Influence of Nisin on the Resistance of Bacillus anthracis Sterne Spores to Heat and Hydrostatic Pressure

2008 ◽  
Vol 71 (1) ◽  
pp. 196-199 ◽  
Author(s):  
JONATHAN CRUZ ◽  
THOMAS J. MONTVILLE
Keyword(s):  
Hydrostatic Pressure ◽  
Bacillus Anthracis ◽  
Pressure Sensitivity ◽  
Log Reduction ◽  
Pressure Sensitive ◽  
Presence And Absence ◽  
Death Kinetics ◽  
Pressure Resistance ◽  
D Values ◽  
D Value

The influence of nisin on the heat and pressure resistance of Bacillus anthracis Sterne spores was examined. The decimal reduction times (D-value) of spores in milk (2% fat) at 80, 85, and 90°C were determined. In the absence of nisin, the D-values were 30.09, 9.30, and 3.86 min, respectively. The D-values of spores heated in the presence of nisin (1 mg/ml) were not significantly different (P = 0.05). However, spores heated in the presence of nisin had a 1- to 2-log reduction in viability, after which the death kinetics became similar to those of spores in the absence of nisin. The z-values all were 11.2°C regardless of the presence or absence of nisin. The pressure sensitivity of B. anthracis Sterne spores in the presence and absence of nisin also was determined. Spores treated with nisin were 10 times more pressure sensitive than were spores subjected to pressure in the absence of nisin under the conditions used in this study.

Comparative Radiation Death Kinetics of Clostridium botulinum Spores at Low-Temperature Gamma Irradiation

1977 ◽  
Vol 40 (5) ◽  
pp. 313-316 ◽  
Author(s):  
ABE ANELLIS ◽  
D. BERKOWITZ ◽  
D. KEMPER
Keyword(s):  
Clostridium Botulinum ◽  
Model System ◽  
Radiation Temperature ◽  
60Co Gamma Rays ◽  
Death Kinetics ◽  
D Values ◽  
Increasing Temperature ◽  
Relationship Of ◽  
Kinetics Of ◽  
D Value

Spores of Clostridium botulinum 33A were irradiated with 60Co gamma rays in 0.067 M Sorensen phosphate buffer (pH 7.0) at −196, −140, −80, −30, or 5 C and incubated in recovery broth for 30 days at 30 C, thus simulating an inoculated pack and eliciting “partial spoilage” data. Resistance of the spores decreased linearly with increasing temperature. A simple empirical equation was derived to predict D values for any desired temperature. An Arrhenius plot of the D value—radiation temperature profile indicated that the death kinetics is not first order. Comparison of the data in this model system with those previously observed in beef indicates a similar radiation death pattern, except that resistance of the spores was somewhat more (1.6-fold) temperature dependent, although significantly more resistant, in the beef. A comparison of the D value-temperature relationship of Streptoccus faecium a21, obtained earlier, with strain 33A in the same model system indicated that the spores were considerably less resistant below −20 C and much more resistant above this radiation temperature.

Hydrostatic Pressure—Temperature effects on Deep-sea Colonisation

1972 ◽  
Vol 73 ◽  
pp. 195-202 ◽  
Author(s):  
Robert J. Menzies ◽  
Robert Y. George
Keyword(s):  
Hydrostatic Pressure ◽  
Deep Sea ◽  
Temperature Effects ◽  
Marine Species ◽  
Pressure Effects ◽  
Pressure Sensitivity ◽  
Temperature And Pressure ◽  
Pressure Resistance ◽  
Increased Activity ◽  
Temperature And Pressure Effects

SynopsisA diverse benthic and bathypelagic fauna was first incontrovertably established by the deep-sea samples of H.M.S.Challenger, and demonstrated the ability of organisms to live and reproduce in the deep, dark and cold abyssal environment of enormous hydrostatic pressure as high as 1000 atm (14 000 psi) on trench floors at 10 000 metres. The investigations of Regnard (1891), Fontaine (1930) and Ebbecke (1935) established that various shallow animals have the capacity to withstand increased hydrostatic pressure. This paper deals with the response of whole organisms, mainly shallow-water metazoans, to hydrostatic pressure-temperature effects. The level of occurrence of pressure-induced increased activity (R1), onset of paralysis or tetany (T) and LD50are discussed for tropical and temperate marine species in relationship to temperature and hydrostatic pressure. The pressure sensitivity and resistance exhibited by different species are examined in relation to various hypotheses and theories such as (1) group effect, in which Schlieper (1968) claims that those shallow species that belong to the group which has successfully colonised the deep sea, such as Echinodermata, Mollusca, Isopoda, have a higher pressure resistance; (2) pressure resistance as a species or genetic property; (3) environmental impact, in which deeper species have a greater pressure resistance; and (4) finally a re-examination of temperature and pressure effects as these relate to deep-sea colonisation.

