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Effect Of Storage Temperature On The Survival Or Growth Of Listeria Monocytogenes On Whole And Fresh-Cut Produce, Juan F. Moreira Calix Nov 2019

Effect Of Storage Temperature On The Survival Or Growth Of Listeria Monocytogenes On Whole And Fresh-Cut Produce, Juan F. Moreira Calix

LSU Master's Theses

Whole and fresh-cut produce are minimally processed and, therefore susceptible to microbial contamination. This study examined the survival or growth of Listeria monocytogenes on whole, and fresh-cut produce at different storage temperatures. Fresh fruits (cantaloupes, pears, pineapples, papayas, and watermelon) and vegetables (broccoli, cauliflower, lettuce, kale, and green bell peppers) were cut into 25 g pieces and were spot inoculated with 0.5 mL (8 Log CFU/mL) of Listeria monocytogenes. Inoculated fresh-cut samples were stored at 4°C or 13°C for 6 days. To represent the outer surface of the produce, cantaloupes and green bell pepper disks (20 ...


Study Of Rheological, Chemical, And Microbiological Properties Of Chami, A Traditional Emirati Soft Chees, Aysha Othman Abdullah Al Katheeri Apr 2018

Study Of Rheological, Chemical, And Microbiological Properties Of Chami, A Traditional Emirati Soft Chees, Aysha Othman Abdullah Al Katheeri

Theses

In this work, ten Emirati Chami cheese samples were collected and analyzed to determine their chemical composition, texture, rheology, and microbiological properties. Chami cheeses showed large variations in moisture (60.9–84.1%), protein (7.5–14.6%), fat (0.5–7.8%), and ash (3.4–8.0%) contents as well as in pH (3.6–4.4), and water activity (0.977–0.999%). The variation in fat content of samples suggested that extra fat was added; this added fat was either butter or vegetable oil as indicated by the fatty acid composition. The different samples showed peaks ...


Phenotypic, Physiological And Growth Interactions Among Salmonella Serovars, Juliany Rivera Calo Dec 2013

Phenotypic, Physiological And Growth Interactions Among Salmonella Serovars, Juliany Rivera Calo

Theses and Dissertations

This thesis consists of four research parts: a literature review that covers Salmonella spp., one of the more prominent foodborne pathogens that represents a major risk to humans (chapter 1). Understanding the growth of Salmonella serovars and strains is an important basis for more in depth research. In this case we studied a) the aerobic and anaerobic growth responses of multiple strains from six different serovars, b) how the spent media from different serovars, more importantly S. Heidelberg, affect the growth of S. Typhimurium, and c) determined whether or not two different serovars undergo competitive interactions when they were grown ...


Biological Methods For Detoxification Of Corn Stover And Corn Starch Pyrolysis Liquors , Mohammad A. Khiyami Jan 2003

Biological Methods For Detoxification Of Corn Stover And Corn Starch Pyrolysis Liquors , Mohammad A. Khiyami

Retrospective Theses and Dissertations

Biological methods were developed to detoxify corn stover and corn starch pyrolysis liquors produced at 400--500°C. Prokaryotic and eukaryotic suspended cells and biofilms were employed for the detoxification process. The continuous of detoxification process was monitored by measuring the change in dissolved oxygen and pH. Total phenolic assay, change in UV absorbance spectra, GC-MS analysis and bioassay were performed to determine the detoxification. Pseudomonas putida and Streptomyces setonii biofilms, developed on Plastic Composite Supports (PCS) fixed to agitator shaft of benchtop computer controlled bioreactor, detoxified 10 and 25% (v/v) diluted corn stover and corn starch pyrolysis liquor (Des ...


