Got Milk? Got LED Lights? Good, Now Keep Them Away From Each Other

Milk and LED lightThe familiar, glowing case of milk, bathed in the aura of LED lighting, is both attractive and energy-efficient. Unfortunately it may also be harming nutritional quality and consumer appeal, according to a new Cornell study.

Although it has been known for some time that sun or light exposure can affect how the nutrition and taste of milk, the exact level of impact has not seen as much research.

The Cornell study compared not only put light-shielded and unshielded milk to the consumer taste test, they also checked how different forms of freshness and microbial contamination matched up.

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Cornell Milk Study: Summary

  • From four milk processing facilities—two with consistently high quality milk, two with known quality challenges—samples were taken of both skim and 2% milk that were fresh (FR) milk and near-code (NC, which means near expiry)
  • Light treatments were administered to half the samples after collection that were equivalent to real-world supermarket casing exposure. Following treatment, the samples were then shielded from all light until testing occurred
  • This meant the NC samples were left shielded for two weeks (as they aged to near-code level) and the FR samples were tested shortly after treatment
  • Chemical and microbial analysis was also done on the samples, in addition to consumer testing
  • Consumer scores indicated that among non-light exposed skim milk, FR samples were liked more than NC samples; though there was less difference among NC samples that did not show post-pasteurization microbial contamination
  • Among the light-exposed samples, consumer scores rated light-exposed FR milk as lower than unexposed FR or unexposed or exposed NC milk—light exposed FR milk even rated lower than the NC samples with microbial contamination
  • Chemical analysis found the riboflavin in milk to be activated by light, releasing electrons that degraded proteins and oxidized milk fats

What This Means

The study goes a fair bit into taste profiles and analysis but the central point is that exposure to LED lights affects milk taste and texture in a way that repels consumers even more than the effects of certain microbial contaminations. The fact that the light-exposed NC samples were more popular than the exposed FR samples suggests that the various free radicals and other elements released by the chemical activity were able to disperse during the storage period. The proposed explanation is that LED light has a wavelength that is just over riboflavin’s absorption maximum, suggesting a way that exposure could lead to the chemical reactions described above.

The impact of this study for consumers is that it gives the milk industry a way to better preserve the quality and nutrition of its products by making sure milk containers are better shielded from light in general but LED specifically. This is easier said than done since even opaque milk bottles can let in some light, but it’s still a worthwhile focus.

Bottom Line

  • Exposing milk to LED lighting can make it taste worse than microbe-contaminated milk
  • LED exposure can also harm nutritional content, but it’s not clear how severe or significant this effect is

Sources for Today’s Article:

Martin, N., et. al., “Exposure of fluid milk to LED light negatively affects consumer perception and alters underlying sensory properties,” Journal of Dairy Science, 2016; http://dx.doi.org/10.3168/jds.2015-9603.

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Hayes, M., et. al., “Consumers sour on milk exposed to LED light,” Cornell Chronicle web site, June 8, 2016; http://news.cornell.edu/stories/2016/06/consumers-sour-milk-exposed-led-light, last accessed June 10, 2016.