Gamma Radiation Inactivation of Enterococci

1990 ◽  
Vol 53 (4) ◽  
pp. 302-305 ◽  
Author(s):  
C. N. HUHTANEN
Keyword(s):  
Gamma Radiation ◽  
Enterococcus Faecium ◽  
Survival Curves ◽  
Radiation Inactivation ◽  
Non Linear ◽  
D Values ◽  
Linear Trends

Radiation survival curves were determined for 7 strains of Enterococcus faecium, 10 strains of E. faecalis, and 8 strains of the proteolytic variety of E. faecalis. The D values (i.e. the doses giving 90% reduction of viable counts) ranged from 5.0–47 kGy for the E. faecium strains, 3.5–21 kGy for the E. faecalis strains, and 3.0–4.5 kGy for the proteolytic variants of E. faecalis. The survival curves were linear for most strains but some exhibited significant non-linear trends.

scholarly journals Survival and mutant production induced by mutagenic agents in Metarhizium anisopliae

1995 ◽  
Vol 52 (3) ◽  
pp. 548-554 ◽  
Author(s):  
V. Kava - Cordeiro ◽  
E.A. Luna - Alves - Lima ◽  
J.L. Azevedo
Keyword(s):  
Gamma Radiation ◽  
Ultraviolet Light ◽  
Metarhizium Anisopliae ◽  
Entomopathogenic Fungus ◽  
Nitrous Acid ◽  
Wild Strain ◽  
Wild Type ◽  
Survival Curves ◽  
Auxotrophic Mutants ◽  
Morphological Mutants

A wild strain of Metarhizium anisopliae, an entomopathogenic fungus, was submitted to three mutagenic agents: gamma radiation, ultraviolet light and nitrous acid. Survival curves were obtained and mutants were selected using different mutagenic doses which gave 1 to 5% survival. Morphological and auxotrophic mutants were isolated. Morphological mutants were grouped in a class with yellow conidia and other with pale vinaceous conidia as opposed to the green wild type conidia. Auxotrophic mutants had requirements for vitamin and aminoacid biosynthesis. More than 58% of the total auxotrophk mutants required proline/aipnine. Gamma radiation showed to be the most efficient mutagenic agent giving 0.2% of auxotrophk mutants followed by ultraviolet light (0.12%) and nitrous acid (0.06%).The conidial colour and auxotrophk mutants isolated until now from M. anisopliae were reviewed.

Modeling Penicillium expansum Resistance to Thermal and Chlorine Treatments

2009 ◽  
Vol 72 (12) ◽  
pp. 2618-2622 ◽  
Author(s):  
BEATRIZ C. M. SALOMÃO ◽  
JOHN J. CHUREY ◽  
GLÁUCIA M. F. ARAGÃO ◽  
RANDY W. WOROBO
Keyword(s):  
Apple Juice ◽  
Weibull Model ◽  
Superior Performance ◽  
Penicillium Expansum ◽  
Heat Inactivation ◽  
Survival Curves ◽  
Biphasic Model ◽  
Log Reduction ◽  
Weibull Models ◽  
D Values

Apples and apple products are excellent substrates for Penicillium expansum to produce patulin. In an attempt to avoid excessive levels of patulin, limiting or reducing P. expansum contamination levels on apples designated for storage in packinghouses and/or during apple juice processing is critical. The aim of this work was (i) to determine the thermal resistance of P. expansum spores in apple juice, comparing the abilities of the Bigelow and Weibull models to describe the survival curves and (ii) to determine the inactivation of P. expansum spores in aqueous chlorine solutions at varying concentrations of chlorine solutions, comparing the abilities of the biphasic and Weibull models to fit the survival curves. The results showed that the Bigelow and Weibull models were similar for describing the heat inactivation data, because the survival curves were almost linear. In this case, the concept of D- and z-values could be used, and the D-values obtained were 10.68, 6.64, 3.32, 1.14, and 0.61 min at 50, 52, 54, 56, and 60°C, respectively, while the z-value was determined to be 7.57°C. For the chlorine treatments, although the biphasic model gave a slightly superior performance, the Weibull model was selected, considering the parsimony principle, because it has fewer parameters than the biphasic model has. In conclusion, the typical pasteurization regimen used for refrigerated apple juice (71°C for 6 s) is capable of achieving a 6-log reduction of P. expansum spores.

scholarly journals How to deal with non-linear pathways towards energy futures

2019 ◽  
Vol 28 (3) ◽  
pp. 20-26
Author(s):  
Stefan Vögele ◽  
Witold-Roger Poganietz ◽  
Philip Mayer
Keyword(s):  
Policy Advice ◽  
Linear Extrapolation ◽  
Energy Futures ◽  
The Past ◽  
Non Linear ◽  
Simplifying Assumptions ◽  
Novel Approaches ◽  
The Creation ◽  
Linear Trends

Energy scenarios currently in use for policy advice are based on a number of simplifying assumptions. This includes, in particular, the linear extrapolation of trends. However, this approach ignores the fact that central variables were highly dynamic in the past. For an assessment of energy futures and the specification of measures, novel approaches are necessary which can implement non-linear trends. In this paper, we show how cross-impact balance (CIB) analysis can be applied to map dynamic trends. Using a small CIB model, we highlight the need for novel approaches in the creation and evaluation of energy futures and the possible contribution of CIB analysis.

