Thermal Inactivation of Salmonella spp., Salmonella typhimurium DT104, and Escherichia coli 0157:H7 in Ground Beef

ABSTRACT: In 19.1% fat ground beef, Escherichia coli 0157:H7 was less heat- resistant at ≥58°C than the Salmonella typhimurium DT104 and Salmonella senftenberg , but at 55°C the D value was similar to DT104 strains and higher than an eight-strain Salmonella cocktail. Inactivation of E. coli 0157:H7 was more temperature-dependent than the cocktail and DT104 strains. E. coli and DT104 strains were more heat-resistant in beef containing 19% fat than 4.8% fat. The cocktail was more thermally stable in stationary as compared to log phase. Freezing of inoculated raw meat decreased heat resistance of the cocktail. The pathogenic strain, growth phase of the organism, state of the meat (fresh or frozen) and meat composition must be considered when designing protocols to verify thermal processes.     

ELISA with enzyme amplification for sensitive detection of staphylococcal enterotoxins in food

A highly sensitive amplified ELISA in microtitre plates for the detection of staphylococcal enterotoxins compared favourably with a commercially available kit. The amplified ELISA demonstrated a reduced effect of the food sample matrix and an ease of handling. Using the amplified ELISA, the influence of different parameters (pH, time, temperature, re-extraction, concentration procedure) on the recovery efficiency and assay reliability was tested on foods implicated in food poisoning outbreaks as well as on spiked foods containing low levels of enterotoxins.     

Controlling and monitoring interfacial reactions in composites of azidosilane modified glass filled polyethylene

Model composites of spherical glass particles dispersed in a matrix of high density polyethylene were prepared with controlled variations in the interfacial structure. Dynamic-mechanical measurements of the composites in the melt state were recorded. The physical properties are found to relate to the morphology, bonding, reactivity, and other characteristics of the interfacial region which can be controlled by the applied chemistry. The interfacial reactions can be monitored in-sity by dynamic-mechanical analysis and differential scanning calorimetry.     

Pilot-Plant Proof-of-Concept for Integrated, Countercurrent, Two-Stage, Enzyme-Assisted Aqueous Extraction of Soybeans

Proof-of-concept for integrated, countercurrent, two-stage, enzyme-assisted aqueous extraction processing of soybeans was demonstrated on a pilot-plant scale (75 kg extruded flaked soybeans) where the protease used to demulsify the cream was recycled into upstream extraction stages. Oil, protein, and solids extraction yields of 98.0 ± 0.5%, 96.5 ± 0.4%, and 86.8 ± 0.5% were achieved by using the integrated countercurrent process. A three-phase horizontal decanter centrifuge efficiently separated the solids from the two liquid fractions (skim and cream). Fine separation between the two liquid fractions was important to reducing the volume of skim contaminating the cream fraction, thereby reducing the amount of enzyme used for cream demulsification and subsequent extraction. We were able to reduce enzyme use when moving from the laboratory to the pilot-plant scale, which reduced the degree of protein hydrolysis and improved cream demulsification. Enzyme-catalyzed cream demulsification was 91.6% efficient and 93.0% free oil recovery from cream was achieved by using the integrated approach.     

Berechnung der Wirbelstromdichten und-kräfte in der Umgebung großer supraleitender Spulen für den magnetischen Einschluß bei der Kernfusion

Übersicht Um die Betriebssicherheit großer supraleitender Magnetsysteme für die Kernfusionsforschung zu gewährleisten, muß die im Magnetsystem gespeicherte Energie schnell entladen werden können. Durch die veränderlichen großvolumigen Magnetfelder werden in benachbarten leitfähigen Strukturen durch Induktion hohe Wirbelströme hervorgerufen. Durch sie treten dort elektromagnetische Kräfte. auf, die einzelne Komponenten mechanisch überlasten können. Zur Berechnung dieser Kräfte wurde eine einfache numerischanalytische Methode entwickelt, die im folgenden vorgestellt und mit Finite-Elemente-Verfahren verglichen wird.

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Calculation of eddy current densities and forces around large superconducting coils for nuclear fusion

Contents The reliable operation of the superconducting magnet systems used for the magnetic confinement in nuclear fusion research requires the ability of a fast discharge of the stored magnetic energy. The corresponding magnetic field variation gives rise to high eddy currents by inductive coupling with surrounding conductive components. The eddy current forces can lead to a mechanical overload of some of these components. A simple numerical-analytical method was developed in order to calculate these forces. This method is presented and compared with the Finite Element Method.

     

Characteristics of Oil and Skim in Enzyme-Assisted Aqueous Extraction of Soybeans

The economic viability of enzyme-assisted aqueous extraction processing (EAEP) of soybeans depends on properties and potential applications of all fractions (skim and insolubles as well as oil). EAEP oil contained lower free fatty acid, phosphorus, and tocopherol contents, similar unsaponifiable matter levels, and higher degrees of oxidation (peroxide and p-anisidine values) than hexane-extracted oil. The phospholipid profile of EAEP fractions was mainly composed of phosphatidic acid, followed by phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine. Most of phospholipids were present in the skim, except for phosphatidic acid, which was the major phospholipid in the cream fraction. Skim and cream contained 55 and 3 % of the soluble carbohydrates in the original extruded flakes, respectively. Soluble carbohydrates of the skim were mainly composed of stachyose (5.8 ± 0.8 mg/mL) and sucrose (9.9 ± 0.8 mg/mL), which were hydrolyzed into glucose, galactose, and fructose after addition of α-galactosidase. Skim and cream peptides contained <20 kDa MW molecules. About 71 % of the skim peptides were <20 kDa MW, with 49 % being <1.35 kDa MW, 22 % being 17–1.35 kDa MW, and 29 % being 44–670 kDa MW. Skim protein and carbohydrate contents make this fraction suitable for replacing water in ethanol fermentations, thereby improving the fermentation rate/production and the nutritional quality of distiller’s dried grains with solubles.     

Reexamination of the Ergothioneine Biosynthetic Methyltransferase EgtD from Mycobacterium tuberculosis as a Protein Kinase Substrate

Ergothioneine has emerged as a crucial cytoprotectant in the pathogenic lifestyle of Mycobacterium tuberculosis. Production of this antioxidant from primary metabolites may be regulated by phosphorylation of Thr213 in the active site of the methyltransferase EgtD. The structure of mycobacterial EgtD suggests that this post-translational modification would require a large-scale change in conformation to make the active-site residue accessible to a protein kinase. In this report, we show that, under in vitro conditions, EgtD is not a substrate of protein kinase PknD.