The Ecology Of Listeria Monocytogenes In Ready-To-Eat (Rte) Meats , Chi Ching Sally Foong Jan 2003

The Ecology Of Listeria Monocytogenes In Ready-To-Eat (Rte) Meats , Chi Ching Sally Foong

Retrospective Theses and Dissertations

Survival and recovery of Listeria monocytogenes in the ready-to-eat (RTE) meat processing environment were studied, from environmental contamination to intervention. This pathogen survived in simulated dust using sand for more than 70 d. Longer daily survival rate and better recovery were obtained when inoculated sand samples were stored at lower temperatures with higher relative humidity levels. L. mononocytogenes survived and grew once in contact with RTE meats. No significant differences (P > 0.05) in attachment were observed for the different selected RTE meats. Desiccated cells of L. monocytogenes were not observed to go into viable but non-culturable (VBNC) state well ...


Delaying The Spoilage Of Fresh And Processed Meats , Priya Sundaram Jan 2000

Delaying The Spoilage Of Fresh And Processed Meats , Priya Sundaram

Retrospective Theses and Dissertations

Various anti-microbial treatments were studied with respect to their use for the shelf-life extension of meat and meat products. The treatments studied were bacteriocins (pediocin AcH and nisin), organic acids, immobilization, ion chelators, high pressure and irradiation. These were then compared using statistical analysis so as to identify treatment effects on the dynamics of growth of the spoilage bacteria. The experiments focused especially on exploiting the potential of pediocin AcH for this purpose;A scale-up method was developed for the purification of pediocin from 50 liters of culture;Pediocin was seen to act in combination with lactic acid on Listeria ...


Antibiotic Resistance Of Salmonella In Swine, Heidi Lea Holcomb Jan 1997

Antibiotic Resistance Of Salmonella In Swine, Heidi Lea Holcomb

Retrospective Theses and Dissertations

No abstract provided.


Survival And Growth Characteristics Of Bacteria In Irradiated Meat , Raveendran Jolarpettai Venugopal Jan 1997

Survival And Growth Characteristics Of Bacteria In Irradiated Meat , Raveendran Jolarpettai Venugopal

Retrospective Theses and Dissertations

Several key factors we investigated in order to improve the safety of foods and to better understand the survival of microorganisms when exposed to stress. Pork patties were irradiated at 0, 0.5, 1, and 2KGy, and stored at 0°C. The shelf life of these irradiated pork patties (aerobically packaged and vacuum packaged; fresh and temperature abused) were studied and predictive models were developed based on generation time and lag phase extension. Next, the physiological response of Salmonella typhimurium ATCC 14028 to media composition and pH was investigated by studying the changes in the cell membrane fatty acids, cell ...


Sensitivity Of Listeria To Irradiation In Raw Ground Meat, As Affected By Type Of Radiation, Product Temperature, Packaging Atmosphere, And Recovery Medium , Rodrigo Tarté Jan 1996

Sensitivity Of Listeria To Irradiation In Raw Ground Meat, As Affected By Type Of Radiation, Product Temperature, Packaging Atmosphere, And Recovery Medium , Rodrigo Tarté

Retrospective Theses and Dissertations

The sensitivity of five strains of Listeria to electron beam irradiation in ground pork were investigated. Ground pork was inoculated with one of five strains of Listeria and irradiated from 0 to 1.25 kGy in 0.25 kGy intervals. Listeria innocua NADC 2841 was more radiation-resistant (D10 = 0.638 kGy) than L. monocytogenes NADC 2045 Scott A (D10 = 0.447 kGy), L. monocytogenes NADC 2783 (a hamburger isolate) (D10 = 0.424 kGy), L. monocytogenes ATCC 15313 (D10 = 0.445 kGy) and L. ivanovii NADC 3518 (D10 = 0.372 kGy), when recovered on tryptic soy agar supplemented with 0.6 ...


