Quantifying the Performance of Pediococcus sp. (NRRL B-2354: Enterococcus faecium) as a Nonpathogenic Surrogate for Salmonella Enteritidis PT30 during Moist-Air Convection Heating of Almonds

2011 ◽  
Vol 74 (4) ◽  
pp. 603-609 ◽  
Author(s):  
SANGHYUP JEONG ◽  
BRADLEY P. MARKS ◽  
ELLIOT T. RYSER
Keyword(s):  
Salmonella Enteritidis ◽  
Phage Type ◽  
Moist Air ◽  
Salmonella Enterica Serovar Enteritidis ◽  
Convection Oven ◽  
Air Heating ◽  
Air Convection ◽  
Convection Heating ◽  
The Mean ◽  
Computer Controlled

Pediococcus sp. NRRL B-2354 was investigated as a potential nonpathogenic surrogate for Salmonella enterica serovar Enteritidis phage type 30 (SE PT30) on the surface of almonds subjected to moist-air heating. Both microorganisms were subjected to various time, temperature, and humidity regimens on almonds processed in a computer-controlled, laboratory-scale, moist-air convection oven. Overall, the mean log reductions for Pediococcus sp. were 0.6 log and 1.4 log lower than those for SE PT30 (P < 0.05) at predicted reductions of 3 and 5 log, respectively. Also, the Dref-values for Pediococcus sp., calculated using a modified inactivation model (accounting for moisture) for SE PT30 on the surface of almonds subjected to moist-air heating (30 to 90% moisture by volume) were ~30% larger than those for SE PT30. Based on these findings, Pediococcus sp. NRRL B-2354 can be used as a conservative surrogate for SE PT30 during moist-air heating, and this organism is also likely to be an acceptable surrogate for steam heating.

Modeling the Effects of Product Temperature, Product Moisture, and Process Humidity on Thermal Inactivation of Salmonella in Pistachios during Hot-Air Heating

2020 ◽  
Vol 84 (1) ◽  
pp. 47-57
Author(s):  
KAITLYN E. CASULLI ◽  
KIRK D. DOLAN ◽  
BRADLEY P. MARKS
Keyword(s):  
Moisture Content ◽  
Salmonella Enteritidis ◽  
Thermal Inactivation ◽  
Mean Squared Error ◽  
Dew Point ◽  
Moist Air ◽  
Product Temperature ◽  
Air Heating ◽  
Air Convection ◽  
Primary Model

ABSTRACT Prior efforts to model bacterial thermal inactivation in and on low-moisture foods generally have been based on isothermal and iso-moisture experiments and have rarely included dynamic product and process variables. Therefore, the objective of this study was to test appropriate secondary models to quantify the effect of product temperature, product moisture, and process humidity on thermal inactivation of Salmonella Enteritidis PT30 on pistachios subjected to dynamic dry- or moist-air heating. In-shell pistachios were inoculated with Salmonella Enteritidis PT30, equilibrated in controlled-humidity chambers (to target water activities [aw] of 0.45 or 0.65), and in some cases, subjected to a presoak treatment prior to heating in a laboratory-scale, moist-air convection oven at multiple combinations (in duplicate) of dry bulb (104.4 or 118.3°C) and dew point (∼23.8, 54.4, or 69.4°C) temperatures, with air speed of ∼1.3 m/s. Salmonella survivors, pistachio moisture content, and aw were quantified at six time points for each condition, targeting cumulative lethality of ∼3 to 5 log. The resulting data were used to estimate parameters for five candidate secondary models that included combinations of product temperature, product moisture, aw, and/or process dew point (coupled with a log-linear primary model). A model describing the D-value as a function of temperature and dew point fit the data well (root mean squared error [RMSE] = 0.86 log CFU/g); however, adding a term to account for dynamic product moisture improved the fit (RMSE = 0.83 log CFU/g). In addition, product moisture content yielded better model outcomes, as compared with aw, particularly in the case of the presoaked pistachios. When validated at the pilot scale, the model was conservative, always underpredicting the experimental log reductions. Both dynamic product moisture and process humidity were critical factors in modeling thermal inactivation of Salmonella in a low-moisture product heated in an air-convection system. HIGHLIGHTS

