Aseptic processing involves sterilising the product and package separately, and filling under sterile conditions. Advantages include better product quality compared with canned products, lower transport and storage costs compared with frozen products, and virtually no restriction on package size. Problems include ensuring adequate heat penetration into the particles to ensure sterility, preventing separation of particles from the carrier liquid, and retention of particle structure and shape. Particulate foods can be sterilised in scraped - surface heat exchangers. Other methods involve heating the particles separately, and combining them during filling. Projects will commence at the International Food Institute of Queensland (IFIQ) on aseptic packaging of a meat and vegetable product, and aseptically packaged mango pieces.

Aseptic Processing of Foods Containing Particulates

Residence time distributions of multiple particles (as affected by process and system parameters) were investigated during non-Newtonian tube flow. Process parameters included flow rate, particle type, carrier fluid viscosity, and particle concentration. The system parameter of interest was the holding tube configuration. Polystyrene and acrylic particles were used as model food particles. Digital imaging analysis was used to obtain residence time data of particles. A novel type of holding tube (chaotic holding tube) was constructed. Comparisons among the straight, single helical, double helical, and chaotic holding tube were performed in terms residence time distribution (RTD) of particles. In addition, the effect of inclination angle (0 º and 45 º) of the chaotic holding tube was investigated. It was found that the narrowest RTD of particles was obtained in the single helical holding tube. RT std in the chaotic holding tube was greater than that in the single helical holding tube, but lower than those in the straight and double helical holding tubes. The most significant process parameter affecting RTD was flow rate. The effect of flow rate was more pronounced for high density (acrylic) particles. Carrier fluid viscosity, particle type, and particle concentration did not have significant effects on the overall RT std. Trends observed in the chaotic holding tube were similar to those observed in the single helical holding tube. However, there were some cases where use of chaotic holding tube resulted in narrower RTD of particles. Changing the inclination angle from 0 º to 45 º in the chaotic holding tube resulted in wider RTD of both types of particles. Denizli, a small town in the Aegean region of Turkey. In 1993, her family moved to the capital city, Ankara, where she attended high school and college. She graduated from Middle East Technical University in 2002, with a B.S degree in Food Engineering. In the summer of 2002, she was admitted to the graduate school at North Carolina State University where she began her Master of Science degree in the Department of Food Science. She currently works as a research assistant in the same department. iii ACKNOWLEDGEMENTS

Zeynep Tanyel

Papers

Residence Time Distribution of Multiple Particles in Four Configurations of Holding Tubes