Selection of variable retort temperature processes for canned salmon

Variable retort temperature processes (VRT), in which retort temperature is a function of rime, were developed for sterilization of Pacific salmon in 307 x 115 steel cans, with objectives of minimizing loss of quality criteria such as surface quality or thiamine, or minimizing process time, all while maintaining constant center-point lethality (F-o). A finite difference computer model of conduction within a finite cylinder was used to Zest different temperature-time profiles. Processes were constrained to include steam vent schedules and to exclude temperature decrease during the heating process as well as temperature modulation during cooling, thereby improving compatibility with typical salmon canning facilities. Rho, the fraction of total lethality accumulated at steam-off rime, was found to be a function of final unaccomplished temperature, retort temperature, salmon thermal diffusivity and container geometry. The search for favorable processes was aided by Random Centroid Optimization (RCO). Minimum surface cook in constant retort temperature (CRT) processes varied with retort temperature and z of surface quality, but the best VRT process was consistently better than the best CRT process. VRT reduced operator's process time from 64 min to 54 min and maintained equal F-o and surface quality. Thiamine losses were reduced from 19.6% loss by CRT to 16.8% loss by VRT.