Why steaming cooks quicker than baking
Have you ever noticed that if you put your hand into an oven which is heated to 212°F (100°C) it doesn't burn immediately but if you put your hand in the steam which is escaping from a kettle at the same temperature it scalds almost straight away? This happens because the energy which was used to vaporise water into steam in the first place is transferred into your skin when the steam condenses and this is many times more energy than air in the oven heated to the same temperature can transfer.
The same principle applies when steaming food, but rather than cooking your hand the additional energy transferred results in the food cooking quicker.
Why a pressure cooker cooks even quicker than steaming
A pressure cooker is essentially a pot which is used to cook food, but rather than allowing steam from boiling water to escape the pot is sealed so that the steam is contained resulting in an increase in pressure inside the pot. This increase in pressure results in the boiling point of water increasing and more energy being transferred into the food, resulting in an even greater reduction in cooking time.
The reduction in cooking time using a pressure cooker can range anywhere from 1/3 to 2/3rds of normal cooking time making it ideal for cooking tasty stews and similar dishes in much shorter timeframes.
Benefits of pressure cooking
As well as the obvious benefit of reducing cooking time, pressure cooking forces steam into food and prevents moisture and nutrients being lost to evaporation resulting in moist, flavour infused, nutrient rich dishes. Pressure cooking also uses much less water than boiling or traditional steaming methods and the flavour rich cooking water can be retained for use in stocks, soups or other dishes if you are not using them immediately.
Using a pressure cooker at high altitude improves cooking times even more as it is able to offset the reduced atmospheric pressure which would otherwise result in water and other fluids boiling at lower than normal temperatures. If for example you are cooking in Santa Fe new Mexico which is more than 7000 feet or 2000 metres above sea level water boils at around 199°F or 92°C which in cooking terms is considered a braising temperature not a boiling temperature so food needs to be boiled longer in order to cook it.
Types of pressure cookers
There are many different designs of pressure cookers but at the end of the day they are all at their essence a sealed pot which is used to cook food using steam and boiling liquid which is able to be heated to higher than normal temperature due to increased pressure.
Broadly I categorise pressure cookers into two types stovetop , and electric. Both have pro's and con's and at the end of the day it is up to your personal preference as to which one you choose. If you have plenty of money and lots of space there is nothing stopping you hving both.
Stovetop Pressure Cookers
Stovetop Pressure cookers are a simple robust sealed pot which generally reach higher temperatures and pressures ( up to 15 PSI) than their electric counterparts. If you wan't a cooker that cooks larger quantities of food quickly and efficiently and will give you decades of trouble free service then a good quality stovetop cooker is probably your best choice. These units are designed to sit on a regular stovetop are simple in their operation but do require supervision to regulate temperature whilst cooking and are definitely not a set and forget kitchen equipment.
If you buy a good Stovetop pressure cooker it will be manufactured from high quality stainless steel and as a result will have the advantage of doubling as a large non pressurised pot which can be used to brown food or reduce cooking liquids before the lid is put on or after it is removed.
In short a good quality stovetop cookers is likely to last a lifetime, and will be generally quicker to use than an electric unit.
Electric Pressure Cookers
Electric pressure cookers work on the same principle as their stovetop counterparts but have the advantage of built in electronics which can carefully control temperature and pressure in the cooker eliminating the requirement for constant supervision. These units generally cook at lower pressures and temperatures so take a little longer to cook than stovetop units.
If you have bench space to spare ,don't need to cook large quantities and wan't a pressure cooker that you can leave to do its thing without supervision then a good quality electric cooker is probably your best choice.
How and when to use a pressure cooker
Pressure cookers are a great cooking tool to use when you want to create a tasty one pot dish quickly and efficiently. You will have no problems finding recipes for your favourite , stew , braise, or curry which can be cooked in a fraction of the. Dishes that can normally be cooked in under half an hour probably won't gain much from pressure cooking as it can take 20 minutes or more to bring the cooker up to pressure and cool it down again.
Always refer to manufacturers operating instructions if you are unsure how to operate a pressure cooker especially if you are using an electric pressure cooker. Although good quality modern pressure cookers are built to high safety standards misoperation or the use of poor qualty units can result in injury.
Referring to manufacturers operating instructions is particularlt important when familiarising yourself with the operation of electric pressure cookers as it will vary from cooker to cooker.
For stovetop cookers the basic steps for use are as follows:
- If required Heat the pot without the lid on and brown any food that requires browning in oil.
- Prepare and add any other required ingredients to the pot.
- Add water and other liquids as called for by recipe. Alway ensure that there is enough liquid in the cooker to prevent it from boiling dry and do not fill the pot above the maximum recommended by the manufacturer ( usually 2/3 full ).
- Seal the lid following the manufacturers instructions.
- Heat the pot over a high heat until desired steam pressure is reached.
- Cook for time called for by your recipe, adjusting temperature in order to maintain required pressure.
- Allow pressure to reduce by cooling the pot or vent pressure by following manufacturers instructions.
- Open the pressure cooker being careful not to burn yourself.
- Do any final required food preperation
- Serve and enjoy.