How Do They Make Decaf Tea?

Caffeine is a stimulant naturally occurring in tea, praised by ancient Chinese scholar Hua Tuo for "mak[ing] one think better." Some people, however, may wish to receive the health benefits or flavor of tea without excess caffeine.

Definition

Decaffeinated (decaf) tea or coffee must have 97% of the caffeine removed. This leaves about 2 to 10 mg caffeine per 8-oz. serving of black tea.

Process

Tea is decaffeinated with a solvent that dissolves the caffeine in tea leaves and is then removed. The tea is then fermented and dried as usual.

Types

The three main solvents used are methylene chloride, ethyl acetate and carbon dioxide (pressurized to form a liquid).

Concerns

Although methylene chloride is harmful when inhaled, the FDA has deemed it safe for use in decaffeination. It's possible to decaffeinate tea with water, but this extracts some of the flavor compounds as well as the caffeine.

Fun Fact

You can make your own semi-decaf tea by brewing a cup, discarding it and brewing a new one with the used tea bag and fresh water, according to a 1996 study by Hicks et al. On average, this produced a cup of black tea with about 9.4 mg caffeine (30 percent of the original caffeine).

References

• Upton Tea Imports: Tea and Caffeine
• UC Berkeley Wellness Letter: Truths about Decaf
• Science Direct: Tea Preparation and its Influence on Methylxanthine Concentration

Resources

• Mayo Clinic: Caffeine Content for Coffee, Tea, Soda and More
• Mindburp: Tea & Caffeine