# Why does the water turn green when cooking jerusalem artichokes? **URL:** \ **Category:** Factual Questions\ **Created:** [March 11, 2012, 7:51am UTC](https://boards.straightdope.com/t/why-does-the-water-turn-green-when-cooking-jerusalem-artichokes/615450 "2012-03-11T07:51:56Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Blue\_Mood](https://avatars.discourse-cdn.com/v4/letter/b/ac91a4/32.png) [@Blue\_Mood](https://boards.straightdope.com/u/Blue_Mood)\ **Post date:** [March 11, 2012, 7:51am UTC](https://boards.straightdope.com/t/why-does-the-water-turn-green-when-cooking-jerusalem-artichokes/615450/1 "2012-03-11T07:51:56Z")
I steamed jerusalem artichokes (sunchokes) in a stainless steel steamer, and the water in the bottom was a lovely emerald green afterwards! A quick google showed this happening to others, but no explanation as to why. Any takers? ---
**Author:** ![The\_Niply\_Elder](https://avatars.discourse-cdn.com/v4/letter/t/8e8cbc/32.png) [@The\_Niply\_Elder](https://boards.straightdope.com/u/The_Niply_Elder)\ **Post date:** [March 11, 2012, 8:57am UTC](https://boards.straightdope.com/t/why-does-the-water-turn-green-when-cooking-jerusalem-artichokes/615450/2 "2012-03-11T08:57:26Z")
Chlorophyll ---
**Author:** ![psychonaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/psychonaut/32/4655_2.png) [@psychonaut](https://boards.straightdope.com/u/psychonaut)\ **Post date:** [March 11, 2012, 2:36pm UTC](https://boards.straightdope.com/t/why-does-the-water-turn-green-when-cooking-jerusalem-artichokes/615450/3 "2012-03-11T14:36:09Z")
> [@The\_Niply\_Elder](#): > > Chlorophyll But lots of other vegetables contain chlorophyll, and yet they don’t turn cooking water green. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 11, 2012, 4:06pm UTC](https://boards.straightdope.com/t/why-does-the-water-turn-green-when-cooking-jerusalem-artichokes/615450/4 "2012-03-11T16:06:37Z")
> [@The\_Niply\_Elder](#): > > Chlorophyll Jerusalem Artichokes don’t contain chlorophyll. If they’re the purple-skinned variety, then the pigment in the skins is probably due to anthocyanins (as also found in red cabbage, blueberries, etc) - and this will react with alkaline water (such as tapwater in a hard water zone) to produce a lurid blue colour. ---
**Author:** ![Ferret\_Herder](https://avatars.discourse-cdn.com/v4/letter/f/e47774/32.png) [@Ferret\_Herder](https://boards.straightdope.com/u/Ferret_Herder)\ **Post date:** [March 11, 2012, 4:32pm UTC](https://boards.straightdope.com/t/why-does-the-water-turn-green-when-cooking-jerusalem-artichokes/615450/5 "2012-03-11T16:32:41Z")
> [@psychonaut](#): > > But lots of other vegetables contain chlorophyll, and yet they don’t turn cooking water green. Some do. I’m fairly sure I’ve seen spinach and broccoli tint water green. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 11, 2012, 7:13pm UTC](https://boards.straightdope.com/t/why-does-the-water-turn-green-when-cooking-jerusalem-artichokes/615450/6 "2012-03-11T19:13:57Z")
I think there might be some conflation abroad in this thread. Jerusalem Artichokes are the tuberous roots of a species of sunflower, _Helianthus tuberosus_ - and they look like [this](http://static.ddmcdn.com/gif/jerusalem-artichokes-2.jpg) or [this](http://chefhermes.com/wp-content/uploads/2011/01/jerusalem-artichokes-v-email.jpg). Under normal circumstances, they do not contain chlorophyll, because they grow underground. _Globe Artichokes_ **do** contain chlorophyll, because they are the scaly flower buds of a type of thistle, _Cynara cardunculus var. scolymus_ - and they look like [this](http://sacredbliss.co.uk/wp-content/uploads/artichoke1.jpg), but _ **they are not the topic of this thread** _. ---
**Author:** ![Blue\_Mood](https://avatars.discourse-cdn.com/v4/letter/b/ac91a4/32.png) [@Blue\_Mood](https://boards.straightdope.com/u/Blue_Mood)\ **Post date:** [March 13, 2012, 8:48am UTC](https://boards.straightdope.com/t/why-does-the-water-turn-green-when-cooking-jerusalem-artichokes/615450/7 "2012-03-13T08:48:45Z")
> [@Mangetout](#): > > If they’re the purple-skinned variety, then the pigment in the skins is probably due to anthocyanins (as also found in red cabbage, blueberries, etc) - and this will react with alkaline water (such as tapwater in a hard water zone) to produce a lurid blue colour. The ones I used were beige-skinned, but I peeled them first anyway. So they were peeled, sitting inside a stainless steel steamer that had no direct contact with the boiling water, yet the water was a bright emerald green afterwards. Obviously some kind of reaction, but what? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 13, 2012, 10:23am UTC](https://boards.straightdope.com/t/why-does-the-water-turn-green-when-cooking-jerusalem-artichokes/615450/8 "2012-03-13T10:23:59Z")
It looks like there’s a family of compounds called leucocyanidins that are related to/precursors of the anthocyanin pigments, but are colourless - seems these are present in plants of the genus _Helianthus_ and are responsible for discoloration after peeling (peeled jerusalem artichokes turn brown-black on exposure to air), so I suggest it’s something to do with this - probably in conjunction with the metals of the pan, and dissolved minerals in the water (obviously not in the steam - which will be more or less pure water, but in the boiling liquid when the juices drip down).