Can you keep soup warm in a slow cooker?
How the Warm Setting Works. The temperature of the warm setting on a slow cooker is 165°F, which is meant to keep pre-heated food hot, but not cook it.
Food can be left in a slow cooker on warm all night long. Cook food fully on high in the slow cooker as warm is designed to hold temperature and not cook food. Then switch to warm before bedtime. Ensure the proper amount of liquid in the cooker to avoid drying out the food or scorching on the bottom of the liner.
The truth is, yes, leaving the slow cooker on and going about your day is safe, as long as you are using the appliance properly.
While leaving it on for days is certainly not recommended, most programmable slow cookers have a 24 hour cycle; after that, the slow cooker would shut off automatically.
Don't leave it on 'warm' all day
The general rule of thumb is that two to four hours is the maximum length of time you can leave food in a slow cooker on warm. After this, it needs to be transferred into the refrigerator.
Put soups or sauces in a thermos.
The thermos was designed for the specific purpose of keeping soup and other liquids warm for long periods of time. When you finish cooking the soup, use a ladle to pour it into your thermos straight away. The thermos will keep it warm for 4 to 5 hours.
For best safety and quality, plan to eat refrigerated soup within 3 to 4 days or freeze it. And avoid letting soup set at room temperature for more than TWO hours. Don't put a large pot of hot soup directly into your refrigerator.
Food should not be at room temperature for more than two hours. Shallow containers or small amounts of hot food can be placed directly in the refrigerator or rapidly chilled in an ice or cold water bath before refrigerating.
Staying Safe With Soup
After preparing your soup, if you don't plan on serving it within two hours, refrigerate it at just below 40 F or keep it at a constant temperature of 140 F or above. Temperatures between 40 and 140 F allow for the growth of harmful bacteria in your soup.
Bring it all to a boil, then simmer. You will know it's done when it's all tender, anywhere from 25 minutes to 3 hours depending on the ingredients.
Is 10 hours too long for a slow cooker?
The Type of Food Inside
Some recipes are safe to cook for more than 8 hours, while some can only be cooked for 5 to 6 hours (although, they can be left in the slow cooker at a warm temperature). Foods that require a long time to get tender can be left for more than 8 hours in a slow cooker e.g meat etc.
Slow cookers are designed to be left to cook for long periods of time, so the truth is that it's entirely safe to leave your slow cooker on overnight, if you're out the house or if you're at work all day, as long as you follow all the directions and the manufacturer's instructions.

The USDA did issue an advisory that “A minimum temperature of 135 degrees for a maximum of 8 hours, or a minimum temperature of 140 degrees Fahrenheit indefinitely also would be adequate to ensure food safety.”
Food that has not been used within two hours, should either be reheated until it is steaming hot and put back in hot holding or chilled down as quickly as possible to 8°C or below. If it has been out for more than two hours throw it away.
Within 2 hours of cooking food or after it is removed from an appliance keeping it warm, leftovers must be refrigerated. Throw away all perishable foods that have been left in room temperature for more than 2 hours (1 hour if the temperature is over 90° F, such as at an outdoor picnic during summer).
According the expert McGee consulted, soup or stock left to cool overnight, then reboiled for 10 minutes and properly refrigerated in the morning is still safe to eat because it isn't cool long enough for the bacteria to germinate and reproduce up to dangerous levels.
The USDA says food that has been left out of the fridge for more than two hours should be thrown away. At room temperature, bacteria grows incredibly fast and can make you sick. Reheating something that has been sitting at room temperature for longer than two hours won't be safe from bacteria.
The best plan is to put leftovers in the refrigerator right after your meal. Food that is sitting out for a party or picnic should be chilled after two hours at typical room temperature. If it's above 90 degrees Fahrenheit (32 degrees Celsius) or more, food should not sit out for more than one hour.
Leaving food out too long at room temperature can cause bacteria (such as Staphylococcus aureus, Salmonella Enteritidis, Escherichia coli O157:H7, and Campylobacter) to grow to dangerous levels that can cause illness.
The FDA recommends that all perishables left at room temperature for more than two hours be discarded. Bacteria grow most rapidly between 40 degrees Fahrenheit (4.4 degrees Celsius) and 140 degrees Fahrenheit (60 degrees Celsius), doubling in amount every 20 minutes.
How do you keep soup warm for a party?
You can set out food in covered dishes (or covered with tin foil), on warming trays or in chafing dishes which will all keep things warm until serving.
-Do not boil your soup.
Don't let it boil for too long. You don't want your vegetables to turn into mush and you don't want to overcook your proteins. That's right, you can most definitely overcook meat in soup. Even though it's in a liquid, it can still get tough and rubbery.
There are no limits to how many times you can safely reheat leftover home-cooked meals. However, best practice is to limit the number of times you do so. More often than not, you wouldn't need to reheat one type of dish more than once. If you are making meals in bulk, separate and store them in individual portions.
Can you overcook something in a slow cooker? Slow cookers are specially designed to cook food for long periods of time, but yes, you can still overcook in a slow cooker if something is left on the wrong setting for longer than it's supposed to be.
Soup is ideal for making ahead of time. Store soup in shallow containers for rapid cooling. Cover and refrigerate soups for up to 3 days. Soups made with fish or shellfish should be refrigerated no longer than 1 day.
No, you can't really overcook soup, only overcook the vegetables so they lose their texture. Soup gets better the more you cook it, so a soup simmered for 2 hours will always taste better than one simmered for 1 hour.
How long can a slow cooker remain on? It depends on your model, so make sure you read the directions. Some can be left on for up to 24 hours, but most recommend eight to 12 hours.
Most cookers automatically shut off after 20 hours. Experts say you should not leave food in the slow cooker for extended hours. In general, leave the food on warm for 2 to 4 hours maximum. After this, your food is ready to be transferred to the refrigerator.
Food should not be at room temperature for more than two hours. Shallow containers or small amounts of hot food can be placed directly in the refrigerator or rapidly chilled in an ice or cold water bath before refrigerating.
I prefer metal thermoses for this, because I feel like they keep the heat better — and my kids tell me the same thing. What you want to do is to fill the thermos with hot water. It could be boiling, but very hot water is really all you need. Seal the container and let it sit while you finish heating the soup.
Can soup be left out for 4 hours?
For best safety and quality, plan to eat refrigerated soup within 3 to 4 days or freeze it. And avoid letting soup set at room temperature for more than TWO hours. Don't put a large pot of hot soup directly into your refrigerator.
According the expert McGee consulted, soup or stock left to cool overnight, then reboiled for 10 minutes and properly refrigerated in the morning is still safe to eat because it isn't cool long enough for the bacteria to germinate and reproduce up to dangerous levels.
Wrap your food in tin foil and a towel.
First, put your food in a sealed container. Next, wrap thick tin foil around the food and be careful not to leave any holes where warm air can escape. Finally, wrap 2-3 towels tightly around the food and foil.
Soup is ideal for making ahead of time. Store soup in shallow containers for rapid cooling. Cover and refrigerate soups for up to 3 days. Soups made with fish or shellfish should be refrigerated no longer than 1 day.