Don’t go towards the light – particularly if you have a dairy product in your hand. That’s the advice of Dr Catherine Birch from Newcastle University, who is trying to raise awareness about how exposure to light has a detrimental impact on the nutrient profile of dairy.
Her research, with Professor Graham Bonwick, has found light can cause the breakdown of vitamins B2, A and D in dairy, as well as oxidising the proteins – which is not only a health concern but impacts on taste, causing something commonly known as ‘sunlight flavour.’
“It contributes significantly to wastage in the UK,” Dr Birch told Food Spark’s sister site Food Navigator.
But natural light isn’t the only culprit, with artificial light, which is commonly used by retailers to display dairy products, also responsible for exacerbating the issue.
“The loss of nutrients in milk is very often due to the way it is displayed in retail stores. If you go into any of the big supermarkets it will either be displayed under fluorescent light… [or] LED systems. They use this to display the milk so it looks good. However, those light sources in particular, cause significant damage,” she said.
“This can happen within 20-30 minutes of being put under these very bright lights. The average amount of time milk is on display is eight hours, so during that time before the customer picks it up, you can get very significant loss of some of the key nutrients.”
A health issue for young and old
The UK population can’t afford to lose key nutrients either, explained Dr Birch, with deficiency in vitamin D in this country linked to increasing incidents of rickets and a lack of calcium a serious issue for bone health.
“It is worth noting that all of the vitamins in milk do not work alone – they are cofactors,” she commented. “For example, if you take a vitamin B12 supplement it will not work without having vitamin B6 and vitamin B9, which is folate, because everything helps something else work. You need a full spectrum of these nutrients.”
The lack of nutrients also spans the generations, with children aged two to five needing a high concentration of nutrients when they move on to cow’s milk, while people in their mid-50s can struggle to absorb vitamin B12 as the stomach lining starts to shrink, which raises the risk of developing osteoarthritis.
Don’t be kept in the dark
But this doesn’t mean that dairy suddenly needs to be stored in a dark room – packaging could be the answer.
Some researchers believe additives, like titanium dioxide, can be mixed with packaging material to block light damage, while Dr Birch advocates for bio-based materials which not only combat light degradation but also the plastic problem.
“It is a relatively new area and the more research that goes into bio-based materials that have protective qualities the better,” she said. “Whoever can get to market first with that is going to lead the way.”
She also called for the development of a scheme for packaging that protects foods from light damage.
“I think the option that would be best not only for consumers’ confidence but certainly for retailers is to move towards certification of the packaging milk comes in, whether that’s cartons or bottles,” she said.
Will consumers see the light?
But it’s not just dairy that susceptible to food spoilage from light, according to Dr Birch, with dairy alternatives, meat, fruit juices, smoothies and olive oil also implicated.
However, she acknowledged that consumer awareness is very limited on the issue and there needs to be a big push to bring it to light.
“The level of consumer awareness needs to be raised quite significantly. Once you get a level where quite a lot of the population understand about the degradation of nutrients, that would give the impetus towards manufacturers and retailers to insist the packaging is certified to say it helps protect nutrients.”