Know your onions! The definitive and surprising guide to organising your fridge

The UK food authority has changed its advice on refrigerating potatoes – and that isn’t the only food whose storage you might want to reconsider

The UK’s self-styled consumer champion, Which?, updated its advice last month on what people should keep in their fridges. The item that has turned the most heads is the potato; it is no longer out, but in.

Why the volte-face?

For a long time, the government’s position was that raw potatoes should not be chilled. This was to avoid “cold sweetening”, the formation of additional cold-induced sugars that, when potatoes are fried, roasted or baked, convert into a chemical called acrylamide, which is thought to pose a cancer risk to humans.

But a recent study has shown that, as the Food Standards Agency put it in its latest update, “home storage of potatoes in the fridge doesn’t materially increase acrylamide-forming potential when compared to storage in a cool, dark place”. Not only is the fridge fine after all, but it makes spuds last three times longer.

What else have we been getting wrong? It turns out that how we refrigerate our foods is a science.

Temperature-wise, this is the most inconsistent area, because you open and close it regularly. So, use it for preserved items, which are designed to last the longest.

This includes unfinished drinks, including non-dairy milks, sodas, fruit juices and water. Screw on the lids properly and stick to the timeframes specified on the packaging. Most should be consumed within seven days.

Opened jars of pickles, jams, syrups, spreads, preserves and ferments (such as miso and kimchi) should have their lids screwed on firmly, or pouches sealed, to avoid spillages and contain smells. The nuts in natural nut butters can go rancid and the oils can separate at room temperature, so the fridge is the place for these, too.

Sauces, including hot, soy, fish, ketchup and mustard, will last longer if kept chilled, so if you use them only occasionally, refrigerate them.

Non-food items: Instagram influencers often have dinky cosmetics fridges, but a sealed container, pouch or ziplock bag in your main fridge will do just as well for beauty products that prefer cool temperatures: nail varnish and other solvent-based products; preservative-free skincare products; balms and eyeliners that tend to melt in the heat. See also: 35mm film and strong glues.

This is the warmest spot, unless you have a freezer compartment above it, so use it for ready-to-eat items that need to be used up quickly: dips, yoghurt, cream, desserts, prepared salads.

The advice from Love Food Hate Waste is that cooked vegetables, like any other cooked food, are best eaten within two days. Other official sources say up to seven. But the basic idea with a fridge – as opposed to a freezer – is that fresh is best: you put in there the food you are going to eat soonest.

Butter in the fridge is considered sacrilege by some diehard foodies, but the official advice is generally to chill butter. The Food Safety Information Council in Australia explains that this is because it is less salted – and therefore less preserved – than it used to be; the higher the temperature, the higher the risk of the oils going rancid. Store in a resealable container and take out a portion in advance to soften for spreading.

Cheese (fresh, cream and hard) is best kept on the top shelf or in the vegetable drawer, wrapped in wax or greaseproof paper (clingfilm for soft cheeses) and stored in a sealed container, lined with a layer of kitchen towel. Be sure to take it out of the fridge in good time before eating, to bring it up to room temperature.

Tomatoes and cucumber will last longer if kept cool, but not too cool, so opt for the top shelf or the door and return them to room temperature up to 24 hours before using (the cold inhibits the flavour).

Cooked meats, fish and poultry – either shop-bought or fully cooled leftovers – go here. Use within two days.

Be sure to use fresh pasta in a timely fashion, according to the package instructions.

Milk doesn’t like the fridge door – it is too warm.

Mushrooms are not happy in plastic bags or containers. Put them in paper bags, perforated packaging or cardboard punnets that avoid the buildup of moisture, which will cause mushrooms to spoil.

Eggs need temperature stability, while ideally staying cool and dry. If you have bought them off a shelf, keep them on a shelf. If you have bought them from a fridge, keep them in yours.

Raw meat, fish and poultry fare best in sealed containers, to avoid cross-contamination, by touch or drip, with other foods. Abide religiously by their use-by dates; do not risk it if the product is in any way iffy.

Even though it takes longer, always defrost in the fridge, to keep thawing bacteria at bay. Place the frozen item in a tray to catch melting liquids and cover loosely. Make sure it is fully defrosted before using, then cook within 24 hours. Never refreeze. Remember, too, that there are plenty of things you can cook from frozen: fresh pasta, dumplings, fish, vegetables, fruit and cooked rice.

People get anxious about cooked rice, because it can cause food poisoning if not stored properly, but you just need to know what to do with it. Cool it down quickly and refrigerate immediately if you know you will eat it within 24 hours. If not, freeze it immediately, preferably in portions. Defrost it, then reheat on the hob or in a microwave, making sure it is piping hot. Eat promptly, discarding any leftovers.

