Inhibition of Listeria monocytogenes , Escherichia coli O157:H7, and Micrococcus luteus by Linear Furanocoumarins in Culture Media.

The linear furanocoumarins psoralen, 5-methoxypsoralen (5-MOP), and 8-methoxypsoralen (8-MOP) were tested as antimicrobial agents against Listeria monocytogenes , Escherichia coli O157:H7 and Micrococcus luteus . The linear furanocoumarins were activated with UV light at 365 nm for 60 min. MICs of these furanocoumarins in tryptic soy broth supplemented with 0.

Inhibition of Listeria monocytogenes , Escherichia coli O157:H7, and Micrococcus luteus by Linear Furanocoumarins in a Model Food System.

Lime peel, parsnip, lemon peel, dried parsley flakes, cold pressed lime oil, and distilled lime oil samples were analyzed for the presence and concentration of the linear furanocoumarins (LFs) psoralen, 5-methoxypsoralen (5- MOP), and 8-methoxypsoralen (8-MOP) by thin layer chromatography and gas chromatography mass spectrometry. Cold-pressed lime oil had the highest LF content (psoralen, 67 ± 29 μg/ml, 5-MOP, 1,634 ± 62 μg/ml, and 8-MOP, 44 ± 2 μg/ml). The antimicrobial effectiveness of LFs against Listeria monocytogenes , Escherichia coli O157:H7, and Micrococcus luteus was tested in a model food system consisting of a slurry of 25% commercial "garden vegetables" baby food in 0.

Isolation and Identification of Adherent Gram-Negative Microorganisms from Four Meat-Processing Facilities.

Biofilms are described as a matrix of microorganisms which have adhered to and colonized a surface. Once formed, biofilms are difficult to remove and may be a source of contamination in food-processing environments. In this study, stainless-steel chips were fixed to surfaces adjacent to food-contact surfaces and cast-iron chips were suspended in the floor drains of four meat-processing plants.

Growth Media and Surface Conditioning Influence the Adherence of Pseudomonas fragi , Salmonella typhimurium , and Listeria monocytogenes Cells to Stainless Steel.

Microorganisms have been shown to adhere to food-contact surfaces and may provide a route for the contamination of processed food. To better understand this phenomenon, the effects of growth media and surface conditioning on the adherence of Pseudomonas fragi , Salmonella typhimurium and Listeria monocytogenes cells to stainless steel were studied. The microorganisms were grown in tryptic soy broth (TSB), 1% reconstituted skim milk (RSM) and RSM with 1% sucrose (RSM + S).

Biofilm Formation by Listeria monocytogenes Utilizes a Primary Colonizing Microorganism in Flowing Systems.

Listeria monocytogenes serotype 3a and Pseudomonas fragi ATCC 4973 were examined for attachment capability and biofilm development on glass coverslips under flowing systems. Tryptic soy broth supplemented with yeast extract was the growth medium. A continuous flow slide chamber was developed for in situ observations using phase-contrast microscopy.

Potential for the Low-Temperature Pasteurization of Dairy Fluids Using Membrane Processing.

Raw milk, reconstituted skim milk, skim milk, sweet whey, and acid whey were membrane processed on different units from several manufacturers using various membranes with pore sizes ranging from nanofiltration through microfiltration. The bulk fluids were inoculated with either Staphylococcus aureus 196E, Salmonella typhimurium var. Hillfarm, and/or Pseudomonas fragi 4973.

Evaluation of Selected Sanitizers to Control Bacteria in a Simulated Sweet Water Coolant System .

Three types of sanitizers commonly used in dairy processing plants were evaluated at varying concentrations and at 25 and 4°C for their ability to control potential spoilage and pathogenic bacteria in water. Test organisms included Pseudomonas fluorescens , Staphylococcus haemolyticus , and Bacillus spp. These had been isolated from samples of sweet water coolants collected in a previous national survey in grade A dairy plants.

Scanning Electron Microscopic Examination of Yersinia enterocolitica Attached to Stainless Steel at Selected Temperatures and pH values .

Attachment of Yersinia enterocolitica to stainless steel surfaces at 35, 21, and 10°C was investigated using scanning electron microscopy (SEM). Cells adhered at all three temperatures, but, in general, the greatest number of adhered cells were observed at pH 8 and 21°C. Multi-flagellated cells were noted under these growth conditions.

Survival of Salmonellae in Refrigerated, Agitated Water and Water/Glycol Mixtures .

Survival of Salmonella typhimurium in refrigerated water and a 30:70 mixture of ethylene glycol and water was studied. Survival was determined with an MPN procedure using 333 ml of the cooling medium. Initial populations were determined by spread plating 1 ml of sample on 3 plates of XLD.

Scanning Electron Microscopic Study on Some Effects of Sodium Hypochlorite on Attachment of Bacteria to Stainless Steel .

Scanning Electron Microscopy (SEM) was used to demonstrate the effects of rinsing with water and various concentrations of sodium hypochlorite (NaOCl) on extracellular attachment fibers of Pseudomonas fragi (ATCC 4793), Salmonella montevideo , and Bacillus cereus (F4165/75) attached to stainless steel chips. Results indicated that use of a water rinse before sanitization with NaOCl was not sufficient to eliminate attached microorganisms and debris.

Composition and Microbiology of Some Native Alaskan Preserved Foods.

Ten samples of native Alaskan processed or partially processed fish and fermenled whale meat were obtained from three of five native Alaskan villages visited in three different geographical areas of the state. Native Alaskan methods of processing/preserving the fish were observed. Samples were analyzed for composition and microbiologically for anaerobic bacteria.

Recipe Hazard Analysis - RHAS - A Systematic Approach to Analyzing Potential Hazards in a Recipe for Food Preparation/Preservation .

A systematic approach to analyzing food preservation - food preparation recipes for potential hazards is presented. The method is based on the Hazard Analysis Critical Control Point (HACCP) concept developed by the food processing industry for identifying potential hazards in processing. The Recipe Hazard Analysis System (RHAS) is used to identify potential hazards in several recipes.