Date of Award
Doctor of Philosophy (PhD)
Whiteside, William S
This research studied the effect of packaging geometry changes on heat penetration and quality attributes of a food system processed in a rotary retort vessel. Studies were conducted to determine the effect of package geometry in a rotary retort on heat penetration, analytical, and physical properties of a model food system processed at optimum conditions. Additionally, heat mapping for each shape was used to determine the heating profiles during retorting. Retort-able trays were filled with a tomato based food simulate and thermally processed in a water immersion, automated batch retort system (ABRS) using rotational speeds of 6 RPM and 11 RPM. Rectangular, triangular, round, and oval shaped trays, constructed of polypropylene and ethylene vinyl alcohol were used. Four retort racks, one shape per rack, were used during processing to hold containers in place. A difference (P<0.05) was observed in average process time at 6 and 11 RPM, with 11 RPM resulting in faster (P<0.05) heating. A retort temperature of 215Â°F and a lethality value of 10 showed the highest average sterilization time for process conditions evaluated by computer modeling (CALsoftâ„¢) and was selected for evaluation of tray geometry. At 6 RPM, the average time to lethally for the triangle shaped tray was higher (P<0.05) than the rectangle or round shaped tray. The average time to lethality for the oval tray was not different (P>0.05). At 11 RPM differences in average time to lethality between tray geometries was insignificant (P<0.05). Subsequent processing runs were performed under optimal conditions for each geometry to produce data for further analysis to study geometry impacts on food model degradation. At 6 RPM, average ascorbic acid (AA) loss compared to control was higher (P<0.05) in the triangle tray compared to oval and rectangle, while the round tray showed higher (P<0.05) change than the oval tray. At 11 RPM, round and oval trays displayed a greater (P<0.05) average AA loss compared to control than either rectangle or triangle tray. In comparing rotational speeds, there was no difference (P>0.05) in AA between 6 RPM and 11 RPM for round or rectangular, while at 6 RPM the triangle shape had greater (P<0.05) change than 11 RPM. Lycopene content change at 6 RPM was not significant (P>0.05). At 11 RPM a higher average change (P<0.05) in lycopene content was observed in oval and round shaped trays. Hexanal average concentration change from control at 6 RPM was higher (P<0.05) in rectangle than oval, with no difference (P>0.05) between triangle and round trays. At 11 RPM, triangle and round exhibited higher (P<0.05) average hexanal when compared to control than the oval tray did. Hydroxymethylfurfural (HMF) absorption at 6 RPM showed no difference (P>0.05) between control and composite samples. At 11 RPM all composite samples showed higher (P<0.05) average absorption than control samples, with average absorption values for rectangle and triangle composites being higher (P<0.05) than round and oval. At 6 RPM, the average L value change from control was different (P<0.05) between oval and round compared to rectangle and triangle, with the rectangle and triangle shape having a higher (P<0.05) average change. At the higher rotational speed, 11 RPM, the round tray displayed higher average L value change (P<0.05). For heat mapping, an ABRS in water spray mode was used for processing at 6 RPM, with the oval tray showing the fastest time to an equilibrium temperature inside the package. The round shape followed, while both the triangle and rectangular packages both displayed differences (P<0.05) in average temperatures at various measurement positions, indicating there still existed a thermal gradient within those shapes. The data gathered during this study indicates the interaction of packaging shape, retort process design, and food product composition is a complex mechanism. There is likely benefit to the researcher to fully understand how each factor effects the outcome of a finished product, so that each independent variable can be manipulated to best enhance the desired product outcome.
Stowe, Curtis, "EFFECTS OF SEMI-RIGID PLASTIC TRAY GEOMETRY ON THERMAL PROCESSING AND QUALITY FACTORS IN RETORTED FOODS" (2015). All Dissertations. 1562.