Essential oil? The controversy over mustard oil

Mustard oil, a key in India and South Asian cuisine, has left a lot of home cooks and even some chefs scratching their heads over one pivotal question for the pungent culinary accouterment: Is it safe?

Due to the toxicity of erucic acid, a component found in mustard oil, the U.S. has banned its sale for consumption, although you can still fine it in many stores as a massage oil.

“For us, it’s part of the tradition. It’s part of south Asian foundation cooking,” says chef Aliya Leekong, creative director for the spice-centric elegant cuisine turned out at New York’s Michelin-starred modern Indian jewel, Junoon. “For us, it’s an obvious ingredient. We use a lot of mustard seed in our cooking, so it’s complementary.”

Head into your local specialty spice shop, pluck a bottle of mustard oil from the shelf, and flip over to the back labeling – don’t be surprised if you see the eye-brow raising, daunting words, “For external use only.” Yipes! What’s that all about, you ask?

Like olive oil to Mediterranean countries, mustard oil in Asian countries like India, Nepal, and Bangladesh is used for lots of purposes, in both cooking and care.

“It almost has a wasabi quality to it – or horseradish. In that vein – it has a nasal-clearing aspect,” says Leekong. So much so, that this Omega-3 rich oil is often cooked to a smoking point in India in order to dilute its eye-watering strength a bit (which, unfortunately, is an act that also burns off those healthy Omega-3’s).

“It’s used in ayurvedic practices, too” says Leekong, a Columbia business school grad-turned-chef who was inspired by the foods of her Indo-Pakastani and Tanzanian parents and her own world travels to ditch spread sheets for spoons. “So people tend to have it on hand for things like, say, a poultice for chest congestion, or for massage.”

But it’s that airway-cleaning component that also holds the key to the controversial questions of safety. Mustard oil comes from seeds of the brassica family (to which, consequently, rapeseed also belongs—the partial source of the crossbreed plant from which canola oil is made).

Brassica nigra (black mustard), alba (white), and juncae (brown) are all sources of mustard seed oil, and contain the acid erucic. In large amounts, erucic acid can indeed be harmful, but up until recently the Federal Drug Administration only confirmed canola oil as GRAS (Generally Recognized as Safe), and left mustard seed to hang in the gray – that is, up until recently.

Last March, the FDA put out the following Import Alert #26-04: “Expressed mustard oil is not permitted for use as a vegetable oil. It may contain 20 to 40% erucic acid, which has been shown to cause nutritional deficiencies and cardiac lesions in test animals.

It is important to note that there is another product referred to as mustard oil that is GRAS (Generally Recognized As Safe) and does have an approved food use. That is essential oil of mustard or volatile mustard oil and is a flavoring produced by steam distillation of black mustard flour or mustard cake.

So, what it all boils down to right now is the same area of scrutiny that you already exercise with lots of products: Careful label reading.

Here, it’s the difference in language—expressed mustard oil (bad) v. essential oil of mustard (good)—that is, at least for now, where you will find your comfort zone. Which for fans of Indian cooking, should clear up the safety questions like a good, hearty whiff of erucic acid.

“Think about mustard – it hits your tongue in a certain way and rounds out the flavors really well – it’s like a heat without the heat. And it works really well with fish,” says Leekong, who’s used mustard oil to craft vibrant curries in the past. “At Junoon, we don’t use [mustard oil] as much in curries because it really is a strong flavor and can dominate that kind of dish. We use a lot in marinades to can give a complexity without it being the first note that hits you when eat it.”

One of her favorite dishes for mustard oil is Monkhish Tikka, which combines a heady mix of mustard oil, roasted chickpea flour, ginger, garlic, garam masala, fenugreek leaves, chili powder, and yogurt.

See how to make Monkfish Tikka.

“The aroma gets really nutty and I think [the mustard oil] complements the other flavors really well. It gives it just a little bit of that edge.”  Leekong advises wisely, and says to use judiciously. “Ration yourself. Test it out and see how like it. It has a pungent taste, so see how much works for you.”