What Gives Onions Their Distinctive Smell?

If you’re anything like me, you’ve encountered the awful situation of having to chop onions in the kitchen when unexpected visitors showed up.

Then what? When you prepare onions, everyone in your home will start crying for no apparent reason, and your house will smell like the devil farted in the kitchen.

What Gives Onions Their Distinctive Smell?


What Precisely Gives Onions their Distinctive Odour?

After my guests left, sneezing and wiping their eyes, I made the decision to conclude the discussion.

I contacted my son-in-law, a chemistry professor, and he completely blew my mind with his explanation of onions.

Why do Onions have such a Pungent Flavour?

Propenylsuplhenic acid, a sulfur-containing acid, is converted by the enzyme alliinase into lachrymatory-factor synthase and thiosulfinate to produce the pungent onion smell.

Onions have a sulphurous odour that is caused by alliinase.

Alliinase, the enzyme that causes the odour, has several positive health effects.

What Causes Allums to Have an Allinase Smell?

Onions have a distinct aroma that has been compared to a cross between a tar pit and a hard-boiled egg.

The mouth, nose, and eye mucous membranes may become irritated by the strong onion odour.

In other words, you taste the onions rather than just smelling them.

The enzyme alliinase breaks down the sulfur-rich propenylsulphenic acid in onions, creating the pungent aroma that is unique to onions.

Because this scent is concentrated in the onion fluids, cutting garlic or onions leaves a persistent scent on the skin.

Why Cutting Onions Makes Them Smell More

While conversing with my son-in-law, I was astonished to discover that only the onions I was cutting had the offensive onion odour while the ones that still had their skins on smelled much better.

The fact that I had already chopped the stinking ones separated them from the fresh ones as the only distinction. What set them apart from the other onions such that they could smell while they discreetly went about their own smelly business?

My smart son-in-law, a professor of physics, has solutions for this as well. It appears that a sulfuric gas is produced when the alliinase enzyme converts sulphate.

Onion flesh undergoes this transformation when exposed to air.

I emitted the unpleasant syn-propanethial-s-oxide gas that is created when air enters an onion’s cells when I cut the onion.

How to Cut Down on Onion’s Strong Odor

I then wanted to know how to deal with the gas leak so that my kitchen would keep its pleasant scent and not turn into a sulphurous swamp.

There are a few unexpected techniques to lessen the strong odour of onions.

Slice a few chilled onions.

Place your unsliced onion in the freezer for 10–20 minutes before to slicing to dramatically limit the emission of sulphur gas.

Chemical reactions typically require heat or ambient temperature to occur (at the most basic level of chemistry).

The cold would impede the chemical reactions. Low temperatures consequently prevent the alliinase process from producing the gas.

Delete the Roots and Peel the Onion Skins

Another great way to reduce the odour is to slice off the onion’s root end before peeling and slicing it.

Put this onion piece in a closed bag or container to contain the onion smell. The base of the onion contains the majority of its sulphur compounds.

Making Use of Water

Onions can also be washed, peeled under running water, rinsed, and then cut into slices to minimise their strong odour.

The water will seal off the onion cells from the atmosphere, preventing the release of sulfuric gas.

The Three Best Methods for Cleaning Your Hands After Working with Onions

Onion juices not only smell strongly of onions but also taste and feel strongly like onions. Your hands will begin to smell strongly of “onion” as soon as you start slicing onions. It could be challenging to get rid of it.

Method 1: A salt-and-soap scrub:

By combining equal parts liquid soap and salt to scrub your hands with for at least a minute, you can get rid of the smell of onions.

Your hands should feel silky smooth and free of the onion odour.

Method 2: Acid Wash

Instead of using pool acid, consider using vinegar or lime juice to get rid of the smell of onions on your skin.

Pour some of these acidic liquids into your hands to use, then scrub vigorously for a minute before rinsing.

Method 3: Rub stainless steel using:

As a last resort, massage your hands together under flowing water while holding a stainless steel bar or spoon.

This will assist in getting rid of the onion smell. Stainless steel may be cleaned to get rid of the sulphur that gives onions their strong smell.


Even though I’ve always loved onions, I now go out of my way to freeze them before I cut and peel them.

I always keep a plastic container handy to further cover the onion’s root portion and decrease its smell.

My house no longer has a strong onion odour as a result of these actions.

I’ll be happy to welcome your visitors into my home while I’m putting the supper together.