Why is it acceptable for someone who would never purchase "expired" milk at the store to pour "expired" milk into a cup of coffee at breakfast? A new study in the Journal of Consumer Research explores the reasons consumers are more likely to consume products that are past their expiration dates if they are in their refrigerators than if they are in a store.
Authors Sankar Sen and Lauren G. Block (both Baruch College/CUNY) explored a phenomenon termed the "endowment effect," meaning that owning a product increases a consumer's valuation of it. The endowment effect has been studied before, but not in regard to perishable products.
"Few people would knowingly purchase products past their freshness dates; in fact, shoppers often leave supermarket shelves in disarray after combing the display for, say, the carton of milk stamped with the freshness date furthest away," the authors write. While there are many possible reasons consumers may want to consume "expired" food in their refrigerators, including "getting their money's worth," the authors found that even when they controlled for costs and motivations, consumers were still more likely to eat or drink expired products that were already in their possession.
"In this research, we show that merely owning a product past its freshness date provides enough reason for people to be willing to consume such expired products...Importantly, this increase in a person's willingness to consume an expired product is accompanied by lower estimates of the perceived risk of getting sick from consuming it," the authors explain.
In three studies, the researchers compared whether people wanted to consume yogurt smoothies that were past or not past their freshness dates. The authors believe that "ownership" of the smoothie shifted the default hypothesis from "shouldn't consume because expired" to "okay to consume."
"If you caught a glimpse of moldy cheese being served at a function you were attending, you wouldn't eat it, thinking it likely that you could get sick from old cheese," write the authors. "However, if that same moldy cheese is in your refrigerator, hey, what's a little mold?"
Sankar Sen and Lauren G. Block. "Why My Mother Never Threw Anything Out: The Effects of Product Freshness on Consumption." Journal of Consumer Research: June 2009.