Before refrigeration, preserving food was a big job. You could salt foods, and in winter, you could bury food in a snow drift and hope the critters didn’t find it. To stay stocked with the essentials, though, you had to work at it — or be rolling in money. Refrigeration is one invention that changed the way we conduct our daily lives. We can preserve food more easily nowadays, so we have much less to worry about when it comes to food-borne illnesses. The food supply is more stable, too. That gallon of milk can last a couple of weeks in the fridge as opposed to a couple of hours on your countertop. That’s huge. It means you don’t need to keep a cow in your backyard if you want a regular supply of milk.
The main function of the refrigerator is to keep fresh and perishable foods from spoiling as quickly due to the rapid growth of bacteria. This is attained when food is kept at a temperature that is lower than 40°F (4°C).
A refrigerant gas such as ammonia or chlorofluorocarbon (CFC) is compressed and cooled so that it turns into a liquid. The liquid is then evaporated, a process that requires energy or heat from the surrounding area. The heat is drawn from the inside of the refrigerator, which thus loses energy, therefore decreasing the temperature inside that area. The whole process then starts again once the liquid becomes a gas and this is how the temperature of the refrigerator is maintained.
The normal temperature of a refrigerator is between -34°F – -41°F. Anything lower than this and it would be too cold and cause the contents of the fridge to freeze, whilst anything higher would mean that bacteria would multiply quicker and food would get spoilt faster.
The coldest area of the fridge is at the top, just under the chill tray or the freezer section and the warmest area is at the bottom, in the crisper drawers where vegetables should be stored and on the inside of the fridge door.
The refrigerator door should be kept closed at all times and should only be kept open for the shortest amount of time possible. Leaving the fridge door open or frequently opening and closing it will cause the temperature inside to rise, as warm air is being drawn in all the time, therefore making the fridge work harder and use up more energy and electricity to lower the temperature back down to where it should be.