Growth of Salmonella Enteritidis Phage Type 30 in Almond Hull and Shell Slurries and Survival in Drying Almond Hulls

2006 ◽  
Vol 69 (4) ◽  
pp. 712-718 ◽  
Author(s):  
AARON R. UESUGI ◽  
LINDA J. HARRIS
Keyword(s):  
Incubation Time ◽  
Rapid Growth ◽  
Salmonella Enterica ◽  
Salmonella Enteritidis ◽  
Phage Type ◽  
Weather Conditions ◽  
Water Sources ◽  
Salmonella Enterica Serovar Enteritidis ◽  
Outbreak Strain ◽  
High Concentrations

Traceback investigation of a 2000 to 2001 outbreak of salmonellosis associated with consumption of raw almonds led to isolation of the outbreak strain Salmonella enterica serovar Enteritidis phage type (PT) 30 on three geographically linked almond farms. Interviews with these growers revealed that significant rain fell during the 2000 harvest when many almonds were drying on the ground. The objectives of this study were to document weather conditions during the 2000 harvest, determine the potential for growth of Salmonella Enteritidis PT 30 in hull or shell slurries, and evaluate survival of Salmonella Enteritidis PT 30 on wet almond hulls during drying. Dry almond hulls and in-shell kernels wetted for 24 h increased in weight by 250 to 300% and 100%, respectively. Both hull and shell slurries supported rapid growth of Salmonella Enteritidis PT 30 at 24°C; slurries containing hulls also supported growth at 15°C. Maximum Salmonella Enteritidis PT 30 concentrations of 6.2 and 7.8 log CFU/ml were observed at 15 and 24°C, respectively. Salmonella Enteritidis PT 30 grown in wet hulls that were incubated at 24°C survived drying at either 15 or 37°C. Reductions of 1 to 3 log CFU/g of dry hull were observed during drying; reductions generally declined as incubation time increased from 2 to 7 days. Evaluation of shipping records revealed that approximately 60% of outbreak-associated almonds had not been exposed to rain, eliminating this factor as the sole cause of the outbreak. However, the data provide evidence that wet almonds may be a greater risk for high concentrations of Salmonella, and specific guidelines should be established for harvesting and processing almonds that have been exposed to rain or other water sources.

Thermal Inactivation Kinetics for Salmonella Enteritidis PT30 on Almonds Subjected to Moist-Air Convection Heating

2009 ◽  
Vol 72 (8) ◽  
pp. 1602-1609 ◽  
Author(s):  
SANGHYUP JEONG ◽  
BRADLEY P. MARKS ◽  
ALICIA ORTA-RAMIREZ
Keyword(s):  
Salmonella Enteritidis ◽  
Thermal Inactivation ◽  
Dew Point ◽  
Traditional Model ◽  
Moist Air ◽  
Validation Data ◽  
Dynamic Surface ◽  
Modified Model ◽  
Air Heating ◽  
Z Value

A traditional thermal inactivation kinetic model (D- and z-value) was modified to account for the effect of process humidity on thermal inactivation of Salmonella Enteritidis PT30 on the surface of almonds subjected to moist-air heating. Raw almonds were surface inoculated to ∼108 CFU/g and subjected to moist-air heating in a computer-controlled laboratory-scale convection oven. Time-temperature data were collected for 125 conditions (five dry bulb temperatures, 121 to 232°C; five process humidity levels, 5 to 90% moisture by volume; and five process durations). Moisture status at the surface of the almond, rather than the humidity of the bulk air, was a primary factor controlling the rate of inactivation; therefore, the D-value could not be a simple function of process temperature. Instead, the traditional D- and z-value model was modified to account for the dynamic water status at the surface of the product under humid heating conditions. The modified model needs only the dew point temperature of the processing air and dynamic surface temperature history of the almonds during moist-air heating. The modified model was more robust and accurate than the traditional model. The accuracy of the modified model was improved by 32 to 44% (in terms of the root mean squared error [RMSE] for the model fit) when compared with the traditional model in all moist-air heating conditions. Also, the prediction error of the modified model (RMSE = 1.33 log reductions) against an independent validation data set was approximately one-half that of the traditional model (RMSE = 2.56 log reduction) in the humidity range of 5 to 90% moisture by volume.

