Download or read book Variation in Resistance to High Hydrostatic Pressure of Escherichia Coli written by Rigoberto Garcia-Hernandez and published by . This book was released on 2016 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: Verotoxigenic Escherichia coli (VTEC) pose a risk for foodborne illness that can lead to death. Thermal food preservation to inactivate VTEC also alters food quality. High hydrostatic pressure (HHP) processing has been adopted by the food industry as an alternative to thermal preservation. However, E. coli exhibits great variability in resistance to pressure. This research evaluated the pressure resistance of VTEC and non-VTEC E. coli in laboratory media and ground beef. A strain cocktail of non-pathogenic E. coli was developed to match the pressure resistance of VTEC. The strain cocktail was validated by pressure treatments in ground beef and vegetable products. Pressure resistance of E. coli is affected by the food matrix. Therefore, the effect of the food matrix and food constituents on pressure resistance of E. coli was determined. Ground beef showed a baro-protective effect on E. coli when compared to treatments in bruschetta and tzatziki at the same pH (5.5). Divalent cations (Ca2+) exerted a baroprotective effect and may partially explain the relative resistance of E. coli in ground beef. To further elucidate mechanisms of pressure resistance, four extremely pressure resistant strains of E. coli, including one VTEC, were generated and cross-resistance to other stressors was evaluated. All four strains of E. coli evolved as extremely pressure resistant strains when treated with consecutive cycles of increasing pressure. Derivative E. coli AW1.7 became sensitive to low pH (2.5) and derivative E. coli AW1.3 exhibited increased resistance to heat and osmotic stress. Comparative analysis of the genome sequence of 3 wild type strains to the respective pressure-resistant revealed that derivative strains exhibited deletion of genetic elements. However, deletions were different without apparent consistency among the strains. In conclusion, the species E. coli contains extremely pressure resistant strains that are not readily inactivated by pressure treatment of food. Knowledge on the strain/matrix interaction during and after pressure treatment will facilitate the design, adoption, and/or combination of different intervention methods to warrant food safety.

Download or read book The Correlation Between Tolerance to Low Water Activity and High Hydrostatic Pressure in Shiga Toxin Producing Escherichia Coli written by Fahad Bazaid and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: High hydrostatic pressure processing (HHP) is extensively applied for the non-thermal pasteurization of foods. One notable feature of HHP mediated inactivation of microbes is the large variation in lethality between strains and the influence of the food matrix. In the following it was hypothesized that the barotolerance of Shiga Toxin producing Escherichia coli could be correlated to tolerance to low water activity environments. The study evaluated the barotolerance of members of the Top 6 STEC serotypes and found variation with O26: H11 and O45: H2 exhibiting higher tolerance to pressure compared to the other bacterial types tested. A negative correlation was found between resistance to high pressure and the NaCl concentration under which E. coli could grow under. For example, E. coli O26: H11 exhibited the highest tolerance to pressure, within 300 MPa, but could only grow under NaCl up to 2.4% w/v. In contrast, E. coli O121: H19 was sensitive to pressure, but could grow in the presence of 6% NaCl. The results suggested that the induction of the stress-response was the likely reason for high barotolerance in salt sensitive strains vs resistant. It was also found that supplementing the suspension medium with amino acids, sugar alcohols and starch could increase the barotolerance of E. coli. Although it is possible that the solutes acted directly as osmolytes it is also proposed that metabolic products and other indirect protective mechanisms were also operating. The study suggests that early induction of the osmotic stress response can be used to predict the resistance to high hydrostatic pressure.

Download or read book The Causative Effects of High Hydrostatic Pressure on the Physiology and Variability of Escherichia Coli written by Paul Chilton and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Innovative Technologies for Food Preservation written by Francisco J. Barba and published by Academic Press. This book was released on 2017-09-21 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: Innovative Technologies for Food Preservation: Inactivation of Spoilage and Pathogenic Microorganisms covers the latest advances in non-thermal processing, including mechanical processes (such as high pressure processing, high pressure homogenization, high hydrodynamic pressure processing, pressurized fluids); electromagnetic technologies (like pulsed electric fields, high voltage electrical discharges, Ohmic heating, chemical electrolysis, microwaves, radiofrequency, cold plasma, UV-light); acoustic technologies (ultrasound, shockwaves); innovative chemical processing technologies (ozone, chlorine dioxide, electrolysis, oxidized water) and others like membrane filtration and dense phase CO2. The title also focuses on understanding the effects of such processing technologies on inactivation of the most relevant pathogenic and spoilage microorganisms to ensure food safety and stability. Over the course of the 20th century, the interest and demand for the development and application of new food preservation methods has increased significantly. The research in the last 50 years has produced various innovative food processing technologies and the use of new technologies for inactivation of spoilage and/or pathogenic microorganisms will depend on several factors. At this stage of development there is a need to better understand the mechanisms that govern microbial inactivation as induced by new and innovative processing technologies, as well as suitable and effective conditions for inactivating the microorganism. - Serves as a summary of relevant spoilage and pathogenic microorganisms for different foods as influenced by the application of innovative technologies for their preservation - Provides readers with an in-depth understanding on how effective innovative processing technologies are for controlling spoilage and pathogenic microorganisms in different foods - Integrates concepts in order to find the optimum conditions for microbial inactivation and preservation of major and minor food compounds

