Why Purple Beans turn green when cooked?

[canadian-gardening]

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Purple beans contain pigments called anthocyanins.
Bean pods also contain chlorophyll, the green pigment used in photosynthesis. In purple beans, the anthocyanins mask much of the chlorophyll, so the pods appear purple.
When you cook them:

1.Heat breaks down the anthocyanins.
2.Some of the pigments leach into the cooking water.
3.The chlorophyll remains much more visible.
4.The beans turn green.

These are the same water-soluble pigments that give color to:
Red cabbage
Blueberries
Purple grapes
Eggplants
Purple carrots

Anthocyanins are very sensitive to:
Temperature
Acidity (pH)
Alkalinity
Oxygen

And that's what ChatGPT says about purple beans.
Link to Growing Food / Vegetables:
https://canadian-gardening.ca/growing-food/vegetables/
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