According to Professor Michelle Francl, making a great cup of tea is more than just boiling water and adding a teabag.
As winter tightens its grip on South Africa, there’s nothing more comforting than a hot cup of tea.
However, according to Michelle Francl, a chemistry professor and author of Steeped: The Chemistry of Tea, making a great brew is more than just boiling water and adding a teabag. It’s a chemical process that can be fine-tuned for flavour, aroma, colour, and health benefits.
“Tea is the world’s most popular beverage, but few people realise just how complex its chemistry really is,” she said.
Francl explains that tea contains hundreds of compounds that affect its taste and aroma. Steeping time, water temperature, and even the type of water used can all influence the chemical make-up of your brew.
“The longer you let anything steep, the more compounds will be extracted. Lighter, more water-soluble molecules come out first. Over time, larger polyphenols are drawn into the infusion, building a more complex flavour, but also increasing astringency,” she says.
She notes that for black and green teas, getting the timing right is essential to balancing flavour and mouthfeel.
“Water temperature also plays a role. Lower temperatures preserve delicate compounds, while boiling water helps extract more antioxidants in certain herbal teas.”
While Francl’s book explores teas made from the Camellia sinensis plant – including black, green, white, and oolong teas – she also shares insights into South Africa’s beloved Rooibos, which comes from a different plant altogether (Aspalathus linearis).
She adds that while most people reach for red Rooibos, the green, unfermented version has higher antioxidant levels.
“Fermented Rooibos has fewer antioxidants because the fermentation process is essentially an oxidation process. Antioxidants act like little sponges, soaking up oxygen. Once they’ve reacted, they can’t function as antioxidants anymore.”
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Brewing the perfect cup of tea
- Use boiling water (100°C): This is especially important for black and Rooibos teas, which benefit from high temperatures to release their full flavour and antioxidant content.
- Steep for 10 minutes: A longer steep ensures more compounds are extracted, resulting in a richer, fuller taste.
- Choose fresh leaves when possible: Loose-leaf tea offers better quality and flavour than many commercial teabags.
- Use filtered water: Minerals in tap water can interfere with the tea’s delicate chemistry and alter the taste.
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