When we questioned consumers on how they store their sauces and condiments, we discovered a lot of confusion, misinformation and downright bad habits - including ones that could be putting their health at risk.
By law, manufacturers are required to put storage guidance on their products. But more than a third of respondents in our research* said they never check to see where condiments should be stored, or for how long. Only a fifth said they always do.
So what's the score: fridge, cupboard or either? We spoke to three food experts - a public analyst, a special adviser on food and drink, and registered dietitian Dr Sarah Schenker - for the lowdown.
What the label advises: After opening, keep refrigerated and use within three months (Hellmann's Real Mayonnaise).
What the experts say: Although it contains vinegar, there's not enough in there to safely store this creamy, egg-rich condiment outside the fridge.
Dietitian Dr Sarah Schenker says: 'Pasteurisation provides an extra layer of safety, but it should still be refrigerated.'
Refrigerating mayonnaise will limit the growth of bacteria that you might have introduced by dipping cutlery into the jar.
What the label advises: Keep in the fridge for two weeks after opening (Saclu00e0 Classic Basil Pesto).
What the experts say: Pesto should definitely be refrigerated.
Nuts in pesto mean it can end up developing mould that produces toxic compounds called mycotoxins, including dangerous aflatoxin, a bacteria that can cause serious liver damage.
The trouble is, you can't see these toxins, so you won't even know if they're there - and if you've eaten them.
Dr Schenker says: 'Mould can be hard to see on pesto (especially if it's green), so don't take any chances either way, and stick to the label advice.'
What the label advises: After opening, refrigerate and eat within eight weeks (Heinz Salad Cream).
What the experts say: Although salad cream contains the preservative potassium sorbate, as well as spirit vinegar, it also contains egg.
Therefore, much like mayonnaise and tartare sauce, it should be refrigerated.
Dr Schenker says: 'Condiments like salad cream might be left outside during summer parties and barbecues, so it's best to decant some into a bowl to use, to prevent the entire bottle standing in warm conditions.'
What the label advises: Refrigerate after opening and use within four weeks (Buckwud Organic Canadian Maple Syrup).
What the experts say: In anything with a sugar content of more than 60%, the sugar acts as a preservative to keep microbial degradation at bay.
Maple syrup falls just short of this, allowing some moulds to get a hold, so store it in the fridge.
If you keep it in a cupboard, you may find mould forming, especially on the lid because of its exposure to air when you open it.
Dr Schenker says: 'People may think that because it's a syrup, it can be treated like others syrups such as golden syrup. But they're from different plants and have different properties, so require different treatment.'
What the label advises: Refrigerate after opening and use within two months (Colman's Tartare Sauce).
What the experts say:Tartare sauce contains egg, so this is definitely one to keep in the fridge.
It also has low acidity and a high water content, which microorganisms love.
Dr Schenker says: 'Remember to check opened jars of so-called 'occasion' sauces, such as tartare sauce or cranberry sauce, before you eat them, because it may be some time since you last had the need to use them.'
What the label advises: Once opened, refrigerate and consume within four weeks (Baxters Redcurrant Jelly).
What the experts say: This is best stored in the fridge once opened.
Dr Schenker says: 'There can be a separation of water on the surface that creates a layer with low sugar content, which is an ideal breeding ground for mould.'
What the label advises: Refrigerate once open and eat within eight weeks (Heinz Tomato Ketchup).
What the experts say: There's no need to keep ketchup in the fridge.
Not only does it contain vinegar, but tomatoes are naturally acidic, and this helps to preserve the product in ambient (room temperature) conditions.
Dr Schenker says: 'Sometimes people keep ketchup in the fridge, simply because they prefer a chilled taste, but otherwise it doesn't need to be refrigerated.'
What the label advises: No guidance about refrigeration, just 'Best before: see cap' (HP Sauce).
What the experts say: HP Sauce contains preservative ingredients including both malt vinegar and spirit vinegar, so it's fine to keep in the cupboard, along with your ketchup.
Dr Schenker says: 'It's vinegar-based, so keeping it in the fridge isn't necessary.'
What the label advises: Store at room temperature (Rowse Squeezy Clear Honey).
What the experts say: Honey naturally contains the preservative hydrogen peroxide.
Not only that, but a high sugar content forces water out by osmosis, creating an inhospitable environment for microorganisms - even at room temperature.
Dr Schenker says: 'Honey is found in hives at an ambient temperature - much like keeping it in a cupboard - so refrigeration isn't necessary.'
What the label advises: Refrigerate after opening and use within four weeks (Colman's Mint Sauce).
What the experts say: After mint, the second most abundant ingredient in this is spirit vinegar.
This acts as a preservative, so there's no need to keep it in the fridge, leaving more space for condiments that need chilling.
But one of our experts, Dr Schenker, takes a more cautious approach because of the way we tend to use these kinds of sauces.
Dr Schenker says: 'The trouble with 'occasion' sauces such as mint sauce is that they sit in the fridge waiting for a special event, like lamb at Easter, then we might not think to use them for another year. That's why it's best to refrigerate them and throw them out if you can't recall when you opened them.'
