Efficacy of light-protective additive packaging in protecting milk freshness in a retail dairy case with LED lighting...

Light emitting diodes (LED) are rapidly developing as dominant lighting systems in dairy retail cases. Bright light is typically chosen to best exhibit milk products. However, high intensity LED lighting may create high potential for detrimental oxidation and destroying milk freshness. In this study, we investigated the interaction between LED light intensity, exposure time, and packaging material on limiting milk oxidation and protecting milk freshness and vitamins. Within 4 h of LED light exposure at an intensity as low as 1068 lx, light-induced oxidation occurred on 2% milkfat milk with commercial packaging including glass and translucent high-density polyethylene (HDPE) bottles. Higher light intensity (>4094 lx) and longer light exposure time (>24 h) rapidly increased the oxidation rate in milk. Polyethylene terephthalate (PET) packaging with lower oxygen permeability rate effectively reduced (P < 0.05) vitamin A degradation under low light intensity within 24 h. A combination of light-protective additive (TiO₂) and oxygen barrier material (PET) successfully reduced (P < .05) the loss of dissolved oxygen and riboflavin, and decreased the formation of final oxidation products in milk, as measured by thiobarbituric reactive substances (TBARS), when exposed to high light intensity within 24 h. Lower LED light intensity in retail case was preferred by 50% of participants in a visual acceptance test; consumers are willing to consider pigmented packaging with limited visibility. Results of this study provides guidance for dairy industry in choosing appropriate LED lighting conditions and packaging to adequately display the milk products as well as minimize the degradation of milk nutrients and flavor.