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Gędas A, Schmidt H, Weiss A. Identification and evaluation of Escherichia coli strain ATCC 8739 as a surrogate for thermal inactivation of enterohemorrhagic Escherichia coli in fruit nectars: Impact of applied techniques on the decimal reduction time. Food Microbiol 2024; 122:104544. [PMID: 38839230 DOI: 10.1016/j.fm.2024.104544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 04/12/2024] [Accepted: 04/13/2024] [Indexed: 06/07/2024]
Abstract
The objective of this study was to identify a suitable surrogate for E. coli O157:H7 strain 19685/91 and O113:H21 strain TS18/08, by assessing their thermal resistance at temperatures of 60 °C, 65 °C, and 72 °C in strawberry nectar. The influence of the matrix and the research methodology on the decimal reduction time (D-value) was investigated. Thermal kinetics and safety assessment demonstrated that E. coli ATCC 8739 is a suitable surrogate. The study demonstrated that the presence of fruit particles in the nectar increased thermal resistance of the tested strains. Variations in D-values were observed depending on the research method employed, with D-values in glass capillaries were up to 6.6 times lower compared to larger sample volumes. Encapsulation of E. coli ATCC 8739 exhibited high efficiency of 90.25 ± 0.26% and maintained stable viable counts after 26 days of storage in strawberry nectar at 4 °C. There were no significant differences in thermal resistance between surrogates directly inoculated into strawberry nectar and those encapsulated in alginate beads. Additionally, the encapsulated strains did not migrate outside the beads. Therefore, encapsulated E. coli ATCC 8739 in alginate beads can be effectively utilized in industrial settings to validate thermal treatments as a reliable and safe method.
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Affiliation(s)
- Astrid Gędas
- Food Microbiology, Hamburg School of Food Science, University of Hamburg, Ohnhorststrasse 18, 22609, Hamburg, Germany; Department of Food Microbiology and Hygiene, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 28, 70599, Stuttgart, Germany
| | - Herbert Schmidt
- Department of Food Microbiology and Hygiene, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 28, 70599, Stuttgart, Germany
| | - Agnes Weiss
- Food Microbiology, Hamburg School of Food Science, University of Hamburg, Ohnhorststrasse 18, 22609, Hamburg, Germany.
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Kalinke I, Kubbutat P, Taghian Dinani S, Ambros S, Ozcelik M, Kulozik U. Critical assessment of methods for measurement of temperature profiles and heat load history in microwave heating processes-A review. Compr Rev Food Sci Food Saf 2022; 21:2118-2148. [PMID: 35338578 DOI: 10.1111/1541-4337.12940] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 02/11/2022] [Accepted: 02/24/2022] [Indexed: 12/23/2022]
Abstract
Limitations of microwave processing due to inhomogeneities of power input and energy absorption have been widely described. Over- and underheated product areas influence reproducibility, product quality, and possibly safety. Although a broad range of methods is available for temperature measurement and evaluation of time/temperature effects, none of them is sufficiently able to detect temperature differences and thermally induced effects within the product caused by inhomogeneous heating. The purpose of this review is to critically assess different methods of temperature measurement for their suitability for different microwave applications, namely metallic temperature sensors, thermal imaging, pyrometer measurement, fiber optic sensors, microwave radiometry, magnetic resonance imaging, liquid crystal thermography, thermal paper, and biological and chemical time-temperature indicators. These methods are evaluated according to their advantages and limitations, method characteristics, and potential interference with the electric field. Special attention is given to spatial resolution, accuracy, handling, and purpose of measurement, that is, development work or online production control. Differences of methods and examples of practical application and failure in microwave-assisted food processing are discussed with a special focus on microwave pasteurization and microwave-assisted drying. Based on this assessment, it is suggested that infrared cameras for measuring temperature distribution at the product surface and partially inside the product in combination with a chemical time/temperature indicator (e.g., Maillard reaction, generating heat-induced color variations, depending on local energy absorption) appear to be the most appropriate system for future practical application in microwave food process control, microwave system development, and product design. Reliable detection of inhomogeneous heating is a prerequisite to counteracte inhomogeneity by a targeted adjustment of process and product parameters in microwave applications.
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Affiliation(s)
- Isabel Kalinke
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University Munich, Freising, Germany
| | - Peter Kubbutat
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University Munich, Freising, Germany
| | - Somayeh Taghian Dinani
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University Munich, Freising, Germany
| | - Sabine Ambros
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University Munich, Freising, Germany
| | - Mine Ozcelik
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University Munich, Freising, Germany
| | - Ulrich Kulozik
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University Munich, Freising, Germany
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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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Comparison of spore inactivation with novel agitating retort, static retort and combined high pressure-temperature treatments. Food Control 2016. [DOI: 10.1016/j.foodcont.2015.08.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Inactivation of Bacillus subtilis spores by pulsed electric fields (PEF) in combination with thermal energy II. Modeling thermal inactivation of B. subtilis spores during PEF processing in combination with thermal energy. Food Control 2014. [DOI: 10.1016/j.foodcont.2013.09.067] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
Over the past three decades, a powerful array of techniques has been developed for expressing heterologous proteins and saccharides on the surface of bacteria. Surface-engineered bacteria, in turn, have proven useful in a variety of settings, including high-throughput screening, biofuel production, and vaccinology. In this chapter, we provide a comprehensive review of methods for displaying polypeptides and sugars on the bacterial cell surface, and discuss the many innovative applications these methods have found to date. While already an important biotechnological tool, we believe bacterial surface display may be further improved through integration with emerging methodology in other fields, such as protein engineering and synthetic chemistry. Ultimately, we envision bacterial display becoming a multidisciplinary platform with the potential to transform basic and applied research in bacteriology, biotechnology, and biomedicine.
