Food Microbiology Commons^™

Evaluation Of Potential Surrogates For Listeria Monocytogenes In Fresh Citrus-Specific Validation Studies, Kimiko Grace Casuga

Master's Theses

The FSMA Produce Safety Rule (PSR) requires citrus packers to more closely assess, manage, and monitor food safety risks. Although there have been no foodborne illness outbreaks and only one recall in fresh citrus, the risk of pathogens coming in on the fruit and cross contamination during washing still exists. Packhouses have dynamic washing systems and in-plant validations may be the only way to demonstrate compliance with the PSR. In-plant validations use surrogates in place of pathogens, and none have been identified or validated for citrus. The aim of this research was to identify a surrogate for use in fresh …

Survival And Inactivation Of Salmonella Enterica And Human Norovirus On Consumer Contact Surfaces, Dorra Simmons

LSU Doctoral Dissertations

Salmonella enterica and human norovirus (HuNoV) are the leading cause of bacterial and viral gastroenteritis worldwide, respectively. One of the most important transmission routes of these pathogens is contaminated surfaces. In this study, we investigated the survival and the disinfection of Salmonella enterica serovar Typhimurium (S. Typhimurium) and HuNoV on selected consumer contact surfaces.

In the case of S. Typhimurium, formica laminate, stainless steel, and plastic cutting board surfaces were inoculated with different microbial loads of cells collected at log (6 h), stationary (24 h), or LTS (14 days) phases. The disinfection efficacy of two disinfectants (sodium hypochlorite or …

Heat, Acid And Osmotic Stress Tolerance Of Leuconostoc Mesenteroides As Influenced By Prior Exposure To Various Mild Stress Conditions, Ingrid C. Osorio Rodriguez

LSU Master's Theses

The importance of Leuconostoc mesenteroides is recognized for its contribution to taste in cultured dairy products. It has been cited for its potential role as a probiotic. Consumer demand exists for new dairy products with health benefits. In the manufacture of probiotic-products survival of Leuconostoc mesenteroides would depend on its ability to tolerate challenging processing and storage conditions. Improved viability by prior exposure to mild stresses can increase stress tolerance toward a more severe stress. Furthermore, it can result in cross-protection due to connection of several proteins in response to stresses. Objective was to evaluate the effect of prior …

The Survival Of Various Pathogenic Organisms In Fats And Oils, Kelsey Ellen Lamb

Theses and Dissertations--Animal and Food Sciences

The research within this thesis sought to determine the ability of various animal derived fats and plant derived oils to support the survival of several pathogenic cocktails over a multitude of storage times. The Salmonella study explored the survival rate of a four strain Salmonella cocktail in beef tallow, pig lard, duck fat, coconut oil, and extra virgin olive oil over seven days at 26˚C and 37˚C storage. The animal fats and the coconut oil supported the survival of the bacteria until the conclusion of the study. The Shiga-toxin producing Escherichia coli study explored the survival rate of a five …

Evidence Of Transmission Of Escherichia Coli O157:H7 To The Tissues Or Phyllo-Plane Of Wheat, From Contaminated Soil, Seeds Or Water, Bismarck Antonio Martinez

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Escherichia coli O157:H7 is a human pathogen that can cause a wide spectrum of disease symptoms, such as bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). Escherichia coli O157:H7 illness are mainly associated with undercooked beef; however, in recent years outbreaks have been linked to fresh produce such as spinach, lettuce, and sprouts. In 2009, flour was implicated as a contamination source in the consumption of raw cookie dough resulting in 77 illness-cases. The objective of this research was to determine the possible route of transmission of E. coli O157:H7 into the phyllo-plane of wheat using contaminated seed, soil …

1% Calcium Chloride Treatment In Combination With Gamma Irradiation Improves Microbial And Physicochemical Properties Of Diced Tomatoes, Anuradha Prakash, Pei-Chen Chen, Richard L. Pilling, Nicole Johnson, Denise Foley

Food Science Faculty Articles and Research

The purpose of this study was to determine the effect of a combination of a 1% calcium chloride dip with low dose irradiation on microbial populations, and biochemical and physical properties, of fresh diced tomatoes during a two-week storage period. Vine tomatoes at the light-red stage (trial 1) and Celebrity tomatoes at the table ripe stage (trial 2) were diced, dipped in 1% CaCl2, and irradiated at 1 kGy from a Co-60 source. Tomatoes were also contaminated with cocktail of nalidixic-acid resistant Salmonella strains (S. Poona, S. Hartford, S. Gaminara, S. Michigan, and S. Montevideo) and subjected to gamma irradiation. …

Irradiation D Values Of Salmonella Spp. In Diced Tomatoes Dipped In 1% Calcium Chloride, Anuradha Prakash, Nicole Johnson, Denise Foley

Food Science Faculty Articles and Research

Outbreaks of salmonellosis have been associated with eating raw domestic tomatoes. In this study, we examined the efficiency of combined irradiation and a 1% calcium chloride dip to reduce the population of Salmonella enterica strains on diced tomatoes. Tomatoes were contaminated with nalidixic acid-resistant strains of S. Hartford, S. Montevideo, or a mixture of 5 strains (S. Hartford, S. Montevideo, S. Poona, S. Michigan, S. Gaminara). We irradiated tomatoes at various doses up to 0.9 kGy from an electron beam source to conduct a D-value study (decimal reduction time required to eliminate 90% of the organism). Surviving Salmonella populations were …

Survival Of Lactobacillus Acidophilus And Bifidobacteria Bifidum In Ice Cream For Use As A Probiotic Food, Sharareh Hekmat

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Ice cream mix (12% fat, 11% milk solids nonfat, 12.5% sugar, and 4.5% corn syrup solids) was fermented with Lactobacillus acidophilus and Bifidobacterium bifidum. Half of the mix was heat treated at 82°C for 30 minutes and cooled to 40-41°C. The other half was warmed to 40-41°C and inoculated with the starter cultures. Both were made into ice cream and stored at -29°C. Survival of L. acidophilus and B. bifidum and of ẞ-galactosidase activity were monitored during 17 weeks of frozen storage. Reinforced clostridial medium was used to enumerate culture bacteria. Colony counts, after fermentation, for both L. acidophilus …