Heat resistance of Bacillus cereus spores in carrot extract acidified with different acidulants

Behavioural pattern of vegetative cells and spores of Bacillus cereus as affected by time-temperature combinations used in processing of Indian traditional foods

“…A similar situation was also reported for a strain of Bacillus anthracis Sterne (Novak et al 2005). The D-values recorded in the present study for three cultures of B. cereus were almost closer to those values reported earlier for the strain of B. cereus ATCC 4342 and 7004 when subjected to heat treatment in buffers of pH 7.0 and milk medium at 90°C (Montville et al 2005;Moussa-Boudjemma et al 2006) and 95°C (Mazas et al 1999a). In a study with spores of B. cereus ATCC 7004 (Mazas et al 1999b), the D-values recorded at 92 and 96°C in saline and milk medium were quite lower to those observed in this study.…”

“…The thermal inactivation pattern of spores of B. cereus cultures observed in most of the earlier studies have revealed that D-values differ very much depending primarily on the strains used and to a lesser extent the extrinsic and intrinsic factors. Earlier studies have reported varying D-values for ATCC strains of B. cereus 4342, 7004 and 9818 in buffers and substrates similar to culture broth and those containing food constituents (Mazas et al 1995(Mazas et al , 1999aGonzález et al 1999;Montville et al 2005;Moussa-Boudjemma et al 2006). A similar situation was also reported for a strain of Bacillus anthracis Sterne (Novak et al 2005).…”

Influence of food matrix on outgrowth heterogeneity of heat damaged Bacillus cereus spores

“…It was previously shown that vegetable based media (broccoli, potato, and courgette) readily facilitate vegetative growth of a number of B. cereus strains which was not different from laboratory media when cultivated at optimal growth temperature . However, other studies report an effect of media composition on spore outgrowth, for example B. cereus spores showed 1 log higher counts on nutrient agar (pH 5.2) compared to nutrient agar supplemented with carrot extract (pH 5.2) (Moussa- Boudjemaa et al, 2006), while in courgette puree an extended lag phase and reduced growth compared to J-broth (laboratory medium) was observed (Choma et al, 2000). These observations are in line with our finding that on broccoli media (pH 5.8) and rice media the time required for colony formation was extended compared to BHI pH 5.5 and BHI pH 7.4 respectively, indicating that vegetables may contain additional factors delaying germination and/or outgrowth or contain suboptimal concentrations of required components.…”

“…Also the food matrix composition may have a considerable impact on the germination and outgrowth efficiency of spores. Commonly applied preservation strategies used by food industry to control spores (and vegetative cells) include the reduction of the water activity by using elevated concentrations of salt or sugar, or lowering of pH with organic acids (Rajkovic et al, 2010), which might affect heat resistance (Mazas et al, 1999;Moussa-Boudjemaa et al, 2006;Samapundo et al, 2014). In addition, stress conditions encountered during spore dormancy such as heat treatment, UV and disinfectant treatment can cause sublethal damage to spores that may increase variability in spore behaviour, especially in combination with non-optimal outgrowth conditions such as low pH, presence of salt or other inhibitory compounds that originate from food.…”

Effect of compression and decompression rates during high hydrostatic pressure processing on inactivation kinetics of bacterial spores at different temperatures

“…Moreover, a continuous inactivation in orange juice was detected, which could be due to spores that are partly germinated, which are sensitive to the lower pH in the juice compared to Tris buffer or milk. These spores, which possibly only finished stage I of germination under pressure (Paidhungat et al, 2002;Wuytack et al, 1998) have lost their resistance against e.g., chemical substances (Setlow, 2003) and are sensitive to the low pH (Leguerinel & Mafart, 2001;Moussa-Boudjemaa, Gonzalez, & Lopez, 2006;Reineke, Mathys, & Knorr, 2011b) and in a sublethal state. Hence, these spores are not inactivated at neutral pH, like in milk or Tris buffer but could recover on nutrient rich agar plates.…”