Online monitoring of dry powder mixing in a bin mixer

Abstract

Dry powder mixing is a common process in the food industry. The aim of dry powder mixing is to improve the mixture quality within the optimum critical mixing time. Therefore, critical mixing time and mixture quality need to be monitored and quantified. An optical camera has advantages of high resolution, short image acquisition time and relatively large sampling area. An optical camera was used to online monitor the mixing process of the dairy-based powder and coffee powder of different sizes in a 5-L bin mixer. A new image analysis method including seven mixing indices and three dispersion indicators, has been developed. This method can provide precise results and identify different effects on mixing performance. This study confirms that the best mixing quality can be achieved when mixing particles of similar size. When the rotation speed is increased from 5 to 15 and 30 rpm, the critical mixing time is shortened. • Online monitoring of food powder mixing in a bin mixer by using optical technique. • A new method to quantify critical mixing time and mixture quality. • Both overall and local mixing change are crucial. • Seven mixing indices provide a comprehensive assessment of the mixing process. • Particle size and rotation speed significantly influence the mixing performance.