Antimicrobial activity of Enterococcus faecium EF 55 against Salmonella Enteritidis in chicks

2009 ◽  
Vol 57 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Mikuláš Levkut ◽  
Juraj Pistl ◽  
Andrea Lauková ◽  
Viera Revajová ◽  
Robert Herich ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Salmonella Enteritidis ◽  
Phage Type ◽  
Antimicrobial Effect ◽  
Lymphocyte Subpopulations ◽  
Mean Values ◽  
Mhc Ii ◽  
Immunological Status ◽  
Oral Inoculation ◽  
The Mean

The protective effect ofEnterococcus faeciumEF 55 againstSalmonella entericaserovar Enteritidis phage type 4 (SE PT4) was studied in 1-day-old chicks. The EF 55 strain (isolated and characterised by the authors earlier) was applied daily (1.109CFU/0.2 ml PBS) for 7 days. Oral inoculation of the SE PT4 strain was performed on day 8 in a single dose of 5.108CFU/0.2 ml PBS. The experiment lasted for 21 days. Samples were collected on day 1 of the experiment to verify the absence ofSalmonella, on day 8 to check colonisation of EF 55 and immunological status in experimental birds, and on days 2, 4, 6, 8 and 14 after SE PT4 infection of chicks. Strain EF 55 sufficiently colonised the digestive tract of chicks after 7 days of application. The highest numbers of EF 55 in the faeces of chicks were observed before SE infection and persisted to day 6 post infection (p.i.) in both the EF and EF+SE groups. PCR confirmed the identity of the EF 55 strain. The counts of SE PT4 strain in faeces of the EF+SE group were significantly reduced in comparison to those in the SE group on days 2 and 14 p.i. (P < 0.01). The significant reduction of salmonellae in the caecum was recorded at the end of the experiment (day 14 p.i.) in the EF+SE group in comparison to the SE group (P < 0.01). At day 4 p.i., colonies ofS. Enteritidis PT4 were found in the liver of chicks of the SE group in a higher concentration than in chicks of the EF+SE group (P < 0.001). Salmonellae were isolated from the liver until days 8 and 6 p.i. in the SE and EF+SE groups, respectively. The mean values of actual lymphocyte subpopulations in the blood and the relative percentage of caecal intraepithelial lymphocyte subpopulations (CD4, CD8, CD44, TCR, MHC II and IgM) were not influenced at a statistically significant level by the application of the EF 55 and/or the SE PT4 strain. The results demonstrate the antimicrobial effect ofE. faeciumEF 55 againstS. Enteritidis PT4.

Multiplication of Salmonella Enteritidis on the Yolk Membrane and Penetration to the Yolk Contents at 30°C in an In Vitro Egg Contamination Model

2008 ◽  
Vol 71 (9) ◽  
pp. 1905-1909 ◽  
Author(s):  
RICHARD K. GAST ◽  
RUPA GURAYA ◽  
JEAN GUARD-BOULDIN ◽  
PETER S. HOLT
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enteritidis ◽  
Vitelline Membrane ◽  
Critical Aspect ◽  
Salmonella Enterica Serovar Enteritidis ◽  
Exterior Surface ◽  
Increased Risk ◽  
The Mean ◽  
Uncommon Location

Refrigeration to limit bacterial multiplication is a critical aspect of efforts to control the transmission of Salmonella enterica serovar Enteritidis (SE) to consumers of contaminated eggs. Although the nutrient-rich yolk interior is an uncommon location for SE contamination in freshly laid, naturally contaminated eggs, migration across the vitelline membrane could lead to rapid bacterial multiplication even when the initial site of deposition is outside the yolk. Multiplication on the yolk membrane (before, or in addition to, multiplication within the yolk contents) could be another source of increased risk to consumers. The present study used an in vitro egg contamination model to compare the abilities of four strains of SE to either multiply in association with the yolk membrane or migrate through that membrane to reach the yolk contents during 36 h of incubation at 30°C. After inoculation onto the exterior surface of intact, whole yolks, all four SE strains penetrated the vitelline membrane to reach the yolk contents (at an overall frequency of 11.5%) after 12 h of incubation. The mean log concentration of SE was significantly higher in whole yolks (including yolk membranes) than in yolk contents at both 12 h (0.818 versus 0.167 CFU/ml) and 36 h (2.767 versus 1.402 CFU/ml) of incubation. These results demonstrate that SE multiplication on the vitelline membrane may both precede and exceed multiplication resulting from penetration into the yolk contents during the first 36 h of unrefrigerated storage, reinforcing the importance of rapid refrigeration for protecting consumers from egg-transmitted illness.

