Pink Kashmiri TeaFriday, August 20, 2010
Green tea turning yellow, and eventually brown, is understandable -- but pink?
Most of the recipes for Kashmiri tea include four things that might account for the color change: Saffron, baking soda, cooking time and aeration.
Saffron is colored orange yellow by the pigment crocin. Crocin is one of the carotenoid pigments (which provide the color of many foods from tomatoes to salmon, and range from orange to red to pink).
Baking soda often causes color changes in foods -- but usually only in foods that contain anthocyanin pigments. Litmus paper is a perfect example: it's blue in the presence of alkaline substances (like baking soda) and red in the presence of acids (like lemon juice). It would appear that that's not an issue in Kashmiri tea -- except for an odd effect that I'll get back to.
Cooking time may be significant, because it would extract as much pigment as possible. Many recipes describe a reddish film that forms on the top of the tea as it cooks -- which would tend to reinforce the notion that the saffron is significant (carotenoids are quite fat-soluble, and fat would accumulate at the top of the brew).
Most of the recipes include much aeration -- either through lost stirring or by pouring the brew from one container to another. This may be causing some oxidation of the pigments. Carotenoids are anti-oxidants that work by absorbing light from the blue-violet end of the spectrum (the damaging high-energy short wavelengths) thus reflecting the longer, low-energy red wavelengths -- so that's the color we see.
Anthocyanins were mentioned earlier, because there is another possibility to be examined:
When certain compounds present in the tea leaves are cooked for long periods, some precursors of anthocyanins are produced. They are molecular fragments of the phenolic compounds that we lump together as "tannins" (they provide the dry, slightly puckering mouthfeel of tea). When these fragments, in turn, react with oxygen, actual anthocyanin pigments are formed. It would be interesting to try the recipe without the baking soda, to see if the red color is enhanced when the chemical environment is more acidic.
There are a lot of arguments about this issue -- without real resolution -- so I'm only providing some of the possibilities. Take your pick!