Effect Of Heat Treatment, Irradiation And Storage Conditions On The Survival, Growth And Virulence Of Heat-Shocked Yersinia Enterocolitica In Ground Pork , Kalpana Shenoy Jan 1995

Effect Of Heat Treatment, Irradiation And Storage Conditions On The Survival, Growth And Virulence Of Heat-Shocked Yersinia Enterocolitica In Ground Pork , Kalpana Shenoy

Retrospective Theses and Dissertations

The heat shock response and thermotolerance of Yersinia enterocolitica in BHI broth and ground pork was studied. Further, the survival and growth of the heat-shocked cells following heat treatment at 55° C and stored at 4 or 25° C under air, vacuum, or modified atmosphere was also examined. Lastly, the irradiation sensitivity of the heat-shocked cells when suspended in pork and packaged either under air or vacuum was determined. As part of the research, virulence of the survivors was examined following heat treatment or irradiation;Exposure of Y. enterocolitica to 45° C for 60 mins. in BHI broth resulted in ...


Classification Of Enterococci And Their Roles In Spoilage Of Pork Products And As Sanitary Indicators In Pork Processing , Linda Marie Knudtson Jan 1992

Classification Of Enterococci And Their Roles In Spoilage Of Pork Products And As Sanitary Indicators In Pork Processing , Linda Marie Knudtson

Retrospective Theses and Dissertations

The genus Streptococcus, including the fecal streptococci, has received intensive scrutiny in recent years, resulting in a new genus Enterococcus, rearrangement of species within the genus, and addition of many new species. To clarify the roles of these bacteria in food microbiology, known strains were examined by using conventional tube tests and API Rapid Strep and MicroScan Pos ID panels. Identification schema were devised to identify 13 species of enterococci and S. bovis and S. equinus by using a minimum of supplemental tests. These schema were used for enterococcal species identification to pinpoint possible sources of fecal contamination. Enterococci were ...


Isolation And Characterization Of Unique Cholesterol-Reducing Anaerobes , Timothy Alan Freier Jan 1991

Isolation And Characterization Of Unique Cholesterol-Reducing Anaerobes , Timothy Alan Freier

Retrospective Theses and Dissertations

New media and methods were used in attempts to isolate cholesterol-reducing bacteria (CRB) that might be used to reduce the cholesterol contents of foods. Media for the enrichment and isolation of CRB were formulated, and a variety of novel sources were sampled to isolate CRB with improved properties;Stable mixed cultures of anaerobic bacteria that converted cholesterol to coprostanol were obtained from the following sources: feces from cattle, goats, horses, and humans; a marine sponge; sediments from rivers, streams, and ponds; standing water; a hog sewage lagoon; and commercial frozen pork brains. Cholesterol-reducing activity was maintained in these cultures after ...


Effects Of Polyphosphates And Heat On Selected Gram-Positive Bacteria Important In Foods , Stephen John Knabel Jan 1989

Effects Of Polyphosphates And Heat On Selected Gram-Positive Bacteria Important In Foods , Stephen John Knabel

Retrospective Theses and Dissertations

In one series of studies, a simple well-plate technique was utilized to determine the effect of various metals on the growth of microorganisms in media containing different polyphosphates. Aspergillus flavus and four Gram-positive bacteria were almost completely inhibited by media containing 1% of various alkaline polyphosphates, whereas four Gram-negative bacteria were not. Significant differences were observed between the type of polyphosphate added, the type of metal added, and the species of Gram-positive bacterium inhibited. A method for determining the amount of calcium and magnesium in water was modified to detect free Mg[superscript]2+ by replacing EDTA with phosphate. The ...


Beta-Galactosidase Activity Of Propionibacterium Shermanii, James Charles Hartley Jan 1972

Beta-Galactosidase Activity Of Propionibacterium Shermanii, James Charles Hartley

Retrospective Theses and Dissertations

No abstract provided.


The Relationships Of A Lipolytic Organism To Rancidity Of Butter, Ralph Victor Hussong Jan 1932

The Relationships Of A Lipolytic Organism To Rancidity Of Butter, Ralph Victor Hussong

Retrospective Theses and Dissertations

No abstract provided.


The Correlation Between The Organisms Found Microscopically And The Bacteriological Deterioration Of Butter , John Albert Nelson Jan 1932

The Correlation Between The Organisms Found Microscopically And The Bacteriological Deterioration Of Butter , John Albert Nelson

Retrospective Theses and Dissertations

No abstract provided.