Reproducibility of the visual palatability of the crumb of bread and a novel sensory evaluation method using images presented on a screen

Aim: Single tests have been used for the sensory evaluation of food. Although food color is the first perception used to determine acceptability, this study was performed to enhance the reliability of evaluations of the visual palatability of the crumb of bread (bread crumb) by reducing ambiguity in the tests. Methods: The optimal illumination color temperature to enhance the visual palatability of white bread crumb was determined by sensory evaluation using photographs with 13 participants in the main test and 27 participants in the retest, and correlations with visual palatability were assessed using coefficients of determination (R2). Results: Illumination color temperature showed a linear relation with the visual palatability of photographs of the crumb, while the light source with the lowest color temperature was associated with lower palatability scores compared to those with a slightly higher color temperature, as shown by duplicate tests. Ultraviolet (UV) illumination was also added as a purple and blue light source, and the linear correlation between visual palatability and visual firmness showed a high R2. Sensory evaluation measurement using a projector, instead of paper-based measurement, was also examined as a simpler method without the need for paper. The correlations with sensory scores showed correspondence between these measurements. Conclusions: High sensory scores for visual palatability were associated with lower visual firmness scores, even with the addition of data obtained under UV light. In addition, sensory evaluation measurement using a projector was confirmed to be useful. Finally, the optimal light source for the crumb of white bread was TL83. While warmer illumination has conventionally been preferred to enhance consumer food acceptance, the results presented here highlight the need for a detailed analysis of the effects of illumination color temperature on visual palatability.