Fuzzy logic was applied to real-time control of a spray-dried whole milk powder processing system developed to increase the powder free fat content. The objective was to provide control of process start-up and operation at a preset power consumption level while providing a whole milk product with greater than 90 free fat content and consistent color. For consistent product quality, the system parameters of powder feed rate, lecithin injection rate, processor screw speed, and circulating water heating and cooling on-times were controlled using the feedback signals from sensors for product color, temperature, and power consumption. The ratio of red to near-infrared (NIR) color values was used as a measure of product color. The control algorithm performance was observed over time for 0.75 kW and 1.12 kW power consumption and 80, 85, and 90 color values, indicating the ratios of the reflected intensities of red and near-infrared colors (red/NIR · 100). The algorithm controlled the process at ±0.074 kW of the desired power consumption and provided whole milk products with the desired color values within ± 3.0 unit deviations. The free fat content was over 95, and lactose was in crystalline form in the final dry milk product.
展开▼