scholarly journals Sensitivity of Planktonic Cells of Staphylococcus aureus to Elevated Hydrostatic Pressure as Affected by Mild Heat, Carvacrol, Nisin, and Caprylic Acid

2020 ◽  
Vol 17 (19) ◽  
pp. 7033 ◽  
Author(s):  
Jyothi George ◽  
Sadiye Aras ◽  
Md Niamul Kabir ◽  
Sabrina Wadood ◽  
Shahid Chowdhury ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Hydrostatic Pressure ◽  
Caprylic Acid ◽  
Health Concern ◽  
Preventive Control ◽  
Mild Heat ◽  
Elevated Hydrostatic Pressure ◽  
Before And After ◽  
D Values ◽  
D Value

Current study investigated effects of elevated hydrostatic pressure exposure in the presence of mild heat and natural antimicrobials against Staphylococcus aureus. Hydrostatic pressure of 350 to 550 MPa with nisin (5000 IU/mL), carvacrol, or caprylic acid (0.5% v/v) were applied for the reduction in four-strain mixture of S. aureus in HEPES buffer at 4 and 40 °C for up to 7 min. Results were statistically analyzed by ANOVA and D-values were additionally calculated using best-fitted linear model. Prior to exposure to treatments at 4 °C, counts of the pathogen were 7.95 ± 0.4 log CFU/mL and were reduced (p < 0.05) to 6.44 ± 0.3 log CFU/mL after 7 min of treatment at 450 MPa. D-value associated with this treatment was 5.34 min (R2 = 0.72). At 40 °C, counts were 8.21 ± 0.7 and 5.77 ± 0.3 log CFU/mL before and after the 7-min treatments, respectively. D-value associated with 40 °C treatment was 3.30 min (R2 = 0.62). Application of the antimicrobials provided additional pathogen reduction augmentation for treatments < 5 min. The results of the current study could be incorporated for meeting regulatory requirements such as Food Code, HACCP, and Preventive Control for Human Food of Food Safety Modernization Act for assuring microbiological safety of products against this prevalent pathogen of public health concern.

Machinery Mold (Galactomyces geotrichum) Survival following Thermal and Hydrostatic Pressure Processing

2019 ◽  
Vol 82 (6) ◽  
pp. 1034-1038 ◽  
Author(s):  
SHIYU CAI ◽  
ABIGAIL B. SNYDER
Keyword(s):  
Limit Of Detection ◽  
Statistical Significance ◽  
Bacterial Pathogen ◽  
High Pressure Processing ◽  
Treatment Level ◽  
Production Environment ◽  
Log Reduction ◽  
Vegetable Products ◽  
D Values ◽  
D Value

ABSTRACT Machinery mold is a foodborne fungus associated with spoilage of fruit and vegetable products, as well as colonization of the food production environment. Galactomyces spp. are not considered heat-resistant molds, although their sensitivity to mild heat treatments, like blanching and pasteurization, as well as to nonthermal treatments, like high pressure processing (HPP), remains unknown. Cultures of two Galactomyces spp. isolates, Galactomyces geotrichum and Galactomyces candidum, were heat treated at 50, 53, and 55°C and HPP treated at 4°C for 90 s at 300, 400, and 600 MPa. The 2-day-old G. geotrichum had a D-value of 0.99 ± 0.04 min and 28-day-old G. geotrichum had a D-value of 1.28 ± 0.07 min at 55°C. Meanwhile, 2-day-old G. candidum had a D-value of 3.13 ± 0.20 min and 28-day-old G. candidum had a D-value of 1.60 ± 0.01 min at 55°C. Overall, the significant differences in D-values between the two cultivation times were modest, and statistical significance was not consistent across all three temperatures. However, the differences were more pronounced at higher processing temperatures. G. geotrichum was only reduced by 0.32 ± 0.07 log CFU/mL after 90 s at 300 MPa. However, increasing the treatment level to 400 MPa for 90 s decreased the counts for G. geotrichum to below the limit of detection (&lt;1 log CFU/mL) following HPP treatment. Meanwhile, the counts for G. candidum survivors at 400 MPa were 1.36 ± 0.08 log CFU/mL and were under the limit of detection at 600 MPa for 90 s. Based on the findings in this study, machinery mold contaminants would be readily inactivated by the processing conditions used to target a 5-log reduction in the bacterial pathogen of concern. HIGHLIGHTS

scholarly journals Correlation of Global Quantities at Material Characterization of Pressure-Sensitive Materials Using Sharp Indentation Testing

