Study of the impacts of electro-activated solutions of calcium lactate, calcium ascorbate and their equimolar mixture combined with moderate heat treatments on the spores of Bacillus cereus ATCC 14579 under model conditions and in fresh salmon

2021 ◽  
pp. 109285
Author(s):  
Pierre Emerson Cayemitte ◽  
Natela Gerliani ◽  
Philippe Raymond ◽  
Mohammed Aider
Keyword(s):  
Bacillus Cereus ◽  
Heat Treatments ◽  
Calcium Lactate ◽  
Equimolar Mixture

Altered Ability of Bacillus cereus Spores To Grow under Unfavorable Conditions (Presence of Nisin, Low Temperature, Acidic pH, Presence of NaCl) following Heat Treatment during Sporulation

2002 ◽  
Vol 65 (12) ◽  
pp. 1930-1936 ◽  
Author(s):  
CHRISTINE FAILLE ◽  
JEANNE MARIE MEMBRE ◽  
MARTINE KUBACZKA ◽  
FRANÇOISE GAVINI
Keyword(s):  
Heat Treatment ◽  
Heat Resistance ◽  
Bacillus Cereus ◽  
Lag Time ◽  
Heat Treatments ◽  
Adverse Conditions ◽  
Mild Heat ◽  
Time Interaction ◽  
Maximal Growth Rate ◽  
Adverse Environmental Conditions

The effect of thermal treatment on the heat resistance of Bacillus cereus spores and their ability to germinate and grow under more or less adverse conditions during sporulation was investigated. Spores produced by sporulating cells subjected to a mild heat treatment (at a temperature 15°C higher than the growth temperature) were more resistant to heat than were spores produced by untreated cells. Spore germination and growth (the lag time, the maximal growth rate, and the occurrence of a decrease in population) may be greatly affected by adverse environmental conditions brought about by the addition of nisin, low temperatures, acidic pHs, and, to a lesser extent, the addition of NaCl. Furthermore, heat treatments applied to sporulating cells or to mature spores induced a modification of the lag time (interaction of both treatments). Therefore, mild heat treatments applied during sporulation may affect the heat resistance of spores and the ability of these spores to germinate under adverse conditions and may thus increase the risk associated with the presence of spores in lightly processed foods.

Inhibition of Bacillus cereus by Garlic Extracts

1982 ◽  
Vol 45 (11) ◽  
pp. 1007-1009 ◽  
Author(s):  
ZAHIRA M. SALEEM ◽  
KHALAF S. Al-DELAIMY
Keyword(s):  
Antibacterial Activity ◽  
Gamma Irradiation ◽  
Bacillus Cereus ◽  
Aqueous Extract ◽  
Allium Sativum ◽  
Heating Time ◽  
Heat Treatments ◽  
Nutrient Agar ◽  
Distilled Water ◽  
Original Activity

Aqueous extract of garlic (Allium sativum, L.) was prepared from a 1:2 (wt/vol) ratio of fresh garlic bulbs to sterilize distilled water. Garlic extracts of 3%, 5% and 10% inhibited the growth of Bacillus cereus on nutrient agar plates 31.3%, 58.2% and 100%, respectively. Extracts from garlic bulbs stored at −18°C are slightly more inhibitory to the growth of B. cereus than extracts from bulbs stored at 15–35°C for 6 months. The greatest extract activity was found when garlic bulbs were extracted and left at 30°C for 4 h before filtration. When the macerate was held at 4°C, 6 h of storage were needed for the extract to reach its greatest activity. Gamma irradiation, at the dose of 570 krads, of garlic bulbs with subsequent freezing before extraction decreased the extracts original activity up to 50%. Exposing the extracts to heat treatments of 80–90°C for a total heating time of 5 min completely destroyed the antibacterial activity of the extract.

