How long foods keep and how refrigeration, containers, temperature and storage conditions affect quality and safety.
Nuts freeze very well because they contain little water. At about 0°F (-18°C) in airtight packaging, cold storage greatly slows fat oxidation; UC Davis guidance gives up to roughly two years of good quality for several intact nut types.
Rancidity is fat oxidation, not a calendar date. It often shows up as an abnormal odor or flavor—old oil, paint, cardboard, or a harsh lingering bitterness—before there is an obvious visual change. Dark nuts are not automatically rancid, and normal-looking nuts can still taste oxidized.
Dry or commercially shelf-stable foods — dry rice and pasta, flour, unopened cans, oil, bread and many unopened packaged products — do not need refrigeration when the label says room-temperature storage is appropriate. Many whole fruits and vegetables also do not. Opening, cutting, cooking or rehydrating can turn a shelf-stable food into a perishable one.
Refrigerator organization is mainly about cold temperature and cross-contamination. Keep ready-to-eat and cooked foods above raw meat and poultry; store raw items low in leakproof containers; use produce drawers; and keep the refrigerator at 40°F or below. The door is warmer and better for less temperature-sensitive items.
Food kept continuously frozen at 0°F (-18°C) remains safe almost indefinitely according to USDA; the recommended freezer timelines are mainly about quality. Flavor, texture and moisture decline, and freezer burn becomes more likely. Any thawing or temperature failure changes the safety question.
When the surface of a recently cut avocado turns brown, it is usually enzymatic oxidation rather than spoilage. The appearance changes much faster than the overall nutrition. You can scrape away a thin layer if you dislike the taste or texture. Mold, a rotten or strongly fermented smell, pronounced slime or deep widespread deterioration point to a different problem.
As a general rule, cooked food and other perishables should not stay at room temperature for more than 2 hours. FDA shortens that limit to 1 hour when the air temperature is above 90°F (32°C). Once food has spent too long warm, refrigerating, freezing or reheating it later does not erase bacterial growth or toxins that may already have formed.
Hard-boiled eggs can be refrigerated for up to 1 week, peeled or still in the shell, according to FDA guidance. Keep the refrigerator at 40°F (4°C) or below and refrigerate the eggs within 2 hours of cooking. The shell generally protects moisture and texture better; peeled eggs should stay in a clean covered container.
The answer depends mainly on texture. On a solid block of hard cheese, a small patch of accidental mold can be removed by cutting at least 1 inch (2.5 cm) around and below it without dragging the knife through the mold. Soft or fresh cheese, plus shredded, sliced or crumbled cheese, should be discarded because growth can extend beyond what you can see. Intentional mold in blue cheese or Brie is a different case.
In the United States, cooked pasta should generally be refrigerated within 2 hours and eaten within 3–4 days, following USDA leftover guidance. The clock starts when the pasta is cooked and reheating does not reset it. If the dish contains meat, seafood, cream or another more perishable ingredient, follow the shorter storage limit for the whole dish.
Yes. In the United States, commercially sold shell eggs should be refrigerated promptly at 40°F (4°C) or below and kept cold until use. U.S. eggs are commercially washed and normally sold under refrigeration, so storing them on the counter after purchase breaks that cold chain. Keep the carton on an interior refrigerator shelf and take out only the eggs you are about to use.
Cooked rice is safest when it is cooled quickly, refrigerated within 2 hours and reheated evenly to 165°F / 74°C. The key hazard is not reheating itself: Bacillus cereus spores can survive cooking, and heat-stable toxin may form if rice spends too long warm.