Eastern Skunk Cabbage Experiment

Symplocarpus foetidus

By late spring each year, the wetland is covered with this lush green plant in my area (Midwest). Skunk cabbage (both eastern and western) pokes its head out flower first. When the greens are fully grown, it looks more like a lettuce than a cabbage.

Eastern skunk cabbage (Symplocarpus foetidus) is native in the Midwest to the eastern coastal region. Western skunk cabbage (Lysichiton americanus) is native to the western coastal region.

https://www.plants.usda.gov/core/profile?symbol=SYFO https://plants.usda.gov/core/profile?symbol=LYAM3

When I first learned about the skunk cabbage (that is, eastern skunk cabbage), I was told that this plant was inedible due to its calcium oxalate content which will give a painful burning sensation in the mouth and the mucus membrane along the alimentary canal. However, I kept hearing or reading about people who successfully had eaten this plant without an unpleasant side effect. Although I also did hear about brave people who tried it and suffered a severe pain, I had to give it a try myself. To be clear, I was aware of the possible danger (allergic reaction, painful burning sensation, and possible death according to Wiki at least) before I embarked on this reluctant experiment–Rachel is the witness of my reluctant, cringing face as I was picking the shoots.

Now, there were many conflicting instructions as to how it should be prepared to render it edible. Some were just straight false information, and some were more detailed, convincing instructions. Also, there was no information on whether they cooked the eastern skunk cabbage or western skunk cabbage (they are in the same subfamily Orontioideae but different genera). And the rest of those who claimed to have eaten the skunk cabbage only mentioned to “do your homework” before trying it without giving any specific instruction.

Experiment 1

The only instruction I started with was to boil the young shoots (before unfurling) in several changes of water. It varied from 3 changes to over 10 changes of water.

easternskunkcabbageshoots

Here are the shoots I’ve gathered. They were still furled as the instruction I found on the web. Now to boil…

On the left is the cooked skunk cabbage after 3 changes of water. You can see the shoots still have some greens. By this point, the leaves had no taste left but still had a burning sensation. On the right is after 10 changes of water. Yes. I did 10 changes of water because the biting/burning sensation was not going away. Even though I was putting teeny tiny amount on my tongue to test it, it was still burning. After the 10th times the greens were disintegrated to almost nothing. The conclusion from this first experiment was that calcium oxalate could not be removed by boiling, which prompted me to look into the chemical properties of calcium oxalate (more toward the end of this post).

My conclusion was that it was inedible not because of the bad taste (there was none left) but because of the strong burning sensation (possibly from calcium oxalate). My other guess at this point was that most, if not all, of the “edible” skunk cabbage was referring to the western skunk cabbage.

When I shared this experiment on Facebook groups, I received a mixed responses. But, lo and behold, there were several people testifying that they sure did have some as a kid (that were prepared by an adult) or that they know as a matter of fact that their acquaintances did eat this plant without hurting themselves. Hence my second experiment…

Experiment 2

Thankfully, one of the group members gave me a link to an Instagram user https://www.instagram.com/wild_food_around_the_world/ (by the way, this forager is an awesome person) who successfully rendered the eastern skunk cabbage edible. So, I had to give it a second try.

Symplocarpus foetidus

I gathered even younger shoots with yellow hearts this time.

I even peeled the greener part of the shoots. Now to boiling…

As per the description, I boiled the shoots in 3 changes of water for at least 5 minutes each time. Interestingly, the water turned a bit green unlike in the 1st experiment in which the water remained clear. After the third boil I air dried the shoots (well, I had to go out for a grocery shopping). When most of the water dried off, I placed them in the dehydrator and started on a high setting for about 3 hours then reduced it to low heat before I went to bed.

In the morning, they were almost completely dried except the thick portion of the hearts. I tasted a tiny bit and felt the burning/biting sensation. My guess was that, in order to render calcium oxalate harmless, it needs to be broken down chemically by heat. So I fried them for about a half a minute until it browned.

Aaaand… It was edible!!

Almost, that is. The crispy parts did not have that strong burning/biting sensation but more on a spicy biting side. Even then, it was not strong and did not leave an unpleasant feeling. However, as you can see on the right, the thick portion that was not crispy all the way was still too strong to eat.

So I asked the person (Shell Yu on Instagram) how it was done; the skunk cabbage hearts were dried in the oven at 380F for 10 minutes. That is close to 200C (it is important for the later discussion).

My conclusion after this second experiment was that it indeed can be rendered edible at a right stage. I also think that there might be a difference in calcium oxalate concentration between the eastern and western skunk cabbage.

Calcium Oxalate

Calcium oxalate

Now, let’s talk about the culprit that is hypothesized to be the reason why skunk cabbage gives the burning sensation. The calcium Oxalate molecule has a different shape depending on its hydration. For example, calcium oxalate dihydrate crystals are octahedral. Due to their spiky shape, some hypothesize that calcium oxalate causes a micro-laceration (or teeny tiny scratches) on our skin, particularly on the mucus membrane. This assumes that the burning sensation is more physical than chemical. However, I found this to be questionable from my experience.

As I was doing my second experiment, I took a larger bite than I could tolerate which made my lips and whole mouth painfully burning. I was already thinking that the sensation was more chemical than physical. Also, it is an organic compound and should be dissolved in an organic solvent (such as, alcohol). So, that was exactly what I did; I rinsed my mouth with homemade honey mead (note that I did not swallow the mead which probably contained dissociated calcium and oxalate). And, voila! The pain was gone after a brief tingling sensation.

Lastly, there are two properties of calcium oxalate that lead me to think why my first experiment failed while the second one succeeded. First, the solubility of calcium oxalate in water is only 0.67 mg/L at 20C, which means, yes, it can be removed by boiling but only in a negligent amount. As the skunk cabbage is boiled, a little more can be removed, but not by much. Second, the melting point of the calcium oxalate crystal is 200C (392F), which cannot be reached by boiling water. This second property is why I think frying or drying/baking in the oven at 380F worked. According to Shell Yu, the slight biting sensation was still there after drying the boiled skunk cabbage in the oven, but it was more like a spice, which was the intended use after powdering it anyway.

On a side note, ingesting calcium oxalate is unlikely to cause kidney stones. Although calcium oxalate monohydrate is the most common compound found in kidney stone, they are formed from urine that contains both calcium and oxalate separately. The danger of ingesting calcium oxalate is in “burning” the alimentary canal lining.

Last Thought on the Edibility of Eastern Skunk Cabbage

My final conclusion is, yes, the eastern skunk cabbage can be edible, but only if it is harvested at the right stage and processed properly. How about the nutritional content? I am certain that any water soluble and heat-unstable micro-nutrients are all destroyed by the cooking process. However, there are some minerals (one of which obviously being calcium) that probably survive the cooking process. I personally don’t think it is worth for its nutritional value but for its novelty.

At the end, I am left with more questions. If an organic solvent can disable the burning sensation of calcium oxalate, will I be able to use the mature greens by processing it in some kind of organic solvent? Will fermentation render it edible? For I am done with torturing my tongue for now, I will come back to it later.

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