How Does a Slow Cooker Work?

A Practical Idea

Slow cookers are really nothing new. Several techniques have been used to cook tough food slowly in its own juices. Native peoples---and numerous boy and girl scouts---used "bean holes"---pits dug in the ground in which hot fires were allowed to burn to coals, then lined with wet plant matter before inserting a pot of food to cook and burying the whole thing. Another technique---the "hay box" consisted of a pot of food heated to a high temperature and then inserted in a box lined with a thick, insulating layer of hay. Both methods used residual or low heat to cook food over a long period with little need for supervision by the cook. When electricity became available in the kitchen, it was only logical that small appliances would replace the bean hole and hay box and by the 1920's cooks were using portable electric cookers that could prepare a whole meal while parents worked and looked after children, putting a whole group of domestic help out of business.

Re-invented by the Rival Company in 1971, the idea was updated as the "Crock Pot" just as American women were re-entering the work force. Today, slow cookers are popular again and are produced in several shapes and sizes that combine ease of preparation, economical use of electricity and an ability to use inexpensive ingredients to make delicious meals.

It's All Inside

Today's slow cookers consist of a liner and shell. The liner is made of crockery, enameled steel or non-stick steel and slips into the shell. Rival's original cooker was one unit, making cleaning difficult. Today's liners are completely immersible. The shell contains the works of the slow cooker, high resistance heating coils that surround the liner, completely contained in a double-sided insulated round or oval container on pudgy feet that lift it off the counter. Since the early cookers were hard to regulate, many can be programmed to turn on and off to cook food perfectly. The food is cooked with a constant heat that is distributed evenly by the thick liner. Crockery still provides the most even heat but the steel liners generally make for more efficient use of energy.

What Successful Slow-Cooker Cooks Know

Tough cuts of meat cook best with slow moist heat, which is what slow cookers do best. Fill no more than three-quarters full to avoid spatters. When starting food in a slow cooker, many cooks sear or heat the surface of the food above 140 degrees to kill any surface bacteria. Crockery is acid-resistant but it's wise to avoid letting acidic foods like tomato-based stews or foods like sauerkraut sit in a steel liner---serve and refrigerate any leftovers promptly. Each slow cooker operates a little differently and it's wise to calibrate yours by checking the actual temperature of each setting before putting food on for six or eight hours, thus avoiding gray, tasteless or still-raw-in-the-middle food at dinner time. Accessories like carrying bags and special cooking racks increase the usefulness of today's slow cookers.