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Bacterial spores as platforms for bioanalytical and biomedical applications. Anal Bioanal Chem 2011; 400:977-89. [PMID: 21380604 DOI: 10.1007/s00216-011-4835-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2010] [Revised: 02/14/2011] [Accepted: 02/22/2011] [Indexed: 01/16/2023]
Abstract
Genetically engineered bacteria-based sensing systems have been employed in a variety of analyses because of their selectivity, sensitivity, and ease of use. These systems, however, have found limited applications in the field because of the inability of bacteria to survive long term, especially under extreme environmental conditions. In nature, certain bacteria, such as those from Clostridium and Bacillus genera, when exposed to threatening environmental conditions are capable of cocooning themselves into a vegetative state known as spores. To overcome the aforementioned limitation of bacterial sensing systems, the use of microorganisms capable of sporulation has recently been proposed. The ability of spores to endow bacteria-based sensing systems with long lives, along with their ability to cycle between the vegetative spore state and the germinated living cell, contributes to their attractiveness as vehicles for cell-based biosensors. An additional application where spores have shown promise is in surface display systems. In that regard, spores expressing certain enzymes, proteins, or peptides on their surface have been presented as a stable, simple, and safe new tool for the biospecific recognition of target analytes, the biocatalytic production of chemicals, and the delivery of biomolecules of pharmaceutical relevance. This review focuses on the application of spores as a packaging method for whole-cell biosensors, surface display of recombinant proteins on spores for bioanalytical and biotechnological applications, and the use of spores as vehicles for vaccines and therapeutic agents.
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Brinley T, Dock C, Truong VD, Coronel P, Kumar P, Simunovic J, Sandeep K, Cartwright G, Swartzel K, Jaykus LA. Feasibility of Utilizing Bioindicators for Testing Microbial Inactivation in Sweetpotato Purees Processed with a Continuous-Flow Microwave System. J Food Sci 2007; 72:E235-42. [DOI: 10.1111/j.1750-3841.2007.00371.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Lassen KS, Johansen JE, Grün R. Comparison of two radio-frequency plasma sterilization processes using microspot evaluation of microbial inactivation. J Biomed Mater Res B Appl Biomater 2006; 78:189-95. [PMID: 16362959 DOI: 10.1002/jbm.b.30476] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In this study, we evaluated gas plasma surface sterilization methods in a specific sterilizer. We have introduced a new monitoring method using 0.4 microm pore size membranes, which in this study gave the information corresponding to 3000 exposed biological indicators per treatment cycle. This enabled us to compare the fraction of inoculates that showed no growth after exposure for 30 different locations in the chamber, and hereby identify weak and strong spots in the chamber with regard to sporicidal effect. Membranes were also used to expose a broad spectrum of soil bacteria for plasma treatment at four different conditions. The organisms were identified using PCR and sequencing. The test showed that Bacillus stearothermophilus spores were inactivated at the slowest rate among the tested microorganisms. Further alpha-proteobacteria (Gram negative) seemed more sensitive than the rest of the tested organisms. The microspot evaluation approach has been a most useful tool in the assessment of sterilization performance in sterilizers that do not have clear measurable parameters related to the sterilization.
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Affiliation(s)
- Klaus S Lassen
- The National Centre for Antimicrobials and Hospital Hygiene, Statens Serum Institut, 5 Artillerivej, 2300 Copenhagen S, Denmark.
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Lassen KS, Nordby B, Grün R. The dependence of the sporicidal effects on the power and pressure of RF-generated plasma processes. J Biomed Mater Res B Appl Biomater 2005; 74:553-9. [PMID: 15765503 DOI: 10.1002/jbm.b.30239] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The sporicidal effect of 20 different radio-frequency plasma processes produced by combining five different gas mixtures [O(2), Ar/H(2) (50/50%), Ar/H(2) (5/95%), O(2)/H(2) (50/50%), O(2)/H(2) (95/5%)] with four power/pressure settings were tested. Sporicidal effects of oxygen-containing plasmas were dependent on power at low pressure settings but not at high pressure settings. In the absence of oxygen no power dependency was observed at either high or low pressure settings. Survivor curves obtained with the use of nonoxygen plasmas typically had a tailing tendency. Only a mixture-optimized Ar/H(2) (15/85%) plasma process was not encumbered by tailing, and produced a decimal reduction time (D value) below 2 min for Bacillus stearothermophilus spores. Scanning electron microscopy showed that a CF(4)/O(2) plasma did more damage to the substrate than the 15/85% Ar/H(2) plasma. The present results indicate that UV irradiation inactivation is swift and power and pressure independent. Additionally, it is produced at low energy. However, it is not complete. Inactivation through etching is highly power and pressure dependent; finally, inactivation by photodesorption is moderately power and pressure dependent. A sterilization process relying on this mechanism is very advantageous because it combines a highly sporicidal effect with low substrate damage.
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Affiliation(s)
- Klaus S Lassen
- The National Centre for Hospital Hygiene (CAS), Statens Serum Institut, Copenhagen S, Denmark.
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Liquid Core Caspules for Applications in Biotechnology. FUNDAMENTALS OF CELL IMMOBILISATION BIOTECHNOLOGY 2004. [DOI: 10.1007/978-94-017-1638-3_10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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McGlynn W, Davis D, Johnson M, Crandall P. Modified Spore Inoculation Method for Thermal-Process Verification of Pinto Beans and Green Beans Canned in Two Large Reusable Containers. J Food Sci 2003. [DOI: 10.1111/j.1365-2621.2003.tb08275.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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