Download or read book Heat and Pressure Resistance of Escherichia Coli and Its Inactivation in the Presence of Antimicrobial Compounds written by Yang Liu and published by . This book was released on 2014 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Verotoxigenic Escherichia coli (VTEC) are pathogens causing severe foodborne disease. E. coli AW1.7 is a heat resistant beef carcass isolate that may be used as a surrogate organism to study the survival of VTEC on food. This dissertation examines the heat and pressure resistance of E. coli and the application of antimicrobial compounds to achieve its inactivation in food. The pressure resistance of E. coli AW1.7 was compared to the resistance of other foodborne pathogens and spoilage organisms relevant in meat. E. coli AW1.7 was the most pressure resistant organism tested. Moreover, the ability of E. coli AW1.7 to resist pressure was comparable to the pressure-resistant mutant E. coli LMM1030. To further study the heat- and pressure resistance of E. coli, E. coli AW1.7 was compared to the heat- and pressure resistance of VTEC strains from different serotypes and phylotypes. E. coli AW1.7 exhibited a higher heat resistance than VTEC strains; however, some VTEC strains also survived in hamburgers grilled to a core temperature of 71°C. Several strains of VTEC exhibited a higher resistance to pressure than E. coli AW1.7. Over one third of tested strains showed 3 log CFU/g or less cell count reduction under high pressure treatment of 600 MPa for 3 min. Therefore, additional treatment processes are required for elimination of VTEC in pressure treated food. Additional treatments were evaluated to achieve the elimination of E. coli in buffers and food matrices. Chitosan was effective in injury E. coli in imidazole and potassium phosphate buffer; chitosan, nisin and lactate combination were effective in yogurt serum; chitosan, nisin and heat were effective in apple juice; and chitosan, Micocin® X and heat had small bactericidal effects in ground beef. A combination of chitosan and high pressure was not effective against E. coli AW1.7 in potassium phosphate buffer, but addition of Micocin® X to increased killing of E. coli AW1.7. In conclusion, this thesis demonstrated that high pressure alone is insufficient to kill E. coli in meat. Bacteriocins, lactate, and chitosan can be applied as additional antimicrobial treatments to kill E. coli in food. And the bactericidal effect is strongly dependent on the food matrix and the preservation method. Some of the VTEC strains tested survived heat treatment and high hydrostatic pressure (HHP) permitted recommendations of E. coli by Canadian regulatory agencies (Health Canada and Canadian Food Inspection Agency). More studies need to be conducted to validate the results.

Download or read book High Hydrostatic Pressure Inactivation of Escherichia Coli written by Bernadette Klotz and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Directed Evolution and Characterization of an Escherichia Coli Mutant Displaying Improved Growth at High Hydrostatic Pressure written by Alice Thu Thao Nguyen and published by . This book was released on 2013 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: High pressure and low temperatures, both of which are inherent to the deep ocean, are fundamental physical parameters to which organisms must adapt, but increased hydrostatic pressure is especially unique to the depths of the ocean. The elusive deep marine environment is home to a plethora of piezophilic ("pressure-loving") microorganisms with incredible physiological adaptations, but unfortunately they are yet still poorly understood. This study documents the selection of an Escherichia coli population, designated L62A, following experimental directed evolution using increasingly higher pressure treatments at 37°C. After 62 transfers and 504 generations, a strain from the L62A population, AN62-1 was obtained at 62 MPa (megapascals), correlating to a hadal depth of 6,124 meters. Through detailed growth studies, it was determined that AN62-1 is piezotolerant and, in contrast to its parental strain, can grow robustly at 59 MPa. AN62-1 has unique colony and internal cell morphology, increased production of monounsaturated fatty acids, and a mutation in the acpP gene, which encodes acyl-carrier protein. This study provides a novel strain of E. coli for future investigations of high-pressure adaptation and demonstrates the feasibility of directed evolution to assess microbial growth adaptation as a function of hydrostatic pressure.

