The dairy industry strives to preserve the quality and safety of milk products while maintaining the freshest possible taste for consumers. To date, the industry has largely focused on packaging milk in light-blocking containers to preserve freshness, but little has been understood about how the packaging itself influences milk flavor. However, a new study in the Journal of Dairy Science, published by Elsevier, confirms that packaging affects taste – and paperboard cartons do
not preserve milk freshness as well as glass and plastic containers.
Lead investigator MaryAnne Drake, PhD, of the North Carolina State University Department of Food, Bioprocessing and Nutrition Sciences, Raleigh, NC, USA, 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.”
To quantify the flavour impacts of packaging, the researchers examined pasteurised whole and skim milk stored in six half pint containers: paperboard cartons, three plastic jugs (made from different plastics), a plastic bag, and glass as a control. The milk was stored in total darkness to control for light oxidation and
kept cold at 4°C (39°F).
HTST milks packaged in HDPE, PET, or glass in the absence of light exposure have no discernable sensory differences
The samples were tested on the day of first processing, then again at 5, 10, and 15 days after. A trained panel examined the sensory properties of each sample, and the research team conducted a volatile compound analysis to understand how the packaging was intermingling with the milk. Finally, the samples underwent a blind consumer taste test on day 10 to see whether tasters could tell any difference between milk stored in the paperboard carton or the plastic jug compared with milk packaged in glass:
Consumers detected differences between skim and whole milk filled into paperboard cartons and glass. Consistent with minimal to no differences by trained panels, consumers could not detect differences between the PET and glass pairings and HDPE and glass. These results are consistent with a previous study, where consumers reported similar flavour and acceptability of milks packaged in PET and HDPE. The results are also consistent with the trained descriptive panel and volatile compound results. Skim or whole milks filled into PET, HDPE or glass were similar in overall flavour profile with no paperboard/cardboard or refrigerator stale off-flavours present by d 15.
The results showed that package type does influence milk flavour, and skim milk is more susceptible to flavour impacts than whole milk. Of the different packaging types, paperboard cartons and the plastic bag preserved milk freshness the least due to the paperboard’s absorption of milk flavour and the transfer of paperboard flavor into the milk. Milk packaged in paperboard cartons, in fact, showed distinct off-flavours as well as the presence of compounds from the paperboard. The final results show that, while glass remains an ideal container for preserving milk flavour, HDPE and PET provide additional benefits while also maintaining freshness in the absence of light exposure.
Paperboard cartons are the most widely used packaging type for school meal programs in the United States, so these findings are especially relevant for the consideration of how young children consume and enjoy milk.
“These findings suggest that industry and policymakers might want to consider seeking new package alternatives for milk served during school meals,” said Drake. 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.
The article is “The role of packaging on the flavor of fluid milk,” by Dylan C. Cadwallader, Patrick D. Gerard, and MaryAnne Drake (https://doi.org/10.3168/jds.2022-22060). It appears in the Journal of Dairy Science, volume 106, issue 1 (January 2023), published by FASS Inc. and Elsevier.