Inactivation kinetics of selected aerobic and anaerobic bacterial spores by pressure-assisted thermal processing

Strong and Consistently Synergistic Inactivation of Spores of Spoilage-AssociatedBacillusandGeobacillusspp. by High Pressure and Heat Compared with Inactivation by Heat Alone

“…This degree of resistance was dissimilar to those of the other two strains of B. coagulans examined (3.7 and 5.4 log 10 reduction) by Scurrah and others (26), indicating that FRR B2723 may be peculiarly HPT resistant. In this study, when processed in either Bolognese or cream sauce in the pilot The observation of variability in HPT resistance within a species noted for B. coagulans (26) has also previously been observed among strains of proteolytic C. botulinum (17) and B. subtilis (18); however, for the several B. amyloliquefaciens strains examined to date by others (1,17,18,23), all have been shown to produce similarly highly HPT-resistant spores in comparison to those of other species examined. In particular, strain TMW 2.479 (Fad 82) has received attention as a potential HPT nonpathogenic surrogate for proteolytic C. botulinum since its resistance to HPT processing was first assessed by Margosch and others (17).…”

“…Contrary to the case for proteolytic C. botulinum, there are a number of published studies suggesting that the most heat-resistant spoilage bacterium of concern for LASSF, Geobacillus stearothermophilus, is not nearly as resistant to thermal processing under high pressure as its heat resistance would predict (2,14,17,21,24). In comparison, strains of the aerobic mesophilic species Bacillus amyloliquefaciens, which produces spores with intermediate heat resistance, have been shown to produce highly HPTresistant spores (1,17,18,23) that under some conditions appear to be stabilized by high pressure against thermal inactivation (16). B. amyloliquefaciens is closely related to Bacillus subtilis and Bacillus licheniformis, but to date, the spores of these related bacteria have been found to be relatively sensitive to HPT processing (17,18,26).…”

“…B. amyloliquefaciens is closely related to Bacillus subtilis and Bacillus licheniformis, but to date, the spores of these related bacteria have been found to be relatively sensitive to HPT processing (17,18,26). A number of B. amyloliquefaciens strains have been proposed as relevant target spoilage organisms for 18) and even as potential surrogates to assess the efficacy of HPT processes with respect to proteolytic C. botulinum (23).In assessing the resistance of spores to inactivation by HPT processing compared with that achieved under thermal-only conditions, the primary approach of others (1,14,21,23,24) has been to compare inactivation as a function of the hold time, mostly assuming log-linear inactivation kinetics. For HPT inactivation, this approach ignores lethality accrued during the preheating, pressure come-up (CUT), and depressurization phases.…”

“…In assessing the resistance of spores to inactivation by HPT processing compared with that achieved under thermal-only conditions, the primary approach of others (1,14,21,23,24) has been to compare inactivation as a function of the hold time, mostly assuming log-linear inactivation kinetics. For HPT inactivation, this approach ignores lethality accrued during the preheating, pressure come-up (CUT), and depressurization phases.…”

Participation in the Center for Advanced Processing and Packaging Studies

“…The spore samples were 141 treated to various combined pressure-thermal treatment conditions by adapting published 142 methods reported earlier (Ahn et al, 2007;). The come-up time 143 of the PT-1 unit was 0.67±0.08 min.…”