Predicting Survival of Salmonella in Low–Water Activity Foods: An Analysis of Literature Data

2014 ◽  
Vol 77 (9) ◽  
pp. 1448-1461 ◽  
Author(s):  
SOFIA M. SANTILLANA FARAKOS ◽  
DONALD W. SCHAFFNER ◽  
JOSEPH F. FRANK
Keyword(s):  
Influencing Factors ◽  
Water Activity ◽  
Predictive Models ◽  
Culture Media ◽  
Weibull Model ◽  
Factor Log ◽  
The Times ◽  
Time Required ◽  
Log Linear ◽  
Fail Safe

Factors such as temperature, water activity (aw), substrate, culture media, serotype, and strain influence the survival of Salmonella in low-aw foods. Predictive models for Salmonella survival in low-aw foods at temperatures ranging from 21 to 80°C and water activities below 0.6 were previously developed. Literature data on survival of Salmonella in low-aw foods were analyzed in the present study to validate these predictive models and to determine global influencing factors. The results showed the Weibull model provided suitable fits to the data in 75% of the curves as compared with the log-linear model. The secondary models predicting the time required for log-decimal reduction (log δ) and shape factor (log β) values were useful in predicting the survival of Salmonella in low-aw foods. Statistical analysis indicated overall fail-safe secondary models, with 88% of the residuals in the acceptable and safe zones (<0.5 log CFU) and a 59% correlation coefficient (R2 = 0.35). A high variability in log δ-values and log β-values was observed, emphasizing the importance of experimental design. Factors of significant influence on the times required for first log-decimal reduction included temperature, aw, product, and serotype. Log β-values were significantly influenced by serotype, the type of inoculum (wet or dry), and whether the recovery media was selective or not. The results of this analysis provide a general overview of survival kinetics of Salmonella in low-aw foods and its influencing factors.

scholarly journals Effect of Challenge Temperature and Solute Type on Heat Tolerance of Salmonella Serovars at Low Water Activity

2001 ◽  
Vol 67 (9) ◽  
pp. 4128-4136 ◽  
Author(s):  
K. L. Mattick ◽  
F. Jørgensen ◽  
P. Wang ◽  
J. Pound ◽  
M. H. Vandeven ◽  
...  
Keyword(s):  
Water Activity ◽  
Heat Tolerance ◽  
Weibull Model ◽  
Microbial Inactivation ◽  
Published Data ◽  
Death Rates ◽  
Factors Affecting ◽  
Serovar Typhimurium ◽  
Death Kinetics ◽  
Fail Safe

ABSTRACT Salmonella spp. are reported to have an increased heat tolerance at low water activity (aw; measured by relative vapor pressure [rvp]), achieved either by drying or by incorporating solutes. Much of the published data, however, cover only a narrow treatment range and have been analyzed by assuming first-order death kinetics. In this study, the death ofSalmonella enterica serovar Typhimurium DT104 when exposed to 54 combinations of temperature (55 to 80°C) and aw (rvp 0.65 to 0.90, reduced using glucose-fructose) was investigated. The Weibull model (LogS = −btn ) was used to describe microbial inactivation, and surface response models were developed to predict death rates for serovar Typhimurium at all points within the design surface. The models were evaluated with data generated by using six different Salmonella strains in place of serovar Typhimurium DT104 strain 30, two different solutes in place of glucose-fructose to reduce aw, or six low-awfoods artificially contaminated with Salmonella in place of the sugar broths. The data demonstrate that, at temperatures of ≥70°C, Salmonella cells at low aw were more heat tolerant than those at a higher aw but below 65°C the reverse was true. The same patterns were generated when sucrose (rvp 0.80 compared with 0.90) or NaCl (0.75 compared with 0.90) was used to reduce aw, but the extent of the protection afforded varied with solute type. The predictions of thermal death rates in the low-aw foods were usually fail-safe, but the few exceptions highlight the importance of validating models with specific foods that may have additional factors affecting survival.

