[Stephan]

Hello all, this is my first post here.  I have a question regarding a colour change I observed in my tea this morning.  I had a little bit of sodium sulfite left over from doing some lead testing on various items around the house; having exhausted all my current testing requirements I thought I might humor myself and test some tea.  I prepared two conical vials and filled each with equal amounts of the tea (honeybush) and added the remaining sodium sulfite. To my astonishment, and horror, there actually was a noticeable colour change.  Now before I start worrying about having elevated lead exposure I need to eliminate any other possibilities.  Here are some things you should know: The loose tea was stored in a glass jar.  To steep the tea I just boiled some water in a stainless pot and used my borosilicate mug with borosilicate infuser.  Those were the only things the tea came into contact with prior to the test.  Also the sodium sulfite was a little cloudy and had some crystallization happening prior to testing, I am not sure if this could influence the outcome. 

I intend to get another test and see if I get a similar reaction with other teas or vinegar left in the stainless pot, any ideas as to what might have caused this reaction would be much appreciated!

Thanks!   

[Borek]

My first idea: tea color depends on pH, sodium sulfite solutions tend to be slightly basic.

Tea color depends on many factors, like water pH and hardness, I don't find it surprising that presence of a salt of weak acid with reducing capabilities changes the color. Actually now that I think about, I would be rather surprised if the color would not change.

[Corribus]

Sodium sulfite test works by reacting with lead to form lead sulfide, a black residue that is pretty insoluble in water.  So my first question would be - did it turn the tea black, or some other color?

Second, the primary pigments in tea are polyphenols and carotenoids, which are easy to reduce/oxidize.  (Hence many of the "antioxidant" health claims of tea.)  As Borek mentions, addition of even a weak reducing or oxidizing agent would be expected to change the color of tea. 

Which is why I asked for the actual color change.