Modeling non-linear survival curves to calculate thermal inactivation of Salmonella in poultry of different fat levels

Juneja, Vijay K.; Eblen, Brian S.; Marks, Harry M.

doi:10.1016/s0168-1605(01)00518-9

Cited by 107 publications

(58 citation statements)

References 13 publications

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“…Even in papers that report D values, it is often stated that the linear portion of the survival curve was used, implying that the actual survival data indicated some type of nonlinear shape. Thus, comparisons of predicted times needed to obtain specified lethalities using nonlinear models with predicted times based on reported D values may not be appropriate; it might be that the shoulders and the tails of the survival curves are affected by the concentrations of the factor being studied, for example, as seems to be the case regarding the effect of fat concentrations on the heat resistance of Salmonella in meat and poultry (7,9). In this work, the survival curves were nonlinear and displayed tailing, and thus it was not possible to report D values and use them for direct comparisons with other published results.…”

Section: Discussionmentioning

confidence: 99%

Predictive Thermal Inactivation Model for Effects of Temperature, Sodium Lactate, NaCl, and Sodium Pyrophosphate on Salmonella Serotypes in Ground Beef

Juneja

Marks

Mohr

2003

Appl Environ Microbiol

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Analyses of survival data of a mixture of Salmonella spp. at fixed temperatures between 55°C (131°F) and 71.1°C (160°F) in ground beef matrices containing concentrations of salt between 0 and 4.5%, concentrations of sodium pyrophosphate (SPP) between 0 and 0.5%, and concentrations of sodium lactate (NaL) between 0 and 4.5% indicated that heat resistance of Salmonella increases with increasing levels of SPP and salt, except that, for salt, for larger lethalities close to 6.5, the effect of salt was evident only at low temperatures (<64°C). NaL did not seem to affect the heat resistance of Salmonella as much as the effects induced by the other variables studied. An omnibus model for predicting the lethality for given times and temperatures for ground beef matrices within the range studied was developed that reflects the convex survival curves that were observed. However, the standard errors of the predicted lethalities from this models are large, so consequently, a model, specific for predicting the times needed to obtained a lethality of 6.5 log 10 , was developed, using estimated results of times derived from the individual survival curves. For the latter model, the coefficient of variation (CV) of predicted times range from about 6 to 25%. For example, at 60°C, when increasing the concentration of salt from 0 to 4.5%, and assuming that the concentration of SPP is 0%, the time to reach a 6.5-log 10 relative reduction is predicted to increase from 20 min (CV ‫؍‬ 11%) to 48 min (CV ‫؍‬ 15%), a 2.4 factor (CV ‫؍‬ 19%). At 71.1°C (160°F) the model predicts that more than 0.5 min is needed to achieve a 6.5-log 10 relative reduction.

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Section: Discussionmentioning

confidence: 99%

Predictive Thermal Inactivation Model for Effects of Temperature, Sodium Lactate, NaCl, and Sodium Pyrophosphate on Salmonella Serotypes in Ground Beef

Juneja

Marks

Mohr

2003

Appl Environ Microbiol

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“…There are multiple variables in addition to time and temperature that affect the kinetics of Salmonella death during cooking of chicken. For example, composition of chicken meat and meat products [4,5], strain of Salmonella [6,7], and size and shape of chicken meat and meat products [7]. One variable that has not received much attention but that could be important is inoculum size.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Effect of Inoculum Size on the Thermal Inactivation of <i>Salmonella</i> Typhimurium to Elimination in Ground Chicken Thigh Meat

Oscar¹

2017

AJFST

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A study was undertaken to investigate and model the effect of inoculum size on the thermal inactivation of Salmonella to elimination in ground chicken by conduction heating. To develop the model, ground chicken thigh meat portions (0.76 cm 3 ) in microcentrifuge tubes were inoculated with 2.0, 3.6, or 5.2 log of a single strain of Salmonella Typhimurium followed by cooking for 0 to 10 min at 52 to 100°C in a heating block. To validate the model, the ground chicken portions were inoculated with 2.8 or 4.4 log of S. Typhimurium followed by cooking for 0 to 9 min at 55 to 97°C. An automated, whole sample enrichment, miniature most probable number (MPN) method with a lower limit of detection of one Salmonella cell per portion was used for enumeration. The MPN data were used to develop (n = 851) and validate (n = 256) a multiple layer feedforward neural network model with two hidden layers of two nodes each. Model performance was evaluated using the acceptable prediction zone (APZ) method. The proportion of residuals in an APZ (pAPZ) from -1 log (fail-safe) to 0.5 log (fail-dangerous) was 0.945 (804/851) for dependent data and 0.945 (242/256) for independent data for interpolation. A pAPZ ≥ 0.7 indicated that model predictions had acceptable bias and accuracy. Thus, the model was successfully validated. The time for elimination of Salmonella at 58°C was 5.6, 7.1, and 8.7 min for inoculum sizes of 2.0, 3.6 and 5.2 log per portion, respectively. This relationship was observed for all cooking temperatures and among all inoculum sizes investigated indicating that inoculum size was an important independent variable to include in the model.

