Generally, there is nothing to worry about when using a pressure cooker, they work very well. In fact it’s usually ’operator error’ that causes most of the accidents with pressure cookers, failure to follow the proper manufacturer’s instructions is probably the greatest danger of pressure cooking.
Pressure cookers made today are usually built with multiple safety features to ensure that ‘explosion‘ issues are a thing of the past, with added safety features such as locks that don’t open until the inside pressure has been released, or extra valves to release any excess pressure. New generation pressure cookers have considerably more safety features than older ones.
Science of Pressure Cooking
Pressure cookers always require liquid in order to cook food under pressure; these cookers will cook food quicker because steam and liquids heat substances faster, compared to ordinary cooking methods. They work by trapping steam from boiling water in the sealed cooker. The steam produced increases the internal pressure and once the pressure level is reached on the cooker regulator, the heat can be lowered either manually or automatically, to maintain the pressure level, any excess pressure will escape as steam from the lid. Almost any food which can be cooked in steam or water based liquids, can be cooked in this way.
Food is cooked above the temperature of the normal boiling point of water, this kills most micro-organisms and because food is cooked in a sealed container and at higher temperatures, the flavors are more concentrated, thus reducing the need to use a lot of seasoning. The mineral and vitamin content of the food does not leach into the water and is preserved during the cooking period due to a shorter cooking time than the cooking in the conventional way.
Types of Pressure cookers
There is a vast difference between the ‘first generation’ pressure cookers manufactured in the 1950’s and 60’s and the new ‘second generation’ pressure cookers of today. The earlier design of pressure cookers would fail occasionally, with terrible results, but today’s cookers are too well engineered for that to happen now as they are built with more care and more safety features.
✓ First Generation
The older ‘first generation’ pressure cookers used a single weighted regulator, most commonly called a ‘vent weight’ or ‘rocker’ valve. The steam pressure from the cooker lifted the weighted stopper, allowing the excess pressure to be released. These types of regulators could sometimes get stuck or clogged with leftover food which would cause more pressure to build up inside, this could then lead to the gasket/seal being blown out. The valve could also dislodge and open suddenly which would cause an ejection of steam and possibly some of the cooking liquid.
There are only two methods to release the pressure of older pressure cookers. The first is the natural release system in which you wait for the pressure to drop on its own. The second is the cold water release system where the pressure cooker is placed in the sink and then cold water is run over it to bring down the temperature and pressure.
✓ Second Generation
New modern ‘second generation’ pressure cookers have a closed system, where very little moisture is allowed to escape. Unlike the weighted top models, the modern pressure valves are spring loaded and in the form of a movable dial or rising valve stem.
They have multiple safety features such as locking devices that won’t allow the pressure lid to be removed until it is safe to do so. Flanges on the interlocking lid that won’t allow the buildup of steam if they are not seated properly, and dual pressure valves for safe pressure regulating. There are also visual pressure indicators that show clearly when the cooker is under pressure and also indicates when the pressure has dropped so making it safe to unlock.
Using a new, modern pressure cooker is so much easier than using the older style cookers. The cooker seals itself automatically at the right temperature setting, when the air has escaped, pressure is formed as the heat in the cooker increases and the indicator rod rises. If there is a buildup of pressure the excess steam is safely vented through a series of secondary valve systems. Therefore, making them a lot safer to use than the first generation cookers.
There is a third generation of pressure cookers. These are simple, electric pressure cookers, whose heat source is automatically regulated to maintain its operating pressure. These electric cookers come with either a mechanical timer or digital controller and some have smart programming which includes pre set cooking times and settings.
Unfortunately, they don’t have as many safety features as the new second generation cookers, so may not give the same peace of mind when using them. They cannot be opened with a cold water quick release method and need to be opened with caution when releasing the steam vapor through the valve.
Safety in Pressure Cooking
- The new second generation pressure cookers are 100 percent safe, totally fool-proof and reliable and cannot be compared to the older first generation pressure cookers where extra safety features were nonexistent. However, there are still some points to remember for safer pressure cooking.
- Apart from operator error, there is a possible danger of the rubber seal failing during cooking, it is highly unusual but it can happen if the sealing gasket isn’t kept clean and dry and inspected regularly. Replacement of the seal is essential if cracks are visible as this will cause sealing gasket failure.
- Failure to ensure that the lid is locked on securely or opening the vessel before the pressure has equalized inside, could result in serious burns or an explosion, so again, common sense and reading the instruction manual will prevent this.
- It is important to check that there isn’t any food left on the rim of the pot from previous use, as this could cause the seal to break.
- The pressure cooker should never be more than two thirds full; otherwise the vents could get blocked.
- Use enough liquid to create the steam that cooks the food. The amount will be recommended in the instruction book but basically, a pressure cooker should never be filled more two-thirds full with solid food, half full for liquids and foods that foam and froth (e.g., rice, pasta), and no more than one-third full for pulses e.g. Lentils etc
Following the manufacturer’s instructions and using common sense, will ensure that your pressure cooker will be perfectly safe to use and will also produce delicious meals far quicker than conventional cooking methods.