Garlic, the Mighty Bulb

By on October 28, 2013

A single clove of garlic is a powerhouse of more than 200 known chemical compounds, including many health-bestowing antioxidants, vitamins, minerals and sulphurous compounds. It is an excellent source of potassium, iron, calcium, magnesium, manganese, zinc, selenium and germanium, as well as antioxidants, such as beta-carotene, and vitamins B6 and C. However, its most medicinally powerful ingredient is a sulphur substance called allicin, a pungent oily liquid that the plant spontaneously creates as a defence mechanism when damaged. 
    Allicin is the secret to garlic’s extraordinary power and explains why it has been used so effectively through the ages to preserve food and prevent and cure disease. It has been the subject of numerous scientific studies, which demonstrate its significant antibiotic, antifungal and antiviral properties. When extracted from crushed raw garlic, allicin kills bacteria or fungi on contact.
    The complex chemistry responsible for making allicin has only begun to be explained in the last few decades. Scientists started to study garlic around the time of the industrial revolution, along with research into the chemical make-up of other plant drugs such as aspirin from the willow and morphine from the opium  poppy. In 1944, scientists working for the Winthrop Chemical Company in the United States found that garlic cloves contain cells that are rich in alliin, a sulphur-containing version of an amino acid and that separate cells contain the enzyme allinase. Alliin itself has almost no smell or taste, but when a garlic clove is  cut or crushed, the cell walls are damaged and alliin and allinase come into contact. This triggers a chemical reaction that forms sulphenic acid, but this is unstable and steadily breaks down into another compound – allicin.
    Allicin is also very unstable and once created, it breaks down into other sulphur compounds called sulphides, which are responsible for garlic’s arresting aroma. Sulphides are made very quickly if garlic is heated or cooked after crushing, but are made slowly if the crushed garlic is left standing or in the fridge. This is why crushed garlic becomes stronger smelling and stronger tasting the longer it is left. Although the majority of the sulphides have therapeutic properties, these eventually break down into polysulphides, which have no health benefits. Therefore, to take advantage of garlic’s health benefits, it is best to eat it as fresh as possible, while allicin is still present.

Used with permission from “Garlic: The Mighty Bulb" by Natasha Edwards; photography by Peter Cassidy, Firefly Books 2012

About Charleen Wyman

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