(167at) Degradation Behavior of Multilayer Packaging Films in Presence of a Highly Acidic Sauce

Highly acidic condiments such as hot sauce have a propensity to degrade packaging films, shortening the shelf life of packaged food. To reveal the degradation mechanism about how hot sauce degrades packaging films, this study investigates the interactions between packaging films and hot sauce. An accelerated immersion test in hot sauce was carried out at 50 °C for 12 weeks. Acetic acid and sodium chloride (NaCl) solutions, two major components in hot sauce, were also used as a control group. The treated surfaces were studied by optical and scanning electron microscopy. The physicochemical changes of the films were monitored by using Fourier-Transform infrared spectroscopy and differential scanning calorimetry. To evaluate the oxidation rate of polymers when exposed to hot sauce, the carbonyl index was also calculated. An oxidative degradation was found when polyethylene (PE) films were exposed to hot sauce and acetic acid, but not sodium chloride solutions. This suggests that the oxidation of PE is likely caused by acids, rather than heat (i.e., thermal oxidation). Moreover, hot sauce appeared to be more aggressive than acetic acid in degrading PE films. For the first time, a degradation mechanism of PE-based multilayer packaging film in the presence of acidic food was proposed. It is expected that the mechanistic discussion could shed lights on designing a more robust multilayer packaging film for safely storing acidic food.