Slow cookers and multi-cookers

Slow cookers are useful for busy people: you fill the bowl with ingredients, switch it on and leave it to do its thing. We’ve tested a range of models, including some multi-cookers.

To be classified as a multi-cooker in our test kitchen, a product must be able to pressure cook as well as slow cook. The pressure-cooking function uses pressure to tenderise the meat so you’ll get a dish that’s usually slow-cooked done double quick. They also double-up as a rice cooker.

Things to consider when choosing a slow or multi-cooker

• Size: a 5 to 6 litre cooker gives a useable volume of 4 litres — a good size for large groups. For 1 or 2 people, 3.5 litres (2 litres useable volume) is enough.
• Glass lid: makes checking easy. It allows you to check progress without lifting the lid.
• Searing function: Slow cookers produce moisture as they cook, which means sauces can end up watery and lacking flavour. Slow or multi-cookers with non-stick metal pans or a built-in searing feature allow you to brown the meat (which produces better flavours) before the slow cooking starts. And at the end of cooking you can turn up the heat or transfer the pan to the stovetop to reduce the liquid and concentrate the flavours — all without creating extra dirty dishes. You’ll pay more for this feature, but you’ll get a more versatile appliance.
• Functions: Some cookers can also steam, cook rice, bake or make yoghurt.
• Bowl shape: a round pot is fine if you plan to cook only stews and curries, but an oval cooker allows you to cook longer cuts of meat such as lamb shanks or roasts as well.
• Settings: Low gently simmers food for a long time. High cooks over a shorter time, although the food may need stirring to improve the flavour and you may have to add water. Warm is for keeping the food at serving temperature – but you shouldn't use this setting for more than 4 hours. Auto cooks food on "high" for a while, then switches to "low".
  

Multi-cooker features to look for

• Pressure settings: more than one setting allows you to adjust the time it takes to cook different dishes. The higher the pressure, the quicker the cooking time.
• Pressure-release valve: a valve you can turn to release steam. It means you don’t have to bother cooling the cooker before you open it.
• Pressure-regulator valve: controls the rate at which steam vents out of the cooker and the degree of pressure inside the cooker.
  

Downsides to multi-cookers

• We found all the tested models fiddly to clean, with areas where food particles can get trapped.
• None of the cooking bowls have handles (which makes it difficult to stir food or remove the bowl without using an oven mitt).
• They all take up lots of room in your kitchen cupboard.

Safety tips

Slow cookers cook food at a low enough temperature to be left unattended for hours. But the food must reach a core temperature of at least 60°C to kill harmful bacteria. All the cookers will produce food that's safe to eat – provided you follow both the cooker's instructions and standard food-safety practices.

To cook food slowly and safely:

• Boil dried beans for at least 10 minutes before slow cooking to destroy toxins which will otherwise survive the lower temperatures of a slow cooker.
• Always completely thaw frozen meat, poultry or vegetables before putting them in the cooker.
• Vegetables cook the slowest, so place them at the bottom and sides of the pot and then add the meat.
• Don't overload the cooker – fill it to about half its capacity (two-thirds at most).
• Don't take off the lid during cooking unless the recipe calls for it. Removing the lid lets heat and moisture escape, so you will have to extend the cooking time.
• Add any dairy products, fish or seafood when you get home – or within the last half-hour of cooking.
• Don't leave cooked food to cool down completely in the bowl or pan. It should cool at room temperature for 2 hours and then go into the fridge.
• Never reheat leftovers in your slow cooker – use a microwave, cooktop, or oven.
• If there's a power cut while you're out, check the temperature of the food with a meat thermometer. If it's lower than 70°C, it's probably not safe to eat.
• Slow cookers cook food at a low enough temperature to be left unattended for hours. But the food must reach a core temperature of at least 60°C to kill harmful bacteria.