17H-16 |
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G. CHEN1, O. H. Campanella1, C. M. Corvalan2, and T. A. Haley3. (1) Dept. of Agricultural & Biological Engineering, Purdue Univ., 1146 Agricultural & Biological Engineering Bldg., West Lafayette, IN 47907-1146, (2) Dept. of Food Science, Purdue Univ., 745 Agriculture Mall Dr., West Lafayette, IN 47907-2009, (3) Food Safety & Regulatory Compliance, Bush Brothers & Co., 1016 E. Weisgarber Rd., Knoxville, TN 37909-2683 Thermal process temperature deviations during canning operations are often unavoidable. The current standard operating procedure to compensate for such a temperature drop is to stop the retort conveying mechanism and issue a complete reprocess once the temperature has returned to its set point. This type of corrective action may leads to severe product quality damage. An alternative action is to adjust the speed of the conveying mechanism. Doing so would minimize the detrimental effects above mentioned. The objective of this research was to develop a sterility-based model predictive control strategy for processing canned foods in continuous retorts. A method called the worst-case scenario is described in this study. The Apparent Position Numerical Solution (APNS) method was used to analyze the effect of process temperature deviation on the total accumulated Fo-value in food containers processed in a hydrostatic sterilizer. When a process deviation occurs, the residence time can be adjusted by adjusting the container conveyor speed to make sure all the food containers obtain the scheduled Fo-value. Because in a hydrostatic retort the steam temperature drop affects each container carrier differently, in order to meet the scheduled process lethality for all containers, the container conveyor speed adjustment must be based on the worst-case carrier. The worst-case carrier is defined as the carrier requiring the lowest conveyor speed to meet the scheduled lethality among all the carriers in the steam chamber at any moment. The method is based on the location of the worst-case which is identified by a computer routine developed in this study. Results of computer simulations showed a good performance of this method for on-line correction of process deviations in hydrostatic retorts. The worst-case scenario method could be suitable for online correction of process temperature deviations in hydrostatic sterilizers and would help to assure product safety, improve quality and enhance production efficiency.
Session 17H, Food Engineering: Thermal processes
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