Mustard Microgreens: Taste, Nutrition & How to Use Them

Mustard microgreens get lumped in with broccoli often enough that people assume the two share broccoli's headline compound, sulforaphane. They don't, not in the same way. Mustard's kick comes from a different Brassica compound entirely, and knowing which one is worth sorting out before anything else, since it's one of the more commonly repeated mix-ups in microgreen writing.

Mustard sits in the Brassica family, alongside Broccoli, Kale and Kohlrabi, all of them peppery to varying degrees, all built around the same family of pungent, sulphur-containing compounds, just not the identical one. This guide covers what mustard microgreens actually are, what's genuinely in them, how they fit into a meal, and what makes them different from their Brassica siblings. For the basics on what separates a microgreen from a sprout or a baby green in the first place, start with What Are Microgreens? A Complete Guide to Nature's Smallest, Most Concentrated Greens, our reference page for everything else on this blog.

What Is a Mustard Microgreen?

Mustard microgreens come from Brassica juncea, the same species grown for mustard greens and, further along, mustard seed. Depending on the cultivar, the leaves range from deep green to a striking reddish-purple, with a slightly serrated or ruffled edge. The flavour is sharp and peppery, closer to wasabi or horseradish than to table mustard condiment.

That heat has a specific chemical origin. Mustard leaves store a compound called sinigrin, a glucosinolate, in intact plant cells. When the leaf is cut, chewed, or otherwise damaged, an enzyme called myrosinase converts sinigrin into allyl isothiocyanate, the pungent compound responsible for mustard's bite (full study here).

It's worth putting a number on how much sinigrin we're actually talking about. A study across sixty leaf mustard genotypes measured total glucosinolate content, overwhelmingly sinigrin, ranging from 1.20 to 30.73 micromoles per gram dry weight (full study here), and a separate study on high-accumulating potherb mustard varieties found aliphatic glucosinolate content, again mostly sinigrin, reaching as high as 91.07 micromoles per gram in the strongest varieties (full study here). That top figure genuinely rivals or exceeds the sinigrin content reported in kale sprouts, which run around 55 to 66 micromoles per gram, a useful comparison point since mustard and kale are often discussed as milder-vs-sharper siblings without the numbers to back up which is actually more concentrated.

Grown to microgreen size, usually harvested at seven to ten days, mustard is one of the faster-growing varieties AgriZen works with, and one of the more assertive on flavour.

Nutrient Profile

A 2019 peer-reviewed comparative study out of the University of Valencia, published in the journal Foods, measured vitamin C, carotenoids, minerals and isothiocyanates across four Brassica microgreens grown side by side, including red mustard, broccoli, kale and radish. All four provided meaningful vitamin C, in the range of 31 to 56 mg per 100 g fresh weight (full study here). The same study found kale carried the highest vitamin C of the four, so mustard is a good, not exceptional, source among its own Brassica siblings on that specific measure.

On vitamin K: mature mustard greens are documented at a wide range depending on the source, roughly 258 to 593 micrograms per 100 g. We don't have a mustard-microgreen-specific figure, so we're presenting the mature-greens range honestly as context rather than a single precise number.

On selenium: mustard greens are occasionally mentioned as a selenium source, but the actual evidence at both the mature and microgreen stage is thin. Mature raw mustard greens carry only trace selenium by most composition tables, well under 1 microgram per 100 g. We're not going to present mustard microgreens as a meaningful selenium source, since the data doesn't support it.

Ratings above are qualitative rather than exact per-serving figures, since published values shift with cultivar, growing conditions and harvest age.

It's worth being precise about what any of this does and doesn't mean. Isothiocyanates including allyl isothiocyanate are an active area of laboratory research, but that research doesn't translate into a claim that eating mustard microgreens treats, prevents or manages any named health condition.

Role in the Body

Mustard's most-discussed compound is allyl isothiocyanate, the isothiocyanate formed when sinigrin breaks down. It's part of the same broad family of Brassica isothiocyanates as broccoli's sulforaphane, but it's a distinct molecule. We go through the wider picture of isothiocyanates and glucosinolates across Brassica microgreens in Sulforaphane & Brassica Compounds: Role in the Body, Sources & Which Microgreens Have It, our dedicated nutrient deep-dive.

Alongside that, mustard is a reasonable source of vitamin C, involved in collagen formation, wound repair and general immune function. We cover vitamin C in more depth in Vitamin C: Role in the Body, Sources & Which Microgreens Have It, our dedicated nutrient deep-dive.

How to Use Mustard Microgreens

Mustard's sharp, peppery heat means it works best as an accent rather than a base ingredient, a small handful goes a long way.

A Quick Growing Note

AgriZen grows every variety the same way, indoors under LED light, watered with RO-purified water, from certified organic seed. We cover that full process, and what the organic-seed certification does and doesn't cover, in How Microgreens Are Grown: From Seed to Harvest.

Frequently Asked Questions

What do mustard microgreens taste like?

Sharp and peppery, with a heat closer to wasabi or horseradish than to a jar of mustard condiment.

Do mustard microgreens have the same compound as broccoli microgreens?

No. Mustard's signature compound is allyl isothiocyanate, formed from sinigrin, while broccoli's is sulforaphane, formed from glucoraphanin. They're related, not identical.

Is mustard actually higher in its signature compound than kale?

In high-accumulating varieties, yes. Mustard's sinigrin content has been measured as high as 91 micromoles per gram dry weight in the strongest genotypes, which meets or exceeds the roughly 55 to 66 micromoles per gram reported for sinigrin in kale sprouts.

Is mustard a good source of selenium?

Not meaningfully, based on the available data. Mature mustard greens carry only trace selenium, well under 1 microgram per 100g by most composition tables. We wouldn't present mustard microgreens as a selenium source.

Which other AgriZen microgreens pair well with mustard?

Within the Brassica family, Broccoli, Kale and Kohlrabi share a similar growing profile, though each is milder on the palate than mustard.

How long do mustard microgreens keep after delivery?

Like any fresh, ready-to-eat leafy product, they're best eaten within a few days of delivery and should be kept refrigerated in the meantime. For the full storage guidance, see How to Store Microgreens at Home to Make Them Last Longer.

A Small, Sharp Addition

Mustard microgreens are a good reminder that the Brassica family isn't a single flavour or a single compound, and that mustard's own signature compound can genuinely rival its milder-seeming siblings in concentration when you look at the actual numbers. Grown indoors under LED light on AgriZen's shelving, watered with RO-purified water, and cut fresh to order, mustard's role is a small one by volume and a distinctive one by flavour.