scholarly journals Modeling the Reduction of Salmonella spp. on Chicken Breasts and Wingettes during Scalding for QMRA of the Poultry Supply Chain in China

2019 ◽  
Vol 7 (6) ◽  
pp. 165 ◽  
Author(s):  
Xingning Xiao ◽  
Wen Wang ◽  
Xibin Zhang ◽  
Jianmin Zhang ◽  
Ming Liao ◽  
...  
Keyword(s):  
Supply Chain ◽  
Predictive Models ◽  
Linear Models ◽  
Weibull Model ◽  
Bacterial Reduction ◽  
Salmonella Spp ◽  
Microbial Risk Assessment ◽  
Microbial Risk ◽  
Log Linear ◽  
Best Fit

The objective of this study was to develop predictive models for describing the inoculated Salmonella reductions on chicken during the scalding process in China. Salmonella reductions on chicken breasts at a 100 s treatment were 1.12 ± 0.07, 1.38 ± 0.01, and 2.17 ± 0.11 log CFU/g at scalding temperatures of 50, 60 and 70 °C, respectively. For chicken wingettes, 0.87 ± 0.02, 0.99 ± 0.14 and 1.11 ± 0.17 log CFU/g reductions were obtained at 50, 60 and 70 °C after the 100 s treatment, respectively. Greater bacterial reductions were observed on chicken breasts than on chicken wingettes (p < 0.05). A logistic (−1.12, 0.06) distribution could describe the bacterial reductions on chicken breasts at 50–60 °C. Weibull, exponential and log-linear models were compared for describing the bacterial reduction on chicken breasts at 70 °C and the Weibull model showed the best fit as indicated by the pseudo-R2, root mean square error (RMSE) and standard error of prediction (SEP) values. For chicken wingettes, a logistic (−0.95, 0.07) distribution could be used to describe the bacterial reduction at 50–70 °C. The developed predictive models could provide parts of the input data for microbial risk assessment of the poultry supply chain in China.

Performance of Different Solid and Liquid Culture Media for the Improvement of Tuberculin Production

2020 ◽  
Keyword(s):  
Culture Media ◽  
Synthetic Medium ◽  
Chemical Properties ◽  
Economic Loss ◽  
Delayed Type Hypersensitivity ◽  
Basic Medium ◽  
Primary Methods ◽  
Lowenstein Jensen ◽  
Time Required ◽  
Modified Media

Tuberculosis (TB) is one of the most important zoonotic bacterial diseases. A huge economic loss which could be direct or indirect are associated with the disease. Currently, the primary methods used for detection of TB in humans and cattle include the measurement of a delayed type hypersensitivity to purified protein derivative (PPD). So, the need for preparation of purified PPD with adequate properties and increasing the final PPD yield with decreasing the time of tuberculin production has stimulated the interest in the development of its preparation. Our study was performed to compare between the standard and modified media for improving tuberculin production. Middle brook 7H10 agar medium was used as a modified basic medium for mycobacterial growth, followed by cultivation of mycobacteria on Middle brook 7H9 broth medium. For the production, strains were inoculated onto the culture medium (Dorest Henly synthetic medium). Other steps for tuberculin production was done according to standard Weighbridge protocol. The results demonstrated that the using of both Middle brook 7H10 agar and Middle brook 7H9 broth instead of Lowenstein-Jensen (LJ) and glycerin broth media which used in currently produced tuberculin, have better physical and chemical properties. In addition, reducing the time required for production by accelerating the time of microbial growth. Also, it was found that the tuberculin produced using modified media was slightly more potent or the same as currently tuberculin produced. So, both Middle brook 7H10 agar and Middle brook 7H9 broth media are recommended for production of tuberculin saving time and increasing potency of the product but more investigation was recommended for estimation types of protein present in both locally prepared and modified tuberculin.

