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Cooking parameters elaborated in the U.S. Department of Agriculture's Food Safety and Inspection Service Cooking Guideline for Meat and Poultry Products (Appendix A) were evaluated for inactivation of Salmonella spp. in pot pies. To prepare dough for pot pies, flour, butter, sugar, salt, and water were mixed, portioned into balls (65 or 85 g each), flattened (ca. 13 or 15 cm diameter, ca. 0.5 cm thick), and hand-pressed into pans (ca. 19.4 cm diameter). Next, a 100-g portion of beef, chicken, or a meat alternative, with or without added gravy (55 g of protein and 45 g of gravy), was inoculated with a cocktail of Salmonella spp. (ca. 6.5 or 7.9 log CFU/g of filling) and distributed onto the pie crust. After covering with a 65-g sheet of dough, pies were heat sealed in nylon polyethylene bags and stored at -20 °C for up to 72 h. Frozen pot pies containing a beef or meat alternative filling were cooked in a convection oven to an internal temperature of 57.8 °C (136°F) instantaneous, 62.8 °C (145°F) and held for 4 min, 67.2 °C (153°F) and held for 34 sec, or 71.1 °C (160°F) instantaneous; whereas chicken pot pies were cooked to an internal temperature of 57.8 °C (136°F) instantaneous, 62.8 °C (145°F) and held for 13 min, 67.2 °C (153°F) and held for 96 sec, or 73.9 °C (165°F) instantaneous. Cells of Salmonella spp. were recovered from uncooked or cooked pot pies by stomaching each pie in peptone water and enumerating pathogen levels via direct plating. Cooking delivered Salmonella spp. reductions of ca. 3.6 to ≥6.3 log CFU/g of pot pie. With few exceptions, when pathogen levels decreased to below detection by direct plating (0.5 log CFU/g of pot pie), cells of Salmonella were not recovered by enrichment. In addition, there were minimal differences in the a w and moisture content of the protein filling before and after cooking, suggesting that enclosing a meat, poultry, or meat alternative filling within a dough wrapping maintained moisture in the filling during the cooking process., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Inc.)

Salmonella and Campylobacter are major foodborne pathogens that cause outbreaks associated with contaminated chicken liver. Proper cooking is necessary to avoid the risk of illness to consumers. This study tested the thermal inactivation of a 4-strain Salmonella cocktail and a 3-strain Campylobacter cocktail in chicken livers separately at temperatures ranging from 55.0 to 62.5°C. Inoculated livers were sealed in aluminum cells and immersed in a water bath. The decimal reduction time (D-values) of Salmonella in chicken livers were 9.01, 2.36, 0.82, and 0.23 min at 55.0, 57.5, 60.0, and 62.5°C, respectively. The D-values of Campylobacter ranged from 2.22 min at 55.0°C to 0.19 min at 60.0°C. Salmonella and Campylobacter had similar z-values in chicken livers of 4.8 and 4.6°C, respectively. Chicken livers can be heated to internal temperatures of 70.0 to 73.9°C for at least 1.6 to 0.2 s to achieve a 7-log reduction of Salmonella. Validation tests demonstrated that heating chicken livers to internal temperatures of 70.0 to 73.9°C for 2 to 0 s resulted in a reduction of Salmonella exceeding 7 logs. Collectively, these data show that Salmonella exhibits higher heat resistance than Campylobacter in chicken livers. Therefore, Salmonella could be considered as the target pathogen when designing thermal treatments or cooking instructions for liver products. These findings will aid in designing effective thermal processing for both industrial and home cooking to eliminate Salmonella and Campylobacter, ensuring consumer safety when consuming chicken liver products., Competing Interests: DISCLOSURES The authors declare no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

A validation study was conducted to investigate the effect of the English muffin baking process to control Salmonella contamination and to study the thermal inactivation kinetic parameters (D- and z-values) of Salmonella in English muffin dough. The unbleached bread flour was inoculated with 3 serovar Salmonella cocktail (Salmonella serovars viz., Newport, Typhimurium, and Senftenberg), and dried back to its preinoculated water activity levels with 7.46 ± 0.12 log CFU/g of Salmonella concentration. The Salmonella inoculated flour was used to prepare English muffin batter and baked at 204.4°C (400°F) for 18 min and allowed to cool at ambient air for 15 min. The English muffins reached 99 ± 0°C (211.96 ± 0.37°F) as their maximum mean internal temperature during baking. The pH and a w of English muffin dough were 5.01 ± 0.01 and 0.947 ± 0.003, respectively. At the end of the 18-min baking period, the Salmonella inoculated English muffins recorded a more than 5 log CFU/g reduction on the injury-recovery media. The D-values of 3 serovar cocktails of Salmonella at 55, 58.5, and 62°C were 42.0 ± 5.68, 15.6 ± 0.73, and 3.0 ± 0.32 min, respectively; and the z-value was 6.2 ± 0.59°C. The water activity (a w ) of the English muffin crumb (0.947 ± 0.003 to 0.9557 ± 0.001) remained statistically unchanged during baking, whereas the a w of the muffin crust decreased significantly (0.947 ± 0.003 to 0.918 ± 0.002) by the end of 18 min of baking. This study validates and documents the first scientific evidence that baking English muffins at 204.4°C (400°F) for 18 min acts as an effective kill step by controlling Salmonella population by >5 log CFU/g., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Inc.)

