Mashed potatoes are not only a staple food in the US; they are a holiday staple. Christmas, Thanksgiving, Easter - any special occasion, they are often served.
As a source of carbs, mashed potatoes often feature throughout the week. That gorgeous, smooth, creamy consistency is a culinary delight.
You can even go beyond simple mash and use it as an ingredient when making dumplings and gnocchi. Whichever potato variety you choose, Russet, Yukon Golds, or any other type that takes your fancy, mashed spuds is food heaven.
But keeping leftover mashed potatoes is not quite as straightforward as you might think. Just throwing them into the fridge doesn't yield the best results.
But, first, you need to think about how long you can leave cooked mashed potatoes out at room temperature.
The answer is no longer than two hours. Any longer and you run the risk of bacteria developing in them.
If you add dairy products, like butter, cream, or milk, to your mash, it's even more important not to leave them out for too long.
It's worth taking a couple of minutes to go into the whys and wherefores.
How long can mashed potatoes sit out?
There is something called the food danger zone. The temperature range of the food danger zone is between 40°F and 140°F.
Suppose you leave food out too long at room temperature. In that case, it can allow bacteria such as Staphylococcus aureus, Salmonella Enteritidis, Escherichia coli O157:H7, and Campylobacter to proliferate to the stage where the level becomes dangerous and can cause illness.
Two hours is the maximum food can be left out, but if room temperature raises above 90°F, the time it can be left out reduces to one hour.
What are mashed potatoes?
Mashed potatoes, also described as mashed taters or tatties, or even mashed spuds, are colloquially known simply as mash.
You make mashed potatoes by boiling peeled potatoes in salted water.
Drain it and add the butter, milk, and salt-and-pepper before mashing with a potato masher.
They are usually served as a side dish to meat or fish. You can also mash them roughly to make what is referred to as "smashed" potatoes.
You can also buy instant dehydrated potatoes (not recommended) and even frozen mashed potatoes for convenience.
Recipes that use patatoes
What is the best potato for mashing?
People tend to have their own preferences for which type of potato makes the best mash.
The most popular are Yukon Gold potatoes or a blend of Red Skinned Russet, and Yukon Gold potatoes. Some people prefer a blend of starchy potatoes to avoid gummy mashed potatoes.
The most important thing is to use potatoes with a waxy consistency to get that rich buttery flavor and a gorgeous creamy texture after mashing.
Why is a starchy potato best for making mashed potatoes?
Russet potatoes (often used as baking potatoes) are densely packed with starchy cells that expand and separate when cooked, producing a dry and fluffy texture.
This type of starchy potato is not only ideal for making a creamy mash, but it's also great for making crispy French fries with a fluffy interior.
Other low-starch potatoes like round red or white-skinned tatties have moister inners with loosely packed cells of starch that stick together, enabling the potato to maintain its shape even after boiling. They work brilliantly well in salads and stews.
Creamers or new potatoes are two more low-starch varieties. They are a little sweeter than some other low starchers since they are harvested when still young before their natural sugars have been converted to starch.
The middle ground in terms of starchiness belongs to potato varieties such as Yukon Golds and Yellow Finns. As they contain a moderate amount of starch, they are suitable for any cooking.
Want to know how much starch a potato contains?
If you don't know how much starch a potato contains, there's a quick and easy way of finding out.
- Halve the potato with a knife
- If the blade of the knife sticks to the potato or the potato leaves a creamy white trace on the blade, it has a high starch content.
- If it doesn't stick or there's no residue on the blade, it has a low starch content.
Do mashed potatoes go bad?
I explained earlier that most food left at room temperature for longer than 2 hours runs the risk of developing sufficient quantities of bacteria that can cause food poisoning.
Mashed potato, with its starchy consistency, is a prime candidate.
What happens after 2 hours?
When mashed potatoes are left outside the fridge at room temperature for more than 2 hours, they can produce a small number of bacteria. They double every 30 minutes.
It doesn't take a mathematical genius to realize that you're talking about millions of bacteria developing if you leave it outside for something like 10 hours.
Hence, leaving mashed potato on the dining table for over two hours, the bacteria can easily spread to your table and, therefore, onto your hands too.
Another concern is the Staphylococcus aureus bacteria commonly found on the skin and in the nostrils and throats of healthy individuals. When confined to these areas, it is harmless.
However, when transmitted onto food products, it can multiply and produce harmful toxins. Although the bacteria can be destroyed by cooking, the toxins they create are not.
Anyone is susceptible to developing a Staph infection. People with chronic conditions like cancer, diabetes, eczema, lung, and vascular disease are at greater risk.
You can unwittingly transmit this bacteria to the foods you are preparing, so it is essential to wash your hands regularly and follow good food hygiene protocols.
Why adding dairy products to mashed potatoes increase the risk of spoilage?
A lot of dairy products contain high fat but low water content. This combination enables bacteria to thrive and multiply.
