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Evelyn, Utami SP, Chairul. Effect of temperature and soluble solid on Bacillus subtilis and Bacillus licheniformis spore inactivation and quality degradation of pineapple juice. FOOD SCI TECHNOL INT 2021; 28:285-296. [PMID: 34018829 DOI: 10.1177/10820132211019143] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Bacillus subtilis and Bacillus licheniformis spores can survive processing temperatures used in the thermal processes of high-acid foods. Therefore, this study investigated the thermal inactivation of B. subtilis and B. licheniformis spores in pineapple juice at different temperatures (85-100°C) and soluble solids (SS, 11-30°Brix). The quality of juices and microbial loads after the thermal treatments during storage at 4 °C for 35 days was then checked. A linear decrease in D-value was observed with increasing temperature of treatment. Furthermore, the D-values determined in pineapple juice were: D90°C=13.2 ± 0.5 mins, D95°C = 6.8 ± 0.9 mins and D100°C = 2.1 ± 1.7 mins for B. subtilis spores, and D85°C = 16.6 ± 0.4 mins, D90°C = 7.6 ± 0.5 mins and D95°C = 3.6 ± 1.5 min, for B. licheniformis. Generally, the susceptibility of the bacteria to soluble solid change was affected by the interaction between temperature, SS and strain. In addition, pasteurization processes of ≥95°C for ≥33.8 mins was needed to ensure a recommended 5-log reduction of B. subtilis spores and limit vitamin C degradation of pineapple juice within three-week of storage at 4 °C.
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Affiliation(s)
- Evelyn
- Department of Chemical Engineering, University of Riau, Pekanbaru, Indonesia
| | - Syelvia Putri Utami
- Department of Chemical Engineering, University of Riau, Pekanbaru, Indonesia
| | - Chairul
- Department of Chemical Engineering, University of Riau, Pekanbaru, Indonesia
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Yang R, Guan J, Sun S, Sablani SS, Tang J. Understanding water activity change in oil with temperature. Curr Res Food Sci 2020; 3:158-165. [PMID: 32914131 PMCID: PMC7473353 DOI: 10.1016/j.crfs.2020.04.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Our recent studies and several publications suggest that the low water activity (aw) of oil in thermal processing might be a major contributing factor towards the increased thermal resistance of bacteria in oils. In this study, we developed a reliable method to measure the water activity of oil by measuring the equilibrium relative humidity in a small headspace. Using this method, water activity of peanut oil was found to decrease exponentially with increasing temperature. A model derived from excess Gibbs free energy was fitted to the observations with an R2 = 99.6% and RMSE = 0.01 (aw). Our results suggest that the sharply reduced water activity of oil resulting from a rise in temperature could cause desiccation of bacteria. This is a possible explanation for the protective effect of oil in thermal processing. A method is presented for the measurement of water activity of oil at temperatures up to 85 °C. The water activity of peanut oil is found to decrease exponentially as the temperature increases. A model is derived to predict the water activity of oil as a function of temperature. Desiccation may happen to bacteria in oil during thermal processing, which explains the protective effect of oil.
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Affiliation(s)
- Ren Yang
- Department of Biological Systems Engineering, Washington State University, P.O. Box 646120, Pullman, WA, 99164, USA
| | - Jiewen Guan
- Department of Biological Systems Engineering, Washington State University, P.O. Box 646120, Pullman, WA, 99164, USA
| | - Sicheng Sun
- Department of Biological Systems Engineering, Washington State University, P.O. Box 646120, Pullman, WA, 99164, USA
| | - Shyam S Sablani
- Department of Biological Systems Engineering, Washington State University, P.O. Box 646120, Pullman, WA, 99164, USA
| | - Juming Tang
- Department of Biological Systems Engineering, Washington State University, P.O. Box 646120, Pullman, WA, 99164, USA
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Huang L. Reconciliation of the D/z model and the Arrhenius model: The effect of temperature on inactivation rates of chemical compounds and microorganisms. Food Chem 2019; 295:499-504. [PMID: 31174787 DOI: 10.1016/j.foodchem.2019.05.150] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 11/30/2022]
Abstract
The effect of temperature on thermal inactivation of microorganisms and thermal degradation of certain chemical compounds can be either described by the Arrhenius model for the rate constant (k) or by the D/z model for the decimal reduction time (D). Although equivalent, it is difficult to directly reconcile these two models which have different model structures. This study hypothesized that the two models can be reconciled by linearization of the inverse of absolute temperature (1/T) and heating temperature (T), and the activation energy (Ea) can be directly calculated from z and their relationship is independent of T. The hypothesis was validated using the z and Ea of various chemical compounds, enzymes, and vegetative cells and spores of microorganisms in various substrates published in the literature. The results of this study show that the empirical models are practically reconciled.
