When to Throw Food Out? Not on the Use-By Date

eggs, salsa, yogurtOn August 24th, I got ambitious and cleaned out my refrigerator.  I found these foods--raw eggs, low-fat yogurt, and mild salsa--all languishing far beyond their so-called "expiration" dates.  I asked 4 of the scientists on the Shelf Life Advice Advisory Board to tell me if I could still eat them or if I had to throw them out.  The first 3 sections of this article let you compare their responses.  I hope their explanations help you make better decisions about what "old" food to discard and when.  Note that the philosophy often followed is "Waste not, want not."


But what about fresh produce, which doesn't come with an expiration date? Check out the last section of this article for the answers to these questions:  "How long can I keep fresh produce?"  "How can I handle various fresh fruits and vegetables so they'll last longer?"  In this section, you'll find a link to a handy produce storage chart that not only answers shelf life questions but also gives tips on proper storage.



Dr. Karin Allen, food scientist: These eggs don't need to be discarded as long as they have been refrigerated the whole time. Don’t use them in cakes or for boiled, poached or fried eggs.  They will work fine for cookies, muffins, omelets, or scrambled eggs.  Make sure that any products containing these aging eggs are thoroughly cooked.


Dr. Timothy Bowser, food process engineer: I might use the eggs, but only in well-cooked items. I would let my nose and eyes judge, discarding them for the slightest imperfection.


Dr. Catherine Cutter, food scientist: If refrigerated, eggs will be fine 3-5 weeks after you buy them.  The quality will deteriorate after that.


Dr. Joe Regenstein, food scientist: Absolutely use the eggs if they were kept in the refrigerator unless they smell. Just do hard-boiled or well-cooked eggs.


For more information about eggs, egg products, and egg substitutes, click here on "Eggs and Egg Whites."  At the right margin are links to several other Q/As about these products.




Dr. Allen: There's no need to discard the yogurt as long as it is unopened and has been refrigerated the whole time.  Yogurt is a fermented dairy product that doesn’t spoil easily, but, if there is visible mold or sliminess, discard the entire carton.  Yogurt can become more sour with time, so it might not be as appetizing to eat it right out of the container.  I recommend mixing it with a small amount of milk (2 parts yogurt and 1 part milk) and using it in place of buttermilk for pancakes, quick breads, etc.


Dr. Bowser: I would discard the yogurt since it is 18 days past the use-by date.

Dr. Cutter: Yogurt should be good for a few weeks after the use-by date.

Dr. Regenstein: I’d use my smell-then-taste test.  If you're really concerned, use the yogurt for cooking.


For more information about yogurt, click here on "Once opened, how long will yogurt remain safe and tasty to use?"  Also, click on other links to yogurt shelf life information at the right margin of this page.



(Salsa ingredients in the container scientists were asked to consider: tomatoes, onions, red pepper, jalapeno, cilantro, olive oil, red wine, salt, black pepper.)


Dr. Allen:  Discard the salsa even if it is unopened.  Fresh salsa contains ingredients that have not been heat treated (cooked), so it could potentially carry listeria.  Listeria is a disease-causing bacteria that can grow even when the food is refrigerated.  In this case, it is not worth taking the risk, so it’s best to throw the salsa out if it is more than a week past its sell-by date.  This advice also applies to sliced deli meats and cheese, hot dogs, and dips like guacamole and hummus.


Dr. Bowser: Salsa is a high-acid food and would smell spoiled or produce a gas which might bloat the container if it was going bad. I would also look for mold, and discard it if any mold is visible. Otherwise, I would probably eat it.


Dr. Cutter: It's acidic, and that's protective.  Spoilage from mold is the main issue.  If there's visible mold or gas bubbling, pitch it!


Dr. Regenstein: Same answer as for the yogurt question.  I’d use my smell-then-taste test.  If you're really concerned, use this older salsa only for cooking.


Note: The shelf life data on salsa that this site posted in the past is more liberal about how long to keep it than some of our scientists quoted in this article. The older recommendations also come from reliable sources. However, how long salsa will last may vary depending upon what's in it, the temperature of your fridge, whether it's been opened or not, and perhaps other factors. Dr. Allen offers this explanation: "Some fresh salsas aren't necessarily acidic enough (low ph) to rely on that for safety, especially if they have a lot of other ingredients for example, onion, mango, or bell peppers. Bottled salsa is a different story."



Dr. Allen prepared a handy, 1-page produce storage chart for the Utah State University Extension booklet Live Well Utah.  Her tips cover common fruits and vegetables, the ones most consumers purchase. Go to page 4 of this booklet, print out a copy, and post it on your fridge or keep it in a kitchen drawer for frequent handy reference.  (You'll also find other useful produce information in this booklet.)


The Product division of Shelf Life Advice has a section on fruits and fruit products and another section on vegetables. (Click on the home page photo to reach one of these divisions.) You can find shelf life information and storage tips about a large number of specific types of produce.  The fastest way to reach this data is by typing the name of the particular product you're inquiring about into the "search" box on the home page.


Also, in the FAQs and TIPs divisions of this site, there are many articles about individual kinds of produce as well as articles with more general information about shelf life and ways to extend shelf life by proper storage.  To find these articles, you can use the indexes. It is a good idea to read up on ethylene to understand which fruits tend to hasten the ripening of which other fruits. Ethylene is an odorless gas that some produce gives off. It can cause some produce stored near it to ripen faster than it otherwise would.


To the right of my photo on the home page, you'll find links to complete lists of FAQs and Tips on ShelfLifeAdvice.com. Here is just a sampling of some articles you may want to consult:


http://shelflifeadvice.com/content/faqs-raw-fruits-and-veggies—-answers-can-protect-your-wallet-and-your-health  (This article and the following explain the effects of ethylene.)



















Karin E. Allen, Ph.D., Utah State University, Dept. of Nutrition, Dietetics, and Food Sciences


Catherine N. Cutter, Ph.D., Pennsylvania State University, Dept. of Food Science


Timothy J. Bowser, Ph.D., Oklahoma State University, Dept. of Biosystems and Agricultural Engineering


Joe Regenstein, Ph.D., Cornell University, Dept. of Food Science


The links to other sources are within the article.



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