When Is It Time to Throw Away Milk?


Kurt Olsen

Do you smell it, read the label, or observe the coffee or tea for suspended particles? Numerous methods exist to determine when milk has gone wrong, but new research indicates that up to half of consumers discard milk based solely on a quick look at the date printed on the carton, regardless of the text surrounding it. Pouring away content that is, in many cases, perfectly excellent and safe to consume is wasteful.

Why cry over discarded milk?

Food waste is a significant issue all around the globe. The United Nations (UN) estimates worldwide food waste from families, shops, and the food service sector totaled 931 million tonnes in 2019. Consumer waste accounts for a considerable share of this amount in many nations. In the United States, for example, consumer waste accounts for more than 48 percent of excess food; in the United Kingdom, this figure is considerably higher, accounting for around 70 percent of trash.

The fact that so much food is produced but not consumed has far-reaching consequences for the environment, the economy, and society. The United Nations estimates that food waste accounts for 8-10% of worldwide greenhouse gas emissions. Furthermore, it is relatively expensive for us. Significant research published in 2013 revealed that the typical American household wastes between $1,365 and $2,275 of food yearly.

Reducing this waste can benefit both people and the environment.

However, understanding when something should be thrown may be difficult for many people, and the product’s label would be an excellent place to go for this information. However, a recent study indicates that here is where uncertainty arises.

Labels, dates, and poor phrasing

One issue with product labels is sometimes uncertainty about the meaning of the information shown, which is exacerbated by the fact that no consistent phrase tackles this. In Europe, for example, there are “best before” and “used by” dates on items that are designed to indicate the quality of the food (the former) and when it is no longer safe to consume (the latter). Labels such as “use by,” “best if used by,” and “sell by” may be found in other areas, as well as containers with no information at all.

Despite their various meanings, many dates may represent the same hazy concept – the “expiry date.” According to a team of Ohio State University researchers, the date is often the only item individuals glance at.

The researchers recorded customers’ eye movements while analyzing milk bottle graphics. When deciding whether to reject milk, participants focused more on the label’s date than the surrounding content.

The 68 participants each saw two flights of milk samples. The first batch of photographs comprised eight half-empty milk cartons with the same phasing but different dates. These dates ranged from six days after the study’s date to a week before. They were shown two actual samples of milk, one fresh and one of inferior quality, that had been allowed to deteriorate.

The second set consisted of unlabeled milk containers and excellent and sour milk samples.

Labels were utilized in both presentations to suggest that the actual samples came from the containers shown in the photographs.

The eye-tracking equipment revealed that participants spent more time looking at the date on the label than the accompanying phrase. They also glanced at the date more often, and their gaze was directed to it 44 percent quicker than it was drawn to the sentences.

Furthermore, even when participants glanced at the wording, the phrase did not affect how long they looked at it.

The quality of the milk, whether sour or not, did impact the participant’s overall choice to throw it away, but it did not affect the information people looked at on the labels.

“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,” said Brian Roe, professor of agriculture, environment, and development economics at The Ohio State University, in a statement.

“However, we were surprised that over half of the viewing sessions had no attention paid to the phrase at all,” he stated. “The date is more noticeable; you have to check it against the calendar.” It’s more practical than the term.

These findings are consistent with earlier research by Roe and reveal that the desire to discard food mostly depends on the date rather than the language on labels.

This might significantly influence future initiatives aimed at reducing food waste.

“It’s nevertheless vital for policy reasons to limit the phrases to two options. But that’s only the start; there has to be a larger discussion about shifting those date horizons back to help reduce food waste,” Roe noted.

Note: The study is published in Waste Management.

What Do the Dates on Milk Mean?

First, it is essential to comprehend what these numerals on the milk bottle genuinely indicate. You may be astonished to discover that, except for infant formula, the USDA’s Food Safety and Inspection Service does not require product dates. Consequently, the dates on milk can differ from manufacturer to manufacturer, and the numbers you see may not even be an expiration date, even if they appear to be.

According to the FSIS, you may encounter four categories of dates:

  • Best if Used By or Before indicates when a product’s flavor or quality will peak.
  • Stores use Sell-By for inventory management
  • Use-By suggests the final date to consume a product for optimal quality.
  • Freeze-By indicates the date a product must be frozen to maintain peak quality.

While a Best if Used By/Before or Use-By date indicates a product’s peak quality before it begins to deteriorate, that doesn’t mean you should throw out milk the day after that date has passed (more on below).

How Long Is Milk Good for After the Expiration Date?

There are no official recommendations, but the following is a general rule of thumb:

  • Three days after the expiration date for open milk
  • Up to seven days after the expiration date for unopened milk

Milk may still be edible after these dates, but you should always check for indicators of deterioration before consumption. Also, remember that these guidelines apply to pasteurized milk, which can be found in grocery stores. Raw or unpasteurized milk has not been treated to eliminate hazardous microorganisms. Raw milk has a reduced expiration life and a high risk of causing contaminated infection.

How to Tell If Milk Is Bad

Although consuming milk after the expiration date is acceptable, you should examine it for signs of possible deterioration. How to tell if milk has gone wrong:

  • First, check the smell: spoiled milk will have an acrid, disagreeable odor that is often immediately detectable. If you cannot use scent, other methods exist to determine whether milk is spoiled.
  • Next, consider the hue: The color of pasteurized milk is white. Mold, ranging from black to blue, may develop in contaminated milk.
  • Next, consider consistency. Milk’s consistency may change from velvety and smooth to chunky or granular when it has gone rancid. This visual indicator indicates the milk is no longer safe to consume because it has begun curling.

Lastly, sample it. If your milk is not showing any other symptoms of deterioration or if you are still dubious about its safety, take a small taste. If you detect acrid or acidic flavors in the milk, you should discard it.
If your milk exhibits any of these signs of deterioration, you should discard it. Milk that has gone bad can cause regurgitation, gastrointestinal cramps, and diarrhea.

How to Make Milk Last Longer

Store Milk Properly

Properly storing your gallon of milk is a simple method to prevent it from spoiling before its expiration date. Although it may seem advantageous, milk should never be stored in the entryway of the refrigerator. Because every time the door is opened, the contents are exposed to higher temperatures. Milk requires consistently low temperatures to prevent the proliferation of pathogens. Instead, milk should be placed at the rear of the rack, where temperatures are the harshest.

Freeze Milk

Freezing milk is yet another method to extend its shelf life. Learn how to freeze milk to prevent food waste when you cannot consume it before it goes bad. We recommend pre-portioning it so that you only defrost what you need when you need it.

The Bottom Line

Typically, milk can be ingested up to three days after its expiration date for opened milk and up to seven days for unopened milk. Before consuming, it is recommended to search for evidence of decay. Examining the milk’s aroma, color, consistency, and flavor will reveal if it is spoiled. Place your milk on a ledge in the rear of the refrigerator to ensure it remains fresh.


Contact Us

For more information or to make comments and suggestions, please contact:
Kurt Olsen
Dairy Development Coordinator, Missouri Department of Agriculture
Phone: (573) 291-5704
E-mail: [email protected]