Luminance Information Suffices to Model Vegetable Freshness Perception

Freshness perception is a quality discrimination process that influences our consumer choice and eating behaviour, especially of fresh products such as vegetables. Moreover, several of the most relevant sensory attributes influencing consumer perception of freshness are related with vision. To investigate which visual cues command the freshness perception in vegetables, we recorded the luminance and chromatic information of the freshness degradation process of four different vegetables (cabbage, strawberry, carrot and spinach) in a temperature, humidity and light controlled environment using a 2D luminance and chromaticity analyzer (TOPCON UA1000). Then, using a color management system to guarantee the exact reproduction of the recorded luminance and chromatic data, we created color and grayscale version of the stimuli. Then, we randomly presented those pictures to subjects who had to rate their perceived freshness using a visual analogue scale. The achromatic results did not differ from the chromatic ones suggesting that color information is not a determinant factor involved in our freshness perception. Furthermore, the results of the freshness perception were highly correlated with image and sub-band statistical measures of the luminance distribution in the images. Additionally, we digitally manipulated the original images of the cabbage stimuli only by modifying their luminance distribution and keeping intact their colour information. When we presented the resulting images, using the same psychophysical experimental setting, the subject’s results showed that the perceived freshness also changed concordantly with the changes of the skewness of the luminance distribution. These results support the hypothesis that the freshness perception of vegetables is highly influenced by the luminance distribution present in that food texture. These findings not only can help represent a way to understand cognitive quality measurements which can be related closely to human perception but also design implementations of automatic food freshness estimators for the food industry.

Arce-Lopera, C. A., Okajima, K., Wada, Y., Masuda, T. (2012). Luminance Information Suffices to Model Vegetable Freshness Perception (9th ed., vol. 12, pp. 865). Journal of Vision. http://www.journalofvision.org/content/12/9/865.short

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