided into three stages. The three stages are:
- Pre-treatment section
- Extraction section
- Post-treatment section.
Pre-treatment section
The tea waste is first collected, shade dried, powdered, and stored in well closed, air-tight containers. The tea waste in mixed with lime and water in a pre-fixed ration which always remains constant. The prepared mixture is the cooked at higher temperatures in a device called cooker-cum-mixer. The tea waste’s tissues loosen by this process which helps in the efficient extraction of caffeine in the extractor.
Extraction section
Here, a solvent is used for the extraction of caffeine for the tea waste mixture. After extraction, the solvent is subsequently recovered and recycled back into the system. The addition of solvent is done to produce crude caffeine. Continuous mode is preferred to batch operation for carrying out the entire operation. To maintain the continuity of the reactor system, a continuous feed of the waste is supplied to the reactor. The waste comes in contact with the solvent in a counter-current mechanism inside the extractor, leading to extraction of caffeine in a stage wise manner. The caffeine is extracted from the mixture of tea waste, lime and water and stored inside a balancing tank in the form of crude caffeine. During storage, the solvent is removed from the crude product by the process of evaporation. Water is separated from the recovered solvent in a solvent-water separator after which the solvent is recycled back into the extractor. The crude product is subjected to further treatment to obtain pure caffeine.
The decaffeinated tea waste residue is transferred to a desolventizer where the entrapped solvent present in the tea waste is removed by heating. The recovered solvent is again recycled back into the extractor.
Post-treatment Section
In the last step, crude caffeine obtained from extraction section which is kept in the storage tank is processed further in order to obtain the final purified caffeine. Here, in this section, crude caffeine is firstly made to dissolve in hot water to separate it from wax. After that, the remaining coloured solution which contains caffeine is treated with activated charcoal and filtered. The activated charcoal being capable of absorbing all impurities absorbs all the impurities and color. The decolorized caffeine solution left behind is then concentrated by means of evaporation and allowed to crystallize. Caffeine crystals are then separated from mother liquor by centrifuging. By centrifuge the small crystals of caffeine tends to agglomerate and thus caffeine is obtained. The caffeine thus obtained is dried further in a drier and pulverized to convert it into powder form before its packing.
Natural and synthetic caffeine
While natural caffeine is obtained from plants often meant to be used in food and beverages, synthetic caffeine is produced in laboratories and manufactured in factories. Synthetic caffeine is made by a chemical synthesis of urea as the raw material and can also be exposed to a number of harsh chemicals including: methylene chloride, ethyl acetate and carbon dioxide.
Synthetic caffeine absorbs through the digestive system much faster than the naturally occurring plant caffeine, causing a quicker spike and a quicker crash unlike the naturally obtained caffeine which provides a more balanced lift due to presence of high level of naturally occurring vitamins that prevent the caffeine crash.
Short-term and long-term effects of caffeine
Caffeine acts as an “antagonist” molecule binding to adenosine receptors on cell surfaces without activating them; acting as a competitive inhibitor for adenosine. Since the molecules are bound to adenosine receptors, the adenosine is blocked from attaching to them and cannot cause the typical response of sleepiness. Caffeine’s status as an antagonist molecule means that the receptor does not do its usual job of causing drowsiness. In fact, caffeine binding to adenosine receptors causes the opposite effect: nerve cell activity speeds up, and brain blood vessels constrict. Thus, consuming caffeine prevents the brain from taking the usual steps to make us tired.
Caffeine binds to adenosine receptors, making the neurons fire more. The pituitary gland of the brain, which regulates the release of many hormones, takes this increase in activity as a signal to release hormones to produce adrenaline, or epinephrine. This adrenaline release leads to other common effects associated with caffeine, such as the heart beating faster or feeling excited.
Caffeine blocking adenosine receptors causes an increase in the activity of the neurotransmitter dopamine. Dopamine, commonly known for its role in pleasure, when released, makes humans feel good and stimulate us to do those pleasurable things again. Dopamine is also linked to focus, attention, and movement.
Too much caffeine can have long-term negative effects. These can include anxiety, increased vasodilation, high blood pressure, and decreased fine motor function. It is also linked to infertility, irregular bowel movements, and heartburn. Since caffeine is linked to increased urination, it can result in long-term dehydration, which will decrease the function of major organs. Insomnia is also a common result of consistent caffeine intake. The symptoms of depression are heightened by caffeine intake. The changes in energy levels while drinking coffee throughout the day can affect mood, which may artificially increase depressive symptoms. Both withdrawal symptoms and overstimulation of the nervous system can lead to headaches, one of the most common complaints of long-term coffee intake.
Conclusion
Although caffeine from tea waste is negligible, but regarding, to the importance of caffeine in the cosmetics industry, healthcare and pharmaceuticals, it is quite conceivable that tea waste can be replaced to fresh tea for caffeine extractions. Extraction of caffeine from tea waste is an environmentally safe practice which leads to the caffeine generation as well as waste management and minimization. It also accounts for the production of natural caffeine which is a much safer and healthier option when compared to synthetically produced caffeine.