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“…Thermal resistance data from PBS or culture broth studies should not be directly extrapolated to food matrices due to the physicochemical complexity of foods (18). Therefore, we also quantified the extent of spore inhibition using retail ground beef (2-kg packages purchased at a local retailer) and a beef gravy model (5% beef extract, 1.7% soluble starch, 1.5% proteose peptone, and 0.5% yeast extract) (20).…”

Section: Methodsmentioning

confidence: 99%

“…Here, we used the same Whirlpack bag technique, but we assessed the effect of heating for a 1:1:1:1 (10 7 spores ⅐ ml Ϫ1 ) mixture of four C. difficile genotypes (PCR ribotype 027, 078, and 077 and an ATCC toxigenic strain). We determined the D values in a complete block design using three food matrices (i.e., a nutritious fat-free gravy model, retail "lean" 7% fat ground beef, and retail 30% fat ground beef) (18) and four heating temperatures (63, 71, 85, and the purportedly more effective 96°C). The 96°C was chosen as a subboiling water temperature for the city of Wooster, OH, where the altitude-adjusted boiling temperature is about 98.8°C.…”

Section: Methodsmentioning

confidence: 99%

Moist-Heat Resistance, Spore Aging, and Superdormancy in Clostridium difficile

Rodriguez-Palacios

LeJeune

2011

Appl Environ Microbiol

105

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Clostridium difficile spores can survive extended heating at 71°C (160°F), a minimum temperature commonly recommended for adequate cooking of meats. To determine the extent to which higher temperatures would be more effective at killing C. difficile, we quantified (D values) the effect of moist heat at 85°C (145°F, for 0 to 30 min) on C. difficile spores and compared it to the effects at 71 and 63°C. Fresh (1-week-old) and aged (>20-week-old) C. difficile spores from food and food animals were tested in multiple experiments. Heating at 85°C markedly reduced spore recovery in all experiments (5 to 6 log 10 within 15 min of heating; P < 0.001), regardless of spore age. In ground beef, the inhibitory effect of 85°C was also reproducible (P < 0.001), but heating at 96°C reduced 6 log 10 within 1 to 2 min. Mechanistically, optical density and enumeration experiments indicated that 85°C inhibits cell division but not germination, but the inhibitory effect was reversible in some spores. Heating at 63°C reduced counts for fresh spores (1 log 10 , 30 min; P < 0.04) but increased counts of 20-week-old spores by 30% (15 min; P < 0.02), indicating that sublethal heat treatment reactivates superdormant spores. Superdormancy is an increasingly recognized characteristic in Bacillus spp., and it is likely to occur in C. difficile as spores age. The potential for reactivation of (super)dormant spores with sublethal temperatures may be a food safety concern, but it also has potential diagnostic value. Ensuring that food is heated to >85°C would be a simple and important intervention to reduce the risk of inadvertent ingestion of C. difficile spores.

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Modeling non-linear survival curves to calculate thermal inactivation of Salmonella in poultry of different fat levels

Cited by 107 publications

References 13 publications

Predictive Thermal Inactivation Model for Effects of Temperature, Sodium Lactate, NaCl, and Sodium Pyrophosphate on Salmonella Serotypes in Ground Beef

Predictive Thermal Inactivation Model for Effects of Temperature, Sodium Lactate, NaCl, and Sodium Pyrophosphate on Salmonella Serotypes in Ground Beef

Modeling the Effect of Inoculum Size on the Thermal Inactivation of <i>Salmonella</i> Typhimurium to Elimination in Ground Chicken Thigh Meat

Moist-Heat Resistance, Spore Aging, and Superdormancy in Clostridium difficile

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