You’re about to learn that you've been getting it wrong for years!
There are, admittedly, more important things going on in the world. But the Great Fridge Debate is hard to ignore, with arguments raging on social media over everything from marmalade to mayonnaise, bread to butter.
So, what should we store in the fridge and what’s better left in the cupboard? Does this change once it’s been opened? What about those confusing condiments? With advice from leading food safety experts, we’ve compiled the ultimate guide of what to keep where.
Tomato sauce: Fridge
Dipping chips in cold ketchup may not be to your taste, but scientists say keeping it in the cupboard has health risks. ‘No one kept tomato sauce in the fridge a decade ago, but then it contained more salt,’ says Dr Peter Barratt of Initial Hygiene.
‘In recent years, food manufacturers have cut the amount of salt, a natural preservative, because of its links to high blood pressure. ’But a lack of salt means tomato sauce is prone to decay, a process accelerated when high temperatures - anything above 16c - help food poisoning bacteria to thrive.
Storing it in the fridge typically between 0c and 4c slows this down and makes the sauce last longer. An unopened bottle can be stored in the cupboard because the seal on the lid stops the germs from getting inside.
Even on a hot day, chocolate should be kept in the cupboard and never the fridge. This applies to ordinary bars, biscuits, truffles and sweets, though there are exceptions for wafers with very thin, easily melted chocolate layers and chocolates with creamy fillings.
Refrigerating chocolate can lead to ‘sugar bloom’, which occurs when it’s chilled then exposed to warmer air. It causes condensation on the surface, dissolving some of the sugar, which recrystallizes as a grainy, white coating. Chocolate also absorbs odours, so there’s a risk it will end up smelling and tasting like last night’s leftovers.
It may be made from dairy, but unlike milk and cream, butter won’t go bad if you keep it out of the fridge for a couple of days. The cream used to make butter is pasteurised, which repels bacteria and lengthens its shelf life. It’s also mostly fat at least 80 per cent - high fat combined with a low water content makes it less friendly to bacterial growth.
Food hygiene expert Dr Lisa Ackerley advises keeping small quantities in a covered butter dish on the table, making it easier to spread than if kept in the fridge. ‘However, I wouldn’t keep it for any longer than a few days as it will go rancid,’ she says.
The biggest risk with eggs is salmonella, a food poisoning bacterium that could cause around hospital admissions and deaths worldwide. Salmonella can live in fresh eggs, even with clean, uncracked shells, but the risk is increased by changes in temperature which can also affect the quality and taste.
Because of this, the Food Standards Agency recommends storing them in the fridge. This can be a pain, as most recipes - particularly baking - call for room temperature eggs, but Dr Stuart-Moonlight says there’s no harm in taking them out a few hours before you need them.
‘However, most eggs in this country are from vaccinated flocks and, therefore, the risk of salmonella is low,’ she says.
Salad dressing & Mayonnaise: Fridge
The fresh eggs and cream in these products can spoil easily, so despite the acidic lemon juice they should be kept in the fridge. ‘They can become rancid if they are kept at room temperature,’ says Dr Lisa Ackerley.
Love it or hate it, Marmite the gloopy yeast extract spread should never be kept in the fridge.
It contains so much salt, which acts as a natural preservative that it will almost never go off even several years down the line.
Refrigerating Marmite even squeezy tubes will make it rock solid and impossible to spread. If it’s been in the cupboard for ages, a sniff will tell you if it’s still edible.
Jam & Marmalade: Cupboard
Unlike tomato sauce, keeping your preserves in the fridge can stimulate mould growth. Food technologist Brian Smith explains this is because condensation caused by trapped hot air forms in the gap between the preserve and the lid, creating the perfect environment for bacteria to germinate. Thanks to their fruit content, jam and marmalade is naturally acidic, which inhibits bacterial growth.
Cheese is high in protein, which acts as an energy source for bacteria to grow and means it’s prone to going off. Soft cheeses such as mozzarella and goat’s cheese have the shortest shelf life because, in addition to the protein, they have low levels of salt.
