Sensory Threshold of Light-Oxidized Flavor Defects in Milk

Reduced fat (2%) milk in high-density polyethylene (HDPE) containers was exposed to fluorescent light in a 6 °C walk-in cooler. Samples were evaluated by 10 trained panelists and by 94 consumers to assess the presence and intensity of sensory differences from unexposed control samples using the semi-ascending paired difference method. Trained panelists detected flavor defects following 15 to 30 min of light exposure; consumers detected defects between 54 min and 2 h. As approximately 50% of plastic containers remain in dairy cases for at least 8 h, these results suggest that the majority of milk on the market in light-transmissible containers is vulnerable to development of detectable light-oxidized flavor defects.