Wondering whether to partake of that expired yoghurt at the back of the fridge? What about that hunk of cheese with the bit of mould on top?
If you're like most of us, you'll take the chance, a new study shows. In fact, spoiled or past-due foods that we would quickly reject at the supermarket are eagerly consumed once they make it home.
That's because consumers are more likely to eat dubious foods once they actually own them, another sign of how people unconsciously give more value to things that are theirs, researchers say.
"We try to come up with justifications about why it's OK to consume what we already own and downplay the reasons why it might not be OK," said study co-author Lauren Block, a professor of marketing at Baruch College in New York City.
Block and her team aimed to examine the so-called "endowment effect". This refers to the extra value people give to things that they own. Studies have shown, for example, that people will sell a product they own for a much higher price than they'd be willing to pay to buy it from someone else.
In the new study, to be published in the Journal of Consumer Research, the Baruch team examined data from 165 students who were questioned about their yoghurt preferences. The students were given a yoghurt smoothie that was past its "best if enjoyed by" date but was still safe to eat. Those in the "endowed" group were told the yoghurt was theirs to keep.
In the latter group, 38% were willing to drink the smoothie either right then or later. But only 13% of the students who didn't own the yoghurt were willing to drink the smoothie. Those who were told to keep their smoothie were also less likely to think it would make them sick.
Implications for health and safety
"Our results help explain why a person might consume expired food that they found in the fridge, but not consume expired food found in a friend's fridge," Block said.
People seem to rationalise eating the expired yoghurt just as many of us adopt the "five-second rule," which states that food that falls on the floor remains edible if it's just there a few seconds, Block said.
The new study has implications for health and safety, experts say, since it suggests that once products make it to consumers' homes, safety labelling such as the "Best Before" date begins to lose its meaning. According to Block, companies could help consumers by doing a better job of communicating information about expiration dates - and not just when it comes to food.
"For example, many consumers do not know that sunscreen, condoms, fire extinguishers and medicine lose efficacy over time," she said. "Our research suggests that consumers may underestimate the risk associated with using products past their expiration dates, and for some products, this might have a negative consequence."
Bacteria not necessarily visible
And what about foods? Fresh, edible products "don't suddenly go bad with overgrowth of bacteria and harmful substances on the expiration date", said Lona Sandon, an assistant professor of clinical nutrition at the University of Texas Southwestern. "But after that freshness date, bacteria may start to grow slowly and ruin the quality of the food."
Canned goods typically have a much longer shelf life, Sandon said, "but leave them too long and you get something that just doesn't taste right. If the can is not dented, bloated, or leaking, the ingredients are probably safe from bacteria," she said. However, "the texture and flavour of the food is likely to be poor. Things like canned tomatoes may start to become more acidic over time. This may not be harmful to your health, but it doesn't taste good." – (Randy Dotinga/HealthDay News, February 2009)
General food safety