It explains why you need to store opened cartons of milk or butter packs in the fridge. A cold environment helps to preserve their freshness.
If you leave milk outside at room temperature, it becomes prone to producing bacteria. These bacteria set about converting lactose into glucose and galactose, which produces lactic acid.
This acid makes Casein, which forms a curd on the top of the milk. The milk is then spoiled and should be disposed of immediately.
Listeria Minocytogenes is another bacteria found in milk and milk products. These bacteria can thrive and reproduce in cold temperatures.
While some people could be immune to this bacterium, older people and pregnant women are highly vulnerable. These bacteria can cause serious poisoning in the elderly and miscarriage in pregnant women.
While I don't wish to frighten the life out of you, it's worth bearing these things in mind so that you handle and store your mashed potato leftovers correctly.
Storing leftover mashed potatoes in your fridge
Most of us cook mashed potatoes, and when there are leftovers, it seems a shame to throw such an enjoyable foodstuff away.
Storage-wise, you now know that you cannot leave them outside the fridge at room temperature for longer than 2 hours - even less if room temperature reaches above 90°F.
Refrigerating or freezing your leftover mashed potatoes is fine, providing you know how to go about it.
Couple of things to consider.
- Adding dairy products, including eggs, to your mashed potatoes can affect how long you can store them.
- Anything you add to the mashed potatoes can affect both the flavor and consistency.
You need to bear these points in mind before refrigerating or freezing.
Follow these steps:
The first thing to remember is that you should refrigerate mashed potatoes within 2 hours of cooking.
Step 1
- Ensure that your fridge's temperature setting is at its lowest to help speed the cooling process and prevent any bacterial growth.
Step 2
- Spoon the mashed potatoes into shallow containers or Ziploc bags, ensuring the depth doesn't exceed 3 inches. This promotes quicker cooling.
If the potato is still particularly hot, you can use the sink cooling method as follows:
- Fill your sink or bowl with a bit of iced water. Transfer the container or Ziploc bag into the water, ensuring that it is only partially submerged.
- Take a ladle or spoon and gently stir the mashed potato to facilitate faster heat loss. You want to get the mash down to a temperature of under 70°F.
- Another way of doing this is to use a cooling paddle. If going down this route, it's best to transfer the mashed potato into a wide bowl.
Step 3
- Once the temperature is below 70°F, you can transfer the potato into a shallow container or Ziploc bag and place it in your fridge, still open, until the temperature drops to 40°F.
- Once it does, you can then put the lid in place or zip the Ziploc bag closed and leave the mash in the fridge until you want to use it.
How long do mashed potatoes last in your fridge?
You shouldn't keep mashed potatoes in your fridge for more than four days.
When you initially refrigerate them, make sure the temperature is below 70°F, and let the temperature drop to 40°F before sealing the container or Ziploc bag.
Secure the package to prevent them from contamination by other food smells.
It's a good idea to check the mashed potato daily, and if you spot any mold growing before the four days are up or you notice an unpleasant smell, you should throw them away.
Storing mashed potatoes in the freezer
It is also possible to freeze mashed potatoes. As they are already mushy, or perhaps we should say creamy, freezing will not do any real harm to the texture.
All you need are some airtight freezer-safe containers or Ziploc bags, and away you go.
As long as you keep them constantly under 0°F, you can freeze mash almost indefinitely. The only thing is that the longer to keep them frozen, the more likely they lose some flavor.
But you can replenish much of the taste by adding some butter or cream or chopped parsley when you thaw and reheat them.
However, it's essential to start with top-quality mash. When appropriately done, freezing can retain flavor and texture, but it doesn't ever improve them.
Before you start the freezing process, keep the two-hour rule in mind.
Here are the steps to follow when freezing mashed potatoes:
- It would be best to let the mashed potato cool down before freezing. Refer back to the two methods discussed earlier.
- Once cooled, divide the potato into portion sizes and transfer it into freezer-safe shallow containers or Ziploc bags.
- Do not stack the bags, or they will stick together en masse after putting mashed potatoes in Ziploc bags.
- Flash freeze them and once the contents turned solid, you can stack the packages if you need to save space.
How long can mashed potatoes remain frozen?
If you have made too much of the mashed potato to eat in one sitting or make it in advance, you can freeze them for long-term storage.
You can keep it in your fridge for up to four days, but if you want to keep it longer, and freezing is the way to go.
With proper storage, mashed potatoes can sit in your freezer almost indefinitely, but after one month, the taste and consistency will begin to deteriorate a little.
Whether you use a lidded container or a Ziploc bag, it's best to evacuate as much air as possible and ensure to seal the container airtight. This helps to keep the mash safe from freezer burn.
Reheating mashed potatoes
There are two ways you can reheat mashed potatoes - on the stovetop or in the oven. You can use the microwave, but it's not something I would recommend as it tends to draw out too much moisture.
