Article ID Journal Published Year Pages File Type
4561572 Food Research International 2015 8 Pages PDF
Abstract

•High-quality milk creates a positive emotional experience for consumers.•Lighting in retail dairy cases affect milk quality if milk is not properly packaged.•Consumers dislike light-exposed milk flavor, using the emotional term “disgust.”•Automated facial expression analysis illustrates consumers' unique response.

Off-flavors in fluid milk often result from light exposure during retail display if milk packaging does not provide light-blocking protection. There is no direct evidence that light-induced oxidation affects milk acceptability. In this 2-part study, effects of fluorescent light exposure (375 lx at the package) on fluid 2% milk packaged in HDPE without and with a (foil) light-blocking overwrap for periods of 8, 72, and 168 h (4 °C) were determined. Study 1 evaluated oxidative stability of milk, as well as consumer acceptability (hedonic 9-pt scale) and explicit emotional response (check-all-that-apply terminology selection) at 8 and 168 h (n = 41). Oxidative stability was measured by riboflavin (Rb) and thiobarbituric reactive substances (TBARS) assays. Rb, a photo-initiator of the oxidation reaction, decreased significantly, with 71% loss by 168 h. TBARS assays showed significant increases in oxidative by-products by 168 h. Within 8 h of light exposure, acceptability decreased significantly from 7.20 (“like moderately”) to 5.85 (below “like slightly”) and decreased further to 3.46 (between “dislike moderately” to “dislike slightly”) by 168 h. Light-protected milk (control) maintained a score of 7.0 over 168 h. Emotion term selection reflected acceptability response; the term disgust was used more frequently for both the 8 h (17.1%) and 168 h (46.3%; p < 0.05) light-exposed milk compared to both light-protected milks (2.4% 8 h; 12.2% 168 h). Light-protected milk had higher frequency of positive emotion term selection (content, calm, good, happy, and pleased) than did light-exposed milk (168 h). In study 2, automated facial expression analysis was completed (n = 12) at 72 h light exposure. Automated facial expression analysis provided evidence for great variety of unique responses from individuals. Light-induced reactions in fluid milk affect emotional response and flavor acceptability of milk, which may be contributing to the reduction in fluid milk sales and decreased milk consumption.

Related Topics
Life Sciences Agricultural and Biological Sciences Food Science
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