Protecting Milk’s Flavor and Nutritional Value
Photo-oxidation occurs when light sources reach food and cause a reaction that can alter odor and taste. The process of photo-oxidation can significantly alter milk. By the time the consumer purchases milk not only has the taste been altered by photo-oxidation, but milk has also lost some of its nutritional value. The vitamin riboflavin, which responds to light and starts the reactions that lead to flavor and odor changes, ultimately is destroyed.
Food Science and Technology Professor Susan Duncan has been conducting research to find a solution to the problem of photo oxidation. The main focus of Duncan’s research is the development of better packaging materials to protect the quality and nutritional value of beverages and foods.
“Milk is typically packaged in high-density polyethylene or polyethylene terephthalate (P.E.T.) containers; however, these materials don’t offer much protection against light,” says Duncan.
Opaque containers offer protection from light. “There are problems with using opaque containers; consumers want to see the milk and visually make sure that the milk is fresh,” says Duncan.
Protecting Milk’s Flavor and Nutritional Value Duncan hopes to identify a packaging material that can block the wavelengths of light that cause photo-oxidation to occur. With advances in technology, Duncan is able to study new materials that might provide better protection for odor and flavor. “If food science researchers like us work together with material manufacturers that produce new materials, some that have new properties for reflecting light but maintain optical clarity, we may be able to optimize the characteristics that better protect milk,” Duncan explains.
There are ways consumers can find milks that have been less affected by photo-oxidation. “Search for a milk product that is in an opaque container, but if you still must see the product, then finding a container that has a plastic sleeve with lots of dyes provides more protection than a clear container.
Another less effective option is reaching in the back of the cooler to find the milk that is most protected from the light,” says Duncan.
While most of the damage to milk occurs in the grocery store, it only takes a few minutes of intense sunlight to cause oxidation.