Whichever you use, it's best not to overheat it or use too high a temperature. Starchy foods, like mashed potatoes, become rather gluey.
Reheating in the stovetop
If you are reheating frozen mashed potatoes, you first need to thaw them. The best way to do this is to transfer them to the fridge and leave them to thaw completely overnight.
- Transfer the mash into a non-stick pan and place it on the stovetop on a medium heat setting.
- Add a little liquid to revive. It can be broth, buttermilk, cream, or half and half. Don't add too much, or it will over-liquefy.
- Gently stir as it warms through. You can add a little more liquid or butter if you need to, but a little at a time until it reaches the desired consistency.
Extra tip:
When adding liquid, you need about half a cup for every four cups of mash. Add it a little at a time to avoid the potato getting too liquidy.
Butter is a great addition—adding a couple of large knobs of butter to make distribution easier works best.
It's important to continually stir the mash as it warms to distribute the heat evenly and stop it from sticking to the pan.
I sometimes add a couple of teaspoons of grain mustard to enhance the flavor.
Reheating in the oven
If you are reheating your mash in the oven, you can't stir it as you go, so you need to add any liquid (see above) and stir it well beforehand.
- Preheat the oven to 350˚F.
- Spread the mash out onto a lightly oiled baking dish.
- Place into the oven and back for 20 to 30 minutes. Ideally, you're looking for an internal temperature of 165˚F.
Frequently Asked Questions
If you leave mashed potatoes at room temperature for longer than two hours, bacteria will begin to form and multiply. If you’ve added dairy to the mash – the risk is heightened. The dairy will turn, giving the mash a sour flavor, and mold may even appear. If either is evident, throw the mash away.
When you mash the potatoes, you release the starch in them. The more you mash, the more starch you get. Too much starch makes the mashed potatoes stodgy and not pleasant to eat. The result is much worst if you use a blender or food processor.
Tip: Use a food mill or a potato ricer for mashing.
When mashed potatoes start getting too old, the liquid begins to separate from the solid. Initially, the liquid is almost transparent, but in time it turns milky, and the mash will develop a sour smell. If this happens - dispose of it.
As well as smelling sour, mash that has turned will also taste sour.
The other clear sign that mash has turned is when spots or patches of mold appear.
When the mash is left too long, it begins to ferment. It may not be noticeable to the naked eye, but your nose will surely detect it.
It all depends on what bacteria have grown. Some spoilage bacteria aren't overly harmful and might simply make you vomit. But if we are talking about pathogenic bacteria, which are often invisible, you could develop food poisoning, which can cause serious illness.
I have mentioned this in the text above several times as it is so important.
Do not leave mashed potatoes out at room temperature for more than two hours.
If you do, you run the risk of allowing potentially harmful bacteria to establish and multiply. If the temperature rises above 90˚F, it shouldn't stay out longer than one hour.
You are very likely to become ill if you do, even if the mash has been kept in the fridge. It's just not worth taking the risk. Throw it away.
How to Store Leftover Mashed Potatoes (How to)
Pin RecipeIngredients:
- leftover mashed potatoes
Instructions:
Storing Leftover in the Fridge:
- The first thing to remember is that you should refrigerate mashed potatoes within 2 hours of cooking.
- Ensure that your fridge’s temperature setting is at its lowest to help speed the cooling process and prevent any bacterial growth.
- Spoon the mashed potatoes into shallow containers or Ziploc bags, ensuring the depth doesn’t exceed 3 inches. This promotes quicker cooling.
If the potato is still particularly hot, you can use the sink cooling method as follows:
- Fill your sink or bowl with a bit of iced water. Transfer the container or Ziploc bag into the water, ensuring that it is only partially submerged.
- Take a ladle or spoon and gently stir the mashed potato to facilitate faster heat loss. You want to get the mash down to a temperature of under 70°F.
- Another way of doing this is to use a cooling paddle. If going down this route, it’s best to transfer the mashed potato into a wide bowl.
- Once the temperature is below 70°F, you can transfer the potato into a shallow container or Ziploc bag and place it in your fridge, still open, until the temperature drops to 40°F.
- Once it does, you can then put the lid in place or zip the Ziploc bag closed and leave the mash in the fridge until you want to use it.
Storing Mashed Potatoes in the Freezer:
- It would be best to let the mashed potato cool down before freezing. Refer back to the two methods discussed earlier.
- Once cooled, divide the potato into portion sizes and transfer it into freezer-safe shallow containers or Ziploc bags.
- Do not stack the bags, or they will stick together en masse after putting mashed potatoes in Ziploc bags.
- Flash freeze them and once the contents turned solid, you can stack the packages if you need to save space.
Notes:
- Adding dairy products, including eggs, to your mashed potatoes can affect how long you can store them.
- Anything you add to the mashed potatoes can affect both the flavor and consistency.
Please note that all nutrition information are just estimates. Values will vary among brands, so we encourage you to calculate these on your own for most accurate results.