Visual Assessment of the State of the Chocolate Mass Using a Vision System
Authors: Shibanov Eduard Dmitrievich , Blagoveshchensky Ivan Germanovich , Nazoykin Evgeny Anatolievich 
Published: December 2024

Introduction: The issues of improving the quality of food 3D printing with chocolate and chocolate glaze have been addressed in many modern studies. Most of the works is devoted to the development of extruders, cooling systems and changes in the composition of raw materials, but the 3D food printing process has not been considered from the point of view of automation. In this work, it is proposed to evaluate the aggregate state of the top layer of the applied material for adaptive control of printing modes. Correct determination of the current state of the material will allow you to increase or decrease the application speed, influence the quality of the product and the overall time of constructing the model. The study conducted practical experiments on cooling chocolate mass using a vision system.

Purpose: To reveal the dependence of the shade of the applied chocolate mass on its temperature during natural cooling, in order to evaluate the possibility of using technical vision as a visual sensor an automated control system for the process of 3D printing with chocolate mass. According to the research hypothesis, the aggregate state of the applied material can be controlled using a technical vision system, based on changes in its shade.

Materials and Methods: The object of the study was the process of natural cooling of liquid chocolate mass (Belgostar chocolate glaze and Belgian Callebaut chocolate). Practical experiments on cooling raw materials were carried out, as a result of which numerical data were obtained. Using the method of data analysis and cleaning, filtered values were obtained, from which graphs were constructed of the dependence of the average color values of the channels: “R”, “G”, “B” in the RGB color space on temperature and cooling time. To study the graphs, the method of visual analysis was used. To control the color of raw materials, a Web camera, a computer and auxiliary software based on the OpenCV library were used. Lighting conditions were studied to conduct a visual assessment of the state of aggregation of chocolate using a Web camera. To conduct the experiment, a light diffuser and several light sources (3000K, 4000K, 5000K) were used.

Results: The dependence of the shade of the applied material on its temperature during natural cooling was revealed. In the course of visual analysis of the constructed graphs, a tendency was established for a sharp change in the color of the samples in all color channels "R", "G", "B" at the time of the onset of crystallization. The most informative color channel was revealed - "B", which showed the largest amplitude of change at the moment of crystallization in all experiments, both for glaze and for chocolate. The lighting conditions for visual assessment of the state of aggregation of chocolate using a Web camera have been studied. The greatest change in color is observed under illumination with a color temperature of 3000K (warm light).

Conclusion: The technical vision system is capable of recording a change in the color of the chocolate mass during its cooling: the moment of the beginning of crystallization of the chocolate mass coincides with the moment of a sharp change in its color, which indicates the presence of an interdependence between the shade of the chocolate mass and its state of aggregation. To actually determine the crystallization process begins, it is necessary to analyze the graph of color changes and find an anomalous and uncharacteristic change.