Black Garlic (Kala Lehsun) at Home: Rice Cooker Method, Claims
Fair warning first: black garlic means a rice cooker running day and night for two to three weeks, and for the first several days the whole house smells of garlic. If you’re still in, here’s how to make black garlic at home with that rice cooker method, how to tell when it’s done or spoiled, what to cook with it, and what it honestly can and can’t do for your health.
The short version
- What it is: whole garlic bulbs held at gentle heat until the cloves turn black, soft and sweet
- Heat: a rice cooker’s keep-warm setting, usually about 60 to 75 °C
- Time: 14 to 21 days, first check at day 10
- Batch: 6 to 10 whole bulbs, depending on the cooker
- Weight loss: the bulbs lose roughly a third of their weight as water
- Keeps: whole bulbs about 3 months in the fridge; peeled cloves 2 to 4 weeks
Prefer to listen? This post as a 4 min video · Video page with transcript
What is black garlic (kala lehsun), and what isn’t it?
Black garlic is ordinary garlic, nothing added, held warm and humid for weeks. Slowly, the sugars and proteins inside react with each other, the same browning that colours a bread crust or roasted coffee, only very slow and at much lower heat. The white clove turns tan, then brown, then glossy black. The sharp, hot bite disappears. What’s left is soft like a date, sweet and a little tangy, often compared to imli (tamarind) or balsamic vinegar.
It’s often sold as “fermented garlic”. That’s misleading. No bacteria or yeast do the work; it’s a heat reaction, which is also why you shouldn’t open the pot and find anything fuzzy or bubbling. Two more mix-ups worth clearing: black garlic isn’t a special variety of lehsun you can buy at a sabzi stall, and it has nothing to do with ek pothi (single-clove) garlic, which is a whole bulb that grew as one round clove.
The black colour comes from melanoidins, the same brown compounds that form on a toasted crust or in roasted coffee beans.
How to make black garlic at home in a rice cooker
You need a rice cooker whose keep-warm setting stays on until you switch it off. Some newer models turn themselves off after 12 or 24 hours, so read the manual or watch it on the first day. A slow cooker on its “warm” setting can work the same way.
- Choose 6 to 10 whole, firm bulbs with tight, unbroken skins and no soft cloves. Big Chinese bulbs are easy; small desi bulbs work too and give a stronger result. Our desi vs Chinese garlic guide explains the difference.
- Don’t peel or wash them. Brush off loose dirt and papery flakes with a dry cloth. Water on the skins encourages mould.
- Wrap each bulb loosely in foil, or put them all in one foil parcel. This holds in moisture so the cloves turn soft rather than drying out.
- Put a steaming rack or an upturned steel plate in the bottom of the cooker, so the bulbs don’t sit directly on the hot base, and place the foil bulbs on it.
- Close the lid and switch to keep-warm. Not cook. Keep-warm.
- Leave it closed for the first 7 days. Opening lets out heat and moisture and sets you back.
- At day 10, unwrap one bulb and cut a clove. If it’s brown in the middle or still smells raw, rewrap it and continue.
- Most batches are ready between day 14 and day 21. Switch off, unwrap and let the bulbs cool and dry on a plate at room temperature for a day or two.
- Store whole bulbs in an airtight box in the fridge.
The smell, the bill and the power cuts
The first 5 to 7 days are the smelly part, and it isn’t subtle. Put the cooker in a well-ventilated spot, such as a utility area or a covered balcony, on a stable, heat-safe surface, well away from curtains, and where children and pets can’t reach it or pull the cord. Check the cord and plug for heat now and then, as you would for any appliance left on for days. The smell softens into something sweeter by the second week.
A keep-warm setting usually draws somewhere around 30 to 60 watts. Over three weeks, that works out to roughly 15 to 30 units (kWh) of electricity, so look at your cooker’s rating and decide whether a jar is worth it to you. A power cut of a few hours only slows things down. If the cooker has been off for a day or more, especially in the first week, check the bulbs for mould before carrying on.
How to tell black garlic is done, or spoiled
| What you see | What it means |
|---|---|
| Black right through, soft, sticky, sweet, slips out of its skin | Done |
| Brown or tan centre, still a raw garlic smell | Needs more days |
| Hard, dry, crunchy, bitter | Overdone or too dry; safe but unpleasant, so wrap tighter next time |
| White, green or blue fuzz, sour or rotten smell, wet slime | Spoiled; throw away the whole batch |
Don’t try to save a mouldy batch by cutting out the bad cloves. Mould threads spread further than you can see, and you can’t know what’s growing in a warm, damp pot, so every bulb goes in the bin and the cooker gets a proper wash.
How to use black garlic in everyday cooking
Treat it more like a sweet-sour paste than like garlic. Two or three cloves go a long way.
