Physiological and mathematical aspects in setting criteria for decontamination of foods by physical means

Smelt, J.P.P.M.; Hellemons, Johan C.; Wouters, Patrick C.; Gerwen, Suzanne J.C. van

doi:10.1016/s0168-1605(02)00242-8

Cited by 88 publications

(49 citation statements)

References 142 publications

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“…[1][2][3][4][5] In addition to this interest in deep-sea life, high-pressure treatment of food has been studied as a novel technique to pasteurize food without a heating process, and an increasing number of food products treated under high pressure have been commercialized. [6][7][8][9] High hydrostatic pressures, in the range of several dozen MPa, are generally assumed to be nonlethal but exert adverse effects on the growth of organisms that are adapted to atmospheric pressure. 2,4,10) Those effects depend not only on the magnitude but also on the duration of pressure applied in combination with temperature, pH, oxygen supply and composition of culture media.…”

mentioning

confidence: 99%

Exploration of the Effects of High Hydrostatic Pressure on Microbial Growth, Physiology and Survival: Perspectives from Piezophysiology

Abe

2007

Bioscience, Biotechnology, and Biochemistry

178

110

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mentioning

confidence: 99%

Exploration of the Effects of High Hydrostatic Pressure on Microbial Growth, Physiology and Survival: Perspectives from Piezophysiology

Abe

2007

Bioscience, Biotechnology, and Biochemistry

178

110

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“…The inactivation of spores requires high temperatures and long heating times, which are costly and detrimental to the nutritional and organoleptic quality of most food products. To minimize the required heat treatment, there is an urgent need in the food industry for tailored preservation procedures, based on models that accurately predict the presence of viable cells at every step of the food production process (6,41). To assess the required heat inactivation procedure for the most resistant cell type, the bacterial spore, we isolated and classified two food contaminants and developed a rapid and sensitive screening method to determine the heat resistance of their spores.…”

mentioning

confidence: 99%

Assessment of Heat Resistance of Bacterial Spores from Food Product Isolates by Fluorescence Monitoring of Dipicolinic Acid Release

Kort

O'Brien

Stokkum

et al. 2005

Appl Environ Microbiol

134

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This study is aimed at the development and application of a convenient and rapid optical assay to monitor the wet-heat resistance of bacterial endospores occurring in food samples. We tested the feasibility of measuring the release of the abundant spore component dipicolinic acid (DPA) as a probe for heat inactivation. Spores were isolated from the laboratory type strain Bacillus subtilis 168 and from two food product isolates, Bacillus subtilis A163 and Bacillus sporothermodurans IC4. Spores from the lab strain appeared much less heat resistant than those from the two food product isolates. The decimal reduction times (D values) for spores from strains 168, A163, and IC4 recovered on Trypticase soy agar were 1.4, 0.7, and 0.3 min at 105°C, 120°C, and 131°C, respectively. The estimated Z values were 6.3°C, 6.1°C, and 9.7°C, respectively. The extent of DPA release from the three spore crops was monitored as a function of incubation time and temperature. DPA concentrations were determined by measuring the emission at 545 nm of the fluorescent terbium-DPA complex in a microtiter plate fluorometer. We defined spore heat resistance as the critical DPA release temperature (T c ), the temperature at which half the DPA content has been released within a fixed incubation time. We found T c values for spores from Bacillus strains 168, A163, and IC4 of 108°C, 121°C, and 131°C, respectively. On the basis of these observations, we developed a quantitative model that describes the time and temperature dependence of the experimentally determined extent of DPA release and spore inactivation. The model predicts a DPA release rate profile for each inactivated spore. In addition, it uncovers remarkable differences in the values for the temperature dependence parameters for the rate of spore inactivation, DPA release duration, and DPA release delay.Bacterial spores are common contaminants of food products, and their outgrowth may cause food spoilage or foodborne illness. They are extremely resistant to heat and other preservation treatments in comparison to vegetative cells. The inactivation of spores requires high temperatures and long heating times, which are costly and detrimental to the nutritional and organoleptic quality of most food products. To minimize the required heat treatment, there is an urgent need in the food industry for tailored preservation procedures, based on models that accurately predict the presence of viable cells at every step of the food production process (6, 41). To assess the required heat inactivation procedure for the most resistant cell type, the bacterial spore, we isolated and classified two food contaminants and developed a rapid and sensitive screening method to determine the heat resistance of their spores.Under nutrient-limited conditions, vegetative cells of Bacillus species undergo the cell differentiation process of sporulation (17, 42). The resulting spores are metabolically dormant and show, besides resistance to heat, resistance to other potentially lethal treatments that include radiati...

