Top 20 Tips for Safely Slow-Cooking Food
Slow cookers are very convenient, easy to use, and allow your food to cook slowly while you do other things. Dishes prepared in this way are tender, flavorsome and delicious. However, keeping food warm for long periods of time can be very hazardous as bacteria can proliferate quickly in the warm food. The temperatures used for slow cooking and warming are close enough, to warrant taking extra precautions to prevent contamination and food safety risks.
Temperatures between 40 -140 degrees F (5-60 degrees C) fall into the "Danger Zone" for prepared foods. Within this range bacteria can thrive, spoil the food, and can lead to dangerous food poisoning. Slow cooker temperatures range from a low simmer setting of 190 degrees F (87 degrees C) to 212 degrees F (100 degrees C). Slow cookers tend to heat and come to the regulated temperatures rather slowly, and so it is easy to see that poorly used slow cookers can mean that ingredients in the dishes can remain in the danger zone for too long or not reach the target temperature for the settings.
So, it is wise to take precautions to prevent slow-cooked food remaining in the Danger Zone for too long. This can occur when frozen food is added to a slow cooker and remains within the danger range during the cooking period. It can also occur when a slow cooker is used to keep food warm over long periods of time after the food is cooked. There are many other tips you can apply to ensure your slow cooked dishes are safe with minimal risk of contamination and food poisoning. Follow the top 20 tips below to enjoy risk-free delicious and healthy slow cooked meals at home.
Slow cookers are a great way to prepare stews, curries and other dishes. However the low temperatures used during cooking means that special care is needed to ensure the food prepared is safe to eat. See the food safety tips in this article. By Kowloonese [CC-BY-SA-3.0], via Wikimedia Commons
Tip 1. Do not put frozen ingredients, in your slow cooker.
Placing large pieces of frozen meat or chicken, or other ingredients in your slow cooker. This increases the risk of food poisoning as the core of these frozen pieces may not be properly cooked and may within the hazardous temperature range for long enough for bacteria to proliferate. This especially applies to chicken and other poultry which are the most contaminated meats and which have been the source of many dangerous food poisoning occurrences throughout the world, including potentially lethal salmonella infections. Using frozen ingredients also increases the risks of cross contamination between raw and cooked food. For food safety, a slow cooker must reach at least 150 degrees F (65 degrees C) in less than 2 hours, preferably 1 hour, and stay there for more than one hour.
Tip 2. Choose dishes with high moisture contents and ensure moisture levels cover the food.
The slow cooking process depends on the liquid in the dish circulating around the food, ensuring even temperatures throughout. Dry pockets or clumps of food in the pot may not heat properly and may remain uncooked. Dishes with low liquid contents may not heat properly. Soups and stews and other dishes with high moisture contents are ideal for slow cooking. The liquid in the dish generates steam at simmer temperatures, which helps with the cooking process and helps raise the temperature within the dish and in the top layers above the danger zone quickly.
Always defrost chicken, poultry, meat and other ingredients thoroughly in the refrigerator before adding to the slow cooker. The temperature in the inner core of the frozen pieces of meat may too low to ensure harmful bacteria, deep inside the pieces are killed by the heat. Frozen meat and poultry will not cook properly in any case, and the dish may be partially uncooked when served.
Tip 3. Keep all the ingredients apart in separate containers in the refrigerator to avoid any chance of cross-contamination, particular from chicken and meat.
Do not mix the ingredients and leave in the crock pot at room temperature before cooking. Also, do not mix the ingredients in the slow cooker insert and store in the refrigerator. The slow cooker insert will take too long to reach the cooking temperature. The ingredients may stay in the danger zone temperature range for too long. Similarly do not store the cooked dish in the slow cooker insert in the refrigerator before re-heating and serving on the next day. It is better to reheat then dish quickly in a microwave or a saucepan, while stirring to prevent burning.
Tip 4. Cut meat, poultry and hard vegetables into medium to small size pieces to ensure the meat is cooked properly and quickly reaches safe temperatures.
Do not aim to cook a whole chicken, leg of lamb or a large roast in a slow cooker. The low temperature of the slow cooker and limited heat circulation mean that the slow cooker will not be able to raise the temperatures in the core of large pieces center of the meat quickly enough to avoid a food-safety risk. This applies even when the large pieces are immersed in liquid. It can be done but it is too risky unless and meat thermometer is used to check the internal temperature of large pieces of meat.