The Artisential® Articulated Laparoscopic Forceps: A Dry Lab Study to Examine Dexterity and Learning Effects in Operators with Different Levels of Laparoscopic Experience

2021 ◽  
Author(s):  
Ibrahim Darwich ◽  
Mohammad Abuassi ◽  
Christel Weiss ◽  
Dietmar Stephan ◽  
Frank Willeke
Keyword(s):  
Learning Effect ◽  
Training Session ◽  
Transfer Task ◽  
Learning Effects ◽  
Laparoscopic Instrument ◽  
Significant Difference ◽  
The Times ◽  
Time Required ◽  
Laparoscopic Experience ◽  
Different Levels

Purpose: The advent of robotic surgery has highlighted the advantages of articulation. This dry-lab study examined the dexterity and learning effect of a new articulated laparoscopic instrument: the ArtiSential® forceps (LIVSMED, Seongnam, Republic of Korea). Methods: A peg board task was designed. Three groups of volunteers with varying levels of laparoscopic expertise were organized to perform the task: expert, intermediate and novice. The participants performed the task using articulated and straight instruments, once before a 30-min training session and once afterwards. The times required to perform the task were recorded. The performances were analyzed and compared between the groups as well as between the straight and articulated instruments. Results: The experts were significantly faster than the novices with both instruments before the 30-min training session (p = 0.0317 for each instrument). No significant time difference was found among the three groups after the 30-min training session. The decrease in the time required to perform the peg-transfer task with the articulated instrument was significantly greater in the novice and intermediate groups (p = 0.0159 for each group). No significant difference in time reduction was observed between the groups with the straight instrument. Regardless of the user, the articulated device was associated with faster task performance than the straight device after 8 hours of training (p = 0.0039). Conclusion: The ArtiSential® articulated device can improve dexterity. A significantly greater learning effect was observed in the novice and intermediate groups in comparison with experts. A plateau in the learning curve was observed after a few hours of training.

scholarly journals Research on the Influencing Factors of the Willingness of New Professional Farmers to Participate in Skills Training and Its Promotion during the Development of Urban ModernAgriculture

CONVERTER ◽  
2021 ◽  
pp. 199-210
Author(s):  
Yixi Liu, Pingyan Guo, Zhiyao Ma, Chun Hu
Keyword(s):  
Influencing Factors ◽  
Skill Training ◽  
Skills Training ◽  
Training Effect ◽  
Training Methods ◽  
Technical Problems ◽  
Agricultural Industry ◽  
Rural Revitalization ◽  
Key Factor ◽  
The Times

Objective: Talent is the key factor in the implementation of the Rural Revitalization Strategy. Based on the willingness and influencing factors of new professional farmers to participate in skill training in the development of modern urban agriculture, this study seeks to study the education of professional farmers from the perspective of demand. Methods: Based on the questionnaire survey data of new vocational farmers in Wenzhou, this study systematically analyzed the current situation, training willingness, training methods, and training effect of new vocational training, and made quantitative statistical analysis of the original basic data. Combined with the characteristics of agricultural industry and post, this study empirically analyzed their perception of participating in skill training and the influencing factors. Results: The number of new vocational farmers willing to participate in training was significantly higher than that of farmers unwilling to participate in training. The frequency of technical problems encountered in agricultural production, the times of training, the evaluation of training effect, effect, cost, teacher level, hardware level, certificate, and other factors have a significant impact on the willingness of new vocational farmers to participate in skills training. Conclusion: This study proposes to build a vocational occupation education system to enhance the training intention of new occupation farmers. During the COVID-19, the innovative form of webcast sales realized the unification of technology and service.

scholarly journals Intrinsic Run-time Row Hammer PUFs: Leveraging the Row Hammer Effect for Run-Time Cryptography and Improved Security

