MATHEMATICAL-MODELING OF BIOCHEMICAL-CHANGES DURING PROCESSING OF LIQUID FOODS AND SOLUTIONS

Thermal processing of liquid food materials and biochemical solutions always results in a distribution of biochemical changes such as bacterial and nutrient concentrations due to variation in temperature history from one liquid element to another. To estimate such distribution, the liquid elements need to be "tagged" and followed, which is computationally difficult for most flow situations of interest. This paper describes a computational procedure for obtaining the full range of biochemical changes during processing without explicity following liquid elements. By use of of the method developed, transient distributions of bacterial death have been obtained for sterilization of liquid in a nonagitated cylindrical enclosure heated from all sides. The conventional procedure of obtaining sterilization based on temperature at the slowest heating zone is shown to be lower than the actual least sterilization of a real fluid element in the system. Nutrient distributions can be similarly calculated by following this method.