A Comparison of Physiological Demand between Self-Propelled and Motorized Treadmill Exercise

2018 ◽  
Vol 7 (4) ◽  
pp. 13-21
Author(s):  
Todd Backes ◽  
Charlene Takacs
Keyword(s):  
Respiratory Exchange Ratio ◽  
Treadmill Exercise ◽  
Cardiopulmonary Exercise Testing ◽  
Mean Value ◽  
The Self ◽  
Mixing Chamber ◽  
Wide Range ◽  
The Subject ◽  
The Mean ◽  
Computer Controlled

There are a wide range of options for individuals to choose from in order to engage in aerobic exercise; from outdoor running to computer controlled and self-propelled treadmills. Recently, self-propelled treadmills have increased in popularity and provide an alternative to a motorized treadmill. Twenty subjects (10 men, 10 women) ranging in age from 19-23 with a mean of 20.4 ± 0.8 SD were participants in this study. The subjects visited the laboratory on three occasions. The purpose of the first visit was to familiarize the subject with the self-propelled treadmill (Woodway Curve 3.0). The second visit, subjects were instructed to run on the self-propelled treadmill for 3km at a self-determined pace. Speed data were collected directly from the self-propelled treadmill. The third visit used speed data collected during the self-propelled treadmill run to create an identically paced 3km run for the subjects to perform on a motorized treadmill (COSMED T150). During both the second and third visit, oxygen consumption (VO2) and respiratory exchange ratio (R) data were collected with COSMED’s Quark cardiopulmonary exercise testing (CPET) metabolic mixing chamber system. The VO2 mean value for the self-propelled treadmill (44.90 ± 1.65 SE ml/kg/min) was significantly greater than the motorized treadmill (34.38 ± 1.39 SE ml/kg/min). The mean R value for the self-propelled treadmill (0.91 ± 0.01 SE) was significantly greater than the motorized treadmill (0.86 ± 0.01 SE). Our study demonstrated that a 3km run on a self-propelled treadmill does elicit a greater physiological response than a 3km run at on a standard motorized treadmill. Self-propelled treadmills provide a mode of exercise that offers increased training loads and should be considered as an alternative to motorized treadmills.

Genomic Analyses of Salmonella enteritidis Phage Type 4 Strains from Austria and Phage Type 8 Strains from the United States

1997 ◽  
Vol 285 (3) ◽  
pp. 379-388 ◽  
Author(s):  
C. Buchrieser ◽  
R. Brosch ◽  
O. Buchrieser ◽  
A. Kristl ◽  
J.B. Luchansky ◽  
...  
Keyword(s):  
United States ◽  
Salmonella Enteritidis ◽  
Phage Type ◽  
The United States ◽  
Genomic Analyses

Salmonella Enteritidis in Meat, Poultry, and Pasteurized Egg Products Regulated by the U.S. Food Safety and Inspection Service, 1998 through 2003

2007 ◽  
Vol 70 (3) ◽  
pp. 582-591 ◽  
Author(s):  
PATRICIA L. WHITE ◽  
ALECIA L. NAUGLE ◽  
CHARLENE R. JACKSON ◽  
PAULA J. FEDORKA-CRAY ◽  
BONNIE E. ROSE ◽  
...  
Keyword(s):  
Food Safety ◽  
Salmonella Enteritidis ◽  
Phage Type ◽  
Control Point ◽  
Electrophoretic Pattern ◽  
Electrophoretic Analysis ◽  
Critical Control Point ◽  
Egg Products ◽  
Inspection Service ◽  
The U.S

