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LEDs in stores could leave a bad taste in your mouth

LEDs in stores could leave a bad taste in your mouth

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By Julien Happich



What this means is that, potentially, all of those money-saving lights installed in stores and in display cases may be creating havoc with milk. Researchers at Cornell’s Department of Food Science discovered that when consumers tasted two-week old milk not exposed to LED light and then fresh milk exposed to light for only four hours—the older milk tasted better. One could wonder what other dairy and non-dairy products are similarly affected.
What happens in the milk is that riboflavin and other photosensitive components are activated by light energy. They release electrons that degrade proteins and oxidize fats. This happens whether the light source is artificial or natural sunlight, however, placing a spotlight (or even low light) on milk might be doing it harm and causing a taste described to be like cardboard or plastic.
So, what’s going on? The LEDs produce wavelengths that are quite different from fluorescent bulbs used in display cases, and emit 460 nanometers in the blue spectrum, creating a broader emission peak than fluorescents. The peak is close to the narrow band where riboflavin absorbs light, which could be selectively destroying the nutrients and damaging the quality of the milk.
I have to say here that it sounds like milk is joining tomatoes and several fruit types that no longer taste like the food of my childhood. But I digress.

Unfortunately today’s packaging allows for light to affect milk, and according to the study, light exposure is a greater factor in milk quality deterioration than its age.
In the study, “Exposure of fluid milk to LED light negatively affects consumer perception and alters underlying sensory properties” published in the June edition of the Journal of Dairy Science, researchers concluded that without LED exposure most pasteurized milk retains its high quality for 14 days. The data from the study could result in better light-shielding packaging for milk that reduces the damaging effects.


This is not the first time that milk taste and integrity was questioned. Promolux, for example, is combating the same problem. They describe the challenge as, “When milk is exposed to sunlight or to the fluorescent lighting commonly found in refrigerated dairy display cases, the light initiates two chemical reactions which result in off-flavors and the loss of nutrients. First, whey proteins, composed of amino acids containing sulfur, degrade and break down, producing ‘sunlight’ flavors reminiscent of burnt feathers or burnt hair that can last for two to three days. In the second reaction, the unsaturated fatty acids in milk lipids (milkfat triglycerides/triacylglycerols) become oxidized, producing malodorous carbonyl compounds that taste metallic or cardboardy and do not dissipate.”

The company cites studies that claim light-related off-flavors developed within 36 hours in almost half of 449 samples of milk in translucent plastic jugs. Another study found that off-flavors were present in approximately 80% of the blow-mold plastic milk containers exposed to fluorescent lighting in supermarket dairy display cases.
Another study, according to Promolux, found that 90% of the added Vitamin A and 8% of the riboflavin was lost from milk in polyethylene containers after 24 hours of exposure to fluorescent lights, with increased loss of these nutrients as the fat content of the milk decreased.
Burnt feathers or burnt hair taste? Now what will I drink with my chocolate cake?

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