2018 ◽  
Author(s):  
Nikolaos Athanasios Anagnostopoulos ◽  
Tolga Arul ◽  
Yufan Fan ◽  
Christian Hatzfeld ◽  
André Schaller ◽  
...  
Keyword(s):  
Random Access ◽  
Physical Unclonable Functions ◽  
Generation Times ◽  
Speed Up ◽  
Run Time ◽  
Commercial Off The Shelf ◽  
Cost Efficient ◽  
Statistical Relationships ◽  
The Times ◽  
Time Required

Physical Unclonable Functions (PUFs) based on the retention times of the cells of a Dynamic Random Access Memory (DRAM) can be utilised for the implementation of cost-efficient and lightweight cryptographic protocols. However, as recent work has demonstrated, the times needed in order to generate their responses may prohibit their widespread usage. In order to address this issue, the Row Hammer PUF has been proposed by Schaller et al. [1], which leverages the row hammer effect in DRAM modules to reduce the retention times of their cells and, therefore, significantly speed up the generation times for the responses of PUFs based on these retention times. In this work, we extend the work of Schaller et al. by presenting a run-time accessible implementation of this PUF and further reducing the time required for the generation of its responses. Additionally, we also provide a more thorough investigation of the effects of temperature variations on the the Row Hammer PUF and briefly discuss potential statistical relationships between the cells used to implement it. As our results prove, the Row Hammer PUF could potentially provide an adequate level of security for Commercial Off-The-Shelf (COTS) devices, if its dependency on temperature is mitigated, and, may therefore, be commercially adopted in the near future.

scholarly journals Evaluating the risk of contracting salmonellosis from egg yolk "parmesan" based on water activity

2020 ◽  
Author(s):  
Dianna Vuu ◽  
BCIT School of Health Sciences, Environmental Health ◽  
Helen Heacock
Keyword(s):  
Water Activity ◽  
Intrinsic Factor ◽  
Egg Yolk ◽  
Minimum Amount ◽  
P Value ◽  
Food Borne ◽  
Food Borne Illness ◽  
Egg Yolks ◽  
Time Required ◽  
Treatment Step

Background: Egg yolk parmesan recipes have been gaining popularity since 2015. Most recipes include a heat treatment step which would kill egg-associated pathogens such as salmonella, however a significant number of recipes do not; resulting in a higher risk of salmonella growth and thus higher potential to cause food borne illness. Methods: Salt-curing affects an intrinsic factor called water activity (Aw). At 0.93 Aw or below salmonella is unable to grow. This study measured the minimum amount of time required for the salt curing process to inhibit the growth of salmonella. To achieve this batches of egg yolk parmesan were made using varying curing durations and then the water activity of the finished product was measured. A one sample t-test statistical analysis was conducted to determine if, with 99% confidence, the water activity of yolks cured for the chosen duration can reliably reduce water activity below 0.93. Results: The minimum amount of time required for the water activity to decrease below 0.93 was 24 hours. Results were as follows: N = 39; the p-value is 0.0000000 and the power is 1.0000000. Conclusion: This is strong evidence to suggest that large grade A chicken egg yolks cured in a 74% kosher salt and 26% white granulated sugar mixture for 24 hours at refrigeration temperature will have a water activity below 0.93. Therefore, it can be concluded that curing for 24 hours will inhibit potential salmonella growth.  

Inactivation of Bacillus cereus ATCC 14579 Spore on Garlic with Combination Treatments of Germinant Compounds and Superheated Steam

2019 ◽  
Vol 82 (4) ◽  
pp. 691-695 ◽  
Author(s):  
YOUNGJE JO ◽  
HYERYEON BAE ◽  
SANG-SOON KIM ◽  
CHOONGJIN BAN ◽  
SANG OH KIM ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Food Industry ◽  
Superheated Steam ◽  
Egg Yolk ◽  
Weibull Model ◽  
Log Reduction ◽  
Combination Treatments ◽  
Treatment Conditions ◽  
Sublethal Injury ◽  
Time Required