- Spread: mash 4 cloves with 1 tablespoon soft butter or ghee and spread it on toast or a hot paratha.
- In daal: stir 2 or 3 mashed cloves into a pot of masoor or moong daal at the end of cooking for a deep, rounded taste.
- Dip: mash 3 cloves into a katori of thick dahi with a pinch of salt and bhuna zeera.
- Chutney: blend 5 cloves with 2 tablespoons imli pulp, a pinch of chilli and salt, and loosen with water.
- Marinade: mash into chicken tikka or paneer marinade in place of some of the fresh garlic.
Black garlic paste made with oil follows the same rule as any garlic in oil: fridge only, used within about 4 days, never left on the counter, because garlic in oil is the classic botulism risk. Our ginger garlic paste storage guide explains why. Peeled black cloves on their own keep 2 to 4 weeks in a closed jar in the fridge, and whole bulbs keep about 3 months. You can freeze them for longer.
What about black garlic powder? It’s possible but fiddly. Slice peeled cloves thinly, dry them at 55 to 60 °C for several hours until brittle, then grind. They’re sticky with sugar, so they take longer than fresh garlic and clump quickly; keep the powder in small airtight jars. More projects like this live in our Zero-Waste Kitchen section.
Myth: black garlic lowers blood pressure, cholesterol or sugar
Black garlic is marketed hard, with claims about heart health, cholesterol, blood sugar, even hair growth. The honest picture is plainer. The long heating changes garlic’s chemistry: it loses most of the sharp compounds that make raw garlic hot, and gains more of a milder one called S-allyl cysteine, and lab tests often measure more antioxidant activity. But a number in a lab test isn’t the same as a change in your blood pressure reading, and there’s no reliable basis to promise that black garlic will lower BP, cholesterol or sugar.
If that’s why you’re interested in garlic, our honest looks at garlic, salt and walking for blood pressure and cholesterol home remedies set out what food can and can’t do. Black garlic is a delicious ingredient. Enjoy it as that.
And black garlic powder for hair? There’s no good evidence it helps, and rubbing garlic of any kind into the scalp can irritate. Keep it on the plate.
Black garlic is gentler on the stomach than raw garlic for many people, but it’s still garlic. If you take a blood thinner such as warfarin or have surgery coming up, tell your doctor about any garlic you eat in large amounts or as a supplement. It is sweeter than fresh garlic, so with diabetes keep it to condiment-sized amounts. Never replace a prescribed BP, cholesterol or diabetes medicine with black garlic or any garlic product; if you’re thinking about changing or stopping a medicine, talk to your doctor first. Keep it and the running cooker away from pets, since garlic is toxic to dogs and cats. Throw away any batch with mould, a sour smell or slime, and get urgent help for vomiting, double vision, slurred speech or weakness after eating any home-preserved food.
Black garlic questions people ask
How do I make black garlic at home?
Wrap whole, unwashed bulbs in foil, put them on a rack in a rice cooker, and leave it on keep-warm for 14 to 21 days without opening it for the first week. It’s ready when the cloves are black, soft and sweet right through.
Is black garlic fermented?
Not really. It’s called fermented, but no microbes are involved; the change comes from slow heat reactions between sugars and proteins.
How long does black garlic take in a rice cooker?
Usually 2 to 3 weeks. Check one bulb at day 10 and keep going until the centre is fully black and soft.
What does black garlic taste like?
Sweet, soft and tangy, a bit like imli or balsamic vinegar, with only a gentle garlic flavour. It has none of raw garlic’s burn.
How do I know if black garlic has gone bad?
Fuzz of any colour, a sour or rotten smell, or wet slime means it’s spoiled. Throw out the whole batch.
How should I store black garlic?
Keep whole bulbs in an airtight box in the fridge for about 3 months, and peeled cloves for 2 to 4 weeks. Black garlic paste in oil stays in the fridge and is used within about 4 days.
What are the side effects of black garlic?
For most people, none beyond those of ordinary garlic, and it’s usually easier on the stomach. People on blood thinners should mention large amounts to their doctor.
Does black garlic lower blood pressure?
There’s no reliable basis to promise that. Enjoy it as food and follow your doctor’s plan for BP, including any medicine you’ve been prescribed.
Is black garlic powder good for hair?
There’s no good evidence that it helps hair, and garlic on the scalp can irritate. It belongs in the kitchen.
Can I make black garlic without a rice cooker?
Yes, in a slow cooker on its warm setting. An oven isn’t practical for three weeks, and most ovens can’t hold such a low, steady heat.
Can I use peeled garlic to make black garlic?
It’s better not to. Peeled cloves dry out and turn hard, and they’re more likely to spoil. Whole bulbs with the skin on keep the moisture in.