In a recent study by Ohio State University, researchers have found that “up to consumers may decide to pour perfectly good milk down the drain based solely on their glance at the date label on the carton”.

The study, published in the journal Waste Management, was carried out using eye-tracking technology and found that 50 percent of participants declared their intent to throw away milk based on the date printed on the container. This decision was made “without even looking at the label phrasing in front of the date”.

Each participant saw one of three phrasing options: “Sell by,” “Best if used by” or “Use by” a given date. They were also shown containers with no label at all.

“We asked them if they intended to discard it, and if they said yes, it didn’t matter which phrase was there,” said Senior Study Author Brian Roe, Professor of Agricultural, Environment and Development Economics at Ohio State University.

“As soon as we changed the printed date, that was a huge mover of whether or not they would discard or not. So we documented both wher their eyes were and what they said was going to happen. And in both cases, it’s all about the date, and the phrase is second fiddle.”

Roe went on to explain that policy makers and industry leaders are currently working towards settling on a universal two-phase system, “one when quality, but not safety, is the concern”. He explained that the second phase is for items safety may be a concern, however he noted that “to date, they haven’t landed on what those phrases would be”.

“If you’re going to have an education campaign, it helps to have a set of phrases out there that people can cling to – but in the end, so few actually look at the phrase. They look at the date,” Roe continued.

“The date signifies a point after which you can expect quality to degrade. If you can get firms to push that date further out, then people are going to be willing to use the milk, or whatever it is, for a few more days, and waste a lot less food.”

Choosing milk to be used in their study, the researchers said that this is because it is “widely consumed and represents about 12 percent of all food wasted by US consumers”.

In the study, each of the 68 participants viewed two flights of milk samples. The first featured images of eight half-empty milk containers with the same phrasing preceding a variety of dates that ranged from six days after to a week before the study day, presented alongside two physical samples each of fresh milk or poor-quality milk that the research team had allowed to go slightly sour. The second featured unlabelled milk containers alongside physical samples of good- or poor-quality milk.

In each presentation, numbering labels implied that the physical samples had been poured from corresponding containers that appeared in the images.

Data from eye-tracking technology showed that overall, participants spent more time fixing their eyes on the date compared to the phrase, looked at the date more frequently and laid their eyes on the date 44 percent faster than on the phrase.

“When participants did glance at the phrase, the type of phrase had no significant effect on how long they fixed their eyes on the words,” researchers explained.

The study authors went on to note that while the quality of the milk affected participants’ intent to throw it away (with souring milk having about a third higher discard probability than fresher milk) the quality factor did not influence what participants spent the most time looking at on the label.

“The milk was intentionally made to smell a bit sour, and it didn’t really fundamentally change the fact that people really focus on the date,” Roe said.

“We were a bit surprised that over half of the viewing sessions featured no attention on the phrase whatsoever. The date is more salient – you have to reference it against the calendar. It’s more actionable than the phrase is.”

Roe noted that, for policy reasons, he believes it is still important to narrow the phrases down to two choices, but he highlighted that is “only the beginning”. Going forward, he said “there needs to be a broader conversation about pushing those date horizons back to help minimise food waste.”