These are called crispers and are designed to alter the airflow and increase the humidity, thereby keeping fruit and veg – which prefer higher humidity – crisp and fresh. But keep your vegetables separate from the fruit: the ethylene that certain fruits (apples, melons and bananas, although you probably won’t refrigerate these; see below) and mushrooms produce will cause other things to ripen and spoil. If you have only one drawer, keep it for the veg and store fruit on middle shelves.

Avocados, like pears, need to ripen at room temperature. Thereafter, you can store them in the fridge, but, like most fruit and veg, you want to use them quickly, to capitalise on the fresh flavours.

Cruciferous vegetables such as cabbage, broccoli, cauliflower, greens, sprouts and Chinese lettuce need to be stored in their original packaging, or a perforated bag, to keep them aerated and avoid the buildup of moisture. It is wise to chill produce in the packaging it came in, because it has been designed to make it last as long as possible. Shrink-wrapped cucumbers, for instance, have been found to last 11 days longer than unwrapped cucumbers.

Root vegetables such as potatoes, carrots, fresh beetroot and parsnips last longer in the fridge. Unless very dirty, the general advice is to wash produce just before you use it, because bacterial growth can occur in the fridge, so you would have to wash it again anyway. If you do wash it before storing it, make sure you dry it thoroughly, as moisture can speed up deterioration.

Bagged salad leaves and lettuce should stay in their original packaging, or in a loosely tied plastic bag, preferably with a sheet of kitchen towel, to absorb excess moisture.

Celery, aubergines, fresh beans, courgettes and fresh ginger will stay fresher and last longer when kept cool in their original packaging.

In terms of alliums, only spring onions and leeks need to be refrigerated. Brown, red and white onions are best kept in an aerated, cool, dry, dark place.

Keep fresh herbs in their original packaging. Once open, bunch, trim the ends and stand in a glass of water, like you would a bouquet of flowers.

And so to fruit. Grapes and berries like to be kept chilled and unwashed, in their original punnets. Melon, if cut, should be stored in a closed container in the fridge. Whole fruit does not need to be chilled. Apples last longer in the fridge, but make sure they can breathe. Whole citrus fruits will last a week on your counter (away from direct sunlight) but three to four times that if kept chilled. There is some disagreement on whether to store them in a mesh bag or a sealed one, but a Cook’s Illustrated experiment suggests that a sealed bag lined with a sheet of kitchen roll will stop the fruit from drying out and avoid excess moisture, which would make it go mouldy.

Bread and other baked goods dry out in the cold, so store them wrapped or sealed (in a plastic bag or a bread bin) in a cool, clean, dry, dark place.

Bananas go black in the fridge. That said, the flesh doesn’t go bad; the skin just bruises.

Sweet potatoes can go hard in the centre and lose their flavour, so they are best stored in a cool, dark place. Same goes with garlic bulbs.

Cake-decorating foodstuffs such as food colouring, flavour extracts, sugar decorations and leftover fondant need to be kept well sealed in a cool, dry, dark spot.

Coldness makes honey crystallise, which isn’t harmful, but does make it harder to use.

Stone fruits don’t much like the cold, so keep them on the counter until ripe. At that point, you could refrigerate them, to slow down the process, but honestly: if you have good ripened apricots or peaches, you are best eating them all there and then.

If they are staples that you use up quickly, keep your favourite condiments, from ketchup to tahini, on a counter or a shelf, away from direct sunlight and heat.

Unless there is a heatwave, the fridge is a big no-no for chocolate. The damp cold results in condensation melting sugar on the surface, which then crystallises and makes the bar look ashy and taste awful. Far better to keep it in a tightly sealed container, at a steady room temperature, no warmer than 20C.

Almost all coffee brands advise against refrigeration, for many reasons: the condensation caused by temperature changes will make it go stale quicker; it will absorb fridge smells; and the cold will spoil the oils. Whether ground or whole bean, it should be kept in an opaque, airtight container on a pantry shelf. The only coffee grounds to visit your fridge should be used ones, in a bowl or a jar with a perforated lid, to deodorise it.

It is not only how you organise your fridge, but also how you use it. There are some basic ground rules that will help you to get the best from it.

First, keep it clean. Mop up spillages immediately. Wipe down the handle and the door daily. Switch it off, empty it and clean it out once every three months, using warm water and washing-up liquid, or a paste of bicarb and water for stubborn stains.

Second, keep your fridge cold. The temperature should always be between 0C and 5C, but the dials on standard home appliances are not necessarily reliable, so get yourself a fridge thermometer. Do not overfill. You want the chilled air to circulate freely and evenly.

Finally – and this can be challenging – keep tabs on what is in there. Stock old in front of new. Know the difference between use-by dates (the ones you never ignore) and best-before dates (an indication of optimum quality). If in doubt, bin it.