Medium cheeses such as cheddar, edam and gruyere are also best kept in the fridge, as the cold locks in acidity and flavour. Hard cheeses such as parmesan and manchego may be stored out of the fridge, as they have low moisture content and, therefore, are less likely to decay. However, ‘once a cheese has come out of its wrapping or a wheel is cut, it’s exposed to micro-organisms in the air and should be refrigerated,’ says Dr Stuart-Moonlight.
Bananas & Avocados: Cupboard
These fruits grow in hot climates, so are unused to the cold. If kept in the fridge, the ripening enzymes are inhibited. As these become inactive, other enzymes which cause cell damage and blackened skin work more efficiently. Because of this, bananas, avocados and citrus fruit are all best stored in a cool (not cold) cupboard, where they can ripen at a normal pace.
Though many people think it makes it last longer, putting bread in the fridge dries it out (the low temperature sucks the moisture out) and makes it go stale faster. However, it can be kept in the freezer for up to three months. Sub-zero temperatures halt the growth of mould, returning it to an almost fresh condition when defrosted.
Fresh herbs: Cupboard
Excess water most domestic fridges are full of condensation can turn the leaves slimy and light every time you open the door makes them yellow. Basil tends to go off faster and will wilt in a fridge overnight — it oxidises faster than drier herbs, such as rosemary and thyme.
It isn’t harmful to eat, but oxidisation ruins the flavour. Experts advise storing herbs in a sealed container, lightly wrapped in a damp cloth or tea towel, which retains just the right amount of moisture to stop them going off.
The delicate flavour of tomatoes, which tend to grow best in hot countries, is best preserved at room temperature. The balance of sugars, acids and compounds known as volatiles are responsible for everything from texture to aroma.
Placing them in the fridge causes these volatiles to disintegrate, as well as slowing down the natural ripening process, which makes them red and juicy. In addition, tomato skins become tougher if kept in the fridge says Dr Stuart- Moonlight.’
Peanut butter: Cupboard
This tends to contain all-natural ingredients: peanuts, oil and a little sugar or salt. Initial Hygiene’s Dr Barratt says: ‘As it’s not packed with preservatives, the peanut butter could start to degrade, ruining the product and risking tummy upsets.
‘However, this is unlikely to be a cause for concern if it is used within three months of opening. ’Peanut oil can withstand high temperatures, so won’t melt if it gets hot in your kitchen. But other nut butters break down more easily and so should be stored in the fridge.
Pickle, Chutney & Mustard: Fridge
These tend to contain less sugar than preserves and less salt than Marmite, so pickles, chutneys and mustard are safer in the fridge particularly once opened. ‘Read the instructions, some might be safe at ambient temperatures,’ says Dr Ackerley. ‘If your friend has made it for you, keep it in the fridge.’ Home-made pickles and chutneys are susceptible to growing mould as the jars haven’t been professionally sealed.
These should be kept somewhere that is cool and dry, but must never be refrigerated.
‘Storing raw potatoes in the fridge may lead to the formation of free sugars, which can increase overall levels of acrylamide, a chemical that has been linked with an increased risk of cancer,’ says Joanna Abishegam-David of the Food Standards Agency. Acrylamide is increased if you fry, roast or bake potatoes.
Apples are one of the few other fruits that benefit from being stored in the fridge. As they ripen, they give off ethylene gas, which is a natural compound that makes nearby fruit and veg ripen and eventually rot. Storing them in the fridge slows the production of ethylene, making them last longer.
Onions, Root Veg & Garlic: Cupboard
A dry, dark cupboard prevents these from sprouting, a process caused by exposure to light. Garlic will go mouldy in a fridge, while cut onions which release a gas called propanethial S-oxide that mixes with parts of the onion to produce sulphur will make other food smell. All are best stored in separate bags or boxes inside a cupboard.
Once open, wine is best stored in the fridge, even red. Decay is caused by oxidation, which turns wine to vinegar, so keeping it corked, upright and cool minimizes oxygen exposure and slows the process. But who has left-over wine?