UBC Theses and Dissertations
Comparision of constant retort temperature and variable retort temperature thermal processes for quality improvement or cost reduction of conduction-heated canned foods Xiang, Bob Yongsheng
Almost all commercial retort processes for canned foods use constant retort temperature (CRT) process. However, variable retort temperature (VRT) process, as one of the potential technologies to improve both the economy and quality of some canned foods, has been receiving increasing attention. The VRT process has been shown to be very promising in this regard, especially in improving food quality and reducing process time. The surface color is an important quality attribute of canned foods. Discoloration and browning of canned foods are the results of various reactions, including Maillard reaction. Heat treatment affects the surface color of canned foods. Surface color changes measured by HunterLab are used to predict both chemical and quality changes in canned foods. In this study I examined the surface color change characteristics of macaroni and cheese (MC). Surface color change of MC followed first order reactions and D values of the surface color change and z value of the surface color change were measured. This study evaluated the application of the "Retort" program and the random centroid optimization (RCO) program for modeling and optimization of VRT thermal processing for conduction-heated foods. This study tested whether canned macaroni and cheese (MC) surface quality would be improved or process times decreased by using the optimal VRT process as compared with the optimal CRT process. From this study, I concluded that the optimal VRT process was superior. It improved the surface quality (i.e., reduced the surface cook value by 8.9-11.2 %) or reduced the process time by 23.6-34.2 % compared with the optimal CRT process.
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