processes and combined
high pressure-temperature treatments was investigated.
Isothermal heat resistance parameters for B. subtilis spores in the
model soup were obtained as D95C ¼ 4.67 min and z ¼ 8.65 C.
These values performed well for estimation of agitating process
lethality on B. subtilis spores in the soup. This also indicated a homogenous
heat load distribution within the product, when agitationwas
used. Agitated processing at 110 C gave 7-log reduction of
spores in the soup after 17 min processing, whereas the same effect
was possible after 53 min processing in static mode. When the
same model organism and product were exposed to combined high
pressure-mild temperature (P/T) treatments, a dramatic synergistic
effect was observed. Pressurization at 650 MPa and 55e65 C for
10 min provided up to 4.5 log kill effect on spores. The results
presented in this work can be used for determination of test conditions
on similar products for evaluation of novel agitating retort
and combined high pressure-temperature (P/T) effects. Further
studies using more heat-resistant spores (12D concept) and
different liquid or semi-liquid products (with solid particles) would
be required for assessing the applicability of the new agitating
retort for sterilization processes. Further investigations on combined
P/T effects when assisted with other germinant systems could
also enable processing at milder temperatures.