“The thearubigins in brewed tea are highly coloured (red-brown) molecules that change according to the acidity of the liquid used. If the water used for the te

“The thearubigins in brewed tea are highly coloured (red-brown) molecules that change according to the acidity of the liquid used. If the water used for the tea infusion is relatively alkaline (for example, due to limescale found in “hard” water), the colour of the tea will be darker and deeper. However, once an acid such as a slice of lemon or lemon juice is added, tea changes colour because of an increase in acidity (reduction in pH) of the beverage itself. Lemon juice is quite strong as a food acid – a few drops are enough to alter the theaurbigins, resulting in a dramatic change in colour. Interestingly, theaflavins are not that affected by the change in acidity, and still retain their normal dark red colour.” Source: https://theconversation.com/ive-always-wondered-why-does-lemon-juice-lighten-the-colour-of-tea-91324 https://theconversation.com/ive-always-wondered-why-does-lem...