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“…Pressure in the range of 200 to 800 MPa is effective at eliminating vegetative bacteria in food (37,39). Pressure treatment at ambient temperatures initiates germination of bacterial endospores (13), but they are not inactivated at 25°C and a pressure over 1,000 MPa (36, 37).…”

mentioning

confidence: 99%

Pressure Inactivation of Bacillus Endospores

Margosch

Gänzle

Ehrmann

et al. 2004

Appl Environ Microbiol

138

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The inactivation of bacterial endospores by hydrostatic pressure requires the combined application of heat and pressure. We have determined the resistance of spores of 14 food isolates and 5 laboratory strains of Bacillus subtilis, B. amyloliquefaciens, and B. licheniformis to treatments with pressure and temperature (200 to 800 MPa and 60 to 80°C) in mashed carrots. A large variation in the pressure resistance of spores was observed, and their reduction by treatments with 800 MPa and 70°C for 4 min ranged from more than 6 log units to no reduction. The sporulation conditions further influenced their pressure resistance. The loss of dipicolinic acid (DPA) from spores that varied in their pressure resistance was determined, and spore sublethal injury was assessed by determination of the detection times for individual spores. Treatment of spores with pressure and temperature resulted in DPA-free, phase-bright spores. These spores were sensitive to moderate heat and exhibited strongly increased detection times as judged by the time required for single spores to grow to visible turbidity of the growth medium. The role of DPA in heat and pressure resistance was further substantiated by the use of the DPA-deficient mutant strain B. subtilis CIP 76.26. Taken together, these results indicate that inactivation of spores by combined pressure and temperature processing is achieved by a two-stage mechanism that does not involve germination. At a pressure between 600 and 800 MPa and a temperature greater than 60°C, DPA is released predominantly by a physicochemical rather than a physiological process, and the DPA-free spores are inactivated by moderate heat independent of the pressure level. Relevant target organisms for pressure and temperature treatment of foods are proposed, namely, strains of B. amyloliquefaciens, which form highly pressure-resistant spores.High-hydrostatic-pressure treatment of foods is a process for food preservation at moderate temperatures. Pressure in the range of 200 to 800 MPa is effective at eliminating vegetative bacteria in food (37,39). Pressure treatment at ambient temperatures initiates germination of bacterial endospores (13), but they are not inactivated at 25°C and a pressure over 1,000 MPa (36, 37). Inactivation of bacterial endospores requires a combination of pressure and moderate heat (21), and the efficacy of pressure treatment is enhanced by the presence of nisin (33, 41), by low pH (41, 43), and by oscillatory compression procedures (10,14). Currently available data indicate that endospores of Bacillus and Clostridium species are inactivated by treatments with pressures ranging from 500 to 800 MPa at temperatures ranging from 60 to 80°C.Studies on the pressure effects on vegetative cells of bacteria have demonstrated that the resistance to pressure strongly varies within strains of one species (4, 12). Likewise, the heat resistance of endospores of various strains of one species may exhibit strong variations (38). The majority of studies on the pressure resistance of bacterial endo...

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Physiological and mathematical aspects in setting criteria for decontamination of foods by physical means

Cited by 88 publications

References 142 publications

Exploration of the Effects of High Hydrostatic Pressure on Microbial Growth, Physiology and Survival: Perspectives from Piezophysiology

Exploration of the Effects of High Hydrostatic Pressure on Microbial Growth, Physiology and Survival: Perspectives from Piezophysiology

Assessment of Heat Resistance of Bacterial Spores from Food Product Isolates by Fluorescence Monitoring of Dipicolinic Acid Release

Pressure Inactivation of Bacillus Endospores

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