U.S – North Carolina State University researchers have found that paperboard milk cartons, used in practically every American school, may not maintain milk freshness as well as other packaging options.

According to a study by Elsevier that was published in the Journal of Dairy Science, packaging has an impact on flavor.

Lead investigator MaryAnne Drake, Ph.D., of the North Carolina State University Department of Food, Bioprocessing and Nutrition Sciences, explained that “milk is more susceptible to packaging-related off-flavours than many other beverages because of its mild, delicate taste.” 

Besides light oxidation, “milk’s taste can be impacted by the exchange of the packaging’s compounds into the milk and by the packaging absorbing food flavours and aromas from the surrounding refrigeration environment.”

The researchers looked at pasteurized whole and skim milk held in six half-pint containers: paperboard cartons, three plastic jugs (made of different plastics), a plastic bag, and glass as a control to measure the flavor impacts of packing.

The milk was kept cool at 4°C (39°F) and stored in complete darkness to prevent light oxidation.

The samples were tested on the day of first processing, then again at five, 10, and 15 days after.

In order to determine how the packaging was interacting with the milk, the research team analyzed volatile compounds and a trained panel evaluated the sensory qualities of each sample.

On day 10, a blind consumer taste test was conducted on the samples to determine whether tasters could detect any differences between milk packaged in glass versus milk stored in a paperboard carton or plastic jug.

The findings demonstrated that milk flavor is affected by package type, and skim milk is more flavor sensitive than whole milk.

Due to the paperboard’s ability to absorb milk flavor and impart that flavor into the milk, paperboard cartons and plastic bags preserved milk freshness the least of all the packaging options.

In fact, milk that had been packaged in paperboard cartons had distinct off flavors as well as chemicals from the paperboard.

The final findings demonstrate that while plastic containers offer extra advantages while still retaining freshness in the absence of light exposure, glass containers continue to be optimum for preserving milk flavor.

These findings are especially pertinent when taking into account how young children eat and enjoy milk as paperboard cartons are the most popular packaging material for school meal programs in the U.S.

“These findings suggest that industry and policymakers might want to consider seeking new package alternatives for milk served during school meals.

“Over time, the consequences of using milk packaging that contributes significant off-flavours may affect how young children perceive milk in both childhood and adulthood,” said Drake.

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