Tip 5. Do not be tempted to completely fill your slow cooker with ingredients or liquid.
Keep the level below half or two-thirds full. An overfull slow cooker bowl will take too long to get to temperatures above the danger zone, due to the limited heating capacity of the slow cooker unit. The contents may not mix properly and it will be very difficult to stir the contents ensuring even cooking throughout the dish.
Tip 6. When you are cooking meat or poultry the USDA recommends that you start cooking the dish using a high setting for the first hour.
The high initial setting ensure the meat passes through the danger zone temperature range quickly and reduces the risk of food poisoning. Alternatively, bring the liquid to be added to the other ingredients to boiling point before added the liquid to the pot. You can also heat the empty pot on a high setting before adding the ingredients. This ensures the ingredients are brought to safe temperatures quickly, even when a low setting is used for the slow cooker. Preheating the crock before adding ingredients and heating the ingredients themselves before adding to the pot will ensure rapid heating at the start, and will shorten the time foods are in the temperature danger zone. This is especially important when cooking meat, chicken or other poultry in a slow cooker.
Tip 7. Do not lift the lid of the slow cooker more than once or twice during the cooking time.
Only remove the lid 1-3 times during the cooking period and keep the time the lid is off to very short periods of time. Each time the lid is removed, the internal temperature in the dish drops by 10 to 15 degrees and the cooking process is slowed by about 30 minutes on a low setting. Keeping the lid on prevents the dish from dropping below the safe temperature range during the cooking period. Make sure that any spoons or other implements used to stir the dish are clean. Do not leave the stirrer on the bench near the slow cooker between the stirrings. You can increase the frequency of the checks towards the end of the cooking time as the food will have been decontaminated by cooking for a long time at temperatures above the danger zone.
Tip 8. You can use a slow cooker to keep food hot for up to two hours before serving, provided the lid is on and the temperature is kept at safe levels.
This ensures the dish is kept above the dangerous range for growth of bacteria. Do not switch off the slow cooker and let the dish come to a warm temperature before serving. Some units have a 'Warm' setting which is safe. Otherwise, removing the dish from the slow cooker, store in suitable containers in the refrigerator and quickly re-heat before serving on the stove top or in a microwave.
Tip 9. Meticulously follow standard food-safety procedures.
- Start with clean equipment
- Avoid cross-contamination between raw and cooked food
- Keep all perishable ingredients refrigerated until preparation time
- Use separate surfaces and utensils for cooked and raw food
- Be very careful with dish cloths and wipers used to wipe surfaces to avoid contamination
- Be especially careful with chicken and poultry and assume it is contaminated with bacteria
- Do not keep food warm for long periods of time. Instead, refrigerate and heat in the microwave or on the stove before serving warm.
Tip 10. Only use the slow cooker on a countertop or other firm surface that is flat and heat-safe.
Do not set the slow cooker on a wooden table or other surface that may be affected by the heat. Instead, place it on a tiled kitchen counter or other heat-safe surface. Use a trivet, or other protective padding underneath the slow cooker to protect the surface underneath. Keep the slow cooker well clear of the wall on all sides. Don't let the slow cooker cord hang over the edge of the table or counter top where it make get entangled or pulled spilling the hot contents. Don't let the cord touch any heated parts of the slow cooker.
Tip 11. Use a programmable slow cooker.
If you intend to use your slow cooker to cook meals while you are out of the house, so the dish is ready when you return, it is wise to use a fully programmable slow cooker. This type of slow cooker can be set to cook on either a high or low setting for a programmed length of time and then to automatically to a warm setting, with temperatures still above the danger zone. Other slow cookers simply switch off after the cooking time has elapsed, and the food may cool to unsafe temperatures well before you eat it. Do not leave the ingredients at room temperature in the cooker insert before the cooking program starts.
Tip 12. Use a slow cooker that has heating elements on the sides and bottom of the pot cavity.
Modern slow cookers have heating elements on the sides of the pot cavity, as well as the bottom, which ensures that the ingredients are heated throughout and that the entire dish reaches cooking temperatures quickly. In older slow cookers, with only a bottom element, the top of the food may not cook properly especially when the moisture content is low and liquid does not easily circulate during the cooking period. These modern slow cookers with side heating elements are safer.