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Affiliation(s)
- Lihan Huang
- Eastern Regional Research Center, USDA Agricultural Research Service, 600 E. Mermaid Lane, Wyndmoor, PA 19038, United States.
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den Besten HM, Wells-Bennik MH, Zwietering MH. Natural Diversity in Heat Resistance of Bacteria and Bacterial Spores: Impact on Food Safety and Quality. Annu Rev Food Sci Technol 2018; 9:383-410. [DOI: 10.1146/annurev-food-030117-012808] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Heidy M.W. den Besten
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
- Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands
| | - Marjon H.J. Wells-Bennik
- NIZO Food Research B.V., 6718 ZB, Ede, The Netherlands
- Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands
| | - Marcel H. Zwietering
- Laboratory of Food Microbiology, Wageningen University, 6700 AA Wageningen, The Netherlands
- Top Institute Food and Nutrition, 6709 PA, Wageningen, The Netherlands
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Georget E, Sevenich R, Reineke K, Mathys A, Heinz V, Callanan M, Rauh C, Knorr D. Inactivation of microorganisms by high isostatic pressure processing in complex matrices: A review. INNOV FOOD SCI EMERG 2015. [DOI: 10.1016/j.ifset.2014.10.015] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Sevenich R, Kleinstueck E, Crews C, Anderson W, Pye C, Riddellova K, Hradecky J, Moravcova E, Reineke K, Knorr D. High-Pressure Thermal Sterilization: Food Safety and Food Quality of Baby Food Puree. J Food Sci 2014; 79:M230-7. [DOI: 10.1111/1750-3841.12345] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 11/25/2013] [Indexed: 12/01/2022]
Affiliation(s)
- Robert Sevenich
- Dept. of Food Biotechnology and Food Process Engineering; Technische Univ. Berlin; Koenigin-Luise-St. 22 D-14195 Berlin Germany
| | - Elke Kleinstueck
- Dept. of Food Biotechnology and Food Process Engineering; Technische Univ. Berlin; Koenigin-Luise-St. 22 D-14195 Berlin Germany
| | - Colin Crews
- Food and Environment Research Agency; Sand Hutton YO41 1LZ York UK
| | - Warwick Anderson
- Food and Environment Research Agency; Sand Hutton YO41 1LZ York UK
| | - Celine Pye
- Food and Environment Research Agency; Sand Hutton YO41 1LZ York UK
| | - Katerina Riddellova
- Dept. of Food Analysis and Nutrition; Inst. of Chemical Technology; 5 Technika 16628 Prague 6 Prague Czech Republic
| | - Jaromir Hradecky
- Dept. of Food Analysis and Nutrition; Inst. of Chemical Technology; 5 Technika 16628 Prague 6 Prague Czech Republic
| | - Eliska Moravcova
- Dept. of Food Analysis and Nutrition; Inst. of Chemical Technology; 5 Technika 16628 Prague 6 Prague Czech Republic
| | - Kai Reineke
- Leibniz Inst. for Agricultural Engineering (ATB) Max-Etyth-Allee 100; 14469 Potsdam Germany
| | - Dietrich Knorr
- Dept. of Food Biotechnology and Food Process Engineering; Technische Univ. Berlin; Koenigin-Luise-St. 22 D-14195 Berlin Germany
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Sevenich R, Bark F, Crews C, Anderson W, Pye C, Riddellova K, Hradecky J, Moravcova E, Reineke K, Knorr D. Effect of high pressure thermal sterilization on the formation of food processing contaminants. INNOV FOOD SCI EMERG 2013. [DOI: 10.1016/j.ifset.2013.07.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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The microbiological quality of commercial herb and spice preparations used in the formulation of a chicken supreme ready meal and microbial survival following a simulated industrial heating process. Food Control 2011. [DOI: 10.1016/j.foodcont.2010.10.