Methods to extract caffeine from tea

Caffeine is an alkaloid present in many foods. Its properties are well known: for example, it stimulates the central nervous system of the human organism and also works as a cardiac stimulant. It is similar to theobromine present in cocoa and theophylline also present in coffee. Caffeine in particular is found primarily in coffee, tea, and the kola nut.

Extract caffeine for home consumption

This is a fairly basic process at home, although there are people who, due to their religion or strict eating habits, avoid caffeine consumption and probably do not know how to extract caffeine from any solid. In any case, it is very easy to get used to and repeat it every day in the morning.

To extract caffeine from tea leaves, for example, you will need:

• At least a gram or two of dried or prepared leaves of the tea plant for use as an infusion. This for each cup of infusion you require. It doesn’t matter if the leaves are packed in teabags or loose. The important thing is that they are dry just before use.
• A specially heated liquid for infusion (the most common is water, but hot milk and other similar opaque liquids of vegetable origin, such as soy milk, almond milk, rice milk, coconut milk or oat milk, are also common) ).
• Depending on the type of tea, you will need to heat the liquid to a different temperature.
• If it is not a pasteurized or pre-boiled liquid at 100°C, please boil it first for food safety. Milks of animal origin tend to increase sharply in volume shortly after boiling. Make sure you haven’t poured too much liquid into the pot and remove it from the heat as soon as it starts to boil to avoid dangerous spillovers in your kitchen.
• Allow the liquid to steep for a few minutes before adding the tea to cool down to the manufacturer’s recommended temperature. Otherwise, the tea may end up too bitter or have an off-flavor. As a general rule, black tea tends to require higher temperatures than green tea.
• A kitchen thermometer can help you determine if the liquid is cold enough for the type of tea you are using.
• In many countries it is customary to leave the tea steeping in the liquid for at least three minutes. Depending on the type of tea and its caffeine concentration, after that time it can become too bitter and may not taste very pleasant.
• Repeat this process several times to get the strength of tea that you like best. Remember that caffeine tastes bitter, so the more bitter your tea is, the more caffeine it will have.

extract caffeine in the laboratory

One way to extract caffeine from tea in a laboratory is to brew it where the water vapor (the reagent) is not lost through evaporation.

Some safety recommendations before continuing:

Remember to wear safety glasses and a gown to prevent any material or reagent from damaging your clothing or skin. Gloves to protect your hands from the heat do not hurt either. It will handle hot liquids and some volatile compounds that can be irritating or burn your skin. It is also ideal if the space you use for preparation has an exhaust fan or hood, some vapors could be toxic if inhaled. You can never be too careful!

You will need:

• -Round bottom flask.
• -Refrigerant tube.
• -Reduced pressure filtration system.
• -Separation funnel
• -Anhydrous sodium sulfate (one tablespoon)
• -Rotavapor
• -Laboratory clamp to hold the flask and the refrigerant tube.
• -Enough water for the infusion.
• -Enough tea leaves

Preparation:

• A boiling round-bottomed flask is used with the water and tea solids.

The obtained solution is then placed in a filtration system under reduced pressure.

• The infusion with sufficient dichloromethane is placed in a separatory funnel and the extract is decanted off by shaking the separatory funnel (letting the dichloromethane vapors escape every few moments because of the volatility of the dichloromethane). After each extraction, the infusion is decanted again and can be repeated twice. There is an intermediate phase of this process in which an emulsion is formed between the aqueous phase (tea infusion) and the organic phase (caffeine extract with dichloromethane) Collect the emulsion that remains from the organic phase because it will later be dehydrated with anhydrous sodium (one tablespoon). The organic phase will become completely transparent, indicating that it is completely dehydrated.
• The organic phase is separated to the rotary evaporator flask. The rotary evaporator will separate the caffeine extract from the dichloromethane. Dichloromethane can be used for other things and we already have our caffeine extract in the laboratory.

References

Nine Valleys (s/f). Extraction of caffeine from coffee. Available at: http://palmera.pntic.mec.es/~atola/Laboratorio/Practicas%203_%20ESO/EXTRACCION%20DE%20CAFEINA%20DEL%20CAFE.pdf

Polytechnic University of Valencia (2013). Extraction of caffeine from tea | | UPV. Available at: https://youtu.be/eD0x11yt6S4