(Images courtesy of FSIS-USDA)
Refrigerator temperatures do not destroy pathogenic or spoilage microorganisms. The lower temperature does, however, slow the growth of microorganisms already in the food. Perishable food will deteriorate, even at refrigerator temperatures, due to spoilage microorganisms, enzymes and oxidation. Time and temperature are important factors in food quality. Here are more tips:
- Maintain your refrigerator between 34°F and 40°F. Refrigerator thermometers are available to help monitor the temperature inside the appliance. See more on thermometers.
- Use food quickly, and don’t expect food to remain high-quality for the maximum length of time. Opened and partially used items usually deteriorate more quickly than unopened packages.
- Foil, plastic wraps or bags or airtight containers are the best choices for storing most foods in the refrigerator. Open dishes may result in refrigerator odors, dried-out foods, loss of nutrients and mold growth.
- Don’t stack foods tightly or cover refrigerator shelves with foil or any material that prevents air circulation from quickly and evenly cooling the food.
- Some foods, including milk, meats and leftovers, should be kept colder than others.
- The coldest part of the refrigerator is usually the area nearest the freezer compartment, but a refrigerator thermometer will provide an accurate check for each appliance.
Keep your freezer at zero degrees (0°) or below to maintain the quality of frozen foods.
Most foods will maintain good quality longer if the freezer temperature is -10 to -20°F. At temperatures between 0 and 32°F, food deteriorates more rapidly. Fluctuating temperatures, such as those in self-defrosting freezers, also may damage food quality. Do not plan to store frozen foods for the maximum suggested time if your freezing unit cannot maintain zero degree temperatures. Even foods stored properly will lose color, texture, flavor and nutritional quality but will not cause food-borne illness.
Freezer temperatures, however, do not destroy pathogenic or spoilage microorganisms, which will begin growing under warmer temperature conditions. When frozen foods are thawed at room temperature, the surface of the food warms enough for microorganisms to grow and multiply.
If your freezer does not have a built-in thermometer, check the temperature frequently.
- One easy way to estimate the freezer’s temperature is to check the consistency of ice cream stored inside the compartment. If the ice cream is not brick-hard, the temperature of your freezer is too warm.
- A warning light or other device may be installed to warn you if the freezer is not operating correctly. A plug protector may be used to keep the electrical plug in the outlet.
Time is an important factor in maintaining high-quality frozen foods. Frozen foods will not last forever. The chart on the associated page lists the maximum length of storage times to help you maintain quality food products.
- Label frozen food items, maintain a rotation system and use the items with the oldest dates first.
- Allow proper air circulation in the freezer.
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Packaging and Freezer Burn
Many products including foil, plastic wrap or bags, freezer paper and airtight containers are designed for frozen food storage. If food removed from the freezer is found to have white, dried-out patches, freezer burn has occurred. Freezer burn means improper packaging allowed air to dry out the food surface.
While freezer-burned food will not cause illness, it may be tough or tasteless when consumed.