Lubricants ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 29
Author(s):  
Carl F. O. Dahlberg ◽  
Jonas Faleskog ◽  
Per-Lennart Larsson
Keyword(s):  
Finite Element ◽  
Material Characterization ◽  
Pressure Sensitivity ◽  
Pressure Sensitive ◽  
The Mean ◽  
Sharp Indentation ◽  
Von Mises ◽  
Von Mises Plasticity ◽  
Hardness Values

Correlation of sharp indentation problems is examined theoretically and numerically. The analysis focuses on elastic-plastic pressure-sensitive materials and especially the case when the local plastic zone is so large that elastic effects on the mean contact pressure will be small or negligible as is the case for engineering metals and alloys. The results from the theoretical analysis indicate that the effect from pressure-sensitivity and plastic strain-hardening are separable at correlation of hardness values. This is confirmed using finite element methods and closed-form formulas are presented representing a pressure-sensitive counterpart to the Tabor formula at von Mises plasticity. The situation for the relative contact area is more complicated as also discussed.

scholarly journals Predicting Pressure Sensitivity to Luminophore Content and Paint Thickness of Pressure-Sensitive Paint Using Artificial Neural Network

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5188
Author(s):  
Mitsugu Hasegawa ◽  
Daiki Kurihara ◽  
Yasuhiro Egami ◽  
Hirotaka Sakaue ◽  
Aleksandar Jemcov
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Data Augmentation ◽  
Percentage Error ◽  
Pressure Sensitivity ◽  
Pressure Sensitive Paint ◽  
Pressure Sensitive ◽  
Artificial Neural ◽  
Paint Thickness ◽  
Artificial Neural Network Ann

An artificial neural network (ANN) was constructed and trained for predicting pressure sensitivity using an experimental dataset consisting of luminophore content and paint thickness as chemical and physical inputs. A data augmentation technique was used to increase the number of data points based on the limited experimental observations. The prediction accuracy of the trained ANN was evaluated by using a metric, mean absolute percentage error. The ANN predicted pressure sensitivity to luminophore content and to paint thickness, within confidence intervals based on experimental errors. The present approach of applying ANN and the data augmentation has the potential to predict pressure-sensitive paint (PSP) characterizations that improve the performance of PSP for global surface pressure measurements.

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.

Effect of High Hydrostatic Pressure on Salmonella Inoculated into Creamy Peanut Butter with Modified Composition

2014 ◽  
Vol 77 (10) ◽  
pp. 1664-1668 ◽  
Author(s):  
TANYA D'SOUZA ◽  
MUKUND KARWE ◽  
DONALD W. SCHAFFNER
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
Water Activity ◽  
High Hydrostatic Pressure ◽  
Peanut Butter ◽  
High Pressure Processing ◽  
Peanut Oil ◽  
Peanut Flour ◽  
Log Reduction ◽  
High Hydrostatic Pressure Processing

Peanut butter has been associated with several large foodborne salmonellosis outbreaks. This research investigates the potential of high hydrostatic pressure processing (HPP) for inactivation of Salmonella in peanut butter of modified composition, both by modifying its water activity as well by the addition of various amounts of nisin. A cocktail of six Salmonella strains associated with peanut butter and nut-related outbreaks was used for all experiments. Different volumes of sterile distilled water were added to peanut butter to increase water activity, and different volumes of peanut oil were added to decrease water activity. Inactivation in 12% fat, light roast, partially defatted peanut flour, and peanut oil was also quantified. Nisaplin was incorporated into peanut butter at four concentrations corresponding to 2.5, 5.0, 12.5, and 25.0 ppm of pure nisin. All samples were subjected to 600 MPa for 18 min. A steady and statistically significant increase in log reduction was seen as added moisture was increased from 50 to 90%. The color of all peanut butter samples containing added moisture contents darkened after high pressure processing. The addition of peanut oil to further lower the water activity of peanut butter further reduced the effectiveness of HPP. Just over a 1-log reduction was obtained in peanut flour, while inactivation to below detection limits (2 log CFU/g) was observed in peanut oil. Nisin alone without HPP had no effect. Recovery of Salmonella after a combined nisin and HPP treatment did show increased log reduction with longer storage times. The maximum log reduction of Salmonella achieved was 1.7 log CFU/g, which was comparable to that achieved by noncycling pressure treatment alone. High pressure processing alone or with other formulation modification, including added nisin, is not a suitable technology to manage the microbiological safety of Salmonella-contaminated peanut butter.

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