Use the science of garlic to bring sweetness or fire to your food

Humans

By understanding garlic's chemistry we can amp up its pungency in a fiery garlic sauce or tame it through gentle cooking to make mellow garlic confit, says Sam Wong

By Sam Wong

11 March 2020

What you need

Garlic

Vegetable oil

Salt

Lemon

GARLIC can be big and fiery or soft and mellow. Understanding the chemistry of its flavour can help us amplify or tame it.

If you sniff a bulb of garlic, it doesn鈥檛 have a strong smell. But if you bite into raw garlic, it will produce a pungent aroma and a burning sensation in your mouth. This is garlic鈥檚 chemical defence, evolved to deter animals from eating the plant.

It is caused by a chemical called allicin, which activates the same pain-sensing receptors that respond to the capsaicin in chilli peppers. Allicin isn鈥檛 present in garlic until its cells are damaged and stores containing an enzyme called alliinase break open. The enzyme acts on alliin, a derivative of the amino acid cysteine, to produce allicin.

Allicin has antibacterial and antifungal properties as it inhibits enzymes called cysteine proteases, which pathogens use to invade the tissues of their hosts. This is possibly why garlic has been touted as a medicine for thousands of years 鈥� Hippocrates recommended it for wound healing, for example.

Garlic becomes less fiery when you cook it, because alliinase is inactivated, stopping allicin production. Allicin is also unstable, quickly reacting to form other odorous compounds. Some of these can persist in the mouth for hours after eating garlic, giving rise to garlic breath. If this happens, eating an apple or salad can help, as enzymes found in many raw fruits and vegetables convert these compounds into odourless molecules.

When we mince or chop garlic, we damage lots of cells. When we leave its cloves intact and cook them slowly, it becomes sweet and mellow instead. Here are two ways to prepare garlic that bring out different sides of its personality.

First, the fiery one: a Lebanese garlic sauce called toum. Peel two bulbs鈥� worth of garlic (roughly 120 grams) and blend in a food processor with half a teaspoon of salt. With the blade still running, slowly add 125 millilitres of vegetable oil, then a tablespoon of lemon juice. Repeat until you have added 500 ml of oil and four tablespoons of lemon juice in total.

The result should be smooth and mayonnaise-like. Garlic contains emulsifiers that coat droplets of fat, allowing them to become suspended in water, but the oil must be added very slowly to make it work. If the emulsion breaks, add an egg white to the mixture and blend again. Toum is a perfect accompaniment to grilled meat, roasted vegetables or falafel.

Garlic confit is a great way to appreciate its mellower side. Peel two bulbs鈥� worth of garlic and cover them with olive oil in a small saucepan. Cook over a very low heat for 45 minutes to an hour, until soft. Keep the cloves in the oil in a jar in the fridge. Mash them on toast, add to salads or eat them with pretty much anything.

For next week

Plain flour

Salt

Vegetable oil

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