Download or read book High Pressure Processing of Food written by V.M. Balasubramaniam and published by Springer. This book was released on 2016-01-28 with total page 758 pages. Available in PDF, EPUB and Kindle. Book excerpt: High pressure processing technology has been adopted worldwide at the industrial level to preserve a wide variety of food products without using heat or chemical preservatives. High Pressure Processing: Technology Principles and Applications will review the basic technology principles and process parameters that govern microbial safety and product quality, an essential requirement for industrial application. This book will be of interest to scientists in the food industry, in particular to those involved in the processing of products such as meat, fish, fruits, and vegetables. The book will be equally important to food microbiologists and processing specialists in both the government and food industry. Moreover, it will be a valuable reference for authorities involved in the import and export of high pressure treated food products. Finally, this update on the science and technology of high pressure processing will be helpful to all academic, industrial, local, and state educators in their educational efforts, as well as a great resource for graduate students interested in learning about state-of-the-art technology in food engineering.

Download or read book The Causative Effects of High Hydrostatic Pressure on the Physiology and Viability of Escherichia Coli written by Paul Chilton and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Pressure Resistance and Stress Response in Escherichia Coli written by Abram Aertsen and published by . This book was released on 2004 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Investigation of Mechanisms of Inactivation of Escherichia Coli by High Hydrostatic Pressure written by Duangkamol Charoenwong and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effects of Hydrostatic Pressure on Escherichia Coli Protein Synthesis written by Gerald McMahon and published by . This book was released on 1980 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Comparative High Pressure Biology written by Philippe Sebert and published by CRC Press. This book was released on 2016-04-19 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: High pressure biology is an old, fascinating and stimulating field of research. One of the major reasons for the interest in studying high pressure is that this environmental factor also plays an important role in thermodynamics and consequently in biology. Pressure, from a biological perspective, has a bearing on all living creatures. The book pre

Download or read book Frontiers in High Pressure Biochemistry and Biophysics written by Claude Balny and published by Elsevier. This book was released on 2002-06-05 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book covering all aspects of high pressure biochemistry and biophysics of proteins. Hydrostatic pressure is a powerful tool for study of biological systems. As a thermodynamic parameter, hydrostatic pressure has been known for a century to act on biological materials in a similar, but not identical, way to temperature. However, pressure was disregarded for a long time by biochemists mainly because the basic concepts (and the thermodynamics) focused on the chemical reactions involved and because general ideas on what pressure can add to the understanding of the behaviour of proteins were lacking. In recent decades, technological progress in the field of physics has shown, along with parameters such as temperature and solvent conditions, that pressure can be used for more refined thermodynamic and kinetic descriptions of biological processes and regulation of biological systems. The effects of pressure on proteins, nucleoproteins and membranes have recently been reviewed and several proceedings books have been published.

Download or read book Extremophiles Handbook written by Koki Horikoshi and published by Springer Science & Business Media. This book was released on 2010-12-08 with total page 1277 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Extremophiles Handbook brings together the rapidly growing and often scattered information on microbial life in the whole range of extreme environments. This book will be a useful reference for finding clues to the origin of life and for exploring the biotechnology potential of these fascinating organisms.

Download or read book Metagenomics and Its Applications in Agriculture Biomedicine and Environmental Studies written by Robert W. Li and published by Nova Science Publishers. This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metagenomics is the study of microbial communities sampled directly from their natural environment, without prior culturing. DNA sequencing (or alternatively, an assay of functional properties) is applied to the culture-independent analyses of complex and diverse ("meta") populations of microbes. The rapid growth of metagenomics entails an expanded focus on microbes in a wide range of basic and applied research fields, ranging from microbiology to agriculture, biomedicine to bioenergy, and from veterinary to clinical medicine. This book is an insightful and inclusive study on metagenomics and its applications.

Download or read book Introduction to Food Engineering written by R. Paul Singh and published by Gulf Professional Publishing. This book was released on 2001-06-29 with total page 787 pages. Available in PDF, EPUB and Kindle. Book excerpt: Food engineering is a required class in food science programs, as outlined by the Institute for Food Technologists (IFT). The concepts and applications are also required for professionals in food processing and manufacturing to attain the highest standards of food safety and quality.The third edition of this successful textbook succinctly presents the engineering concepts and unit operations used in food processing, in a unique blend of principles with applications. The authors use their many years of teaching to present food engineering concepts in a logical progression that covers the standard course curriculum. Each chapter describes the application of a particular principle followed by the quantitative relationships that define the related processes, solved examples, and problems to test understanding.The subjects the authors have selected to illustrate engineering principles demonstrate the relationship of engineering to the chemistry, microbiology, nutrition and processing of foods. Topics incorporate both traditional and contemporary food processing operations.