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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Johansson E, Adhikari A, Reponen T, Yermakov M, Grinshpun SA. Association between increased DNA mutational frequency and thermal inactivation of aerosolized Bacillus spores exposed to dry heat. AEROSOL SCIENCE AND TECHNOLOGY : THE JOURNAL OF THE AMERICAN ASSOCIATION FOR AEROSOL RESEARCH 2011; 45:376-381. [PMID: 31660000 PMCID: PMC6816487 DOI: 10.1080/02786826.2010.538452] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Inactivation of viable bioaerosol particles, especially stress-resistant microorganisms, has important implications for biodefense and air quality control. It has earlier been shown that the loss of viability of bacterial endospores due to exposure to dry heat is associated with mutational damage. Previous studies, however, used non-aerosolized spores, long exposure times, and moderately elevated temperatures. This study was designed to investigate the mechanism of inactivation of aerosolized Bacillus endospores exposed to high temperatures for sub-second time periods. Bioaerosol was tested in a continuous air flow chamber under two flow rates, 18 L/min and 36 L/min. The chamber had a cylindrical electric heating element installed along its axis. The estimated characteristic exposure temperature (T exposure ) ranged from 164°C to 277°C (with an uncertainty of 21-26°C). To quantify mutational frequency, spores were cultivated after dry heat exposure on tryptic-soy agar and on antibiotic nalidixic acid media. Increases in the exposure temperature caused viability loss and increase in mutational frequency of the spore DNA. Significant association was found between the inactivation factor and the mutational frequency ratio (heat exposed versus non-exposed) with R2 of 0.985 for both flow rates combined. The results suggest that mutational damage is involved in the causal chain of events leading to inactivation of aerosolized endospores exposed to heat for sub-second time periods.
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Desai SV, Varadaraj MC. Behavioural pattern of vegetative cells and spores of Bacillus cereus as affected by time-temperature combinations used in processing of Indian traditional foods. JOURNAL OF FOOD SCIENCE AND TECHNOLOGY 2010; 47:549-56. [PMID: 23572684 PMCID: PMC3551094 DOI: 10.1007/s13197-010-0099-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 02/03/2010] [Accepted: 02/08/2010] [Indexed: 12/27/2022]
Abstract
This study was undertaken to evaluate the behaviour of vegetative cells and spores of four potent native toxigenic food isolates of Bacillus cereus as affected by selected time-temperature combinations used in processing of Indian traditional foods. The vegetative cells of B. cereus when subjected to sublethal heat treatments, individually, in different heating menstra showed a sigmoidal inactivation pattern, with D-values in the range of 3.45 min at 60 °C to 10.6 min at 56 °C in saline. Accordingly, the z-values recorded across the heating menstra ranged from 9.3 °C in culture broth to 24 °C in whole milk. Similarly, the inactivation pattern for spores for the same isolates was curvilinear with D-values ranging from 4.4 min at 95 °C in whole milk to 19.45 min at 85 °C in saline. The z-values for spores ranged from 16.6 °C in saline to 38.4 °C in whole milk. The thermal inactivation pattern observed for vegetative cells and spores indicate that the death rate was not constant during the process of heat treatment.