The U.S. Food Safety and Inspection Service (FSIS) tests for Salmonella in meat, poultry, and egg products through three regulatory testing programs: the Pathogen Reduction–Hazard Analysis and Critical Control Point (PR-HACCP) program, the ready-to-eat program for meat and poultry products, and the pasteurized egg products program. From 1998 through 2003, 293,938 samples collected for these testing programs were analyzed for the presence of Salmonella enterica serotypes. Of these samples, 12,699 (4.3%) were positive for Salmonella, and 167 (1.3%) of the positive samples (0.06% of all samples) contained Salmonella Enteritidis. The highest incidence of Salmonella Enteritidis was observed in ground chicken PR-HACCP samples (8 of 1,722 samples, 0.46%), and the lowest was found in steer-heifer PR-HACCP samples (0 of 12,835 samples). Salmonella Enteritidis isolates were characterized by phage type, pulsed-field gel electrophoretic pattern, and antimicrobial susceptibility. Phage typing of 94 Salmonella Enteritidis isolates identified PT13 (39 isolates) and PT8 (36 isolates) as the most common types. One isolate from a ready-to-eat ham product was characterized as PT4. Electrophoretic analysis of 148 Salmonella Enteritidis isolates indicated genetic diversity among the isolates, with 28 unique XbaI electrophoretic patterns identified. Of these 148 isolates, 136 (92%) were susceptible to each of 16 antimicrobials tested. Two isolates were resistant to ampicillin alone, and 10 isolates were resistant to two or more antimicrobials. Isolation of Salmonella Enteritidis from FSIS-regulated products emphasizes the need for continued consumer education on proper food handling and cooking practices and continued work to decrease the prevalence of Salmonella in meat, poultry, and pasteurized egg products.

Occurrence and Characterization of Salmonella from Chicken Nuggets, Strips, and Pelleted Broiler Feed

2007 ◽  
Vol 70 (10) ◽  
pp. 2251-2258 ◽  
Author(s):  
O. BUCHER ◽  
R. A. HOLLEY ◽  
R. AHMED ◽  
H. TABOR ◽  
C. NADON ◽  
...  
Keyword(s):  
Salmonella Enteritidis ◽  
Phage Type ◽  
Significant Risk ◽  
Pfge Pattern ◽  
Human Consumption ◽  
Chicken Nuggets ◽  
Isolation And Identification ◽  
Chicken Nugget ◽  
Pelleted Feed ◽  
Broiler Feed

Raw, frozen chicken nuggets and strips have been identified as a significant risk factor in contracting foodborne salmonellosis. Cases of salmonellosis as a result of consuming partly cooked chicken nuggets may be due in part to Salmonella strains originating in broiler feed. This study was undertaken to determine the occurrence and characterize the strains of Salmonella contaminating chicken nuggets, strips, and pelleted feeds, in an attempt to demonstrate whether the same Salmonella strains present in broiler feed could be isolated from raw, frozen chicken nuggets and strips available for human consumption. Salmonellae were recovered using the Health Canada MFHPB-20 method for the isolation and identification of Salmonella from foods. Strains were characterized by serotyping, phage typing, antimicrobial resistance typing (R-typing), and by pulsed-field gel electrophoresis (PFGE). Salmonellae were isolated from 25-g samples in 27% (n = 92) of nugget and strip samples, 95% (n = 20) of chicken nugget meat samples, and from 9% (n = 111) of pelleted feed samples. Salmonella Heidelberg, Salmonella Enteritidis, and Salmonella Orion were the most commonly isolated serovars from chicken nuggets and strips, nugget and strip meat, and pelleted broiler feeds, respectively. Salmonella Enteritidis phage type (PT) 13a with PFGE pattern SENXAI.0006 and R-type sensitive as well as Salmonella Enteritidis PT13a with PFGE pattern SENXAI.0068 and R-type sensitive were isolated from pelleted feed, and chicken nugget and strip meat in two separate instances. Data showed that Salmonella strains isolated from broiler feed were indistinguishable from strains isolated from packaged raw, frozen chicken nuggets and strips. However, results did not rule out the possibility that breeding stock or contamination during processing may have contributed to chicken meat contamination by Salmonella.

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