Sensory Threshold of Light‐Oxidized Flavor Defects in Milk

Abstract

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.

Light-induced formation of free radicals in cream cheese

“…Oxidation measured by direct ESR spectroscopy (e.g., formation of radicals), however, does not hold information about the origin of the radicals in lipids or proteins and such mechanistic information will depend on analysis of oxidation products. Dairy products are very sensitive to light exposure, and off-flavours were detected after as little as 15-20 min of exposure to 2000 lux of fluorescent light (Chapman, Whited, & Boor, 2002). Specific aroma compounds are related to either protein or lipid oxidation; detection of such specific compounds may provide further knowledge about the oxidation taking place in the actual product.…”

Effects of Pro‐Oxidants and Antioxidants on the Total Antioxidant Capacity and Lipid Oxidation Products of Milk During Refrigerated Storage

“…In the United States, 68% of milk purchased is packaged in clear HDPE containers (Keoleian and Spitzley ). Milk typically remains in the dairy case for at least 8 h and the average light intensities in supermarkets range from 750 to 6460 Lux, with a median intensity of 2000 Lux (Chapman and others ). Untrained consumers could detect differences between light‐exposed samples (2000 Lux) and non‐illuminated samples after 54 min to 2 h of exposure (Chapman and others ).…”

Comparing quality and emotional responses as related to acceptability of light-induced oxidation flavor in milk

“…Flavor changes due to light exposure occur rapidly and off-flavors can be detected within 54 min to 2 h of light exposure by untrained panelists (Chapman, Whited, & Boor, 2002). From the point of processing until retail purchase, milk may receive 7 or more days of light exposure (Senyk and Shipe, 1981).…”

“…From the point of processing until retail purchase, milk may receive 7 or more days of light exposure (Senyk and Shipe, 1981). About 50% of milk packages remain in the retail lighted dairy case for 8 h or more, providing ample time for flavor and nutrient degradation (Chapman et al, 2002). The incentive for the dairy industry to identify optimized packaging options to protect fresh milk quality is related to improving milk sales, which corresponds to increasing consumer acceptability and motivation for consuming milk.…”