Modern multi cookers like the Instant Pot have grown in popularity in recent years. One of the many reasons is that they allow you to prepare meals more quickly than if you were cooking on the hob, and far more quickly than using your slow cooker. In fact, one of the selling points of this way of cooking is that you can achieve “slow cooked textures in pressure cooked times”. That’s not to say that a multicooker doesn’t slow cook too, because it does, but the appeal of the multicooker is that with one of the many cooking options being pressure cooking, you also have the option not to plan what you’re going to cook too far in advance. What is indisputable is that pressure cooking is a faster way to cook but what many people are unsure of is how a pressure cooker works and why it is faster than cooking either using a slow cooker or on the hob.
Firstly, a little bit of physics. We all know that hot air rises. When you cook in a regular pot on the hob, a lot of the heat escapes. Once moisture in the food turns into steam, which happens at 100°C, a lot of that moisture escapes through evaporation. However, in a pressure cooker, there’s nowhere for that hot air and steam to go. It is trapped! Because the hot air and steam are trapped, a pressure cooker allows you to heat the moisture i.e. steam and water, above its normal limit of 100°C and the trapped hot air and moisture within the food speeds up the cooking process.
In other words, the moisture surrounding the food reaches higher temperatures than it would without the pressure which speeds up the chemical processes involved in cooking. It also doesn’t cause the food to dry out like it would in an oven or on the hob because the moisture has nowhere to go. Slow cooking also uses heat and moisture to cook food but over a much longer period, often half a day. To give you some idea of the time it takes to cook the same food in an Instant Pot on high pressure compared to both a slow cooker and on the hob, check out these comparison tables: