Variable retort temperature processes (VRT), in which retort temperatu
re 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 pr
ocess time, all while maintaining constant center-point lethality (F-o
). A finite difference computer model of conduction within a finite cy
linder was used to Zest different temperature-time profiles. Processes
were constrained to include steam vent schedules and to exclude tempe
rature decrease during the heating process as well as temperature modu
lation during cooling, thereby improving compatibility with typical sa
lmon canning facilities. Rho, the fraction of total lethality accumula
ted at steam-off rime, was found to be a function of final unaccomplis
hed temperature, retort temperature, salmon thermal diffusivity and co
ntainer geometry. The search for favorable processes was aided by Rand
om Centroid Optimization (RCO). Minimum surface cook in constant retor
t 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 loss
es were reduced from 19.6% loss by CRT to 16.8% loss by VRT.