Garlic

Allium sativum

Family: Amaryllidaceae Part used: Bulb (cloves)

Key Compounds

• Alliin
• Allicin
• Ajoene
• Diallyl disulfide
• Diallyl trisulfide
• S-allylcysteine
• Quercetin
• Kaempferol

Traditional Use

• Ancient Egyptian food and medicine — worker rations during pyramid construction; bulbs found in Tutankhamun's tomb (c.1323 BCE)
• Ancient Greek medicine — Hippocrates prescribed it; Olympic athletes ate it
• Roman military medicine — soldiers ate garlic for strength; Pliny recorded 61 uses
• Medieval European epidemic response — used during plague outbreaks; basis of 'Four Thieves Vinegar'
• First World War wound treatment — used as antiseptic when pharmaceutical supplies ran out

The compound that makes garlic medicinally active doesn’t exist in a whole clove.

Alliin — the precursor — sits inert and odourless inside intact garlic cells. The enzyme alliinase sits in a separate cellular compartment. Break the cell wall — by crushing, chopping, or chewing — and alliin meets alliinase, and allicin forms within seconds. The pungent smell, the antimicrobial activity, the cardiovascular effects: all of it comes from this collision. The plant did not make allicin for you. It made allicin for whatever bit into it. You are next in line.

Louis Pasteur demonstrated garlic’s antimicrobial properties in laboratory conditions in 1858. The Egyptians had been feeding it to pyramid workers for approximately 5,000 years before that. Pasteur had a better explanation for why it worked. They had the pyramid.

Meet the plant

A bulb-forming perennial grown as an annual. Underground: a compound bulb of 4–20 cloves wrapped in papery white skin. Above ground: flat, strap-like leaves of a grey-green colour, reaching 60–90 cm, and a flowering stem called a scape that curls into a loop before straightening and producing a flower head. The garlic scape is edible and increasingly popular; it tastes like mild garlic and arrives a few weeks before the main harvest.

The flower head, when it appears, is unusual: a spherical cluster of tiny white or pink flowers mixed with bulbils — tiny aerial cloves that can be planted but are rarely used commercially. Most cultivated garlic produces few or no viable seeds. It has reproduced vegetatively for so long that it has essentially abandoned the sexual reproduction option.

Five thousand years and a laboratory

The oldest documented garlic is from ancient Egypt. Clay tablets from Kahun (~1900 BCE) mention it. Workers at Giza received garlic as part of their rations. Bulbs were found in Tutankhamun’s tomb, placed there c.1323 BCE. The Egyptians gave garlic to their most important dead person and their construction workforce. That covers a reasonable spectrum.

The ancient Greeks were more specific about uses. Hippocrates — who said “let food be thy medicine” — recommended garlic for pulmonary complaints, as a laxative, and for uterine health. Greek soldiers and Olympic athletes ate it. Dioscorides wrote about it around 70 CE with enough detail to suggest he had done his own testing. The Romans spread garlic across their empire with their armies. Pliny the Elder documented 61 medicinal uses in Naturalis Historia. Sixty-one is commitment.

Medieval Europe reached for garlic during epidemic outbreaks. “Four Thieves Vinegar” — a preparation of garlic steeped in vinegar with other herbs — became famous during plague years. The story attached to it involves four thieves robbing houses during the Black Death while protected by the mixture. The actual evidence for plague protection is limited; the preparation exists in historical documents and still gets made today.

During the First World War, when pharmaceutical antiseptics ran out, British military doctors used garlic juice directly on wounds. The antimicrobial activity that Pasteur had demonstrated in a laboratory proved usable at a field station in France. The pyramid builders would not have been surprised.

Japan has grown its own garlic for over a thousand years. The modern story is Aomori — a prefecture in northern Honshu with the right cool climate for long, slow garlic development. Aomori now produces approximately 70% of Japan’s domestic garlic. The premium variety, ホワイト六片 (White Six Cloves), is larger, milder, and considerably more expensive than imported garlic. And then Aomori did something unusual with the ingredient.

