Thermal destruction kinetics of spores of selected Bacillus strains in skimmilk and skimmilk concentrate

Behringer, Richard R.; Keßler, H. G.

doi:10.1016/0958-6946(92)90020-m

Cited by 14 publications

(8 citation statements)

References 12 publications

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“…The addition of casein in a concentration of 2.5% to the heating medium phosphate buffer did not change the heat resistance of Clostridium sporogenes spores (Amaha and Sakaguchi 1954). This is in contrast to studies on the heat resistance of mesophilic Bacillus spores performed in milk (9.4%-40.0% dry matter) and infant formula (9.8%-49.5% dry matter) concentrates where an increased heat resistance was observed at higher dry matter contents (Behringer and Kessler 1992;Stoeckel et al 2013). The increased heat resistance of the spores in concentrates was explained with the lower water activity of the heating media at the high dry matter contents ) caused by high lactose and mineral salt contents.…”

Section: Inactivation Of Bacillus Cereus Spores In MCCcontrasting

confidence: 65%

Thermal inactivation of Bacillus cereus spores in micellar casein concentrates–effect of protein content and pH development

Stoeckel

Atamer

Hinrichs

2014

Dairy Sci. & Technol.

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The spore count of micellar casein concentrate (MCC), an ingredient widely used in dairy processing, has to be reduced to increase the shelf life of intermediate and final dried products, and to guarantee the suitability for trade and export. A heat treatment of the concentrate prior to drying ensures low cell counts in the final product. However, it is not known whether spores are protected from inactivation in MCC, especially at high protein concentrations. Therefore, in this study, we examined the influence of the heating medium (water, whole milk, and MCC with 1.5%-14.3% protein) on water activity, buffering capacity, pH development during heating and Bacillus cereus IP5832 spore inactivation. With increasing protein content, the buffering capacity also increased. Water activity, pH drop during heating, and D values for the inactivation of B. cereus spores were not significantly different in all the media examined. Hence, the heat resistance of the spores was not affected by the protein content of the MCC. Also, the heat resistance in MCC was not different to the heat resistance in milk. Dairies can use the temperature-time combinations established for the heating of milk to design the processes aiming at the thermal treatment of MCC.

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Section: Inactivation Of Bacillus Cereus Spores In MCCcontrasting

confidence: 65%

Thermal inactivation of Bacillus cereus spores in micellar casein concentrates–effect of protein content and pH development

Stoeckel

Atamer

Hinrichs

2014

Dairy Sci. & Technol.

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“…Environmental conditions, including thermal variation (causing sublethal heat shock), chemical stress and matrix composition, are all known to be able to enhance the thermoresistance of spore-forming bacteria (in both spore and vegetative forms) including Cl. perfringens (Craven 1990;Behringer and Kessler 1992;Heredia et al 1997). Only the work by Juteau et al (2004), which looked at the spores and vegetative forms together, gives information on the persistence of the vegetative forms of Cl.…”

Section: Inactivation Of Src and Mcbmentioning

confidence: 99%

Using temperature and time criteria to control the effectiveness of continuous thermal sanitation of piggery effluent in terms of set microbial indicators

Cunault¹,

Pourcher²,

Burton³

2011

Journal of Applied Microbiology

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Aim: To determine the minimal conditions (temperature–time), necessary to achieve set sanitation targets for selected microbial indicators during the continuous thermal treatment of pig slurry. Methods and Results: The effectiveness of thermal treatment between 55 and 96°C was studied using Escherichia coli, enterococci, sulfite‐reducing Clostridia (SRC), mesophilic culturable bacteria (MCB), F+‐specific and somatic phages. Identification of SRC and MCB was performed using 16S rRNA gene analysis. Ten minutes at 70°C or 1 h at 60°C was sufficient to reduce the vegetative bacteria by 4–5 log10, but it had little effect on somatic phages nor on spore formers, dominated by Clostridium sp. At 96°C, somatic phages were still detected, but there was a reduction of 3·1 log10 for SRC and of 1·4 log10 for MCB. At 96°C, Clostridium botulinum was identified among the thermotolerant MCB. Conclusion: Only those hygienic risks relating to mesophilic vegetative bacteria can be totally eliminated from pig slurry treated at 60°C (60 min) or 70°C (<10 min). Significance and Impact of the Study: Hygiene standards based on the removal of the indicators E. coli and enterococci can easily be met by treatment as low as 60°C (enabling, a low‐cost treatment using heat recovery). However, even at 96°C, certain pathogens may persist.

