The Complete Book of Pressure Cooking. L.D. Michaels

      1 A PAN that is usually much thicker than an average saucepan. It will resist high pressures and withstand the effects of sudden cooling.

      2 A LID that is similarly thick and which can be fastened down tightly. The lid will contain …

      3 A PRESSURE VALVE OR WEIGHTS that control the pressure inside the pan. Some models have a spring-loaded flip-up valve, some have a spring-loaded indicator and some have a series of weights that fit over a small escape vent. The escape vent must be kept clear of food particles at all times; if it becomes clogged, even slightly, pressure will build up inside the cooker and at the very least you will find that the food overcooks. If your cooker has a valve there may be more than one “position” – typically for “full” pressure and for a “lower” pressure. If your pressure cooker has weights, then don’t be surprised if they are considerably lighter than the markings on them. The 15lb weight with my old Prestige cooker weighs 126g (about 5 oz) – it’s the combination of the weight sitting over a vent and having steam forced through it from underneath that causes the pressure build-up inside. Most “weight” systems consist of three sections: an inner (L) weight, a sleeve making the pressure up to (M) and then an outer sleeve to make up the normal operating pressure (H) or 15 psi. Another device is the valve that revolves slowly when the cooker is at the right pressure. This gives you a visual check on what you are doing. Such a device is found on one of Europe’s best selling models. The lid will also have …

      4 A SAFETY VALVE. This is to prevent the inside from becoming overpressurized or overheated. Most valves have two components: one that is sensitive to pressure and which blows out at around 3½–4 atmospheres, and another that melts suddenly and rapidly if the heat becomes excessive. The valves are usually of rubber composition with a metal core, or of one sort of rubber on the outside with an inner plug of a different type of rubber composition. Under normal circumstances and with proper use, the safety valve should never “blow” unless after a time it becomes worn.“Blowing” occurs, if:(a) The pressure valve has become blocked and steam can’t escape at the rate at which it should. This will happen if the pressure valve isn’t cleaned regularly or if you are cooking foods that froth up and your saucepan is overfilled (to more than two-thirds).(b) You have let all the moisture leave the cooker, either by not putting in enough to begin with or by overcooking. In these circumstances, the pan ceases to be a pressure cooker and starts acting like an oven. The food will be spoilt and the safety plug will melt to prevent too much damage.You hear dreadful stories about safety valves blowing and directing a stream of extremely hot mashed food at the kitchen ceiling. Most of the stories are apocryphal. The more recently designed models tend to “blow” at a lower pressure than the earlier ones so that the cook has enough warning and the worst that happens is a messy dribble.

      5 A TRIVET. This is a small inverted tray with holes in it that almost exactly fits the bottom of the pan. The water that makes the pressurized steam is placed underneath the trivet and food can be placed on top of it so that at no stage does the food touch the water. In some lower-cost models, the trivet is simply a bent piece of thick metal wire which does the same job. The food is then properly steamed and the valuable nutrients that could dissolve in the water are retained in the food. The trivet is not used for all recipes, of course.If you use the pan with the trivet and with another pan resting inside, but with the lid off, you then have a double boiler, which is suitable for making delicate sauces. Some makes offer you a wire basket, or pannier, that does the same job but is easier to lift out.

      6 DIVIDERS AND SEPARATORS. These are containers, some of them solid, some punctured with small holes, that rest on top of the trivet. You can put different sorts of food in them and, because the cooking is done by steam, the flavours don’t mix. You can easily cook three sorts of vegetable together and not have them all taste like one another.The separators with holes in them should be used wherever possible so that the steam can penetrate freely all around the food. It is only food that is liquid or in very small particles (like rice) that should be cooked in a solid separator. Since the steam can’t get at the food that easily, the cooking is done largely by the heat of the pressure cooker, and not the pressure, so cooking takes a little longer.

      7 A GASKET. This is a silicone or rubber-composition seal that fits between the lid and the pan, depending on the precise mechanical means of closure. The gasket ensures that the cooker is sealed tight. If steam is seen escaping from beneath the lid, then the gasket is faulty and will need replacing. Almost certainly you will find that you have been cooking at a lower temperature and pressure than you intended and, as a result, your food will be undercooked.

      8 A MEANS OF CLOSURE. A pressure cooker needs to be mechanically secure. There are a number of different mechanical devices used. Some require you to twist the lid carefully into a series of locking lugs on the top of the pan, some have massive handles and springs, some depend on an eccentric oval fitting lid slotting into place and with some there are twisting handles over the lid that are then screwed up to tighten into lugs on the pan.Most pressure cookers are designed so that you can’t open them under pressure, though a few are.Most early mistakes in pressure cooking come from incorrect closure of the appliances. Read your instruction manual carefully!