The report, Milk: Light exposure and depletion of key nutrients, found that just two hours of exposure to light emitting diodes (LED) lighting was enough to reduce the vitamin A content in milk. After 16 hours, vitamin A content was half the amount expected.
“While milk is just one component of a healthy diet, it is an important one, providing people with many essential nutrients including vitamins, protein and minerals,” said Dr Catherine Birch, co study author and senior researcher at Newcastle University’s school of natural and environmental sciences.
“Many people do not realise that exposure of milk to indoor light can have a detrimental effect. The damaging effects of light can be influenced by the light intensity and time of exposure, so longer exposure to light causes milk to deteriorate faster.”
Along with the University’s professor Graham Bonwick, Dr Birch also found 20 minutes of indoor light exposure reduced riboflavin levels decrease by 28%.
One study mentioned in the report found that exposure to LED lighting systems with a low intensity of 1068 lux (lx) caused degradation of a range of essential nutrients in milk within four hours.
A higher intensity light (greater than 4094 lx) combined with longer exposure time rapidly increased the oxidation processes, the paper’s research team found.
The team added that this light degradation of essential nutrients was not only a function of light wavelength but also included exposure time and light intensity.
Sunlight and artificial lighting
Light from all sources, including natural sunlight and artificial sources, such as fluorescence or light emitting diodes (LEDs), increases the nutrient loss in milk over a relatively short time scale of 25 minutes.
These bright lights are typically chosen to best exhibit milk products. However, high intensity LED lighting can drive detrimental oxidation processes, which can accelerate loss of freshness of milk.
This process includes vitamin and protein degradation, which can alter the organoleptic properties and shorten the shelf-life of the product.
To meet the challenge of stemming the decline in consumption of fluid milk, the report called on the dairy industry to take a systematic approach to correct factors that affect light degradation of essential nutrients.
However, a spokesperson for DairyUk refuted the research claims adding, “There’s no conclusive evidence that LED lighting in-store negatively impacts the nutrition of milk and in reality dairy products are not subjected to high intensity light for extended periods of time.
“This is evident in the off-shelf testing which takes place by Public Health England in compiling compositional tables, which determine the nutritional information permitted to be displayed on products.”
The report, commissioned by lighting specialists Noluma, added that in order to avoid excessive wastage, retailers should strive to find solutions to protect milk products and preserve the nutrient content for the benefit of consumers.
One recommendation would be to utilise packaging design that has demonstrated and been certified for light protection performance.
“Our surveys indicate that UK consumers are increasingly concerned about the light damage issue in brands they love and trust, especially when nutritional content is affected, as is the case when dairy products are sold in inadequate packaging,” said Georgia Kollias, vice president of global brand development at Noluma.
“Many consumers would choose light-protected milk for their families if they had that option so we’re encouraging retailers and manufacturers to give them that choice.”