LED Fixture for Products Susceptible to Photooxidation

Despite a willingness to adopt optimizaed technologies, many food processing plants, dairies and pharmaceutical manufacturing facilities have been hamstrung by the need for light sources that emit longer wavelengths. That’s because short wavelengths cause light-oxidized flavor defects. Photooxidation is a problem at wavelengths of light below 500nm. Certain foods, such as dairy products, beer and chocolate, are most at risk of photooxidation, because exposure to short wavelengths of light changes the products’ flavor and reduces their shelf life. In a study in Pennsylvania, for example, almost half of 449 samples of milk in translucent plastic jugs were reported to have developed pronounced light-induced off-flavors within 36 hours. The same photooxidation process can also reduce the shelf life of many pharmaceuticals. Up until now, facilities producing these kinds of products couldn’t take advantage of ultra-efficient LED lighting technology without risking damage to the products they produced. But innovation is tenacious, especially when born of necessity.

Recently, Precision-Paragon [P2] has come out with a unique solution to the problem: the QHC LED. This LED fixture has total internal reflection (TIR)­–based short wavelength light suppression optics. The new fixture is the first LED high-bay that does not emit light waves below 500nm. This is accomplished by adding a special TIR optic to the fixture that absorbs wavelengths of light below 500nm and retransmits them at longer wavelengths.As a result, facilities creating products susceptible to photooxidation can benefit from LED lighting technology for the first time.

It’s an elegant answer to a problem that has vexed manufacturers and dairies for decades. Research on the shelf life of perishable products has found that temperatures on perishable products can vary significantly within a retail display case. Several studies have also suggested that the deterioration generally precedes microbial spoilage. Here’s a look at what happens in more detail: Milk exposed to sunlight or to fluorescent lighting (wavelengths below 620 nm), common in store dairy cases, develops light-oxidized flavor. The light initiates a chemical reaction in milk that modifies specific proteins and fats, resulting in the characteristic off-flavors. Certain vitamins (e.g., riboflavin and vitamin A) are similarly susceptible to light-induced degradation. As for beer and wine, when placed under short wavelength light, they become “light struck.” While it sounds benign, it’s actually very similar to being skunked. This reaction is stronger in light or pale drinks and it creates an off odor and taste that is very unappealing to consumers.

The QHC is capable of replacing a 465-watt high-pressure sodium fixture with just 139 watts of LED lighting, delivering a 70 percent energy reduction. It allows food processing and pharmaceutical manufacturing plants to fully embrace cutting-edge energy efficient lighting, rather than having to make do with decades-old lighting technology. While more solutions to the problem may soon be on the horizon, the QHC provides a very effective—and efficient—workaround to the photooxidation issue.

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