Effect of Using Milk as a Heating Menstruum on the Apparent Heat Resistance of Bacillus stearothermophilus Spores1

1977 ◽  
Vol 40 (4) ◽  
pp. 228-231 ◽  
Author(s):  
J. L. MAYOU ◽  
J. J. JEZESKI
Keyword(s):  
Heat Resistance ◽  
Bacillus Stearothermophilus ◽  
Survival Curves ◽  
Ph Range ◽  
D Values ◽  
D Value

Heat resistance at 121.1 C (250 F) of Bacillus stearothermophilus spores was studied using two heating menstrua. D values of 3.8 and 3.5 min were obtained when spores were heated in 0.01 M PO4 buffer, pH 6.5, and in skimmilk, pH 6.5, respectively. With buffer as a heating menstruum. increasing the pH from 6.5 to 7.2 resulted in an increase in the D value from 3.8 to 4.1 min. When the pH of skimmilk was increased from 6.5 to 7.2, D values increased from 3.5 to 5.2 min. Skimmilk as a component of the enumeration medium inhibited germination and/or outgrowth of B. stearothermophilus spores; however, this inhibition was not influenced over the pH range of 6.0 to 7.2. Addition of 10% skimmilk, pH 6.5, to the medium for enumeration of spores heated in buffer at pH 6.5 or 7.2, in each instance reduced the number of spores that could be recovered but did not change the slopes of survival curves.

scholarly journals Gamma irradiation in the control of pathogenic bacteria in refrigerated ground chicken meat

2000 ◽  
Vol 57 (3) ◽  
pp. 389-394 ◽  
Author(s):  
Marta Helena Filet Spoto ◽  
Cláudio Rosa Gallo ◽  
André Ricardo Alcarde ◽  
Maria Sílvia do Amaral Gurgel ◽  
Lucimara Blumer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Radiation Dose ◽  
Gamma Radiation ◽  
Salmonella Typhimurium ◽  
Gamma Irradiation ◽  
Pathogenic Bacteria ◽  
Chicken Meat ◽  
Chicken Breast ◽  
D Values

This work evaluated the effect of gamma radiation on reducting the population of Staphylococcus aureus, Escherichia coli and Salmonella typhimurium in ground chicken breast stored under refrigeration. The experiment included a control and 4 doses of gamma radiation (2.0, 4.0, 6.0 and 8.0 kGy) along with 5 periods of storage under refrigeration (1, 7, 14, 21 and 28 days). Samples of ground chicken breast were inoculated with Staphylococcus aureus (ATCC 14458), Escherichia coli (ATCC 11105) and Salmonella typhimurium (ATCC 0626), irradiated at temperatures between 4 and 8°C and stored under refrigeration (5°C) for 28 days. The increased radiation dose and period of storage under refrigeration caused a reduction of Staphylococcus aureus, Escherichia coli and Salmonella typhimurium populations in the ground chicken breast. Mean radiation D values determined for Staphylococcus aureus and Escherichia coli were 0.41 and 0.72 kGy, respectively. Gamma irradiation was an effective treatment for chicken meat conservation because the radiation dose of 6.0 kGy kept the ground chicken breast within the microbiological limits established by the Brazilian legislation, for up to 28 days under refrigeration.

Evaluating Pediococcus acidilactici and Enterococcus faecium NRRL B-2354 as Thermal Surrogate Microorganisms for Salmonella for In-Plant Validation Studies of Low-Moisture Pet Food Products

2015 ◽  
Vol 78 (5) ◽  
pp. 934-939 ◽  
Author(s):  
ERDOGAN CEYLAN ◽  
DERRICK A. BAUTISTA
Keyword(s):  
Enterococcus Faecium ◽  
Thermal Inactivation ◽  
Food Product ◽  
Food Products ◽  
Pediococcus Acidilactici ◽  
Pet Food ◽  
Death Time ◽  
Salmonella Serovars ◽  
D Values ◽  
Thermal Death Time

Pediococcus acidilactici ATCC 8042 and Enterococcus faecium NRRL B-2354 were investigated as potential surrogates for Salmonella serovars using thermal death time kinetics in products such as dry pet foods. The D-values of P. acidilactici ATCC 8042, E. faecium NRRL B-2354, and a cocktail of seven Salmonella serovars associated with low-moisture products were determined in a preservative-free dry pet food product at moisture levels of 9.1, 17.9, and 27.0% and heated between 76.7 and 87.8°C. The D-values were calculated by least squares linear regression. The D-values of P. acidilactici ATCC 8042 were higher than those for the Salmonella serovar cocktail but lower than those for E. faecium NRRL 2354. At 9.1% moisture, D-values of 6.54, 11.51, and 11.66 min at 76.7°C, 2.66, 3.22, and 4.08 min at 82.2°C, and 1.07, 1.29, and 1.69 min at 87.8°C were calculated for Salmonella serovars, P. acidilactici ATCC 8042, and E. faecium NRRL B-2354, respectively. The data suggest that the thermal inactivation characteristics of P. acidilactici ATCC 8042 can be utilized as a surrogate to predict the response of Salmonella in dry pet food products that are thermally processed at <90°C.

Genetic changes in the performance of egg laying strains of hens in Australia

1981 ◽  
Vol 21 (108) ◽  
pp. 46 ◽  
Author(s):  
RW Polkinghorne
Keyword(s):  
Egg Production ◽  
Egg Laying ◽  
Feed Consumption ◽  
Rapid Progress ◽  
Feed Conversion ◽  
Upward Trend ◽  
Genetic Changes ◽  
Non Linear ◽  
Linear Trends ◽  
Made In

Results from the South Australian Random Sample Tests in the period 1966 to 1978 were analyzed to determine if there had been any changes in the average performance of commercially available egg production strains. Average age at sexual maturity was found to have declined by about 0.5 days per year, and eggs per hen housed to have increased by about 1.7 eggs per year during the period analyzed. Non-linear trends were detected for feed consumption, feed conversion efficiency and income over feed and chick costs. For hen-day egg production, a non-linear upward trend was apparent with the most rapid progress having been made in the latter part of the period analyzed.

Sign in / Sign up

Export Citation Format

Share Document