Shelf Life Can Be Deceiving Indicator of Food's Naturalness, Study Finds

Grocery shoppers frequently use a food's shelf life as a shortcut to judge its naturalness, but new research indicates this perception may be inaccurate. A study from the University of British Columbia (UBC) Sauder School of Business found that consumers often associate shorter shelf lives with healthier, more natural foods, even when differences in longevity are due to packaging technology rather than processing.

The research team conducted a series of experiments using products such as potato chips, pasta sauce, mayonnaise, and granola bars. Participants consistently viewed items with shorter shelf lives as more natural and healthier, regardless of whether the ingredients and nutritional information were similar or if the difference in shelf life was solely attributable to improved packaging.

In one experiment involving mayonnaise, where one product had a longer shelf life solely due to a better seal, participants still perceived the shorter-shelf-life option as more natural. Even when explicitly informed that packaging improvements were the reason for extended freshness, shoppers continued to rely on shelf life as their primary indicator. Similarly, potato chips with a five-month shelf life were rated as more natural and healthier than nearly identical chips with a nine-month shelf life.

When presented with pasta sauce options, approximately 70% of participants favored a sauce with a one-year shelf life when asked to prioritize natural foods. However, this preference dropped to 43% when the focus shifted to reducing food waste, suggesting that consumers also associate longer shelf lives with less waste.

"Our research shows consumers are using shelf life as a shortcut for judging whether foods are natural," said Yann Cornil, an associate professor at UBC Sauder and co-author of the study, which was published in the Journal of Consumer Psychology. "It sometimes can be diagnostic, but shelf life is also very much dependent on the quality of the packaging, which has nothing to do with food naturalness."

Cornil noted that this reliance on shelf life can be "misleading," as packaging technologies have advanced significantly, much like refrigeration did decades ago, to enhance food preservation without necessarily altering the food's core composition.

The tendency to equate shorter shelf life with less processing could lead consumers to overlook products that are equally healthy and instead choose items that are more prone to spoilage. Many shelf-stable foods, such as canned beans, frozen fruits and vegetables, and dried oats, maintain their freshness for extended periods due to preservation methods and packaging, not necessarily added ingredients.

Registered dietitian Kelly Springer stated that a shorter shelf life does not automatically signify a healthier product. "Better seals, oxygen barriers and moisture-control packaging help foods stay fresh longer while maintaining quality and safety," Springer explained. She advised consumers to examine nutrition labels for fiber, protein, added sugar, and sodium content rather than relying solely on the expiration date.

For instance, some dairy products like milk, yogurt, and kefir can last longer due to pasteurization and fermentation. Similarly, guacamole can have an extended refrigerated shelf life due to high-pressure processing and advanced packaging, not necessarily added preservatives.

Cornil also pointed out that saturated fat content can be a factor, and that an abundance of unrecognizable or difficult-to-pronounce ingredients might signal excessive processing. "It's not always true, but I would say that it is more diagnostic than shelf life information," he added.

These findings are particularly relevant as a significant portion of the American diet, approximately 55% of daily caloric intake, comes from ultra-processed foods. Understanding the factors that genuinely indicate a food's healthfulness beyond its shelf life can help consumers make more informed choices.