scholarly journals Modelling the inactivation of Staphylococcus aureusat moderate heating temperatures

2021 ◽  
Vol 39 (No. 1) ◽  
pp. 42-48
Author(s):  
Veronika Lehotová ◽  
Karla Miháliková ◽  
Alžbeta Medveďová ◽  
Ľubomír Valík
Keyword(s):  
Weibull Model ◽  
Primary Data ◽  
Coefficient Of Determination ◽  
Decimal Reduction Time ◽  
Capillary Method ◽  
Fitting Procedure ◽  
Bacterial Contaminants ◽  
Weibull Models ◽  
One Step ◽  
Log Linear

The survival of bacterial contaminants at moderate processing temperatures is of interest to many food producers, especially in terms of the safety and quality of the final products. That is why the heat resistance of Staphylococcus aureus 2064, an isolate from artisanal Slovakian cheese, was studied in the moderate temperature range (57–61 °C) by the capillary method. The fourth decimal reduction time t<sub>4D</sub>- and z-values were estimated in two steps by traditional log-linear Bigelow and non-linear Weibull models. In addition, a one-step fitting procedure using the Weibull model was also applied. All the approaches provided comparable t<sub>4D</sub>-values resulting in the following z-values of 11.8 °C, 12.3 °C and 11.3 °C, respectively. Moreover, the one-step approach takes all the primary data into z-value calculation at once, thus providing a more representative output at the reasonable high coefficient of determination R<sub>2</sub> = 0.961

Persistence of Non-O157 Shiga Toxin–Producing Escherichia coli in Dairy Compost during Storage

2017 ◽  
Vol 80 (12) ◽  
pp. 1999-2005 ◽  
Author(s):  
Hongye Wang ◽  
Muthu Dharmasena ◽  
Zhao Chen ◽  
Xiuping Jiang
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Survival Data ◽  
Weibull Model ◽  
Storage Conditions ◽  
Scientific Data ◽  
Pathogen Population ◽  
Weibull Models ◽  
Subsequent Storage ◽  
Log Linear

ABSTRACT Dairy compost with 20, 30, or 40% moisture content (MC) was inoculated with a mixture of six non-O157 Shiga toxin–producing Escherichia coli (STEC) serovars at a final concentration of 5.1 log CFU/g and then stored at 22 and 4°C for 125 days. Six storage conditions—4°C and 20% MC, 4°C and 30% MC, 4°C and 40% MC, 22°C and 20% MC, 22°C and 30% MC, and 22°C and 40% MC—were investigated for the persistence of non-O157 STEC in the dairy compost. During the entire storage, fluctuations in indigenous mesophilic bacterial levels were observed within the first 28 days of storage. After inoculation, the non-O157 STEC population increased 0.69 and 0.79 log CFU/g in the dairy compost with 30 and 40% MC at 22°C within the first day, respectively; for all other storage conditions, the pathogen population decreased rapidly. After the 125-day storage, the reductions of non-O157 STEC for 4°C and 20% MC, 4°C and 30% MC, 4°C and 40% MC, 22°C and 20% MC, 22°C and 30% MC, and 22°C and 40% MC storage conditions were &gt;4.52, &gt;4.55, 3.89, &gt;4.61, 3.60, and 3.17 log CFU/g, respectively. All the survival curves showed an extensive tail, indicating non-O157 STEC can survive at least for 125 days in the dairy compost. The survival data were analyzed with log-linear with tailing and Weibull models. Compared with the log-linear with tailing model, the Weibull model was found to be a better choice for predicting the survival of non-O157 STEC in dairy compost owing to a high overall R2 value (0.8738 to 0.9909). The decay rate of non-O157 STEC was higher in dairy compost stored at 4°C compared with at 22°C, and the same trend was found for the compost with 40% MC versus 20% MC. In addition, two non-O157 STEC serotypes (STEC O145 and O45) were detected on the last day of the longitudinal study and may deserve special attention in the Big 6 STEC group. Our results have provided scientific data for risk assessment of the microbiological safety of dairy compost to control non-O157 STEC during subsequent storage of dairy compost.