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Affiliation(s)
- Shivalingsarj Vijaykumar Desai
- Human Resource Development, Central Food Technological Research Institute (Council of Scientific and Industrial Research), Mysore, 570 020 India
| | - Mandyam Chakravarathy Varadaraj
- Human Resource Development, Central Food Technological Research Institute (Council of Scientific and Industrial Research), Mysore, 570 020 India
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11
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Arroyo C, Cebrián G, Pagán R, Condón S. Resistance of Enterobacter sakazakii to pulsed electric fields. INNOV FOOD SCI EMERG 2010. [DOI: 10.1016/j.ifset.2009.11.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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SHIGEMOTO MAYUMI, NAKAGAWA KAYO, SAKAMOTO JINJ, TSUCHIDO TETSUAKI. Thermal Death of Bacillus subtilis Spores in Oil-Water Systems. Biocontrol Sci 2010; 15:27-31. [DOI: 10.4265/bio.15.27] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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13
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Staack N, Ahrné L, Borch E, Knorr D. Effects of temperature, pH, and controlled water activity on inactivation of spores of Bacillus cereus in paprika powder by near-IR radiation. J FOOD ENG 2008. [DOI: 10.1016/j.jfoodeng.2008.05.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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14
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Johny AK, Darre M, Hoagland T, Schreiber D, Donoghue A, Donoghue D, Venkitanarayanan K. Antibacterial Effect of Trans-Cinnamaldehyde on Salmonella Enteritidis and Campylobacter jejuni in Chicken Drinking Water ,. J APPL POULTRY RES 2008. [DOI: 10.3382/japr.2008-00051] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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15
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MIN S, REINA L, ZHANG QH. WATER ACTIVITY AND THE INACTIVATION OFENTEROBACTER CLOACAEINOCULATED IN CHOCOLATE LIQUOR AND A MODEL SYSTEM BY PULSED ELECTRIC FIELD TREATMENT. J FOOD PROCESS PRES 2007. [DOI: 10.1111/j.1745-4549.2002.tb00488.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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16
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Byrne B, Dunne G, Bolton DJ. Thermal inactivation of Bacillus cereus and Clostridium perfringens vegetative cells and spores in pork luncheon roll. Food Microbiol 2006; 23:803-8. [PMID: 16943086 DOI: 10.1016/j.fm.2006.02.002] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2005] [Revised: 02/09/2006] [Accepted: 02/09/2006] [Indexed: 11/27/2022]
Abstract
The aim of this study was to design a thermal treatment(s) for pork luncheon roll, which would destroy Bacillus cereus and Clostridium perfringens vegetative cells and spores. B. cereus and C. perfringens vegetative and spore cocktails were used to inoculate luncheon meat. Samples were subjected to different temperatures and removal times. The decimal-reduction times (D-values) were calculated by linear regression analysis (D = -1/slope of a plot of log surviving cells versus time). The log(10) of the resulting D-values were plotted against their corresponding temperatures to calculate (-1/slope of the curve) the thermal resistance (z-values) of each cocktail. The D-values for vegetative cells ranged from 1 min (60 degrees C) to 33.2 min (50 degrees C) for B. cereus and from 0.9 min (65 degrees C) to 16.3 min (55 degrees C) for C. perfringens. The D-values for B. cereus spores ranged from 2.0 min (95 degrees C) to 32.1 min (85 degrees C) and from 2.2 min (100 degrees C) to 34.2 min (90 degrees C) for C. perfringens. The z-values were calculated to be 6.6 and 8.5 degrees C for B. cereus vegetative and spores, respectively, and 7.8 and 8.4 degrees C for C. perfringens vegetative cells and spores, respectively. The D-values of B. cereus and C. perfringens suggest that a mild cook of 70 degrees C for 12s and 1.3 min would achieve a 6 log reduction of B. cereus and C. perfringens vegetative cells, respectively. The equivalent reduction of B. cereus and C. perfringens spores would require the pork luncheon meat to be heated for 36 s at 105 and 110 degrees C, respectively. The results of this study provide the thermal inactivation data necessary to design a cooking protocol for pork luncheon roll that would inactivate B. cereus and C. perfringens vegetative cells and spores. The data may also be used in future risk assessment studies.
