title: Glossiness and perishable food quality: visual freshness judgment of fish eyes based on luminance distribution.
abstract: BACKGROUND
  Previous studies have reported the effects of statistics of luminance distribution on visual freshness perception using pictures which included the degradation process of food samples. However, these studies did not examine the effect of individual differences between the same kinds of food. Here we elucidate whether luminance distribution would continue to have a significant effect on visual freshness perception even if visual stimuli included individual differences in addition to the degradation process of foods.
  
  
  RESULTS
  We took pictures of the degradation of three fishes over 3.29 hours in a controlled environment, then cropped square patches of their eyes from the original images as visual stimuli. Eleven participants performed paired comparison tests judging the visual freshness of the fish eyes at three points of degradation. Perceived freshness scores (PFS) were calculated using the Bradley-Terry Model for each image. The ANOVA revealed that the PFS for each fish decreased as the degradation time increased; however, the differences in the PFS between individual fish was larger for the shorter degradation time, and smaller for the longer degradation time. A multiple linear regression analysis was conducted in order to determine the relative importance of the statistics of luminance distribution of the stimulus images in predicting PFS. The results show that standard deviation and skewness in luminance distribution have a significant influence on PFS.
  
  
  CONCLUSIONS
  These results show that even if foodstuffs contain individual differences, visual freshness perception and changes in luminance distribution correlate with degradation time.
authors.affiliation: Food Function Division, National Food Research Institute, National Agriculture and Food Research Organization, Ibaraki, Japan.
authors.forename: Takuma
authors.initials: T
authors.lastname: Murakoshi
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Masuda
authors.forename: Ken
authors.initials: K
authors.lastname: Utsumi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tsubota
authors.forename: Yuji
authors.initials: Y
authors.lastname: Wada
mesh_terms: D000818:Animals; D005123:Eye; D005399:Fishes; D063427:Food Quality; D007600:Judgment; D010775:Photic Stimulation; D013997:Time Factors; D014796:Visual Perception
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