Thermal Death of Bacillus subtilis Spores in Oil-Water Systems

Shigemoto, Mayumi; Nakagawa, Kayo; Sakamoto, Jin; Tsuchido, Tetsuaki

doi:10.4265/bio.15.27

Cited by 7 publications

(7 citation statements)

References 12 publications

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“…Furthermore, the significantly greater z ‐values of the spores presented in the oils compared to those in aqueous buffer, suggesting that, the inactivation mechanism of the spores in these matrices may be different (Ababouch and Busta ). Shigemoto and others () reported that Bacillus subtilis spores survived better at higher soybean oil content in an oil–water emulsion system. However, they observed a higher death rate in the initial phase.…”

Section: Factors Influencing the Thermal Resistance Of Pathogens In Lmentioning

confidence: 98%

“…A number of studies have focused on the protective effect of lipid materials on microorganisms during heat treatments (Ababouch and Busta ; Ma and others ; Shigemoto and others ; Li and others ). Ma and others () observed unusually greater heat resistance of Salmonella strains in peanut butter with a w of 0.45 in comparison to many high‐moisture foods such as ground beef but with higher a w , attributed to the high fat content (approximately 53%) and low a w of peanut butter.…”

Section: Factors Influencing the Thermal Resistance Of Pathogens In Lmentioning

confidence: 99%

“…However, they observed a higher death rate in the initial phase. The spores in the oil phase may have a lower death rate in comparison to those in aqueous phase, suggesting that location of spores in the emulsion system may be important and related to the thermal resistance (Shigemoto and others ). The thermal resistance of spores may be affected by change in the location of spores during heating from aqueous phase to oil phase.…”

Section: Factors Influencing the Thermal Resistance Of Pathogens In Lmentioning

confidence: 99%

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Influence of Water Activity on Thermal Resistance of Microorganisms in Low‐Moisture Foods: A Review

Roopesh

Tang

Villa-Rojas

et al. 2016

Comp Rev Food Sci Food Safe

263

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A number of recent outbreaks related to pathogens in low-moisture foods have created urgency for studies to understand the possible causes and identify potential treatments to improve low-moisture food safety. Thermal processing holds the potential to eliminate pathogens such as Salmonella in low-moisture foods. Water activity (a w ) has been recognized as one of the primary factors influencing the thermal resistance of pathogens in low-moisture foods. But most of the reported studies relate thermal resistance of pathogens to a w of low-moisture foods at room temperature. Water activity is a thermodynamic property that varies significantly with temperature and the direction of variation is dependent on the product component. Accurate methods to determine a w at elevated temperatures are needed in related research activities and industrial operations. Adequate design of commercial thermal treatments to control target pathogens in low-moisture products requires knowledge on how a w values change in different foods at elevated temperatures. This paper presents an overview of the factors influencing the thermal resistance of pathogens in low-moisture foods. This review focuses on understanding the influence of water activity and its variation at thermal processing temperature on thermal resistance of pathogens in different low-moisture matrices. It also discusses the research needs to relate thermal resistance of foodborne pathogens to a w value in those foods at elevated temperatures.

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Section: Factors Influencing the Thermal Resistance Of Pathogens In Lmentioning

confidence: 98%

Section: Factors Influencing the Thermal Resistance Of Pathogens In Lmentioning

confidence: 99%

Section: Factors Influencing the Thermal Resistance Of Pathogens In Lmentioning

confidence: 99%

See 1 more Smart Citation

Influence of Water Activity on Thermal Resistance of Microorganisms in Low‐Moisture Foods: A Review

Roopesh

Tang

Villa-Rojas

et al. 2016

Comp Rev Food Sci Food Safe

263

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“…A translocation of spores from the water phase or the boundary surface into the oil phase due to increased hydrophobic interactions at elevated temperatures could be possible and has also been proposed to play a role in the protective effect of fat against thermal inactivation of B. subtilis. [42] Factors, which could facilitate the association of endospores to the interface or even penetration of endospores into the oil droplets, could include altered spore surface properties (e.g. due to reversible or irreversible protein unfolding), decreased viscosity of the oil at high temperatures or increased Brownian motion.…”

Section: Hpt Endospore Inactivationmentioning

confidence: 99%

“…[42] The heat conductivity of lipids, altered water availability in oily environments or effects of free fatty acids have been suggested as playing a role in the different resistance of endospores in oily environments. [10][11][12]14] The detailed mechanism of the protective effect of fat against HPT treatments is still unknown.…”

Section: Hpt Endospore Inactivationmentioning

confidence: 99%

High pressure inactivation ofClostridium botulinumtype E endospores in model emulsion systems

Schnabel

Lenz

Vogel

2015

High Pressure Research

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Clostridium botulinum type E is a cold-tolerant, neurotoxigenic, endospore-forming organism, primarily associated with aquatic environments. High pressure thermal (HPT) processing presents a promising tool to enhance food safety and stability. The effect of fat on HPT inactivation of C. botulinum type E spores was investigated using an emulsion model system. The distribution of spores in oil-in-water (O/W) emulsions and their HPT (300-750 MPa, 45-75°C, 10 min) inactivation was determined as a function of emulsion fat content (30-70% (v/v) soybean oil in buffer). Approximately 26% and 74% of the spores were located at the oil-buffer interface and the continuous phase, respectively. Spore inactivation in emulsion systems decreased with increasing oil contents, which suggests that the fat content of food plays an important role in the protection of C. botulinum type E endospores against HPT treatments. These results can be helpful for future safety considerations.

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Survival of Clostridium difficile spores at low water activity

et al. 2017

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Clostridium difficile is frequently found in meat and meat products. Germination efficiency, defined as colony formation, was previously investigated at temperatures found in meat handling and processing for spores of strain M120 (animal isolate), R20291 (human isolate), and DK1 (beef isolate). In this study, germination efficiency of these spore strains was assessed in phosphate buffered saline (PBS, a ∼1.00), commercial beef jerky (a ∼0.82/0.72), and a-adjusted PBS (a ∼0.82/0.72). Surface hydrophobicity was followed for spores stored in PBS. After three months and for all PBS a levels tested, M120 and DK1 spores showed a ∼1 decimal reduction in colony formation but this was not the case when kept in beef jerky suggesting a protective food matrix effect. During storage, and with no significant a effect, an increase in colony formation was observed for R20291 spores kept in PBS (∼2 decimal log increase) and beef jerky (∼1 decimal log increase) suggesting a loss of spore superdormancy. For all strains, no significant changes in spore surface hydrophobicity were observed after storage. Collectively, these results indicate that depending on the germination properties of C. difficile spores and the media properties, their germination efficiency may increase or decrease during long term food storage.

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Thermal Death of Bacillus subtilis Spores in Oil-Water Systems

Cited by 7 publications

References 12 publications

Influence of Water Activity on Thermal Resistance of Microorganisms in Low‐Moisture Foods: A Review

Influence of Water Activity on Thermal Resistance of Microorganisms in Low‐Moisture Foods: A Review

High pressure inactivation ofClostridium botulinumtype E endospores in model emulsion systems

Survival of Clostridium difficile spores at low water activity

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