How long is it SAFE to keep your leftovers? As fridges groan across the land, a microbiologist explains just how long you can keep the turkey, pigs in blankets and mince pies

Another mince pie any-one? Already lining up the recipes for turkey curry and parsnip soup?

It's Boxing Day and there is barely a fridge in the land that isn't groaning with leftovers. But how long can you safely keep them for?

We enlisted the help of microbiologist Dr Martin Goldberg, of Nottingham Trent University, to find out . . .

TURKEY

Food poisoning from turkey affects thousands every year.

The key to keeping it safe, says Dr Goldberg, is to cool the bird as fast as possible.

'You shouldn't refrigerate warm food because it raises the temperature inside the fridge,' he warns.

'This can cause bacteria in the food to start multiplying.'

 First, get the turkey down to room temperature by cutting it into thin slices to speed cooling. Then, pop it straight in the fridge

In Britain, fridges run at between 3c and 5c, which limits — but doesn't fully prevent — growth of most bugs. Bacteria will start to grow in any temperature over 8c.

'The problem with turkey is that because the carcass is so large, it takes ages to cool — and the longer it's warm for, the more likely bugs are to grow in it,' says Dr Goldberg. 'Get it down to 6c as quickly as possible.'

Of course, as you cooked your bird yesterday, this advice will be too late. But here's what you should ideally have done — and what you can do next year.

First, get the turkey down to room temperature by cutting it into thin slices to speed cooling. Then, pop it straight in the fridge. This prevents bacteria called clostridium perfringens from spoiling the meat.

This bacteria, the third most common cause of food poisoning in the UK, is usually transferred to us by poor hand-washing.

'Clostridium perfringens forms spores that can withstand cooking,' says Dr Goldberg. 'As the food cools, these spores start to germinate and grow very rapidly. They produce bacteria and it's these that causes food poisoning.'

Once you take the bird out of the oven, its internal temperature remains high for a long time, so you need to cool it down.

Eating these little sausages wrapped in bacon days after they've been cooked might not be as chancy as you'd think

Provided you cooked it well, to at least 60c, other bugs, such as salmonella and campylobacter, should have been killed and so are no danger in leftovers.

If you're worried that you didn't cool down the turkey quickly enough yesterday, you may need to be more cautious. Store the meat in several small, shallow, airtight containers in the fridge.

Eat by: 3-4 days

VEGETABLES

Eating veg that's past its best won't really hurt you.

'The problem with vegetables isn't bacteria, which can cause serious illness, but fungi,' says Dr Goldberg. 'Fungal spores are like plant seeds — they're every-where in the air. And they're highly resistant to cooking.

'Keeping cooked veg in the fridge will slow down growth, but not prevent it.

'The most common fungi you'll see are mucor, penicillium and aspergillas fungi. They love sugar, so naturally sweet vegetables such as potatoes and parsnips are perfect.

'After a week or so you'll see the fungi on them — they go furry or develop black or green patches. But if you eat them, it won't make you ill.'

You can always reheat them — Dr Goldberg says Christmas veg will be safe to eat after being reheated (but only once) to above 60c for ten minutes.

Eat by: ONE WEEK

PIGS IN BLANKETS

Eating these little sausages wrapped in bacon days after they've been cooked might not be as chancy as you'd think.

'Like turkey, the bacon and sausage may contain clostridium perfringens. But because pigs in blankets are so small, they cool down much more quickly, so it's not as much of an issue,' says Dr Goldberg.

Wrap all meat in foil or clingfilm before you put it in the fridge, to stop it being contaminated by other food.

'One worry is that before they were cooked, the meat was handled by someone with staphylococcus aureus, a bug that's found in a quarter of the population's noses and skin.

'If this gets on the sausages or bacon and they're not stored at below 4c before they're cooked, the bacteria can grow and make a fast-acting toxin, which is resistant to cooking. This can make you horribly sick within half an hour of eating. Even reheating won't help — it kills the bugs, but not the toxin.'

Make sure you refrigerate pigs in blankets thoroughly before and after cooking.

Eat by: 3-4 days

STUFFING

'Whatever flavour you opt for, stuffing is really only bread, vegetables and spices,' says Dr Goldberg. 'So again it's only fungi that will be the problem.'

Keep stuffing in the fridge or in a cool place.

Shop-bought cranberry sauce will tell you the date by which it should be eaten. If you make your own, rest assured it will last you long into 2016

Eat by: ONE WEEK

CRANBERRY SAUCE

Shop-bought cranberry sauce will tell you the date by which it should be eaten. If you make your own, rest assured it will last you long into 2016.

'Cranberry sauce is basically a mixture of sugar and acid — neither of which bacteria like,' says Dr Goldberg.'

Instead, fungus is the thing to fear, because it does like sugar. But it will take weeks to form.

Eat by: 1-2 MONTHS

SAUSAGE ROLLS

As with pigs in blankets, the main danger is that the meat has been contaminated by staphylococcus aureus when raw. But there's an extra concern, as sausage rolls served in a buffet can spend hours out at room temperature.

When they get above 8c, bugs start to multiply. The warmer it is, the quicker they do so.

'Put out the food just before it is served to guests eat and replace it in the fridge the moment they have finished eating,' says Dr Goldberg.

Eat by: 3 days

MINCE PIES

Pastry will go soft after a few days, even if kept in the fridge in an airtight container, but the sugar in the mincemeat will keep out any bugs.

Eat by: ONE WEEK

HAM

Ham has been cured with salt — which, like sugar, draws out water — so it won't give you too many problems. Make sure you cover it with foil or clingfilm before you put it in the fridge, to keep it moist and protect it.

But again, staphylococcus aureus may be a problem — so if it's left on work surfaces and you put your sausages there, it can transfer easily.

Eat by: ONE WEEK

SOFT CHEESE & PATE

These buffet table staples may contain the listeria bacteria, which can cause severe illness and even death.

'Listeria can survive and grow even down to a temperature of 0c,' says Dr Goldberg.

'And it can live quite happily in foods that are 10 per cent salt. It's a tough so-and-so.'

While healthy people do sometimes get listeria, it's much more of a problem for pregnant women — in whom it can trigger spontaneous abortion — the elderly and anyone whose immune system is damaged.

Smoking is an effective preservation method, says Dr Goldberg, but again, be careful of staphylococcus aureus, especially if the salmon is being left out in a buffet

While it multiplies more slowly than some other bugs, the sheer length of time for which soft cheeses and pates are kept, and left out in the warm on buffet tables, creates problems. So keep them covered in the fridge for as long as possible.

Eat by: USE-BY DATE

(but avoid altogether if you are in an at-risk category).

SMOKED SALMON

Smoking is an effective preservation method, says Dr Goldberg, but again, be careful of staphylococcus aureus, especially if the salmon is being left out in a buffet.

Keep it in the fridge for as long as possible and don't store it close to raw meat in case of cross-contamination.

Eat by: ONE WEEK

CHRISTMAS PUDDING & CAKE

THESE have a very high sugar content, preventing nasties from growing, and contain a lot of dried fruit, which bugs hate as it contains little water.

'A Christmas pudding is basically sugar, dried fruit and alcohol,' says Dr Goldberg. 'Nothing much grows in that.'

Eat by: EARLY NEW YEAR

CHOCOLATE

Chocolate keeps almost indefinitely. 'It has a low water content so nothing can grow in it,' says Dr Goldberg. 'It will go off eventually because of oxidation, but even when it does there's nothing nasty in there.'

Store it somewhere cool outside the fridge.

Eat by: 6 MONTHS