Do Food Product Dates Make Consumers Safer or Just Poorer?

Poor ManFood product dates encourage food waste—that’s what the creators of hypothesized. To find out if they were right, they hired Harris Interactive to conduct a survey to test the theory.


More than 2,000 American adults responded to the following question about 10 food products: “To the best of your knowledge, which of the following refrigerated food products, if any, would be considered unsafe to consume once the date printed on the packaging has passed?”  The correct answer?  If properly handled, NONE of the products listed would cause illness if used shortly after the so-called “expiration” date.  Yet, 76% of respondents checked at least one.  Since most people don’t consume food they believe is unsafe to eat, the survey strongly suggests that most Americans throw out a lot of perfectly good food because the date on the package has passed, and they fear the product will make them sick.


The five products most often checked as being unsafe after the printed date were the following: milk, checked by 61% of respondents; cottage cheese, by 57%;  mayonnaise, by 54%; yogurt, by 50%;  and eggs, by 45%.


In these tough economic times, no one wants to waste food and money. Still, news about recalls of contaminated products keeps food-borne illness in people’s minds.  Consumers want to avoid getting sick, so they probably discard all those products they think are unsafe to eat. But consider the facts about the products mentioned above:


Milk, if properly refrigerated will remain safe, nutritious, and tasty for about a week after the “sell-by” date and will probably be safe to drink longer than that, though, with time, there’s a decline in nutritional value and taste.  (In general, a “sell-by” date anticipates use beyond that time.)


Cottage cheese is no longer a fragile product, especially the commercial Pasteurized varieties with protective packaging and preservatives that are mold inhibitors.  Dean’s says its cottage cheese lasts for 10-14 days after the date on the carton (or 10-14 days after opening if this period ends before the printed date). 


Store-bought mayonnaise is acidic and contains preservatives, so it’s well protected from contamination. Mayonnaise is often blamed for illnesses actually caused by the products it’s mixed with. Unopened, refrigerated Kraft mayonnaise can be kept for 30 days after its expiration date or 3-4 months after opening, the company told ShelfLifeAdvice. 


Yogurt will remain good 7-10 days after its “sell-by” date.  If kept longer, it will develop a stronger taste and the bacterial cultures (which act as preservatives) will start to die off.


Eggs, properly refrigerated, should last at least 3-5 weeks after the “sell-by” date, according to Professor Joe Regenstein, a food scientist at Cornell University.  Many consumers don’t know this and discard eggs when they reach the “sell-by” date! 


Some respondents checked these products in the survey: cheddar cheese (29%), orange juice (29%), margarine (19%), olives (15%) and mustard (12%).  All remain safe to consume even after they are open and past the “sell-by” or “use-by” date (assuming proper handling).  Among the different categories of survey respondents, women did 8% better than men, older people did better than younger ones, and married folks surpassed singles.  But overall, the answers showed widespread misunderstanding of product dating.


What don’t consumers understand?  Two-thirds of the participants in the survey assumed “use-by” dates to be about safety when they’re actually about quality (taste, texture, appearance, odor, and maintenance of nutritional values stated on the packaging).  The “use-by” (or “best if used by”) date indicates the last day that the item is at its best.  However, the decline in quality is generally gradual and, at first, imperceptible.  As time goes on, the consumer can usually tell (by the product’s appearance, scent, and/or texture) whether or not it is still of good enough quality to be enjoyable to eat. 


A “sell-by” date tells the store manager when the product should be taken off the shelf, so shoppers should look for products that have not reached that date.  However, “sell by” is not a safety date either. It usually means that the product will remain of top quality for at least a few days past that date.


To make matters even more confusing, many products have a date but no preceding words such as “best by” or “use by.”  Without that wording, consumers have an even harder time estimating when to discard edible items. 


Regenstein points out, the “use-by” dates on food packages are very conservative and assume a certain amount of product abuse (mishandling).  If properly handled, most foods will outlive the expiration dates at least for a short time.


