What expiry dates actually mean

Expiry date of foods. pic courtney africa

Expiry date of foods. pic courtney africa

Published Jun 29, 2016

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No one wants to serve spoiled food to their families.

Conversely, consumers don’t want to throw food away unnecessarily. The United States Department of Agriculture estimates Americans toss out the equivalent of U$162 billion (R2.4 trillion) in food every year at the retail and consumer levels.

Plenty of that food is discarded while still safe to eat. Part of these losses are due to consumers being confused about the “use by” and “best before” dates on food packaging.

Contrary to popular impression, the current system of food product dating isn’t really designed to help us figure out when something from the fridge has passed the line from edible to inedible.

For now, food companies are not required to use a uniform system to determine which type of date to list on their food product, how to determine the date to list or even if they need to list a date on their product at all.

The Food Date Labeling Act of 2016 aims to distinguish between foods that may be past their peak, but still okay and foods that are unsafe to consume.

How are these dates even generated? Food producers, particularly small-scale companies just entering the food business, often have a difficult time knowing what dates to put on their items.

But manufacturers have a few ways – both art and science – to figure out how long their foods will be safe to eat.

Consumer confusion

One study estimated 20% of food wasted in UK households is due to misinterpretation of date labels. Extending the same estimate to the US, the average household of four is losing $275-455 per year on needlessly trashed food.

Out of a mistaken concern for food safety, 91% of consumers occasionally throw food away based on the “sell by” date – which isn’t really about product safety at all. “Sell by” dates are actually meant to let stores know how to rotate their stock.

A survey conducted by the Food Marketing Institute in 2011 found that among their actions to keep food safe, 37% of consumers reported discarding food “every time” it’s past the “use by” date – even though the date only denotes “peak quality” as determined by the manufacturer.

Here’s how producers come up with those dates:

Figuring out when food’s gone foul

Larger food companies may conduct microbial challenge studies on food products. Based on the conditions used for testing, the company would then calculate the actual shelf life based on formulas using the estimated shelf life from the rapid testing.

Smaller companies may list a date on their product based on the length of shelf life they have estimated their competitors are using, or they may use reference materials or ask food safety experts for advice on the date to list on their product.

Even the best dates are only guidelines

Consumers themselves hold a big part of food safety in their own hands. They need to handle food safely after they purchase it, including storing foods under sanitary conditions and at the proper temperature.

If a product has a use-by date on the package, consumers should follow that date to determine when to use or freeze it. If it has a “sell by” or no date on the package, consumers should follow storage time recommendations for foods kept in the refrigerator or freezer and cupboard.

l Nwadike works for Kansas State University and the University of Missouri. This article first appeared in The Conversation.

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