Use a Refrigerator AND a Freezer Thermometer
Alice Henneman, MS, RD, UNL Extension in Lancaster County
Joyce Jensen, REHS, CFSP, Lincoln-Lancaster County Health Department
The numbers used to adjust the temperature on most home refrigerators only raise or lower the temperature. They do not match specific temperatures. A different setting may be needed during warmer months than colder months to maintain the same temperature. Using a refrigerator/freezer thermometer is the only way to assure your refrigerator and freezer is at the correct temperature.
40 degrees F or lower is the recommended refrigerator temperature to slow bacterial growth and maintain quality. Freezing occurs at 32 degrees F; adjust refrigerator accordingly between 32 degrees F and 40 degrees F to prevent unwanted freezing, such as freezing milk.
0 degrees F or lower is the recommended freezer temperature. At this temperature, bacterial growth will be stopped. However, freezing does not kill most bacteria, nor does it stop flavor changes that occur over time. Though food will be safe indefinitely at 0 degrees F, quality will decrease the longer the food is in the freezer.
Most refrigerator/freezer thermometers are either liquid-filled or bimetallic-coil thermometers. The United States Department of Agriculture describes these thermometers as follows.
Liquid-filled thermometers are the oldest types of thermometers used in home kitchens. As the temperature increases, the colored liquid (usually an alcohol solution) inside the thermometer expands and rises to indicate the temperature on a scale.
Bimetallic-coil thermometers contain a coil made of two different metals with different rates of expansion that are bonded together. The bimetal element is coiled, fixed at one end, and attached to a pointer stem at the other end. As the temperature increases, the pointer will be rotated by the coiled bimetal element to indicate the temperature.
Purchase refrigerator/freezer thermometers in the housewares section of department, appliance, culinary and grocery stores. Buy two! Place one in your refrigerator and one in your freezer. It may be the best $10 to $20 investment you ever make. Two more tips:
1) Place the thermometer in the front of the refrigerator/freezer in an easy-to-read location.
2) Check temperature regularly -- at least once a week.
NOTE: If the freezer compartment isn't a separate freezer compartment, but a compartment inside the refrigerator, it may be impossible to obtain a 0 degrees F temperature. One sign of this will be soft ice cream. Plan to use food within a few weeks.
Learn how to handle your food during a power outage in this article from the Food and Drug Administration.
For a chart on how long to store common foods in your refrigerator and freezer, visit Food Storage