Effect of light‐barrier property of packaging film on the photo‐oxidation and shelf life of cookies based on accelerated tests

The influences of intensity of ultraviolet (UV) light, light‐barrier property of packaging film on the fat photo‐oxidation and accelerated shelf life of cookies were studied. Unpacked cookies were stored at a temperature of 408C and a relative humidity (RH) of 50% for 10 to 65 days, with an intensity of the UV light of 0.3, 1.9 and 9.5 mW/cm 2 . Meanwhile, the same batch of cookies was packed with oriented nylon/polyethylene, polyethylene terephthalate/oriented nylon/polyethylene and bi‐oriented polypropylene/vacuuming aluminized casting polypropylene and stored at the same temperature and RH and UV‐light intensity of 1.9 mW/cm 2 for more than 40 days. The peroxide values (POV) of cookies were measured under the storage conditions. The results showed that the intensity of the UV light and light‐barrier property of film had notable influence on the photo‐oxidation rate and accelerated shelf life of cookies. According to the threshold of POV, unpacked cookies were rancid less than 32 and 11 days when exposed in light of 1.9 and 9.5 mW/cm 2 in the accelerated test, respectively. In contrast, the shelf life of unpacked cookies in darkness, or cookies packed in high light‐barrier package was more than 75 days. Logarithm of POV and store‐time relationship under different UV‐light illumination was successfully fitted by linear regression under the same temperature, RH and the accelerated shelf‐life‐based oxide index was estimated. Copyright © 2008 John Wiley & Sons, Ltd.