Reliable Food Expiry Dates Require Light-Sensitivity Estimation

A more reliable method for predicting shelf life accounts for light sensitivity as well as temperature and will help supply fresher, tastier food products.

In a new study, scientists noted that the bright, intense light of retail displays is widely known to cause the formation of off-flavors, loss of nutrients, and color fading in photosensitive food and beverages. But conventional methods to test the shelf life of these products focuses on the effect of heat and ignores the effect of light, leading to underestimations in shelf life shown on product expiration labels. The scientists decided that a more reliable test was needed.

The scientists exposed soft drink containing saffron, which contains light-sensitive substances, to different levels of light at increasing temperatures. During exposure, samples were analyzed for bleaching rate, pigment content, and pigment degradation products. The results obtained clearly showed that shelf life testing of light-sensitive foods must take into account the effect of light. They found that the beverage grew lighter in color as light intensity increased, confirming that light can cause a dramatic decrease in beverage quality. Based on these observations, the scientists developed a new mathematical model that measures light sensitivity as well as temperature to provide a more reliable method for predicting shelf life.

The study was carried out by Lara Manzocco, Ph.D., and colleagues of the dipartimento di scienze degli alimenti, Universita` di Udine (Udine, Italy) and appeared in the June 6, 2008, online issue of the Journal of Agricultural Food Chemistry.


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