HEAT RESISTANCE OF Bacillus stearothermophilus SPORES AT DIFFERENT WATER ACTIVITIES

Hätnulv, B. G.; Johansson, Marie; Snygg, Bengt Göran

doi:10.1111/j.1365-2621.1977.tb01225.x

Cited by 41 publications

(18 citation statements)

References 14 publications

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“…As far as we know, there is no reported study on the effect of CO 2 treatment on the inactivation ratio (approximately 5-log-cycle) of G. stearothermophilus in a food system. Spore heat inactivation decreases in proportion to the decrease of water activity of the spore suspension medium (Alderton, Chen, & Ito, 1980;Harnulv et al, 1977;Mazas et al, 1999;Murrell & Scott, 1965). In our experiments suspension addition of glucose, sodium chloride and ethanol decrease water activity of the solution.…”

Section: Resultssupporting

confidence: 48%

“…However, CO 2 treatment did not decrease the inactivation ratio of G. stearothermophilus spores in ethanol solution. Several works have suggested that sugars and salts increase the heat resistance of microorganisms (Harnulv, Johanson, & Snygg, 1977;Mazas, Martinez, Lopez, Alvarez, & Martin, 1999). Addition of glucose and sodium chloride decreased inactivation ratios of baker's yeast by hydrostatic pressure (Hayashi, 1992).…”

Section: Resultsmentioning

confidence: 99%

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Inactivation of food poisoning bacteria and Geobacillus stearothermophilus spores by high pressure carbon dioxide treatment

et al. 2009

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Section: Resultssupporting

confidence: 48%

Section: Resultsmentioning

confidence: 99%

Inactivation of food poisoning bacteria and Geobacillus stearothermophilus spores by high pressure carbon dioxide treatment

et al. 2009

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“…It is generally recognized that sucrose is the most protective depressor, while glucose, sodium chloride, and lithium chloride show a clearly lower influence or even an opposite effect. Glycerol shows an intermediate behavior (13,19,20,26,37). Interactions between the influences of water activity and heating temperature were often observed.…”

mentioning

confidence: 99%

Effect of Water Activities of Heating and Recovery Media on Apparent Heat Resistance of Bacillus cereus Spores

Coroller¹,

Leguérinel²,

Mafart³

2001

Appl Environ Microbiol

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Spores of Bacillus cereus were heated and recovered in order to investigate the effect of water activity of media on the estimated heat resistance (i.e., the D value) of spores. The water activity (ranging from 0.9 to 1) of the heating medium was first successively controlled with three solutes (glycerol, glucose, and sucrose), while the water activity of the recovery medium was kept near 1. Reciprocally, the water activity of the heating medium was then kept at 1, while the water activity of the recovery medium was controlled from 0.9 to 1 with the same depressors. Lastly, in a third set of experiments, the heating medium and the recovery medium were adjusted to the same activity. As expected, added depressors caused an increase of the heat resistance of spores with a greater efficiency of sucrose with respect to glycerol and glucose. In contrast, when solutes were added to the recovery medium, under an optimal water activity close to 0.98, a decrease of water activity caused a decrease in the estimated D values. This effect was more pronounced when sucrose was used as a depressor instead of glycerol or glucose. When the heating and the recovery media were adjusted to the same water activity, a balancing effect was observed between the protective influence of the solutes during heat treatment and their negative effect during the recovery of injured cells, so that the overall effect of water activity was reduced, with an optimal value near 0.96. The difference between the efficiency of depressors was also less pronounced. It may then be concluded that the overall protective effect of a decrease in water activity is generally overestimated.It has been recognized that the heat resistance of bacterial spores depends on the medium in which the spores are heated. The maximum thermostability of most microorganisms was found in the range of between 0.2 and 0.4 water activity (1,3,27,28,29). In typical ranges of water activities which are found in foodstuffs (a w Ͼ 0.8), the heat resistance of microorganisms generally increases at decreasing water activities. However, the apparent effect of the water activity of the medium on spores or vegetative cells is complicated by the specific effect of solutes which are used as depressors. It is generally agreed that the occurrence of such solutes in the medium reduces the heat resistance of microorganisms. This antagonism between the protective effect of an increase in water activity and the opposite specific effect of depressors can explain conflicting data from various authors.The influence of salt on the thermostability of microorganisms is disputed and depends on the heated type of microorganism. Some authors found no effect of the sodium chloride concentration on the heat resistance of bacteria (9,29,32,42). Others observed a reduced heat resistance of microorganisms at increasing salt concentrations (7,12,22,23). On the contrary, a protective effect of salt was found in several studies (6,14,26,35,38,39,40). Corry (14) deduced from his data that sodium chloride had a therm...

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“…Other studies have shown that water activity may play an essential role in microbial inactivation of food powders (Zhao and Cranston, 1995;Calvo and Torres, 2010). An increase in water content reduced the heat resistance of spores and increased carbon dioxide sorption by microbial cells (Härnulv et al, 1977;Kumagai et al, 1997);…”

Section: Discussionmentioning

confidence: 99%

Microbial Reduction and Quality Changes in Powdered White and Black Pepper by Treatment with Compressed Oxygen or Carbon Dioxide Gas

Kawachi

Suzuki

Uosaki

et al. 2015

FSTR

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HEAT RESISTANCE OF Bacillus stearothermophilus SPORES AT DIFFERENT WATER ACTIVITIES

Cited by 41 publications

References 14 publications

Inactivation of food poisoning bacteria and Geobacillus stearothermophilus spores by high pressure carbon dioxide treatment

Inactivation of food poisoning bacteria and Geobacillus stearothermophilus spores by high pressure carbon dioxide treatment

Effect of Water Activities of Heating and Recovery Media on Apparent Heat Resistance of Bacillus cereus Spores

Microbial Reduction and Quality Changes in Powdered White and Black Pepper by Treatment with Compressed Oxygen or Carbon Dioxide Gas

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