Conjugated linoleic acid content and organoleptic attributes of fermented milk products produced with probiotic bacteria.

The effect of probiotic bacteria on the formation of conjugated linoleic acid (CLA), microbial growth, and organoleptic attributes (acidity, texture, and flavor) of fermented milk products was determined. Four probiotic bacteria, Lactobacillus rhamnosus, Propionibacterium freudenreichii subsp. shermanii 56, P.

Effect of gas environment and sorbate addition on flavor characteristics of irradiated apple cider during storage.

Apple cider, with (0.1%) and without potassium sorbate, was packaged in polystyrene containers and exposed to three different gas environments: oxygen flush, nitrogen flush, and atmospheric air. To evaluate the effects of irradiation (2 kGy) and storage on flavor and microbial quality, these irradiated apple cider samples were compared to a control, unirradiated sample exposed to atmospheric air.

Inactivation of Escherichia coli O157:H7 and other naturally occurring microorganisms in apple cider by electron beam irradiation.

Two Escherichia coli O157:H7 strains, SEA 13 B88 gfp 73ec and B6-914 gfp 90ec, together with two bacteria, three yeasts, and two molds that were randomly selected from a collection of microorganisms found on apples or in apple cider, were inoculated into apple cider and subjected to electron beam irradiation at several doses between 0.0 and 2.3 kGy at the Iowa State University Linear Accelerator Facility.

Effects of processing treatment and sorbate addition on the flavor characteristics of apple cider.

Processing treatments used to produce a microbiologically "safe" apple cider were evaluated to determine the impact of these treatments on the overall flavor characteristics. Apple cider with (0.1%) and without (0%) potassium sorbate was subjected to four processing treatments: untreated, irradiated at 2 kGy, irradiated at 4 kGy, and pasteurized.

Enhanced Bacteriocin Production by Propionibacterium thoenii in Fed-Batch Fermentation .

Synthesis of the bacteriocin propionicin PLG-1 as well as culture growth and organic acid production by Propionibacterium thaenii P127 were followed in fed-batch fermentations conducted for 504 h in a sodium lactate broth. Average concentrations of viable cells were higher in two small-scale fed-batch fermentations than in batch fermentations: 2.2 × 10 cells per ml versus 3.

Improvement of Detection and Production of Propionicin PLG-1, a Bacteriocin Produced by Propionibacterium thoenii .

Propionibacterium thoenii P127 produces propionicin PLG-1 in liquid culture at relatively low concentrations and slow production rates. The goal of this study was to increase the sensitivity and reproducibility of the standard well-diffusion assay for bacteriocin activity as well as to improve production of propionicin PLG-1 under controlled conditions in a fermenter. Several conditions were varied in the well-diffusion assay.

Long-Term Storage Stability of the Bacteriocin Propionicin PLG-1 Produced by Propionibacterium thoenii and Potential as a Food Preservative .

Propionicin PLG-1, a bacteriocin produced by Propionibacterium thoenii strain P127, was tested for characteristics that could determine its usefulness as a food preservative: long-term storage stability and effectiveness in a food model system. Partially purified propionicin PLG-1 samples, lyophilized and nonlyophilized, were stored at 25, 4, and -20°C. Bacteriocin activity increased by as much as 200% over the first 10 days of storage in nonlyophilized samples stored at 25 or 4°C.

Survey of Propionibacteria for Ability to Produce Propionic and Acetic Acids.

Ninety strains of Propionibacterium were screened for their ability to lower the pH of maltose broths. Strains attaining a pH <5 in enriched maltose broth consisted of 12 strains of Propionibacterium acidipropionici , 2 of Propionibacterium jensenii , and 3 of Propionibacterium thoenii . These 17 strains were further tested for their ability to produce propionic acid on maltose, lactose, lactate, and starch and their ability to produce propionic acid on various concentrations of maltose and lactate between 0.

Optimization of Banana Juice Fermentation for the Production of Microbial Oil.

Apiotrichum curvatum ATCC 20509 (formerly Candida curvata D), a lipid-accumulating yeast, was grown in banana juice. The optimum conditions for biomass production in shake flasks were 30 degrees C growth temperature, efficient aeration, a juice concentration of 25%, and preliminary heat treatment at less than sterilization conditions. Under controlled conditions in a fermentor, 20% banana juice was optimum.

Fermentation of Bananas and Other Food Wastes to Produce Microbial Lipid.

Candida curvata D, a lipid-accumulating yeast, was grown on a variety of carbohydrate-rich waste materials. C. curvata lacks the necessary enzymes to grow well on cellulosic materials, such as corncobs and oat hulls, but it grew well on materials rich in sugar, such as molasses and ripe bananas.

Preservation of High-Moisture Corn by Microbial Fermentation.

High-moisture corn samples (27% moisture) were inoculated with Lactobacillus plantarum and/or Propionibacterium shermanii and stored in sealed containers or under carbon dioxide atmosphere for 60 d at 26°C. Growth of the inoculated organisms was observed in the corn, and the final pH of inoculated samples was significantly lower than the final pH of uninoculated samples. Mold growth was prevented in all samples, and the initial yeast population was drastically reduced in those samples inoculated with P.

Survey of Commercially Available Cheese for Enterotoxigenic Escherichia coli .

Seventy-eight commercial cheese samples were tested for the presence of Escherichia coli . None of the 136 E. coli isolates obtained produced either heat-labile or heat-stable enterotoxin, as measured in standard assays.

Enterotoxin Production in Milk by Enterotoxigenic Escherichia coli .

Three enterotoxigenic strains and one nonenterotoxigenic strain of Escherichia coli were grown in milk at an initial pH of 6.5 to 8.5.

Production of Bacillus cereus Enterotoxin in Defined Media in Fermenter-Grown Cultures.

Enterotoxin, measured in capillary permeability factor (CPF) units, was produced by cultures of Bacillus cereus growing in defined media containing glucose, basal salts, and amino acids under controlled conditions in a small fermenter.