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Affiliation(s)
- B Byrne
- Ashtown Food Research Centre, Teagasc, Ashtown, Dublin, Ireland
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Kort R, O'Brien AC, van Stokkum IHM, Oomes SJCM, Crielaard W, Hellingwerf KJ, Brul S. Assessment of heat resistance of bacterial spores from food product isolates by fluorescence monitoring of dipicolinic acid release. Appl Environ Microbiol 2005; 71:3556-64. [PMID: 16000762 PMCID: PMC1169001 DOI: 10.1128/aem.71.7.3556-3564.2005] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
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 degrees C, 120 degrees C, and 131 degrees C, respectively. The estimated Z values were 6.3 degrees C, 6.1 degrees C, and 9.7 degrees 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 (Tc), the temperature at which half the DPA content has been released within a fixed incubation time. We found Tc values for spores from Bacillus strains 168, A163, and IC4 of 108 degrees C, 121 degrees C, and 131 degrees 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.
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Affiliation(s)
- Remco Kort
- Laboratory for Microbiology, Room C-809, Swammerdam Institute for Life Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018WV Amsterdam, The Netherlands.
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Gradel KO, Sayers AR, Davies RH. Surface Disinfection Tests with Salmonella and a Putative Indicator Bacterium, Mimicking Worst-Case Scenarios in Poultry Houses. Poult Sci 2004; 83:1636-43. [PMID: 15510546 DOI: 10.1093/ps/83.10.1636] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Surface disinfection studies mimicking worst-case scenarios in badly cleaned poultry houses were made with 3 bacterial isolates (Salmonella enteritidis, Salmonella senftenberg, and Enterococcus faecalis), and 3 1% disinfectant solutions, formaldehyde (F; 24.5% vol/vol), glutaraldehyde/benzalkonium chloride (G; Bio Komplet Plus), and a peroxygen compound (P; Virkon S), with World Health Organization (WHO) standard hard water as a control. Materials (concrete paving stones, steel feed chain links, wooden dowels, and jute egg belts) and organic matter found commonly in poultry houses (feed, fats, egg yolk) were used in the tests. Organic matter inoculated with high numbers of stationary phase cultures was added to materials and dried for 24 h at different temperatures (6, 11, 20, or 30 degrees C), immersed in solutions for set time periods (5, 15, or 30 min), and dried again for 25 h (6, 11, or 30 degrees C). Then, traditional recovery procedures (using 10-fold dilutions until 10(-4), i.e., a most probable number method) were applied. For the 2 Salmonella isolates, the efficacy of the solutions was (in decreasing order): formaldehyde > glutaraldehyde/benzalkonium chloride > peroxygen compound > WHO hard water, except when feed chain links with fats were disinfected using 30 degrees C before and after disinfection, for which the peroxygen compound seemed more effective. Enterococcus faecalis was equally or less susceptible than S. enteritidis and S. senftenberg, indicating its suitability as an indicator bacterium. For the peroxygen compound, S. senftenberg was more susceptible than S. enteritidis in spite of higher minimum inhibitory concentrations to this disinfectant for the former.
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Affiliation(s)
- K O Gradel
- Danish Institute for Food and Veterinary Research, Department of Poultry, Fish, and Fur Animals, Hangøvej 2, 8200 Arhus N, Denmark.
