Dr Jo Buckley tells us the chemistry behind the way stainless steel could remove garlic smells.
The medical properties of garlic were recognised over 5000 years ago. It’s provides a triple-whammy of effectiveness. It’s an antimicrobial – studies have found it effective at reducing bacterial infections. It’s an antiviral – helping to fight viruses and parasites and it’s an anti-fungal agent too. It also helps prevent strokes and heart attacks as it enlarges blood vessels, promotes blood flow and helps to reduce heart disease by preventing a build up of unwanted chemicals in arteries.
But for all of these health benefits, there’s one major drawback. You’ll inevitably end up with stinky hands after you’ve been handling it, and the smell takes a while to diminish. So before you reach for the soap and water, chemistry can offer another method for you to try.
A common ‘old wives tale’ suggests rubbing garlicy hands on something made from stainless steel, such a spoon or a kitchen tap. This idea has even spawned a new product – stainless steel soap; a soap-sized chunk of the stuff which you can use in place of normal soap. A bar of stainless steel soap will set you back a few quid, so is it worth forking out?
Whilst the scientific data is sketchy, chemistry tells us stainless steel could remove garlic smells. Garlic is packed with sulfur-containing chemicals, responsible for its characteristic taste and odour. Allicin is thought to be the culprit guilty for making your hands whiff but it’s only created when two chemicals react – the enzyme alliinase and a sulfur-containing amino acid called alliin, which are held in separate portions within the cell walls of the garlic clove and only mix when the garlic is squished.
You can try it yourself – a bulb of garlic doesn’t smell of very much at all but slice into it and smell again. The chemical reaction converting alliinase and alliin into allicin is almost instantaneous.
When allicin degrades it produces even more smelly sulfurous compounds, including diallyl disulfide, all contributing to garlic’s characteristic aroma.
So how can stainless steel help? Stainless steel is an iron alloy with minimum of 10.5% chromium by mass. This layer of chromium is what makes stainless steel less likely to rust, corrode or stain. Chromium forms an oxide when it remains in contact with air and water, making it more durable. It’s believed this oxide layer helps to remove unwanted smells. The sulphur-containing chemicals left on your hands may form a chemical bond to the chromium oxide and cling to the surface of the soap, not to your hands.