Soluble reduced nicotinamide adenine dinucleotide oxidase from Bacillus cereus T spores and vegetative cells. II. Properties

1969 ◽  
Vol 15 (11) ◽  
pp. 1313-1317 ◽  
Author(s):  
D. H. Ashton ◽  
L. C. Blankenship
Keyword(s):  
Bacillus Cereus ◽  
Nicotinamide Adenine Dinucleotide ◽  
Vegetative Cell ◽  
Thermal Inactivation ◽  
Dipicolinic Acid ◽  
Heat Treatments ◽  
Nicotinamide Adenine ◽  
Flavin Mononucleotide ◽  
Vegetative Cells ◽  
Reduced Nicotinamide Adenine Dinucleotide

Two soluble reduced nicotinamide adenine dinucleotide (NADH2) oxidases purified from extracts of Bacillus cereus T spores were compared with vegetative ceil soluble NADH2 oxidase. The minor spore component and vegetative cell soluble NADH2 oxidase reacted equally well with riboflavin or flavin mononucleotide (FMN), were inhibited by 15 mM dipicolinic acid (DPA), and possessed similar thermal inactivation characteristics at 80 °C. Activity of the major spore component was stimulated by a factor of 3.6 when riboflavin replaced FMN as the coenzyme. The major spore component was not inhibited by DPA and resisted heat treatments which inactivated vegetative cell soluble NADH2 oxidase. These observations indicate that the minor spore component and vegetative cell soluble NADH2 oxidase are identical while the major spore component is a distinct protein.

Bacillus cereus in Refrigerated Milk Submitted to Different Heat Treatments

2009 ◽  
Vol 72 (6) ◽  
pp. 1301-1305 ◽  
Author(s):  
GEORGIANA S. B. AIRES ◽  
EDUARDO H. M. WALTER ◽  
VALÉRIA C. A. JUNQUEIRA ◽  
SALVADOR M. ROIG ◽  
JOSÉ A. F. FARIA
Keyword(s):  
Bacillus Cereus ◽  
Shelf Life ◽  
Storage Period ◽  
Heat Treatments ◽  
Pasteurized Milk ◽  
Standard Plate ◽  
Plate Counts ◽  
Experimental Trials ◽  
Incubation Temperatures

The possibility of the survival, germination, and multiplication of Bacillus cereus in extended-shelf-life milk prompted research into the occurrence of the bacteria in refrigerated milk submitted to different heat treatments. Samples were submitted to ultrapasteurization (138°C for 2 s), “superpasteurization” (96°C for 13 s), and pasteurization (74°C for 15 s) and stored under refrigeration at 4 ± 2°C for up to 6 weeks. The milk was analyzed for its sensory quality and for the quantitative determination of mesophilic and psychrotrophic B. cereus in the vegetative form at incubation temperatures of 7 and 30°C, in addition to standard plate counts and psychrotrophic counts. In the three experimental trials, the psychrotrophic B. cereus counts were below the detection limit of the methodology (<10 CFU/ml) in all of the samples analyzed, independent of the heat treatment and storage period. The count of mesophilic B. cereus was restricted to samples of superpasteurized and pasteurized milk from a single trial, reaching 4.0 × 101 and 7.0 × 105 CFU/ml, respectively. Although the pasteurized milk had higher populations of mesophilic B. cereus after the second week of storage, flavor defects resulting in sensory rejection of the product did not appear before the fourth week of storage. The results of this research indicate that superpasteurization and ultrapasteurization are adequate for maintaining the product at refrigeration temperatures for 6 weeks. Pasteurized milk produced under clean conditions should have a shelf life limited to less than 2 weeks.

