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I recently purchased this vegetable at a farmers' market without getting its name. It was marketed as organic/fresh/local in the Northeastern United States in late September.

enter image description here

The leaves are thin and non-waxy, but a little moist (when I try to slide my fingers across the leaves they stick a little).

When I tasted a small portion of a leaf raw, I immediately felt moderate burning in the mouth which I (mistakenly) believed to be oxalic acid at first. In reality, it was a mustardy spicy/sharp taste (which I didn't expect from greens). Because I don't know the name of this plant, I'm not sure if this is the case. In light of that concern, does it require any special preparation to be safe for healthy individuals?

nanofarad
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    It looks like it might be green wave mustard... Which would also explain the spicy taste/feeling. – AMtwo Sep 27 '20 at 22:44
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    Unlikely to be oxalic; Ruhbarb leaves contain oxalic are are regarded as relatively toxic. – blacksmith37 Sep 28 '20 at 00:34
  • @AMtwo that looks like it could be right and I could be misinterpreting the sharp flavor as oxalic acid; would you mind adding a brief answer? – nanofarad Sep 28 '20 at 01:22
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    Rhubarb leaves are toxic because of *high* levels of oxalic acid. Some greens with lower levels of oxalic acid, such as [sorrel](https://en.wikipedia.org/wiki/Sorrel) and [wood sorrel](https://en.wikipedia.org/wiki/Oxalis) are both edible and delicious. The oxalic acid gives them a sour, lemony taste. I wouldn't describe them as sharp/spicy. – csk Sep 28 '20 at 02:00
  • @csk Yep, I think that was a fundamental misunderstanding that I had when writing the question. Do you suggest I delete it, or leave it up for an answer that fully describes this? – nanofarad Sep 28 '20 at 02:12
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    @nanofarad how about an [edit] that makes the post clearer - like you already did? You can always add more relevant details to improve the post. – Stephie Sep 28 '20 at 04:16
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    @csk: while sorrel may be lower in oxalic acid than rhubarb leaves (whcih are not eaten because of their high oxalic acid content), the oxalic acid content of sorrel is very high - chewing some leaves is fine, but it should not be eaten as a main vegetable dish. The dose makes the poison! – cbeleites unhappy with SX Sep 28 '20 at 17:12

2 Answers2

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From the photo & description of the leave look & feel, these sound like green wave mustard--a variety of mustard greens with curly leaves.

Mustard greens have a "spicy" or peppery taste, which also seems to align with your experience.

Mustard greens can be safely eaten raw or cooked. It can be a raw salad ingredient, or be sauteed, braised, grilled, etc. Because of the assertive flavor, some people find it best when mixed with other leafy greens to balance out that spiciness you describe.

AMtwo
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I'll tackle the other part of the question: dealing with high oxalic acid levels (or more precisely: a high oxalic acid : calcium ratio).

I'm aware of two traditional ways of preparing food from high oxalic acid vegetables:

  1. When cooking the vegetables, soluble oxalic acid gets distributed throughout the veggies and the cooking water as well. Throwing away the cooking water will get rid of the corresponding part of the oxalic acid.

  2. Oxalic acid forms insoluble salts with kations like Ca²⁺ (Fe²⁺, ...). Thus, if you prepare (or eat) vegetables that are high in oxalic acid with sufficient food that is high in Ca²⁺, calciumoxalate will precipitate and mostly prevent the oxalic acid from being absorbed.

    E.g., in my home region, spinach is traditionally cooked with milk: spinach contains something between 1.2 and 13 g Oxalic acid per kg fresh weight. A part of it is already present as insoluble salts (Ca-oxalate, Fe-oxalate). To precipitate 1 g of oxalic acid (calculated anhydrous), you need 450 mg of Ca²⁺. As a very rough guesstimate, 1 l milk contains 1.2 g Ca²⁺, so 375 ml milk to precipitate 1 g of oxalic acid (yielding 1.45 g of calcium oxalate).

    If the vegetable was indeed high in oxalate, you may find a slightly gritty texture due to the calcium oxalate.

    If you prefer to use cheese instead of milk, keep in mind that sour milk cheeses tend to be low in calcium (the calcium is in the whey) whereas rennet-based cheeses are high in calcium.

Bon appetit :-)

cbeleites unhappy with SX
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