17H-15 |
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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 deviations during canning operations are often unavoidable and can lead to important losses to food manufacturers. Many canners have adopted on-line deviation correction methods for their computer automated batch retorts. However, additional research work is required before these methods can be commercially applied to the operations of continuous retorts. The objective of this research is to develop a sterility-based model predictive control strategy for processing canned foods in continuous retorts. The fixed-point method will be presented in this study. The Apparent Position Numerical Solution (APNS) method was employed to analyze the effect of process temperature deviations on the total accumulated Fo-value in food containers processed in a hydrostatic sterilizer. The Fixed-Point method, for speed adjustment of container conveyor, was developed for automatic accommodation of process deviations. The Fixed Point (FP) is a point, for convenience, selected to be very close to the steam chamber exit. Therefore, the traveling time from the FP to the steam chamber exit is so short that the process temperature can be viewed as constant during this length of time, and the accumulated Fo-value in each container located between the FP and the steam chamber exit is almost uniform. By calculating the time needed for the container at the FP to obtain the scheduled Fo-value for the entire process, an adjusted conveyor speed setting can be determined. When the process deviation disappears, the conveyor will come back to its normal speed after an additional period of adjustment. Results of simulations show a good performance of this method for on-line correction for process temperature deviations in hydrostatic retorts. The fixed-point method is powerful for online correction of process temperature deviations in hydrostatic sterilizers (also called hydrostatic retorts) and can help assure product safety, improve quality and enhance production efficiency.
Session 17H, Food Engineering: Thermal processes
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