Quality-based control for drying food materials

A fuzzy control system has been developed and tested for a continuous, hot-air drying process. The system has been tested for soybean drying, however many elements are common to other food processing control problems. The control system includes: a supervisory level which considers quality criteria (fuzzy and crisp); a feedforward controller which sets process residence time; and a feedback corrector. The supervisory level is rule-based and determines the appropriate set points for drying air temperature and relative humidity, given target levels of product quality (moisture, viability and seed coat crackage). Feedforward rules effect changes in drying time for specific process disturbances (air temperature and inlet moisture content)