Another major source of confusion: “use-by” dates refer to the UNOPENED product.  Consumers who don’t realize that may keep some open products (salad dressings, for example) long past the time when they’re at their best.


Consumers would worry less and waste less if more were aware of these facts:


- In general, properly refrigerated foods don’t cause illness because most harmful bacteria don’t grow in cold environments, or they grow slowly. However, there are some pathogens to beware of. For example, the pathogen Listeria can grow in the refrigerator and can be dangerous for pregnant women and those with weakened immune systems.  Vegetables can develop pathogens that cause botulism if wrapped in an airtight manner. For more information on these dangers, see “FAQs on Bacteria” on


- “Spoilage” bacteria (the ones that make food taste bad, become slimy or discolored, or smell bad) grow faster than the types of the bacteria that cause illness. Therefore, the “yuk” factor forces most people to discard old items before it becomes a health risk.


- To some extent, consumers can trust their senses.  If the product looks, smells, and feels okay (isn’t slimy), it’s probably okay to eat for 4-7 days after the expiration date.


- Pathogens don’t grow on frozen food.  If it was safe to eat when it went into the freezer, it will remain safe while frozen no matter how long.  The dates on frozen food are quality dates only.


- Shelf-stable dry products (containing no moisture or fat) may last long past the “use-by” date.


- Most food-borne illness is not caused by food that’s past its “use-by” date. It is caused by mishandling of food somewhere along the food chain. About one-quarter of the American population suffers from a food-borne illness every year. About 31% of all food contamination originates in the home. But most isn’t from “old” food.  Rather, it’s from mistakes such as these: not washing hands well before handling food, keeping food at the wrong temperature, cross-contamination (bringing a food that’s served uncooked in contact with raw, contaminated items), and not washing raw poultry, fruits, or vegetables well.  Good kitchen hygiene can do much to keep consumers healthy.


The key to prolonging shelf life, according to Regenstein, is keeping foods stored properly. Frozen food should be properly wrapped, refrigerators need to be properly set, and most other products stored should be in the coolest, driest place in the kitchen/pantry.


Although many consumers discard more food than they need to, sometimes it’s smart to throw something out, especially if it’s moldy. Some molds produce dangerous toxins that may spread throughout an edible item. It’s a good idea to throw out the entire item if mold appears anywhere in it, especially if the product is a soft cheese or jelly. Cans of food should also be discarded if the can is badly dented, bloated, or rusty. Pathogens causing botulism could be inside.


According to research by former University of Arizona anthropologist Timothy Jones, Americans throw away more than 40 percent—some 29 million tons—of all the food the country produces, creating both an environmental and an economic problem. There is waste all along the food chain, but by far the most occurs in homes, restaurants, schools, and other eating places.  According to Jones' study, the average American household wastes 14% of its food purchases. estimates that if 61% of Americans (the percentage that thought milk was spoiled when it reached the date on the bottle or carton) needlessly discard a quarter gallon of milk each month, they could be wasting over $700 million a year. Combining this figure with all the other foods in the survey, estimates that billions might be wasted every year by American households discarding good food.


This survey was conducted online within the United States by Harris Interactive on behalf of Shelf Life Advice LLC between March 8-10, 2010 among 2,482 respondents age 18+. No estimates of theoretical sampling error can be calculated; a full methodology is available.


Harris Interactive is one of the world's leading custom market research firms, leveraging research, technology, and business acumen to transform relevant insight into actionable foresight.



   It Says “Use by Tomorrow,” but You Don’t Have To

   FAQs on Food Product Dating

  “Is It Spoiled?” When in Doubt, Check It Out

   FAQs on Bacteria

   FAQs on Mold


(ShelfLifeAdvice sources are mostly government and university sites, food scientists, and food manufacturers. Specific sources are listed at the end of all write-ups.)


Clemson University Extension “Safe Handling of Dairy Products” 


Environmental Protection Agency  “Basic Information about Food Waste”  “Statistics on poverty & food wastage in America” 



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