Inactivation Kinetics of Pathogens during Thermal Processing in Acidified Broth and Tomato Purée (pH 4.5)

2017 ◽  
Vol 80 (12) ◽  
pp. 2014-2021 ◽  
Author(s):  
Evann L. Dufort ◽  
Jonathan Sogin ◽  
Mark R. Etzel ◽  
Barbara H. Ingham
Keyword(s):  
Thermal Inactivation ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
E Coli ◽  
Log Reduction ◽  
Tomato Puree ◽  
Weibull Models ◽  
Canned Foods ◽  
D Values ◽  
Log Linear

ABSTRACT Thermal inactivation kinetics for single strains of Shiga toxin–producing Escherichia coli (STEC), Listeria monocytogenes, and Salmonella enterica were measured in acidified tryptic soy broth (TSB; pH 4.5) heated at 54°C. Inactivation curves also were measured for single-pathogen five-strain cocktails of E. coli O157:H7, L. monocytogenes, and S. enterica heated in tomato purée (pH 4.5) at 52, 54, 56, and 58°C. Inactivation curves were fit using log-linear and nonlinear (Weibull) models. The Weibull model yields the time for a 5-log reduction (t*) and a curve shape parameter (β). Decimal reduction times (D-values) and thermal resistance constants (z-values) from the two models were compared by defining t* = 5D* for the Weibull model. When the log-linear and Weibull models match at the 5-log reduction time, then t* = 5D* = 5D and D = D*. In 18 of 20 strains heated in acidified TSB, D and D* for the two models were not significantly different, although nonlinearity was observed in 35 of 60 trials. Similarly, in 51 of 52 trials for pathogen cocktails heated in tomato purée, D and D* were not significantly different, although nonlinearity was observed in 31% of trials. At a given temperature, D-values for S. enterica &lt;&lt; L. monocytogenes &lt; E. coli O157:H7 in tomato purée (pH 4.5). When using the two models, z-values calculated from the D-values were not significantly different for a given pathogen. Across all pathogens, z-values for E. coli O157:H7 and S. enterica were not different but were significantly lower than the z-values for L. monocytogenes. These results are useful for supporting process filings for tomato-based acidified food products with pH 4.5 and below and are relevant to small processors of tomato-based acidified canned foods who do not have the resources to conduct research on and validate pathogen lethality.

scholarly journals Evaluation of the Thermal Inactivation of a Salmonella Serotype Oranienburg Strain During Cocoa Roasting at Conditions Relevant to the Fine Chocolate Industry

2021 ◽  
Vol 12 ◽  
Author(s):  
Runan Yan ◽  
Gabriella Pinto ◽  
Rebecca Taylor-Roseman ◽  
Karen Cogan ◽  
Greg D’Alesandre ◽  
...  
Keyword(s):  
Foodborne Pathogens ◽  
Thermal Inactivation ◽  
Linear Models ◽  
Control Point ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Critical Control Point ◽  
Chocolate Industry ◽  
Weibull Models ◽  
Log Linear

Cocoa roasting produces and enhances distinct flavor of chocolate and acts as a critical control point for inactivation of foodborne pathogens in chocolate production. In this study, the inactivation kinetics of Salmonella enterica subsp. enterica serotype Oranienburg strain was assessed on whole cocoa beans using roasting protocols relevant to the fine chocolate industry. Beans were inoculated with 107–108 log10 CFU/bean of Salmonella Oranienburg and roasted at 100–150°C for 2–100 min. A greater than 5 log10 reduction of S. Oranienburg was experimentally achieved after 10-min roasting at 150°C. Data were fitted using log-linear and Weibull models. The log-linear models indicated that the roasting times (D) needed to achieve a decimal reduction of Salmonella at 100, 110, 115, 120, 130, and 140°C were 33.34, 18.57, 12.92, 10.50, 4.20, and 1.90 min, respectively. A Weibull model indicated a decrease in the Salmonella inactivation rate over time (β &lt; 1). Statistical analysis indicated that the Weibull model fitted the data better compared to a log-linear model. These data demonstrate the efficacy of cocoa roasting in inactivation of Salmonella and may be used to guide food safety decision-making.

scholarly journals Modelling inactivation kinetics of waterborne pathogens in municipal wastewater using ozone

2019 ◽  
Vol 25 (6) ◽  
pp. 890-897
Author(s):  
Achisa C Mecha ◽  
Maurice S Onyango ◽  
Aoyi Ochieng ◽  
Maggy NB Momba
Keyword(s):  
Municipal Wastewater ◽  
Bacterial Species ◽  
Weibull Model ◽  
Inactivation Kinetics ◽  
Waterborne Diseases ◽  
Bacterial Inactivation ◽  
Survival Curves ◽  
Water Matrix ◽  
Weibull Models ◽  
Log Linear

