Explore the chemistry behind caffeine in tea
Caffeine in tea is a complex interplay of chemistry, environment, and processing methods. In this blog we delve into its chemistry, presence in various tea types, and how it differs from the caffeine in coffee. We will also tap into the origins of caffeine and will look at the chemistry – but we will keep that part as short as possible, promised!
What is caffeine?
Caffeine is a natural stimulant found in various plants, including coffee beans, tea leaves and cacao beans. Chemically it is classed as an alkaloid and it belongs to the methylxanthines. Interestingly, it is actually part of the natural defence mechanism of the tea plant.
When consumed, caffeine has several effects on the body, with the stimulating effects on the nervous system, heart and lungs most commonly known.
The Origins of Caffeine
The discovery of caffeine can be traced back to the early 19th century when a German physician exploring coffee identified a similar compound in tea eight years later, initially labelled as “theine.” Eventually, research confirmed the identical nature of caffeine in both beverages, leading to the universal term ‘caffeine’ for this stimulating molecule.
Caffeine in Tea vs. Coffee
Tea, on average, contains 2.5 to 3.5 % caffeine per mg, whereas coffee ranges from 1% to 1.7 %. A typical cup of tea (brewed with 3 g of tea leaves) contains on average 26 mg of caffeine, while the 94 mg found in an equivalent cup of coffee (brewed with 8.3 g of coffee). This establishes that while tea contains more caffeine overall, the personal intake might be lower compared to coffee.
What makes caffeine in tea different?
The caffeine journey through tea and coffee offers nuanced insights into their physiological effects. Tea, thanks to L-Theanine, an essential amino acid, elicits a distinctive response compared to coffee. L-Theanine influences neurotransmitters, enhancing mental focus and cognitive performance while fostering a positive mood boost. In tea, caffeine collaborates with built-in relaxants and antioxidants, such as EGCG and L-Theanine, delivering a harmonious energy boost with relaxing health benefits.
Unlike coffee, where caffeine molecules are more freely available, tea’s bonded caffeine requires the body to break these bonds for absorption, resulting in a slower, sustained impact.
The processing methods further contribute to variations; black tea’s robust processing accelerates absorption, offering a quicker boost, while green tea’s gentler process results in a delayed, prolonged effect.
The infusion method, involving water temperature and steeping time, adds another layer of complexity to caffeine concentration. In essence, the intricacies of tea provide a gentler, yet potent, mental energy experience compared to the immediate kick and potential jitters from coffee.
Tea Types and Caffeine Levels
Black tea, crafted by full-oxidation, tends to have the highest caffeine levels, as it steeps at high temperatures. Oolong, green, and white teas follow in descending order, with slightly lower caffeine content due to variations in harvesting, processing and steeping times and temperatures.
Herbal tisanes, made from botanicals other than Camellia sinensis, are caffeine-free. For those seeking an energy boost, matcha, made from powdered green tea leaves, can offer the most caffeine since instead of just infusion, we get to consume the leaf itself.
With the accepted daily caffeine limit of 400 mg, tea enthusiasts can enjoy multiple cups without concern. While we established that the oxidation of the tea is generally not an indicator of how much caffeine we will intake, here are some rough averages:
- Black Tea: typically 30-40 mg/cup, sometimes up to 65 mg/cup
- Green Tea: typically 10-40 mg/cup, sometimes up to 50
- Oolong Tea: typically 18-20 mg/cup, sometimes up to 40
- White tea: the most variable! Anywhere from 5-65 mg/cup
- Coffee: typically 85-100 mg/cup
- Matcha: typically 70-120 mg/cup
Understanding Other Factors Influencing Caffeine Levels in Tea
Contrary to popular belief which we just discussed, the six main types of tea (green, black, white, oolong, yellow, and dark) do not inherently determine the caffeine content. Instead, several factors contribute to the caffeine levels in tea:
- Natural Environment: Soil quality, sunlight exposure, moisture, altitude, and shading influence the composition of substances in tea leaves, affecting caffeine levels.
- Fertilisation: Artificial fertilisation enhances plant development, resulting in higher caffeine levels in fertilised tea compared to naturally grown varieties.
- Picked Parts of the Plant: Different parts of the tea tree contain varying caffeine levels. Buds, often believed to have lower caffeine, can be more caffeinated than mature leaves.
- Seasonality: The season of harvest influences caffeine content, with some theories suggesting higher caffeine levels in spring compared to summer and autumn harvests.
- Brewing Time: Caffeine is highly soluble in water, so longer steeping times increase the caffeine concentration in the tea. Brewing techniques, such as cold brewing, alter the caffeine content and extract sweet compounds over bitter and astringent ones, hence, making a less caffeinated infusion due to the lower temperatures.
Conclusion
Caffeine is actually a naturally occurring substance in plants such as coffee beans and tea leaves. So yes, tea does contain caffeine, but the dosage per cup is generally a lot lower than in coffee. Also, the interaction with other components in a tea brew make the absorption slower and the effects more gentle.
Different tea varieties have different amounts of caffeine and that’s not necessarily the result of the production method. Things like how the plants are grown, which parts of the plants are used and the brewing time play an important role.
