High-Temperature Food Preservation and Characteristics of Thermophilic Microorganisms

Jay, James M.

doi:10.1007/978-1-4615-4427-2_17

Cited by 26 publications

(24 citation statements)

References 38 publications

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“…Subculturing of Bacillus sporothermodurans, for instance, results in formation of less heat-resistant spores as compared with those from freshly isolated ®eld strains (Huemer et al 1998). According to Jay (1992), bacterial cells are less heat resistant while in the logarithmic phase than in the stationary phase of growth. For MAP it is suggested that the difference in heat resistance (D-values) among strains in heat inactivation experiments are primarily dependent upon the level of subculturing and not on the strain (Sung and Collins 1998).…”

Section: Strains and Culture Conditionsmentioning

confidence: 99%

Heat inactivation data for Mycobacterium avium subsp. paratuberculosis: implications for interpretation

2001

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Aims: We discuss several factors that are critical for heat inactivation experiments and which should be taken into account for future research. Methods and Results: On the basis of examples from the literature we discuss critical factors in¯uencing the calculated heat inactivation of Mycobacterium avium subsp. paratuberculosis (MAP). Furthermore, using a modelling approach, we show that tailing of the inactivation curve of MAP is caused by the presence of cell clumps and not by a more heat-resistant cell fraction. Conclusions: The experimental conditions of the MAP heat inactivation studies of different research groups vary signi®cantly and lead to considerable differences in results and conclusions. Therefore, a more consensual approach should be employed in future studies. In addition, our model on clumping of MAP can be used to predict the decimal reduction of MAP during heat treatment and to study the effect of clumping on other lethal effects. Signi®cance and Impact of the Study: We discuss several factors that should be carefully considered in heat resistance experiments. This is essential for a thorough interpretation of results from experiments and should be given proper attention in future experiments and publications on this topic.

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Section: Strains and Culture Conditionsmentioning

confidence: 99%

Heat inactivation data for Mycobacterium avium subsp. paratuberculosis: implications for interpretation

2001

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“…The increase in heat tolerance of bacteria due to composition of growth environments has been discussed for decades. It has been mentioned that the presence of fat in heterogeneous food systems can affect the cell moisture content resulting in increased heat tolerance (Farkus 1997;Jay 2000). In addition, environmental stresses such as low water activity, increase in osmolarity, or reduction in nutrients may induce the production of heat shock proteins responsible for increased bacterial heat resistance (Doyle and others 1997; Juneja and others 1998;Duffy and others 1999).…”

mentioning

confidence: 99%

Oil‐in‐Water Emulsion as a Model System to Study the Growth of Escherichia coli O157:H7 in a Heterogeneous Food System

Prachaiyo

McLandsborough

2003

Journal of Food Science

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Oil-in-water emulsions (hexadecane, minimal media [M9], and Tween 20) were used as model system to study the growth of Escherichia coli O157:H7. Stationary-phase cell density decreased as the hexadecane concentration was increased (0%, 5%, 20%, and 40% [w/v]) and biphasic growth was observed in 40% emulsions supplemented with 0.4% glucose. Thin aggregate fimbriae (curli) were observed using SEM, and a greater percentage (P < 0.001) of curli-producing colonies were isolated from 40% emulsions. Heat resistance (55 °C) of emulsiongrown cells was greater than broth-grown cells, indicating that growth and physiology under heterogeneous conditions differ from cells grown in liquid.

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“…It was also believed that the low water activity of the freeze-dried immobilized alginate beads would contribute to the heat resistance of the immobilized cells. Heat resistance in microbial cells is known to increase with decreasing water activity, moisture, or humidity (Jay 2000). This could potentially explain why the combination of heat and acid was more detrimental to free cells than to the IFDC in liquid media.…”

Section: Food Microbiology and Safetymentioning

confidence: 99%

“…This could be partly due to the significantly (p < 0.05) higher humidity level and lower fat content in the meat models containing the original L. sakei (Table 1). Higher humidity is detrimental to survival, whereas higher fat content is beneficial (Ahmed and others 1995;Jay 2000). The differences in heat resistance between L. sakei and L. sakei Cm + could also be due to the freeze-drying process used (ingredients or process itself ).…”

Section: Heat Resistance In the Meat Modelmentioning

confidence: 99%

“…Increasing the solid content typically decreases humidity, moisture, or water activity. According to Jay (2000), dried microbial cells heated in test tubes are considerably more heat-resistant than the same moist microbial cells. Because it is well established that protein denaturation occurs at a faster rate when heated in water than in air, the same author suggested that the mechanism of death results from protein denaturation, or is closely associated with it.…”

Section: Food Microbiology and Safetymentioning

confidence: 99%

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A Comparison of the Effect of Meat Formulation on the Heat Resistance of Free or Encapsulated Cultures of Lactobacillus sakei

Lemay¹,

Champagne²,

Gariépy³

et al. 2002

Journal of Food Science

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The protective culture, Lactobacillus sakei Bactoferm-B2, is not particularly resistant to commercial cooking conditions of meat products. Encapsulation in lyophilized alginate beads supplemented with glycerol was tested as a means to protect L. sakei against heat treatment in broth culture, and in an acidified chicken meat model (pH 5.0). Significantly enhanced (p < 0.05) cell protection by encapsulation was observed in liquid media acidified to pH 5.0 and 5.7, but not in the meat model. Indeed, unencapsulated freeze-dried cells were significantly more resistant (p < 0.05) in meat. Meat model constituents, such as the binders and meat itself, provided protection to the free cells.

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High-Temperature Food Preservation and Characteristics of Thermophilic Microorganisms

Cited by 26 publications

References 38 publications

Heat inactivation data for Mycobacterium avium subsp. paratuberculosis: implications for interpretation

Heat inactivation data for Mycobacterium avium subsp. paratuberculosis: implications for interpretation

Oil‐in‐Water Emulsion as a Model System to Study the Growth of Escherichia coli O157:H7 in a Heterogeneous Food System

A Comparison of the Effect of Meat Formulation on the Heat Resistance of Free or Encapsulated Cultures of Lactobacillus sakei

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