Microbial water pollution is a key concern leading to waterborne diseases. This study evaluated the disinfection of wastewater using ozonation. The following aspects were investigated: inactivation efficiency against <i>Escherichia coli, Salmonella</i> species, <i>Shigella</i> species, and <i>Vibrio cholerae</i>; modelling of inactivation kinetics using disinfection models; and evaluation of microbial regrowth studies. 99% bacterial inactivation was obtained within 15 min, irrespective of the water matrix, showing the strong oxidizing potential of ozone. The disinfection data were fitted into the log-linear and Weibull models. The survival curves were non-linear and fitted the Weibull model (fractional bias and normalized mean square error equal to 0.0), especially at high bacterial concentrations (10<sup>6</sup> CFU/mL). The inactivation occurred in two stages: an initial rapid stage (15 min) and a final slow stage exhibiting a tailing mechanism (15-45 min) probably as a result of the self-defence mechanisms adopted by the bacteria to limit oxidative stress. Considering the pattern of survival curves, no significant differences (<i>p</i> > 0.05) were observed among the four tested bacterial species; thus showing that ozone was effective against all the bacteria tested. There was minimal bacterial regrowth in the treated samples 24 h after ozone disinfection with reactivation values of 0-5% obtained.

IMPACT OF AIS AND STRESSED OUT AN EMPLOYEES TO THEIR PERFORMANCE AT PT EFRATA RETAILINDO

2019 ◽  
Vol 5 (1) ◽  
pp. 22-30
Author(s):  
Wiwit Ayu Retno Sari ◽  
Suhendro Suhendro ◽  
R. Riana Dewi
Keyword(s):  
Information Systems ◽  
Work Stress ◽  
Quantitative Research ◽  
Linear Regression Analysis ◽  
Accounting Information ◽  
Multiple Linear Regression Analysis ◽  
Primary Data ◽  
Coefficient Of Determination ◽  
Accounting Information System ◽  
Accounting Information Systems

This research aims to test the influence of accounting information system and work stress on performance of employees of PT Efrata Retailindo. The type of research used in this research is quantitative research. The source of the data in the research is primary data. The population in this study are all employees of PT Efrata Retailindo totalling 47 people. Sampling techniques in the study using a purposive sample. While the data collection method used is to use the questionnaire to all employees of PT Efrata Retailindo. Data analysis techniques using multiple linear regression analysis. Based on the results of the study it can be concluded that work stress had no effect on performance of employees of PT Efrata Retailindo, while information systems accounting effect on the performance of the employees of PT Efrata Retailindo. The value of the coefficient of determination (R2) amounting to 0.106. This indicates that variansi on a variable performance practice undertaken by the company PT Efrata Retailindo of 10.6% can be explained by work stress variables and accounting information systems, while the remaining 89.4% explained by other factors outside the researched.

PENGARUH MOTIVASI KERJA, KOMPETENSI, DAN KOMPENSASI TERHADAP KINERJA KARYAWAN RUMAH SAKIT UMUM DAERAH (RSUD) KABUPATEN KEPULAUAN MENTAWAI

2020 ◽  
Author(s):  
Syofrinal
Keyword(s):  
Linear Regression ◽  
Work Motivation ◽  
Regression Coefficient ◽  
Employee Performance ◽  
Primary Data ◽  
Coefficient Of Determination ◽  
Reliability Test ◽  
Mentawai Islands ◽  
Regression Test ◽  
Analytical Tools

The purpose of this study is to test the Influence of Work Motivation, Competence, and Compensation Against Performance Employees Regional General Hospital (RSUD) Mentawai Islands District. This study is a census. The data used are primary data by taking sample of 79 (seventy nine) respondents. This research uses analytical tools such as validity, reliability test, multiple linear regression test, t test, F test and coefficient of determination (R2). The results of this study illustrate that all variables have an effect on employee performance except the compensation variable. The results can be described by the equation Y = 12.752 + 0.248X1 + 0.396X2 + 0.051 X3, where X1 = Work Motivation, X2 = Competence, and X3 = Compensation. This means that the constant of 12.752 states that factors other than the variables X1, X2, and X3 that affect employee performance of 12,752. Work Motivation coefficient of 0.248 states that if the variable X1 added one unit will add the effect of employee performance of 0.248 with the assumption that the competence and compensation variables are constant. The regression coefficient X2 of 0.396 is that if the variable X2 increases one unit will increase the employee performance by 0.396 with the assumption that the variable of work motivation and compensation is constant. Furthermore, with X3 regression coefficient of 0.051. This means that with other factors considered constant, the effect of compensation is less than that of work motivation and competence.