What the label advises: Once opened, keep in the fridge and use within six weeks (Branston Original Pickle).
What the experts say: This is fine to keep in the cupboard, as it contains preservatives including vinegar.
The main problem with pickles is that stray crumbs of bread, or morsels of food such as cheese, can be introduced when you stick a knife in - so use a clean one.
Dr Schenker says: 'Pickles and chutneys originally came about as a way of preserving fresh fruit and vegetables, so, by their very nature, they're OK outside the fridge.'
What the label advises: Store at room temperature, away from heat and direct sunlight (Filippo Berio Extra Virgin Olive Oil)
What the experts say: Storing olive oil in the fridge will solidify the triglycerides and monounsaturated fatty acids, so keep it in a cupboard instead.
Although refrigerating it doesn't affect the quality, it doesn't lengthen its life either, and you'll find yourself having to warm it back up to room temperature to pour it out.
Dr Schenker says: 'This is just a pure ingredient, so there is nothing that can contaminate it, such as bacteria. Therefore it's fine at an ambient temperature.'
What the label advises: Refrigerate after opening (Kikkoman Soy Sauce)
What the experts say: Dr Schenker says: 'There's no need to refrigerate soy sauce, because anything with such a high salt content is highly preserved.'
Refrigeration is only required if you're concerned about keeping the quality and flavour at their peak for longer.
What the label advises: Once opened, keep refrigerated and use within six weeks (Sharwoods Green Label Mango Chutney)
What the experts say: Acetic acid and a high sugar content act as preservatives to keep microbial degradation at bay, so mango chutney doesn't need refrigeration.
Dr Schenker says: 'Much like pickle, mango chutney has also gone through a process of being preserved, so it doesn't need to be in the fridge.'
What the label advises: Ensure the lid is closed and store in a cool, dry place out of direct sunlight (Sarsons Malt Vinegar)
What the experts say: Vinegar has an indefinite shelf life at room temperature, and can therefore be safely kept in a cupboard for years.
Dr Schenker says: 'The high acidity of vinegar means that any contaminant such as bacteria or mould getting into the bottle wouldn't stand a chance of living.'
What the label advises: Keep refrigerated and use within three months (Nando's Peri Peri Sauce Medium)
What the experts say:This contains vinegar as one of the main ingredients, which helps to preserve it.
Although the suggestion is to keep it refrigerated, it can be safely kept in a cupboard in ambient conditions.
Dr Schenker says: 'Some chilli sauces also contain high amounts of sugar, which give extra preservative protection.'
What the label advises: Best before end: see cap (Lea & Perrins Worcestershire Sauce)
What the experts say: Some people think that because it contains fish, it has to be refrigerated once opened.
However, because it's already a fermented product, it won't go off and it's fine to store it in a cupboard.
Dr Schenker says: 'Fermented foods can last for ages because, technically, they've already “gone off”. However, like wine, they will eventually oxidise, especially as you get towards the end of the bottle and more air gets in.'
Oxidation is when a food starts reacting to oxygen - like cut apples going brown - and the process can affect such things as flavour or appearance, including colour.
What the label advises: After opening, keep refrigerated and use within three months (Colman's Original English Mustard)
What the experts say: Feel free to either refrigerate or keep this vinegar-rich condiment in a cupboard - it's just a matter of preference.
Dr Schenker says: 'Storing mustard in the fridge is more about preserving the colour, which may change in a warmer environment.'
What the label advises: After opening, keep refrigerated and use within one month (Maille Dijon Original Mustard)
What the experts say: Made with wine, this French mustard also contains the preservatives potassium metabisulphite and citric acid.
Dr Schenker says: 'These preservatives mean it's fine to keep it in a cupboard, although keeping it in the fridge may help to preserve its kick and punchiness for longer.'
What the label advises:After opening, keep refrigerated and use within three months (Maille Wholegrain Mustard)
What the experts say:Like Dijon mustard, this can be kept in the cupboard, thanks to preservatives including vinegar and lactic acid.
Dr Schenker says: 'Be extra vigilant about not contaminating the product with bits of other food, as the texture could make it hard to see whether mould is developing.'
What the label advises:Once opened, keep refrigerated and consume within six weeks (Haywards Piccalilli)
What the experts say:This pickle contains enough vinegar, as well as preservative potassium sorbate, to be kept in ambient conditions after opening.
However, storing it in the fridge may help to keep the colour true, so either solution is fine.
Dr Schenker says: 'Keeping it in the fridge might also help to keep the vegetables in it crispy, but that's down to preference.'
'[I] only throw away things like soy sauce when they look so dusty that I might end up poisoned.'
'I rarely throw condiments away unless they've clearly gone off. I've fed the kids pesto with the mould scraped off...No one died.'
'I don't normally check where they should be stored or for how long. As for them going off, you can tell by the 'see it, smell it' judgment.'
Which? Twitter poll, January 2020. 'Do you ever look at the label of condiments to check where they should be stored and for how long?' Sample size 444.