Answer: Not nearly as long as everyone thinks!
First of all, you must keep your refrigerator below 40°F (but above 32°F). Bacteria and mold can still grow on the food in the fridge, but they grow more slowly than at room temperature. Listeria bacteria grow well in cold temperatures1. If your fridge is extremely full and you don’t have 10 people living in your house, there is a good chance that old food needs to be thrown out. It is very hard to remember when you opened food. Keep a permanent marker by the fridge. When you open something like mayonnaise, write the date on it. That way you’ll know how old it is.
General Guidelines:
In general, leftovers are good in the fridge for 4 days. After that, throw them out.
Milk and juice are good for 1 week after opening, providing you did not drink directly out of the container.
Open mayonnaise is good for 2 months. Sticking a knife directly in the jar can contaminate it so buy the squeeze bottle. Most people keep mayo much too long.
Ketchup, jelly, and peanut butter are good for 6 months after opening. My sister got food poisoning from a natural peanut butter that had been in her fridge for 1.5 years.
Salad dressings are good for 3 months after opening.
Salsa is good for 1 month after opening.
Cottage cheese and cream cheese are good for 1 week after opening.
For information about how long other foods can be kept, please go to the website Still Tasty.
Some people are set in their ways. They think their mayonnaise is fine for a year and they leave food out for hours and have never had a problem. I know people who taste raw ground beef to make sure their meatballs are properly seasoned because that is how they did it in the old days. These people have every right to eat what they want and run their kitchens how they please. I respect their choice and even admire their carefree lifestyle. But please, be considerate of others. Don’t feed your guests the casserole that sat out all night, your salad dressing that expired in 2006, or the deli meat you purchased 2 weeks ago. My mother-in-law recently gave my husband food poisoning by making him a ham sandwich using deli meat that was about 2 weeks old. Some questionable food that wouldn’t make you sick would probably still make a pregnant women, young child, or elderly person sick.
Find out how long food will be good in the fridge when the power goes out on the next page.
For more great information about food safety please go to the web sites of STOP Foodborne Illness, California Poison Contol, and USDA Food Safety.
--Annie Pryor, Ph.D.