My fridge often has a random collection of storage containers and takeout boxes full of leftovers. I have a very organized friend who immediately writes the date on a label before refrigerating leftovers. I’m not that good.
Instead, my husband and I do the sight or smell test. It’s probably okay to eat it if it doesn’t smell or look weird. When we really aren’t sure how old the remains are – or even What something is – we drop it. It turns out that experts agree that this is a good way to filter out leftovers.
Use your eyes and nose
“The (food) spoilage process goes through three stages,” says Keith Warriner, a professor in the Department of Food Science at the University of Guelph in Ontario, Canada. “First you smell unpleasant odors, then you notice some deterioration, such as wilting or discoloration of the meat, and then visible growth such as slime on chickens or mold on cheese.”
It’s easier to tell if fruits and vegetables are going bad because you may see mold or browning. However, other foods such as chicken or pasta show no visible signs of deterioration.
The sniff test works on some things like meat, fish and milk, says Warriner. “These have a high protein content and therefore produce ammonia and esters with low thresholds. Other products where the smell is masked (marinated meat, cheese) are more difficult to detect.”
However, it’s important to note, says Warriner, that while food contaminated with pathogens like salmonella may look and smell good, it can still make you sick.
After so many days, throw away your leftovers
The limit to keep most leftovers fresh and safe is approx three to four daysaccording to the U.S. Department of Agriculture’s Food Safety and Inspection Service. It takes much longer and the risk of bacteria increases.
Experts like Warriner say: “The general consensus is five days. As soon as you put food in the fridge, microbes start to grow and if pathogens are present, dangerous levels can be reached.”
Bacteria – such as E. coli, salmonella and listeria – can cause this Foodborne illnesses. Symptoms can range from a simple queasy stomach to more serious diarrhea, vomiting and dehydration.
“It’s important to note that not all germs are the same,” says Jacob Tuell, MPH, Ph.D., manager of food safety and quality assurance and director of the muscle nutrition division of the Institute of Food Technologists.
“Perishable microorganisms that cause food to spoil are not the same as pathogenic microorganisms that make us sick,” he says. “Perishable microorganisms make food unpleasant over time, but do not pose a safety risk.”
Storing food in the so-called “danger zone” (40°F to 140°F) for too long can trigger the growth of bacteria that can cause illness.
“It would be more important to me to know the history of my leftovers—were they cooled and kept cold immediately after serving?—than how long they were stored,” says Tuell. “Unfortunately, foods can harbor pathogens but show no obvious signs of spoilage.”
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Best before and consumption dates
If you have leftovers in store-bought packaging, it’s not a bad idea to check the best-by or use-by date.
“The best-before date is an indication of when a food should be consumed to ensure the highest quality and has nothing to do with food safety,” says Tuell. “As long as it is handled properly, such as when it needs to be refrigerated, most foods can be safely consumed well past their expiration date.”
Warriner recommends paying attention to the dates in cured meats, pasteurized soups, soft cheeses and vacuum-packed meats. In these cases the date is based on food safety.