The chemistry

Allicin is unstable. It forms quickly and then keeps reacting — converting into diallyl disulfide, diallyl trisulfide, ajoene, and other compounds. The specific profile depends on what you do with the garlic: raw garlic produces allicin directly; oil-macerated garlic produces ajoene; heat drives the allicin into dimethyl sulfide compounds that are milder. This is why raw, cooked, aged, and black garlic have genuinely different chemistry and different effects. They are the same plant processed differently.

S-allylcysteine (SAC) is the compound that makes aged garlic extract and black garlic different from fresh. When garlic is aged in alcohol solution or fermented over weeks, allicin converts into SAC, which is odourless, stable, and more bioavailable than fresh allicin. Most of the clinical cardiovascular research on garlic supplements uses aged garlic extract standardised for SAC. The smell is gone. The activity is not.

The 10-minute rule is real biochemistry: alliinase, the enzyme that converts alliin to allicin, is temperature-sensitive. If you crush garlic and immediately apply heat above 60°C, the enzyme deactivates before completing the conversion. Let crushed garlic sit for 10 minutes at room temperature, and the conversion completes before the enzyme meets the heat.

What people actually do with it

Raw garlic: crush a clove, wait 10 minutes, add to food. Maximum allicin. Strongest effect. Persistent breath. Adding raw garlic to finished dishes — crushed into dressings, rubbed on toast, mixed into hummus — preserves the compound profile that heat would destroy.

Roasted garlic: a whole head in the oven at 200°C for 40–45 minutes produces something that barely resembles raw garlic in flavour or chemistry. The allicin has converted and dispersed. What remains is sweet, soft, caramelised paste with mellow organosulfur compounds and excellent spreadability. The antimicrobial activity is lower. The culinary value is its own thing entirely.

Black garlic: 30–40 days at 60–80°C produces cloves that are black, soft, sweet, and complex. Umami-heavy, with notes of balsamic vinegar and tamarind. Use as a condiment, add to sauces and marinades, eat directly. Japan has been doing this commercially since the 1980s and Aomori has the best reputation for quality.

Aged garlic extract: capsules or liquid, standardised for S-allylcysteine. Odourless. Most cardiovascular supplement research uses this form. Available everywhere.

In Japanese cooking: garlic (ninniku, ニンニク) is fundamental in ramen, gyoza, yakitori, Korean-influenced yakiniku, and Chinese-influenced dishes. It sits alongside ginger and green onion as a baseline aromatic. Less culturally embedded than in Mediterranean or Southeast Asian cuisine — Japan has dishes without garlic — but present throughout.

Could you grow this yourself?

Yes, and garlic is one of the most satisfying crops to grow. Plant individual cloves in autumn (October–November in most of Japan), point upwards, 3–5 cm deep, 15 cm apart. They overwinter as green shoots and bulk up in spring. Harvest when the lower leaves start to yellow — usually June in most of Japan.

The basic principle: garlic needs a cold period (vernalisation) to develop proper bulbs. Japan’s winters provide this naturally in most regions.

Softneck varieties (sold in supermarkets, braids well): earlier harvest, longer storage, better for warmer regions. Hardneck varieties (hardier, more complex flavour, includes purple-striped types): needs proper cold, does not store as long, better for cooler northern regions. Either works in most of Japan.

Pull the scapes (the curling flower stalks) when they appear in June — this redirects the plant’s energy to the bulb. The scapes are excellent stir-fried or made into pesto.

Cure harvested bulbs in a dry, ventilated area for 3–4 weeks before storage. Properly cured garlic stores for months at room temperature.

Aomori conditions — cool climate, well-drained soil, late spring harvest — produce the large mild bulbs that carry that prefecture’s premium reputation. The same principles apply anywhere with cold winters.

Garlic (ニンニク) in Japan

Garlic is everywhere in Japanese food without being the defining flavour it is in Mediterranean or Southeast Asian cuisine. It goes into ramen tare, gyoza filling, yakitori seasoning, fried rice, and most dishes that have travelled through Chinese or Korean food culture. It is present and necessary without usually being the lead.