Inactivation of Bacillus cereus spores in milk by mild pressure and heat treatments

2004 ◽  
Vol 92 (2) ◽  
pp. 227-234 ◽  
Author(s):  
Isabelle Van Opstal ◽  
Cathérine F. Bagamboula ◽  
Suzy C.M. Vanmuysen ◽  
Elke Y. Wuytack ◽  
Chris W. Michiels
Keyword(s):  
Bacillus Cereus ◽  
Heat Treatments

Influence of Heat Treatments on Microstructures in an Fe-Co-V Alloy

1974 ◽  
Vol 32 ◽  
pp. 512-513
Author(s):  
S. Mahajan ◽  
M. R. Pinnel ◽  
J. E. Bennett
Keyword(s):  
Single Phase ◽  
Alloy Composition ◽  
Supersaturated Solid Solution ◽  
Cell Formation ◽  
Heat Treatments ◽  
Air Cooling ◽  
Iced Brine ◽  
Transmission Electron ◽  
The Matrix ◽  
Bcc Structure

The microstructural changes in an Fe-Co-V alloy (composition by wt.%: 2.97 V, 48.70 Co, 47.34 Fe and balance impurities, such as C, P and Ni) resulting from different heat treatments have been evaluated by optical metallography and transmission electron microscopy. Results indicate that, on air cooling or quenching into iced-brine from the high temperature single phase ϒ (fcc) field, vanadium can be retained in a supersaturated solid solution (α2) which has bcc structure. For the range of cooling rates employed, a portion of the material appears to undergo the γ-α2 transformation massively and the remainder martensitically. Figure 1 shows dislocation topology in a region that may have transformed martensitically. Dislocations are homogeneously distributed throughout the matrix, and there is no evidence for cell formation. The majority of the dislocations project along the projections of <111> vectors onto the (111) plane, implying that they are predominantly of screw character.

Microstructural Development in Nb-Ti Multifilamentary Superconductors During Processing

1985 ◽  
Vol 43 ◽  
pp. 190-191
Author(s):  
A. W. West
Keyword(s):  
Heat Treatment ◽  
Critical Current Density ◽  
Copper Matrix ◽  
Wire Drawing ◽  
Heat Treatments ◽  
Microstructural Development ◽  
Final Size ◽  
Density Values ◽  
The Wire ◽  
Multifilamentary Superconductors

The influence of the filament microstructure on the critical current density values, Jc, of Nb-Ti multifilamentary superconducting composites has been well documented. However the development of these microstructures during composite processing is still under investigation.During manufacture, the multifilamentary composite is given several heat treatments interspersed in the wire-drawing schedule. Typically, these heat treatments are for 5 to 80 hours at temperatures between 523 and 573K. A short heat treatment of approximately 3 hours at 573K is usually given to the wire at final size. Originally this heat treatment was given to soften the copper matrix, but recent work has shown that it can markedly change both the Jc value and microstructure of the composite.

Microstructure Development in a High Current Density NbTi Superconducting Composite

1985 ◽  
Vol 43 ◽  
pp. 186-189
Author(s):  
P. J. Lee ◽  
D. C. Larbalestier
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Cold Drawing ◽  
Heat Treatments ◽  
Grain Structure ◽  
Fine Grain ◽  
Boundary Film ◽  
Quantitative Basis ◽  
Cold Worked ◽  
Very High

Several features of the metallurgy of superconducting composites of Nb-Ti in a Cu matrix are of interest. The cold drawing strains are generally of order 8-10, producing a very fine grain structure of diameter 30-50 nm. Heat treatments of as little as 3 hours at 300 C (∼ 0.27 TM) produce a thin (1-3 nm) Ti-rich grain boundary film, the precipitate later growing out at triple points to 50-100 nm dia. Further plastic deformation of these larger a-Ti precipitates by strains of 3-4 produces an elongated ribbon morphology (of order 3 x 50 nm in transverse section) and it is the thickness and separation of these precipitates which are believed to control the superconducting properties. The present paper describes initial attempts to put our understanding of the metallurgy of these heavily cold-worked composites on a quantitative basis. The composite studied was fabricated in our own laboratory, using six intermediate heat treatments. This process enabled very high critical current density (Jc) values to be obtained. Samples were cut from the composite at many processing stages and a report of the structure of a number of these samples is made here.

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