Little is known about the effect of retail light-emitting diode (LED) exposure on consumer acceptance of milk. The study objective was to determine effects of fluorescent and LED lighting under retail storage conditions on consumer acceptance of milk. Consumer acceptance of milk stored under retail conditions was determined through sensory evaluation (2 studies; n=150+ each) and analytical measures (dissolved oxygen, secondary oxidation products, riboflavin retention). Study 1 evaluated milk stored in high-density polyethylene (HDPE) packages for 4h under LED light (960 lx). Commercially available HDPE package treatments included translucent HDPE (most commonly used), white HDPE [low concentration (1.3%) TiO], and yellow HDPE; in addition, HDPE with a higher TiO concentration (high white; 4.9% TiO) and a foil-wrapped translucent HDPE (control) were tested. Translucent and control packages also were tested under fluorescent light. Study 2 evaluated polyethylene terephthalate (PET) packages for 4h under fluorescent and LED light (1,460 lx). The PET packaging included 2 treatments (medium, 4.0% TiO; high, 6.6% TiO) as well as translucent HDPE (exposed to fluorescent), clear PET (fluorescent and LED), and light-protected control. Overall mean acceptability of milk ranged from "like slightly" to "like moderately" with significantly lower acceptability for milk exposed to fluorescent light. Milk in HDPE and PET packages had comparable overall acceptability scores when exposed to LED light. Only the fluorescent light condition (both PET and HDPE) diminished overall acceptability. Fluorescent light exposure negatively influenced flavor with significant penalty (2.0-2.5 integers) to overall acceptability of milk in translucent HDPE and clear PET. The LED also diminished aftertaste of milk packaged in translucent HDPE. Changes in dissolved oxygen content, as an indication of oxidation, supported the observed differences in consumer acceptance of milk stored under fluorescent and LED light. Consumers like the flavor of fresh milk, which can be protected by selecting appropriate packaging that blocks detrimental light wavelengths.

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Fluorescent light exposure has well documented negative effects on fluid milk by causing oxidation reactions that change milk components, create off-flavors, and degrade vitamins. Increased use of light-emitting diode (LED) lights in retail dairy cases is occurring to save energy, but the effects of LED light on fluid milk are not known. While the most commonly used milk package, made of high density polyethylene material, does not control oxygen from reaching the product, the package material used for most soda packages, polyethylene terephthalate (PET), does limit oxygen transfer in and out. This project studied if packaging that interfered with LED and fluorescent light passing through the package, while controlling the amount of oxygen, could protect milk flavor and vitamins. Chemical measures of oxidation, such as dissolved oxygen, were taken to compare to sensory testing. Sensory testing of milk found that PET with higher light interfering additives was most successful and produced milk similar to light-protected milk through 8h LED light exposure. Changes in dissolved oxygen content were associated closely with oxidation changes in milk. Consumer testing of the most successful packages found that consumers liked milk stored under LED light more than milk stored under fluorescent light. LED light is less detrimental to milk quality than fluorescent light and PET with high levels of light interfering additives can protect milk quality through typical retail storage conditions. v ACKNOWLEDGEMENTS I am incredibly grateful for the many opportunities and experiences I have had here at Virginia Tech. The food science department is truly a family and my success would not have been possible without the guidance, advice, and support of many individuals. First, I would like to thank my committee members, Susan Duncan, Joe Marcy, and Sean O'Keefe for their guidance and advice as I completed my project. You supported me when I needed it while pushing me out of my comfort zone to gain the best experiences and better myself. Especially Dr. Duncan, your mentorship and support over the last few years have been invaluable. Special thanks to

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