Caffeine is an alkaloid found naturally in the fruits, seeds or leaves of more than 60 plants. For example, 263 mg / l in tea, 530-600 mg / l in coffee, 30-210 mg / l in cola drinks, and 110-710 mg / l in chocolate contain caffeine.

Almost half of the world's caffeine production comes from natural sources. In other words, it is obtained from coffee production and tea waste. The other half is obtained by various synthetic methods. Nearly 70 percent of the caffeine produced is used in cola drinks. The remaining part is used in the pharmaceutical sector.

According to the Turkish Food Codex Communiqué on Black Tea (Communiqué no: 2015 / 30), the amount of caffeine contained in the dry substance of tea should be at least 1,6 in black tea or percolating bag.

According to the Turkish Food Codex Communiqué on Coffee and Coffee Extracts (Communiqué no: 2016 / 7), caffeine must be at least 1 by weight based on dry matter in ground dry coffee. In the coffee extract, soluble coffee extract or soluble coffee, caffeine should be between 2,5-5,4 by weight in the coffee-based dry matter.

Caffeine is determined by spectrophotometric method in authorized laboratories within the scope of chemical analyzes. This method is based on the measurement of the electromagnetic radiation waves absorbed or emitted when atoms, molecules or ions pass from one energy level to another. In the determination of caffeine, a number of standards are considered in addition to the provisions of the communiqué described above:

• TS 8129 Coffee - Determination of caffeine - Reference method
• TS ISO 20481 Coffee and coffee products - Determination of caffeine content using high performance liquid chromatography (HPLC) - Reference method
• TS 4600 ISO 3720 Black tea - Recipe and key features

This standard describes the parts of the plant suitable for the production of black tea consumed as a beverage and the chemical properties to determine whether the correct method is applied in the production of tea. This standard does not apply to decaffeinated black teas.