UV LIGHT POSES SERIOUS CHALLENGE FOR PET CONTAINERS

The challenge of preventing harmful impacts from UV light should not be ignored by makers of beverages, food and other consumer products packaged in PET according to research studies by Milliken & Company, a leading provider of high-performance plastic additives.

“When examining the variety of threats to consumer products packaged in PET, the effect of UV light is one of the least studied, least understood and most complex, throughout the various consumer category segments and regions of the world,” said Michael Purcell a market manager with Milliken Chemical, a division of Milliken & Company, a leading chemicals and textiles company.

“As global brand owners pursue continued growth through the development of new products and packages that create and cater to new consumption occasions, we are just beginning to understand the challenge ahead presented by the damaging effect that UV light can have on beverages, food and personal care products,” he said. “From our research, we have discovered that the interaction of UV light and various beverage components is extremely complex and can negatively impact the vital brand elements of color, flavor and nutritional value, often in unexpected ways.”

Purcell’s comments were prepared for delivery at Barrier PET Packaging and Shrink Sleeves Conference, an industry event scheduled for Feb. 10-12 in Brussels, Belgium. During his presentation, Purcell reported on ongoing research by Milliken Chemical, which has conducted extensive testing on the impact of UV light on beverages packaged in PET containers.

Using accelerated UV exposure testing in refrigerated UV chambers, Milliken scientists simulated retail store environments and explored the impact of UV light on beverages at various levels of light exposures and at various levels of UV protection.

“One of the most important discoveries from this work is an appreciation of the extreme complexity of the impact of UV light on beverages,” Purcell said. “Not only does UV light impact color, flavor and nutritional ingredients individually, there is also a matrix effect in which the impact of light on a given component can cause it to react with other beverage components in a series of events.”

For example, citric acid together with trace metals under UV exposure can destabilize color; while vitamin B12 is quite stable alone, it is degraded when in combination with vitamin C and UV light.

Another important research finding has been that taste and nutritional content are much more fragile under UV light than color.

“While changes in color caused by UV light exposure are the most dramatic and most easily documented, color is often not the most fragile beverage component,” Purcell said. “Our studies have shown that taste is actually the most fragile component when exposed to UV light, followed by vitamins and then color.”

Milliken’s research has also demonstrated that the level of UV protection in a PET container can be critically important in determining whether the product will be adequately protected for color, taste and nutritional value during extended shelf life and use in the home.

“As a new area of inquiry, the industry has not yet established a general standard for UV protection in PET containers,” he said. “While some PET additives provide UV absorption through the 370 nanometers (nm) range, our studies have shown that only at the 390 nanometer protection level are you achieving complete protection against the impact of harmful UV light. By 390 protection, I mean packaging that allows only 5% of 390 nm wavelength light to pass through the walls of the package.”

Milliken’s research studies have demonstrated that there is a significant difference between 370 and 390 UV protection of color, taste and vitamins.

“From our studies, we determined that some color, taste and nutritional components are damaged significantly by UV light in the higher ranges, above 370,” he said. “For many product components, going from 370 to 390 protection is not 10 percent better, it is often 100 percent better