Application of Digital Image Processing in Monitoring some Physical Properties of Tarkhineh during Drying

In this study, digital image processing was employed to investigate the effect of the shape of Tarkhineh loaves and drying temperature on the physical properties of this product. Our results revealed that the cylindrical and spherical shapes had no crackbut the slab shape had some cracks merely at 90C. The volume changes of Tarkhineh during drying greatly depended on the drying temperature. The samples showed a continuous volume reduction and shrinkage at 25C. However at 55C and 90C, the samples volume first increased, but decreased subsequently. There was a correlation between the color change and moisture content of Tarkhineh as the obtained regression model was able to predict the moisture content according to the color with an accuracy of 96.3%. As the drying time increased, the histogram moved towards darker gray levels; in addition, its base became wider and its height decreased. The textural properties of Tarkhineh images experienced a great deal of changes during the early 1.5 h of drying. However, the intensity of these changes was reduced thereafter. This research indicated that the application of visual machines and the image processing could be a rapid technique that enables monitoring of the physical properties variations of Tarkhineh during drying. PRACTICAL APPLICATIONS: Tarkhineh is a traditional fermented food, primarily produced in western provinces of Iran. There is little information on the shape and thickness of Tarkhineh on its physical changes during drying since this product is dried in various shapes. In this study, digital image processing was employed to investigate the effect of the shape of Tarkhineh loaves and drying temperature on the physical properties of this product. According to the obtained results, cracking occurred only at 90C and in the case of slab‐shaped samples while the drying temperature had a substantial effect on the dimensional changes of the samples. Owing to significant changes in Tarkhineh appearance during drying, some of its physical properties such as dimensional changes and crack percentage could be realized through digital image processing. Regarding the correlation between the parameters resulted from image analysis such as color and image texture parameters with the physical properties, application of image processing as a rapid method may enable the monitoring of Tarkhineh physical changes during drying. Utilization of this method could be generalized to similar products and used for online monitoring in production lines.