I microwave water in order to make tea. After it is microwaved and I drop the tea bag(green tea) into the water, thick white foam builds up on the top.
What is it and should I worry about drinking it?
When you boil water in a cup in a microwave, it will often boil without forming bubbles, because unlike a kettle with a rough heating element or inner surface, a clean ceramic cup has few nucleation points. Nucleation points allow pockets of gas to form, which become bubbles as the water boils.
When you add the teabag to the hot water, you are essentially introducing thousands of nucleation points very quickly, and so lots bubbles form very quickly - your foam. You should exercise caution when heating water this way prior to adding a teabag, as if you heat it for too long it can superheat, and will boil explosively out of the mug when you add the teabag.
This may not be direct answer to your question about what the foam is made up of. But when it forms and how to avoid it.
This often happens if the water is not warm enough.
If you like to avoid it, you can try these steps:
The "white" foam is caused by denatured proteins in the tea leaves when heated. Same when you boil meat, eggs or fish.
protected by Community♦ Mar 4 '13 at 14:14
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