It’s an essential item for any home cook, but an expert warns that you should never use aluminium foil to store your leftovers.
Dr Zachary Cartwright, a food scientist for Aqualab in Chicago, says food wrapped in foil is at risk of infection by dangerous bacteria.
Unlike safer options such as Tupperware containers and sealable plastic bags, foil does not create an airtight seal.
Airtight conditions prevent air and in turn oxygen from getting to the food, which most dangerous pathogens need to grow.
‘Aluminum foil alone cannot create a completely airtight seal because it’s not inherently adhesive and [it] doesn’t conform perfectly to surfaces,’ Cartwright told Southern Living.
Eating leftovers that have been wrapped with foil can risk serious food poisoning that can even be fatal.
Dr Cartwright’s warning follows outage over Tesco‘s decision to replace the hard plastic lids on the supermarket’s hummus pots with ‘flimsy’ covers.
Following Tesco’s decision, experts warned the flexible covers don’t make hummus pots airtight, which lets microbes such as bacteria, fungi and viruses thrive.
It’s an essential item for any home cook, but an expert warns that you should never use aluminium foil to store your leftovers
It follows outage over Tesco’s decision to replace the hard plastic lids on the supermarket’s hummus pots (right) with ‘flimsy’ flexible plastic covers. The hard lids are better at creating an airtight environment for the hummus than the soft lids
Aluminium foil – which replaced tin foil on the market decades ago because it is cheaper and more durable – is useful for cooking fish or transporting sandwiches.
But it is not suited for wrapping leftovers with, according to Dr Cartwright, despite the popular habit of doing so.
Much safer options are using Tupperware containers, sealable plastic bags or even cling film, because these can create an airtight seal that help prevent microbe growth.
Examples of risky microbes that grow on food are staphylococcus (staph) – bacteria that can multiply on food and make a toxin that causes food poisoning.
Another bacteria is Bacillus cereus which can produce poison that causes fever, vomiting, abdominal pain and diarrhoea.
Improper aluminium foil storage also increases the risk of Clostridium botulinum and Listeria monocytogenes growing, the expert said.
While these two bacteria are rarer, both can result in serious illness.
Clostridium botulinum produces toxins that can block nerve functions and can lead to respiratory and muscular paralysis, warns the World Health Organisation.
Although aluminium foil is often a good method for cooking food or transporting your lunch to work, it is not suited for storing leftovers in the fridge
Aluminium foil replaced tin foil on the market decades ago because it is cheaper and more durable – but its use is not without health hazards
When people eat food contaminated with L. monocytogenes, they may develop a disease called listeriosis, which can be very serious for pregnant women, people older than 65 and people with weakened immune systems.
Primrose Freestone, a senior lecturer in clinical microbiology at the University of Leicester, also stresses the importance of airtight containers for leftover food.
She says you’re at risk of ‘potentially life-threatening food poisoning’ if you have not stored and re-heated leftovers correctly.
She also stresses that a typical fridge temperature between 37°F (3°C) and 40°F (5°C) is not enough to stop all dangerous microbes from growing – which is why freezing may be a better choice.
‘Cold only slows down the growth of pathogens such as Staphylococcus or Bacillus cereus,’ Professor Freestone told MailOnline.
‘Only freezing solid at minus 20°C stops food poisoning bacteria from growing.’
What’s more, aluminium is at risk of reacting with acidic and salty foods and leaching into the leftovers, such as a tangy tomato sauce, according to Dr Cartwright.
Aluminium intake over time has been linked with neurotoxic developmental disorders as well as damage to the kidneys, liver and bones.
Electron micrograph of Bacillus cereus, which can produce poison that causes fever, vomiting, abdominal pain and diarrhoea
Overall, you’re best using sealable plastic containers for leftovers, which Professor Freestone admits are great for saving money and reducing food waste.
Other good tips for storing leftovers include labelling and dating the containers so you can accurately keep track of what needs eating up.
Always eat leftovers within two days and discard them if you notice any dubious signs – such as unusual smells or textures, which could be mould.
‘Bacteria exist everywhere in our world, including in kitchens – and the foods within them,’ Professor Freestone writes in a recent article for The Conversation.
‘The bacteria that cause food to spoil can grow rapidly with the right nutrients, moisture and temperatures.
‘Some double in numbers in as little as 20 minutes.
‘Leftovers can be safe to eat so long as you take the right precautions.
‘But if you’re ever in doubt, or don’t think you’ll eat them within two days, storing them in the freezer will give you more flexibility than storing them in the fridge.’