24-05-2025
You're chopping onions wrong! Scientists reveal how to cut the vegetable without crying - and their method is surprisingly simple
From Italian pasta sauces to Indian curries, dishes from around the world all feature one key ingredient - the humble onion.
While they're undoubtedly delicious, onions can be a nightmare to chop.
Thankfully, the days of reaching for the tissues or succumbing to the swimming goggles are a thing of the past.
Scientists have revealed how to cut onions without crying - and their method is surprisingly simple.
According to a team at Cornell University, the secret to tear-free onion cutting is simply a sharp knife and a slow cut.
This method reduces the amount of onion juice that sprays into the air and gets into your eyes.
'Our findings demonstrate that blunter blades increase both the speed and number of ejected droplets,' the team explained.
'[This provides] experimental validation for the widely held belief that sharpening knives reduces onion-induced tearing.'
Previous studies have shown that onions cause eye irritation due to the release of a chemical called syn-propanethial-S-oxide.
However, until now, the best tactic to reduce the amount of this chemical spewed into the air during slicing has remained a mystery.
To answer this question once and for all, the team set up a special guillotine which could be fitted with different types of blades.
During their trials, they sliced onions with varying knife sizes, sharpness, and cutting speed.
As they cut the onions, the researchers filmed the setup to assess exactly how much juice was being ejected into the air.
Their results revealed that the amount of spray came down to two key factors.
Firstly, the sharpness of the knife - with sharp blades resulting in less spray.
'Duller knives tended to push down on the onion, forcing its layers to bend inward,' the experts explained in a statement.
'As the cut ensued, the layers sprang back, forcing juice out into the air.'
Secondly, the speed of the cut was found to affect the amount of juice released.
While you might think that a quick cut would result in less spray, surprisingly this wasn't the case.
'Faster cutting also resulted in more juice generation, and thus more mist to irritate the eyes,' the team explained.
Based on the findings, if you want to cut your onions with minimal tears, it's best to opt for a sharp knife and a slow cut.
'Beyond comfort, this practice also plays a critical role in minimizing the spread of airborne pathogens in kitchens, particularly when cutting vegetables with tough outer layers capable of storing significant elastic energy prior to rupture,' the experts added in their study, published in arXiv.
CAUSES OF BAD BREATH (HALITOSIS)
There are a number of possible causes of halitosis:
Poor oral hygiene
This is the most common cause. Bacteria that build up on your teeth – particularly between them – as well as your tongue and gums, can produce unpleasant-smelling gases. These bacteria are also responsible for gum disease and tooth decay.
Food and drink
Eating strongly flavoured foods, such as garlic, onions and spices, is likely to make your breath smell. Strong-smelling drinks, such as coffee and alcohol, can also cause bad breath.
Bad breath caused by food and drink is usually temporary. Good dental hygiene will also help.
Smoking
As well as making your breath smell, smoking stains your teeth, irritates your gums, and reduces your sense of taste.
It can also significantly affect the development of gum disease, another major cause of bad breath.
Crash dieting
Crash dieting, fasting, and low-carbohydrate diets are another possible cause of bad breath. They cause the body to break down fat, which produces chemicals called ketones that can be smelled on your breath.
Medication
These include: nitrates – these are sometimes used to treat angina; some chemotherapy medication; and tranquillisers (phenothiazines).
If the medication you're taking is causing bad breath, your GP may be able to recommend an alternative.
Medical conditions
In rare cases, bad breath can be caused by certain medical conditions. In dry mouth (xerostomia), the flow and composition of saliva may be affected.
Dry mouth can sometimes be caused by a problem in the salivary glands or by breathing through your mouth instead of your nose.
In some cases, gastrointestinal conditions can also cause bad breath. For example, a bacterial infection of the stomach lining and small intestine (H. pylori infection) and gastro-oesophageal reflux disease (GORD) have been linked to bad breath.
Other medical conditions that can cause bad breath include diabetes and lung, throat, or nose infections – for example, bronchiectasis, bronchitis, tonsillitis, and sinusitis.