Tip 13. Always use a food thermometer to ensure the food in your slow cooker is above 150 degrees F (65 degrees C) before serving.
Using a food temperature is a good way to check that your dish is safe before eating it. Power outages may have occurred or the slow cooker may have switched off and the food may have cooled down after the cooking cycle. Read the temperature in several locations in the dish to check for 'warm spots', where the food may not have come to safe temperatures quickly enough or may have cooled down. There are various apps and websites that list target temperatures for various foods and dishes. This is the best way to ensure that your food is safe to eat when you serve it.
Tip 14. Do not leave cooked food in the slow cooker to cool down in the bowl before serving.
Serve and eat the food cooked in the slow cooker immediately, or leave on low or warm setting before serving. Do not switch the cooker off and let the dish cool down in the insert. Instead, transfer any leftovers into shallow containers and refrigerate before reheating and serving. The temperature of the food may drop into the danger zone when cooling down, allowing bacteria to proliferate, especially if the food is contaminated with serving spoons or in other ways.
Tip 15. Get the timing right and use staged addition of ingredients.
Vegetables cook slower than meat, chicken or other poultry. So it makes sense to put the vegetables in first and to add the meat later. Try to cut the meat and vegetables in pieces of similar size, to ensure all the pieces cook evenly in about the same time. This avoids over-cooking and under-cooking. Stick to the settings and cooking times specified in the recipe. Stage addition helps to prevent ingredients being served when they are under-cooked.
Tip 16. Use recipes specifically designed for slow cookers.
Unless you are very experienced, it is best to stick to recipes that have been specifically designed for slow cookers. Cooking times, liquid levels and combinations of ingredients can all go wrong if you try to make up your own recipe. Adequate cooking time, and the size of the pieces of meat are especially important. Minor changes to the ingredients using substitutes is generally acceptable and safe.
Tip 17. If the power goes out, discard the dish.
If power goes off during the cooking period there is a risk that harmful bacteria may have been proliferating after the dish cooked down when the heating failed. It is also very hard to know the stage in the cooking cycle the power failure occurred and so resume the cooking. So it is best and safer to throw out the contents and start again if a blackout occurs.
Tip 18. Do not use the slow cooker insert pot to store food in the refrigerator.
The insert is designed to retain heat. This has two consequences. If you place the insert containing food in the refrigerator it won't cool quickly enough and bacteria may proliferate in the food. If you place a cold, refrigerated insert with food inside into you slow cooker, it may take a long time before the insert and the food reaches the safe temperature zone. So, do not use the insert for keeping dishes in the refrigerator. Transfer the food to other containers for storage.
Tip 19. Never use the 'Warm' setting to cook food.
The 'Warm' setting is too low to cook food and it will take a very long time to transition through the danger zone and there may be a build-up of bacteria. Similarly the food may not be cooked properly when it is served. It is also a good idea to pre-heat the empty insert on a high setting for 10-15 minutes so that it is well heated before you add the food. The warm setting should only be used to keep the food warm after being cooked. On this setting the food will be kept above the danger zone temperature range.
Tip 20. Maintain perspective, be aware of the risks and assume there are sources of contamination present in the ingredients and your kitchen.
You cannot completely reduce all risks to zero when using a slow cooker. None of the ingredients, cooking utensils are completely sterile all of the time, nor do they need to be if you take sensible precautions. The best perspective is to treat everything as potentially contaminated, or as potential sources of contamination. This means that you will always take precautions needed to keep your ingredients, and cooked food, out of the danger zone for as short a time as possible.
Chicken is almost always contaminated, and you need to treat it as such. Sensible, simple precautions will greatly reduce the risk that the real or supposed contamination will cause food poisoning or other health problems. Ignoring the risks, and assuming that everything is sterile increases the likelihood that problems will develop.
Regularly sanitize your cutting boards, counter tops, and cooking utensils with a mixture of one teaspoon of chlorine bleach to one pint (500 ml) of water.
Sponges and dishcloths can contain bacteria and can spread them around the kitchen from raw food to cooked food. So replace or sterilize them in boiling water regularly and use a different set for raw and cooked food, and for food preparation and food serving areas.