Caffeine, Decaffeinated Or Caffeine-Free?
My rule of thumb is coffee before one o’clock and tea after, a self-imposed regime to reduce the impact of caffeine on my body. Caffeine blocks a chemical in the brain called adenosine which normally makes you feel sleepy, giving the pleasant high of being alert and energetic. Of course, it is all delusional as tea also contains caffeine, the leaves containing more caffeine by weight than coffee beans. However, because coffee is brewed at higher temperatures and with a higher concentration of solids, there is more caffeine in the drink.
Typically, black tea has more caffeine than other types of tea. After harvesting black tea leaves undergo full oxidation, a process that darkens the leaves and enhances their flavour profile. It also breaks down cellular structures in the leaves, making caffeine more soluble and easier to extract during brewing. Often brewed at higher temperatures and for longer durations further increasing caffeine extraction in black tea compared with less oxidized teas like green or white tea.
Other factors influencing caffeine levels in black tea include leaf size (smaller leaves release caffeine faster), and growing conditions such as altitude and soil composition. While black tea generally contains more caffeine, variations can occur based on specific blends, brewing methods, and environmental factors.
Other factors that influence the caffeine level of teas include the physical size and processing that tea leaves have undergone. Broken or crushed leaves, which are typically used in tea bags, have a larger surface area exposed to water, leading to faster and higher caffeine extraction compared to whole leaves.
Obviously, the amount of tea used can affect the caffeine levels as does brewing time. Longer brewing times extract more caffeine, with up to 92% extracted within ten minutes, although they also increade the bitterness of the drink. Water temperature also has an effect, brewing at almost boiling point can extract almost all the available caffeine in a matter of minutes whereas cooler water slows the process.
Decaffeinated tea is tea which has caffeine present in its leaves but which has been subjected to a process that removes as much caffeine as possible. Manufacturers typically do this by using one of four solvents, methylene chloride, ethyl acetate, carbon dioxide, or water. The important point to remember, though, that irrespective of the process used, the leaves will still have traces of caffeine in them.
Caffeine-free tea is another kettle of boiling water as teas such as mint, rooibos, chamomile, hibiscus, and ginger tea are made from herbs and flowers which are caffeine-free and do not have to go through a decaffeination process. Technically, they are tisanes and not teas at all.
So if you want to drink tea, whether caffeinated or decaffeinated, you will be ingesting some level of caffeine, otherwise you should drink herbal teas which are caffeine-free but not teas.
All clear?