ABSTRACT Garlic is one of the most popular spices in the food industry because of its unique flavor, aroma, and health benefits. However, garlic is easily contaminated by spore-forming Bacillus cereus from the soil. We studied inactivation of B. cereus spores using superheated steam (SHS) and germinant compounds such as l-alanine, inosine, and disodium 5′-inosinate. Treatment with SHS and germinant compounds (50 mM l-alanine plus 5 mM disodium inosine 5′-monophosphate) on B. cereus spores was more effective than SHS treatment alone. The inactivation trends were analyzed using the Weibull model, and a time required to achieve a 3-log reduction was determined. These values at 120°C after SHS and germinant compounds plus SHS were 2.14 and 1.26 min, respectively. In addition, SHS and germinant compounds plus SHS treatments inactivated B. cereus ATCC 14579 spores effectively without causing sublethal injury. Levels of inactivation of B. cereus spores enumerated on mannitol–egg yolk–polymyxin and overlaid with Brilliance Bacillus Cereus were not significantly different for all treatment conditions. Therefore, germinant compounds plus SHS treatment can be used effectively to control B. cereus ATCC 14579 spores on garlic. HIGHLIGHTS

scholarly journals Exponentially Increased Thermal Resistance ofSalmonellaspp. andEnterococcus faeciumat Reduced Water Activity

2018 ◽  
Vol 84 (8) ◽  
pp. e02742-17 ◽  
Author(s):  
Shuxiang Liu ◽  
Juming Tang ◽  
Ravi Kiran Tadapaneni ◽  
Ren Yang ◽  
Mei-Jun Zhu
Keyword(s):  
Relative Humidity ◽  
Thermal Resistance ◽  
Silicon Dioxide ◽  
Linear Relationship ◽  
Water Activity ◽  
Enterococcus Faecium ◽  
Content Type ◽  
Low Moisture Foods ◽  
Log Linear ◽  
Insight Into

ABSTRACTSalmonellaspp. exhibit prolonged survivability and high tolerance to heat in low-moisture foods. The reported thermal resistance parameters ofSalmonellaspp. in low-moisture foods appear to be unpredictable due to various unknown factors. We report here that temperature-dependent water activity (aw, treatment temperature) plays an important role in the sharply increased thermal resistance ofSalmonella entericaserovar Enteritidis PT 30 and its potential surrogateEnterococcus faeciumNRRL B-2354. In our study, silicon dioxide granules, as carriers, were separately inoculated with these two microorganisms and were heated at 80°C with controlled relative humidity between 18 and 72% (resulting in corresponding aw,80°Cvalues for bacteria between 0.18 and 0.72) in custom-designed test cells. The inactivation kinetics of both microorganisms fitted a log-linear model (R2, 0.83 to 0.97). Reductions in the aw,80°Cvalues of bacterial cells exponentially increased theD80°C(the time needed to achieve a 1-log reduction in a bacterial population at 80°C) values forS. Enteritidis andE. faeciumon silicon dioxide. The log-linear relationship between theD80°Cvalues for each strain in silicon dioxide and its aw,80°Cvalues was also verified for organic wheat flour.E. faeciumshowed consistently higherD80°Cvalues thanS. Enteritidis over the aw,80°Crange tested. The estimated zaw(the change in aw,80°Cneeded to changeD80°Cby 1 log) values ofS. Enteritidis andE. faeciumwere 0.31 and 0.28, respectively. This study provides insight into the interpretation ofSalmonellathermal resistance that could guide the development and validation of thermal processing of low-moisture foods.IMPORTANCEIn this paper, we established that the thermal resistance of the pathogenS. Enteritidis and its surrogateEnterococcus faecium, as reflected byDvalues at 80°C, increases sharply with decreasing relative humidity in the environment. The log-linear relationship between theD80°Cvalues of each strain in silicon dioxide and its aw,80°Cvalues was also verified for organic wheat flour. The results provide new quantitative insight into the way in which the thermal resistance of microorganisms changes in low-moisture systems, and they should aid in the development of effective thermal treatment strategies for pathogen control in low-moisture foods.

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