I come from a country which is very aware of the importance of spring water. The Scottish whisky industry has grown up along side the burns and springs of the countryside and the difference that it makes is instantly clear in the product. Without varying the production method much at all a single malt whisky from Islay, where the water has it’s own distinct peaty character, is immediately recognisable and could never be confused with a dram produced from the clear water of the highlands.
This huge impact from something as simple as the type of water is supposed to hold true for tea as well. A lot has been written about the type of water that is used to create the perfect cup and even about the ruinous effects that the wrong brewing liquid can have on high quality leaves. This is usually put down to the effect that minerals in the water can have on the flavour profile of the tea but it is rarely explained or backed up scientifically. Forever a scientist at heart, I thought I’d investigate to see how much we really need to worry about what’s in our kettles.
As it turns out mineral composition really can affect how the tea infuses. A study in the journal Food Chemistry has shown that the levels of calcium in the water can determine how much of the organic matter present in the tea leaves make it in to the infusion and how the caffeine and polyphenols it contains interact. Higher levels of calcium inhibited extraction of organic matter, caffeine and polyphenols. The specific effects this has on the flavour of the tea were not discussed so whilst the study shows that water mineral composition can have an effect it also showed that scientists often miss the point! It does suggest though that if you live in a hard water area it could be worth switching to bottled water for your tea to prevent too much calcium from interfering with your brew.
The pH of the water is also important with any alkalinity causing polyphenols to oxidise. This is slightly more worrying if you’re drinking anything but black tea as the levels of oxidation are carefully managed and are an integral part of making the tea taste as it should. If you are going to use mineral water and are concerned about this be sure to check the pH as anything much higher than 7.5 could cause oxidation.
So it seems there really is more to the water quality debate than tradition and personal preference and yet another element to be added to the quest for the perfect cup of tea. Watch this space for more findings as and when they emerge.
Reference: Couzinet-Moisson, A. et. al. – Interaction mechanisms between caffeine and polyphenols in infusions of Camellia sinensis leaves. Food Chemistry 119(1):173-181
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