Study on the Buying Motives and Prospects for Small Car Users in Hosur City

2016 ◽  
Vol 3 (9) ◽  
pp. 75
Author(s):  
Priya N ◽  
A Ravi
Keyword(s):  
Reference Group ◽  
Fuel Efficiency ◽  
Marketing Strategies ◽  
Primary Data ◽  
Buying Behavior ◽  
Consumer Orientation ◽  
One Step ◽  
Convenience Sampling ◽  
And Behavior ◽  
The City

Liberalization in 1991. The availability of many alternatives within the city provides an opportunity to the consumers to make a rational decision after considering all the options. Today is an era which is characterized by a consumer’s market where the manufacturers and marketers not only take into consideration the consumer orientation to make them satisfied but goes one step ahead of achieving. Consumer delight. Consumers look for those differentiating parameters, which may help them to make the best decision and can be proved as value to money proposition for them. It makes more important to analyze the consumer perceptions and behavior of the passenger car owners which will give the feedback pertaining to designing the marketing strategies. The objective of this paper is to investigate those differentiating parameter and effect of the reference group that influences the consumer buying behavior of car owners within the city of Hosur.The primary data was collected from 191 respondents, located Hosur in using convenience sampling .The results revealed the strong influence of attributes like price, fuel efficiency in buying decision and importance of reference group.

Pengaruh Sistem Pengendalian Internal Pemerintah Terhadap Kinerja Pemerintah Daerah

2021 ◽  
Vol 2 (2) ◽  
pp. 100-109
Author(s):  
Mattoasi Mattoasi ◽  
Didiet Pratama Musue ◽  
Yaman Rauf
Keyword(s):  
Control System ◽  
Internal Control ◽  
Local Governments ◽  
Quantitative Research ◽  
Primary Data ◽  
Coefficient Of Determination ◽  
Quantitative Research Methods ◽  
Internal Control System ◽  
The Government

PThis study aims to determine the effect of the internal control system on the performance of local government Case Study in Gorontalo Regency. This study uses quantitative research methods, and the data sources use primary data obtained from questionnaires distributed to respondents. Meanwhile, the data analysis used in this research is descriptive quantitative analysis using statistical t-test and coefficient of determination test (ajusted R-Square). The results showed that the internal control system had a positive effect on the performance of local governments with a determinant value of 48.7%. The result of this study contribute to the government to establish and implement a more effectives Internal Constrol Systems (ICS).  

An Investigation of Coping Strategies Adopted by Small-Scale Sugarcane Growers in Bungoma County, Kenya

2021 ◽  
Vol 3 (1) ◽  
pp. 89-102
Author(s):  
Protas Fwamba Khaemba ◽  
Philomena Muiruri ◽  
Thomas Kibutu
Keyword(s):  
Coping Strategies ◽  
Survey Design ◽  
Primary Data ◽  
Coefficient Of Determination ◽  
Farm Income ◽  
Small Scale ◽  
Sugarcane Farming ◽  
Income Generating Activities ◽  
Household Heads ◽  
By Products

This paper reports on one of the findings of a study undertaken to investigate the coping strategies used by small-scale sugarcane growers in Bungoma County, Kenya. A descriptive survey design was used. A multi-stage sampling procedure was employed in the selection of the divisions, villages, key respondents, and sugarcane farmers to be interviewed. Primary data were collected using questionnaires from 100 small-scale sugarcane growers’ household heads from Bumula Sub-County. Data were collected during the month of December 2016.  Qualitative data collected were analysed thematically. Quantitative data was analysed using regression in SPSS version 23 and Microsoft Excel. Results from small-scale sugarcane farmers in Bumula Sub-County revealed a declining farmers’ participation in sugarcane farming activities in the area. Coping strategies identified included off-farm income-generating activities, sale of sugarcane by-products and non-contracted cane farming. Significance test qualification was based on a percentage of adjusted R2 and within 0.3 to 0.7 ranges for Beta weight value.  The correlation coefficient (R-value) for the model was 0.362, indicating a moderately positive relationship between variables. The coefficient of determination (R2) was found to be 0.284 (28.4%). Adopted coping strategies accounted for 28.4% variability in the declining farmers’ participation in sugarcane farming. This result suggests the existence of other factors that explain the remaining 71.6% of the variation in the declining farmers’ participation. Farmers should enhance both on-farm and off-farm income-generating activities, sugarcane by-products value addition, and non-contracted cane farming in order to reverse the outcome and result in an enhanced farmers’ participation in sugarcane farming activities by 36.2%

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.

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