Two things are distinctly Japanese.

The first is Aomori. Japan’s garlic industry is centred in one prefecture, which happens to produce a product that is demonstrably better than most imported garlic. Aomori garlic is sold as a premium domestic product with specific variety branding (ホワイト六片). Markets and food halls stock it separately from standard imported garlic at a substantial price premium. The regional identity is real and commercially significant.

The second is black garlic. Japan did not invent fermented garlic preparations — Korea and other Asian traditions have their own — but Japan industrialised and exported the specific modern black garlic format that is now sold globally. Aomori produces it at scale. It is sold as a health product (portable, shelf-stable, odourless, high S-allylcysteine content), as a premium food ingredient, and as a gift item (黒にんにく is a popular omiyage from Aomori). The product category exists worldwide now largely because Japan developed and exported it.

Raw garlic consumption in Japan is lower per capita than in Mediterranean or Korean food cultures, but supplement use is high. Aged garlic extract (such as Kyolic brand, a Japanese product that went global) has a strong market. The preference for the benefits without the smell is culturally consistent.

Things you’re probably wondering

Why does garlic smell so strongly? The smell doesn’t exist in intact garlic. Alliin, a sulfur amino acid, is stored separately from alliinase, an enzyme. Crush or chop a clove and the cell walls break, alliin meets alliinase, and allicin forms within seconds. Allicin is the source of the sharp, pungent smell. Allyl methyl sulfide — a downstream product — gets absorbed into the bloodstream and excreted through the lungs and skin for up to 48 hours. This is why garlic breath persists long after the meal.

Why do you have to let crushed garlic sit before cooking? Because the allicin-forming enzyme reaction needs time — about 10 minutes — to complete. If you crush garlic and immediately apply heat, the enzyme alliinase is deactivated before it finishes converting alliin to allicin. Let crushed garlic sit at room temperature for 10 minutes before adding it to heat, and the conversion completes fully. This is basic enzyme chemistry.

What is black garlic and why is Japan known for it? Black garlic is regular garlic fermented and aged at 60–80°C for 30–40 days in controlled humidity. Maillard reactions drive the colour change and flavour transformation. The pungent allicin converts into mellower compounds including S-allylcysteine. The resulting cloves are black, soft, sweet, and complex. Japan, particularly Aomori Prefecture, became the primary modern producer and innovator of black garlic as a premium food and health product.

Did Louis Pasteur really test garlic? Yes. In 1858, Pasteur demonstrated that garlic juice inhibited bacterial growth in cultures. He was not the first to observe garlic’s antimicrobial properties — that had been documented across five millennia and multiple civilisations — but he was the first to demonstrate it under modern laboratory conditions. He arrived approximately 5,000 years after the Egyptians.

Where does Japan’s garlic come from? Aomori Prefecture produces about 70% of Japan’s domestic garlic. The main variety is ホワイト六片 (White Six Cloves). China supplies the bulk of imports. Aomori garlic is sold as a premium domestic product at prices significantly higher than imported garlic.

Botanical details

The full compound list

See Also

• Ginger — same culinary pairing tradition across Asian cooking
• Onion — same Allium genus; shares organosulfur chemistry
• Turmeric — another ancient food-medicine with complex absorption chemistry

References

• Rivlin, R.S. (2001). Historical perspective on the use of garlic. Journal of Nutrition, 131(3), 951S–954S.
• Bhatt, D.L. et al. (2001). Antiplatelet therapy. Journal of the American College of Cardiology, 38(5), 1396–1421.
• Amagase, H. et al. (2001). Intake of garlic and its bioactive components. Journal of Nutrition, 131(3), 955S–962S.
• Ried, K. et al. (2016). Garlic lowers blood pressure in hypertensive subjects: systematic review and meta-analysis. Maturitas, 83, 17–24.
• Bae, S.E. et al. (2014). Changes in S-allyl-L-cysteine contents and physicochemical properties of black garlic. LWT — Food Science and Technology, 55(1), 397–402.