Chemistry Blog

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Nov 24

Does stainless steel really get rid of garlic smells? Round 2.

by Mark | Categories: Uncategorized | (249969 Views)


Some time ago we put the old wives’ tale that stainless steel gets rid of garlic whiffs to the test. The results were inconclusive and with hindsight the control probably wasn’t ideal. So we are having another go, this time with the backing of the Royal Society of Chemistry and a consortium of chemistry outreach folk from the Universities of Hull, Sheffield, York, Leeds, Bradford and Huddersfield (the Yorkshire Chemistry Outreach Group).

This is where you come in

We need as many people as possible to perform a simple experiment to test whether stainless steel really is an effective odour remover.

You’ll need: A clove of garlic. A knife. A blindfold. A plastic spoon and a stainless steel table spoon of about the same size.

What to do:

  1. Wash and dry your hands (so they don’t smell of anything to start with).
  2. Slice out a piece of garlic.
  3. Rub the freshly cut garlic between your hands for about 10 seconds.
  4. Under running water, rub one palm with the back of the stainless steel spoon for about 10 seconds. Then rub the other palm with the plastic spoon, again under running water, for 10 seconds (the plastic spoon is our control experiment). Make sure you remember which hand was rubbed with which spoon.
  5. Find a willing volunteer. Ask them to close their eyes or put a blindfold on – with their eyes closed, they are less likely to notice any signals from you about which hand has had what treatment.
  6. Hold a hand under their chin (that way each hand will be the same distance from the test subjects nose) and ask them to smell it. Then do the same with the other hand.
  7. Ask them which hand smelt more strongly of garlic.
  8. Let us know whether one hand smelt more than the other, or whether they smelt the same using this survey below.

What causes the whiff?

Garlic is packed with sulfur-containing chemicals, which are responsible for its characteristic taste and odour. Allicin, in particular, is thought to be the culprit most guilty of making your hands (and breath) pong, but it’s only created when two chemicals react – the enzyme alliinase and a sulfur-containing amino acid called alliin. These 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. When cells are crushed, the chemical reaction converting alliinase and alliin into allicin is almost instantaneous.

And when allicin degrades, it produces even more smelly sulfurous compounds, including diallyl disulfide. These all contribute to garlic’s characteristic aroma.

The chemistry of garlic.
www.compoundchem.com

How might stainless steel banish the pong?

The scientific data on whether the stainless steel trick actually works to get rid of stinky garlic hands is sketchy – although chemistry tells us that it might well work. Stainless steel is an iron alloy with a 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 is in contact with air and water, making it more durable. It’s possible that this oxide layer could help to remove unwanted smells. The idea is that the sulfur-containing chemicals left on your hands after chopping garlic may form a chemical bond to the chromium oxide and cling to the surface of the soap, not to your hands, solving the smell problem. But we don’t really know.

We’ll need plenty of tests if we are going to be sure of our results, otherwise it’s just more anecdote. And we’ll get back to you, to let you know whether it’s worth forking out for stainless steel soap soon.

Over the next few months, we’ll be asking for more help from citizen scientists to check the efficacy of tips that may make flowers live longer, peeling a boiled egg easier and extend the burning time of candles. Check out the Hit or Myth blog to find out more.

The Conversation

Mark Lorch, Professor of Science Communication and Chemistry, University of Hull and Joanna Buckley, Materials chemist and science communicator, University of Sheffield

This article was originally published on The Conversation. Read the original article.

7 comments

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  1. Alfredo M. Claussen

    I rub my hands on the stainless steel sink, not a spoon. It works every time. I’m no chemist, but a Chemical engineer, so I am not prone to old housewives stories!. It definitely works for me. NOTE: my sink is made of 304 type austenitic Stainless steel, that is around 18% Cr and 8 % Niquel…

  2. Puja Pal

    Crushed or fresh garlic contains sulfer containing compounds like alliin, ajoene, s-allylcysteine, enzymes, saponins and many other maillard reaction elements so it can make reaction with stainless steel.

  3. Ramona A (LRSC

    I did this experiment myself and it does work. I used a stainless cooking spoon and a plastic cooking spoon but how did the stainless spoon remove the odor without adding any special solution is what I don’t understand.

  4. Mackenzie

    I did this experiment and it did seem to work for me. The hand that i rubbed with the stainless steel spoon had much less of an odor than the one I rubbed with a plastic spoon. I am not sure how or why this works, but it did seem to work for me!

  5. Intissar el hani

    This is very interesting experiment I will perform the experiment and double check on that. This is a very interesting reaction that occurs between the garlic and stainless steel.

  6. Amy F (LRSC)

    That’s super crazy that garlic doesn’t have an odor until the two internal chemicals mix. That makes sense why chefs prefer to crush or mince their cloves. So I take it that the steel metal is reacting with one of these chemicals, or it’s altering it into something new. Maybe that’s why it becomes odorless. Reminds me of an antidote for toxins from plants and animals. In another sense, we can alter something poisonous and turn it into something harmless. For example, table salt is harmless, but it was derived from inedible chemicals that could kill a human. So it makes sense how combining elements will completely change them from what they were. In this case it’s garlic odor.

  7. marianah1995

    Wow this is amazing..

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