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Jagannath A, Nakamura I, Tsuchido T. Modelling the combined effects of pH, temperature and sodium chloride stresses on the thermal inactivation of Bacillus subtilis spores in a buffer system. J Appl Microbiol 2003; 95:135-41. [PMID: 12807463 DOI: 10.1046/j.1365-2672.2003.01952.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS The inactivation of Bacillus subtilis 168 spores subjected to the combined stress of pH, temperature and sodium chloride in a buffer system was modelled. METHODS AND RESULTS Bacillus subtilis 168 spore suspension in 50 mmol l-1 potassium phosphate buffer was heated in an open system using a block heater. A second order polynomial equation was used to describe the relationship between pH, temperature, sodium chloride concentration and the logarithm of the decimal reduction time (D-value) of the spores. Response surface graphs were constructed to predict the inactivation within the experimental domain. The data obtained were also compared with those reported for B. subtilis in different media and foods included in a large reference-based database of thermal inactivation (ThermoKill Database, TKDB R9100), which was constructed in the laboratory. CONCLUSIONS All the variables studied seemed to have a significant effect on the inactivation of B. subtilis 168 spores in potassium phosphate buffer. The coefficient of determination, r2, and an analysis of the residuals from the model indicated the adequacy of the model to predict the inactivation of B. subtilis spores within the range of the experimental variables studied. SIGNIFICANCE AND IMPACT OF THE STUDY The findings of this study will enable a better understanding of the inactivation of B. subtilis spores under the influence of the studied environmental variables. The model can be used by food industries to assess and monitor the shelf life of food products in the event of a chance contamination by B. subtilis spores.
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Affiliation(s)
- A Jagannath
- Department of Biotechnology, Faculty of Engineering, Kansai University, Yamate-cho, Suita, Osaka, Japan
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Gradel KO, Jørgensen JC, Andersen JS, Corry JEL. Laboratory heating studies with Salmonella spp. and Escherichia coli in organic matter, with a view to decontamination of poultry houses. J Appl Microbiol 2003; 94:919-28. [PMID: 12694458 DOI: 10.1046/j.1365-2672.2003.01933.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS To determine a temperature-humidity-time treatment that eliminates Salmonella and Escherichia coli in substrates representing organic matter in poorly cleaned poultry houses, i.e. worst case scenario laboratory tests. METHODS AND RESULTS Organic matter (poultry faeces and feed) in a 2.5-cm layer was inoculated with 2 x 10(5)-3 x 10(6) Salmonella g(-1), left undried or dried at ca. 30% relative humidity (RH) during a 10-day period, and temperature increased at 1 degrees C h(-)1 to the final heating temperature of 50, 55, 60, 65 or 70 degrees C and held at 16-30 or 100% RH. All samples were tested for Salmonella according to predetermined sampling time schedules and faecal samples were also tested for naturally occurring E. coli. Overall, humidity was an important factor in the elimination of Salmonella and E. coli. Results for recovery of Salmonella and E. coli were highly associated. CONCLUSIONS The application of >/=60 degrees C and 100% RH during a 24-h period eliminated Salmonella and E. coli in all samples. Escherichia coli could be used as an indicator bacterium for the elimination of Salmonella. SIGNIFICANCE AND IMPACT OF THE STUDY The results from worst case scenario laboratory tests could be applied in steam heating of persistently Salmonella-infected poultry houses. The use of E. coli as an indicator bacterium for the validation of Salmonella results should be considered.
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Affiliation(s)
- K O Gradel
- Danish Veterinary Institute, Department of Poultry, Fish and Fur-bearing Animals, Aarhus N, Denmark.