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“…At 120°C, the spores were destroyed after 5 to 15 min (20). The thermal kinetics of B. anthracis inactivation in buffer solutions, however, cannot be used to predict its destruction in foods, because the heat resistance can be increased by food components, such as protein and fat (3,18).…”

mentioning

confidence: 99%

“…Single colonies from TSA incubated at 37°C overnight were transferred to tryptic soy broth (TSB) (Acumedia Manufacturers, Inc., Baltimore, MD). The tubes were incubated at 37°C for 18 h. Cultures were then spread onto new sporulation medium (NSM) that contained the following (per liter of distilled water): 3 g tryptone (Difco, Inc., Sparks, MD), 3 (14). The plates were incubated at 37°C for 48 h and then at room temperature for 24 h. The biomass from three plates was suspended in 30 ml sterile distilled water (dH 2 O).…”

mentioning

confidence: 99%

Thermal Inactivation of Bacillus anthracis Spores in Cow's Milk

Labuza

Diez-Gonzalez

2006

Appl Environ Microbiol

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Decimal reduction time (time to inactivate 90% of the population) (D) values of Bacillus anthracis spores in milk ranged from 3.4 to 16.7 h at 72°C and from 1.6 to 3.3 s at 112°C. The calculated increase of temperature needed to reduce the D value by 90% varied from 8.7 to 11.0°C, and the Arrhenius activation energies ranged from 227.4 to 291.3 kJ/mol. Six-log-unit viability reductions were achieved at 120°C for 16 s. These results suggest that a thermal process similar to commercial ultrahigh-temperature pasteurization could inactivate B. anthracis spores in milk.In 2001, the intentional release of anthrax spores through the U.S. Postal Service prompted increasing concern for a potential bioterrorist attack, including food terrorism. Due to the vulnerability of the food supply system, food and water could be deliberately contaminated and are considered two of the most viable targets for bioterrorism (7). Milk, as a product consumed every day especially by children, poses a high probability/high severity risk potential if Bacillus anthracis spores were purposely added to it at the farm, truck delivery, or processor level (23). In order to enhance milk safety against purposeful contamination with a biological agent, it is necessary to develop effective heat treatments capable of inactivating biological agents, such as large amounts of anthrax spores, that could be deployed immediately by milk processors in the event of a bioterrorist attack (23).Bacillus anthracis is a spore-forming, gram-positive bacillus that causes anthrax. There is very limited information about heat inactivation of B. anthracis spores in the literature, as most studies have focused on the heat resistance of other Bacillus species. The effects of different heating methods (boiling, moist heat, and dry heat) on heat inactivation of B. anthracis spores have also been reported (6,12,17,19,20). In general, it was reported that in different buffer solutions B. anthracis spore counts could be reduced by at least 10 6 CFU/ml if the spores were heated at 90°C for 20 min, at 100°C for 10 min, and 105°C for 5 to 10 min (12,19). At 120°C, the spores were destroyed after 5 to 15 min (20). The thermal kinetics of B. anthracis inactivation in buffer solutions, however, cannot be used to predict its destruction in foods, because the heat resistance can be increased by food components, such as protein and fat (3, 18).Because milk is not considered a vehicle of natural B. anthracis infections, very few studies have investigated the thermal resistance of B. anthracis spores in milk. In one recent study, standard pasteurization conditions (63°C, 30 min; 72°C, 15 s) killed 4 log CFU/ml vegetative B. anthracis cells but had no effect on spores (14). The authors concluded that standard pasteurization processes had little effect on the viability of B.anthracis spores (14). In another study, Novak et al. (13) reported the inactivation of B. anthracis strain Sterne in skim milk by 0.45 log CFU/ml after 90 min at 72°C, 8.1 log CFU/ml after 60 min at 100°C, and 7.7 log...

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Thermal destruction kinetics of spores of selected Bacillus strains in skimmilk and skimmilk concentrate

Cited by 14 publications

References 12 publications

Thermal inactivation of Bacillus cereus spores in micellar casein concentrates–effect of protein content and pH development

Thermal inactivation of Bacillus cereus spores in micellar casein concentrates–effect of protein content and pH development

Using temperature and time criteria to control the effectiveness of continuous thermal sanitation of piggery effluent in terms of set microbial indicators

Thermal Inactivation of Bacillus anthracis Spores in Cow's Milk

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