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Tremoulet F, Rabier P, Gas G. Inhibition of Bacillus stearothermophilus Spores in a Liquid Medium by Free Fatty Acids with and without Heat: Possible Mechanisms for the Microbiological Stability of Canned Fat-Duck Liver. J Food Sci 2002. [DOI: 10.1111/j.1365-2621.2002.tb09467.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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22
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Critical factors determining inactivation kinetics by pulsed electric field food processing. Trends Food Sci Technol 2001. [DOI: 10.1016/s0924-2244(01)00067-x] [Citation(s) in RCA: 238] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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23
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Murphy R, Marks B, Johnson E, Johnson M. Thermal Inactivation Kinetics of Salmonella and Listeria in Ground Chicken Breast Meat and Liquid Medium. J Food Sci 2000. [DOI: 10.1111/j.1365-2621.2000.tb16076.x] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Modi KD, Chikindas ML, Montville TJ. Sensitivity of nisin-resistant Listeria monocytogenes to heat and the synergistic action of heat and nisin. Lett Appl Microbiol 2000; 30:249-53. [PMID: 10747260 DOI: 10.1046/j.1472-765x.2000.00708.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Nisin, a bacteriocin produced by some strains of Lactococcus lactis, acts against foodborne pathogen Listeria monocytogenes. A single exposure of cells to nisin can generate nisin-resistant (Nisr) mutants, which may compromise the use of nisin in the food industry. The objective of this research was to compare the heat resistance of Nisr and wild type (WT) Listeria monocytogenes. The synergistic effect of heat-treatment (55 degrees C) and nisin (500 IU ml-1) on the Nisr cells and the WT L. monocytogenes Scott A was also studied. When the cells were grown in the absence of nisin, there was no significant (alpha = 0.05) difference in heat resistance between WT and Nisr cells of L. monocytogenes at 55, 60 and 65 degrees C. However, when the Nisr cells were grown in the presence of nisin, they were more sensitive to heat at 55 degrees C than the WT cells. The D-values at 55 degrees C were 2.88 and 2.77 min for Nisr ATCC 700301 and ATCC 700302, respectively, which was significantly (alpha = 0.05) lower than the D-value for WT, 3.72 min. When Nisr cells were subjected to a combined treatment of heat and nisin, there was approximately a four log reduction during the first 7 min of treatment.
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Affiliation(s)
- K D Modi
- Graduate Program in Microbiology and Molecular Genentics and Department of Food Science, New Jersey Agricultural Experiment Station, Cook College; Rutgers, The State University of New Jersey, New Brunswick, NJ 08901-8520, USA
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Mazzotta AS, Montville TJ. Characterization of fatty acid composition, spore germination, and thermal resistance in a nisin-resistant mutant of Clostridium botulinum 169B and in the wild-type strain. Appl Environ Microbiol 1999; 65:659-64. [PMID: 9925597 PMCID: PMC91076 DOI: 10.1128/aem.65.2.659-664.1999] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/1998] [Accepted: 10/29/1998] [Indexed: 11/20/2022] Open
Abstract
The membrane fatty acids, thermal resistance, and germination of a nisin-resistant (Nisr) mutant of Clostridium botulinum 169B were compared with those of the wild-type (WT) strain. In the membranes of WT cells, almost 50% of the total fatty acids were unsaturated, but in those of Nisr cells, only 23% of the fatty acids were unsaturated. WT and Nisr spores contained similar amounts (approximately 23%) of unsaturated fatty acids, but the saturated straight-chain/branched-chain ratio was significantly higher in Nisr spores than in WT spores. These fatty acid differences suggest that Nisr cell and spore membranes may be more rigid, a characteristic which would interfere with the pore-forming ability of nisin. Nisr C. botulinum did not produce an extracellular nisin-degrading enzyme, nor were there any differences in the sodium dodecyl sulfate-polyacrylamide gel electrophoresis patterns of coat proteins extracted from WT and Nisr spores, eliminating these as possible reasons for nisin resistance. Nisr spores had thermal resistance parameters similar to those of WT spores. In WT spores, but not in Nisr spores, nisin caused a 40% reduction in thermal resistance and a twofold increase in the germination rate. Because the nisin-induced increase in the germination rate of WT spores occurred only in the presence of a germinant (a molecule that triggers germination), nisin can be classified as a progerminant (a molecule that stimulates germination only in the presence of a germinant).
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Affiliation(s)
- A S Mazzotta
- Department of Food Science, Cook College, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901-8520, USA
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Effect of monoglycerides on the thermal inactivation kinetics ofBacillus cereusF4165/75 spores. Food Microbiol 1998. [DOI: 10.1006/fmic.1998.0191] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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