Thermal resistance among Salmonella serovars has been shown to vary, however, such data are minimal for Salmonella inoculated onto low moisture foods. We evaluated survival and subsequent thermal resistance for 32 strains of Salmonella from four serovars (Agona, Enteritidis, Montevideo, and Tennessee) on flaxseed over 24 weeks. After inoculation, flaxseeds were adjusted to a w  = 0.5 and stored at 22 °C. After 24 weeks at 22 °C, strains of serovar Agona had a significantly slower rate of reduction compared to those of Enteritidis and Montevideo (adj. p < 0.05). Inoculated flaxseeds were processed at 71 °C with vacuum steam pasteurization at 4 time points during storage. Average initial D 71°C values ranging from 1.0 to 1.5 min were similar across serovars. Over 24 weeks, D 71°C varied in a serovar-dependent manner. D 71°C at 8, 16, and 24 weeks did not change significantly for Enteritidis and Montevideo but did for Tennessee and Agona. While significant, the differences in D 71°C over time were less than 1 min, indicating that storage time prior to heat treatment would have a minimal effect on the processing time required to inactivate Salmonella on flaxseed., Competing Interests: Declaration of competing interest The authors declare we have no conflicts of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Abstract: Low-water-activity (aw) foods (including those containing fat) are often implicated in outbreaks of Salmonella spp. The influence of fat content on survival in foods such as peanut butter remains unclear. Certain Salmonella serovars can survive for long periods in harsh temperatures and low moisture conditions. The objective of this study was to determine the influence of fat content on the survival of Salmonella in low-aw foods and expand an existing secondary inactivation model previously validated for lower-fat foods. Whey protein powder supplemented with peanut oil was equilibrated to five target aw values (aw < 0.60), inoculated with a dried four-strain cocktail of Salmonella, vacuum sealed, and stored at 22, 37, 50, 60, 70, and 80°C for 48 h, 28 days, or 168 days. Survival data were fitted to Weibull, Biphasic-linear, Double Weibull, and Geeraerd-tail models. The Weibull model was chosen for secondary modeling due to its ability to satisfactorily describe the data over most of the conditions under study. The influence of temperature, fat content, and aw on the Weibull model parameters was evaluated using nonlinear least squares regression, and a revised secondary model was developed based on parameter significance. Peanut butter, chia seed powder, toasted oat cereal, and animal crackers within the aw range of the model were used to validate the modified model within its temperature range. Fat content influenced survival in samples held at temperatures ≥50°C, whereas aw influenced survival at 37 and 70°C. The model predictions demonstrated improved % bias and % discrepancy compared with the previous model. Weibull model predictions were accurate and fail-safe in 38 and 58%, respectively, of the food and environmental conditions under study. Predictions were less reliable for peanut butter held at 80°C. This study provides data and a model that can aid in the development of risk mitigation strategies for low-aw foods containing fat., (Copyright ©, International Association for Food Protection.)

Abstract: Isothermal inactivation experiments often are used to investigate the thermal resistance of pathogens, such as Salmonella, in foods; however, little is known about the reproducibility of such experimental methodologies. The objective of this study was to quantify the reproducibility of Salmonella isothermal resistance results via a six-laboratory comparison. Inoculation was performed at a single location and then distributed to each laboratory for isothermal analysis. Salmonella Agona 447967 was inoculated into oat flour, re-equilibrated to a water activity (aw) of 0.45, and then packaged and distributed to each laboratory. Before conducting the inactivation trials, each laboratory was required to verify the inoculated product's aw, enumerate Salmonella population levels, and verify that the isothermal treatment medium was at the target temperature (80°C). All laboratories were required to process at least three replications, collect at least six sample time points with three subsamples at each sampling point, enumerate survivors using an identical plating methodology and media, and verify that the temperature did not substantially change during isothermal treatment. The log-linear model was fit to the Salmonella survivor data, and the resultant D-values were statistically compared via Welch's t test (α = 0.05). Two significant differences in thermal inactivation kinetics were identified as potentially resulting from suspected methodology deviations. Two of the inoculated batches distributed for analysis yielded significantly lower D-values, which likely resulted from a deviation in the inoculation procedures. One laboratory yielded significantly lower D-values, which was likely the result of temperature deviations. Overall, excluding the D-values resulting from deviations, the inactivation results were reproducible, yielding D-values of 30.2 ± 3 min. These results indicate that isothermal inactivation results can be reproducible but that even minor methodology deviations can substantially affect measured Salmonella thermal resistance., (Published 2020 by the International Association for Food Protection. Not subject to U.S. Copyright.)

Abstract: The viability of Shiga toxin-producing Escherichia coli (STEC), Salmonella, and Listeria monocytogenes within plant- and beef-based burgers was monitored during storage and cooking. When inoculated (ca. 3.5 log CFU/g) into 15-g portions of plant- or beef-based burgers, levels of STEC and Salmonella decreased slightly (≤0.5-log decrease) in both types of burgers when stored at 4°C, but increased ca. 2.4 and 0.8 log CFU/g, respectively, in plant-based burgers but not beef-based burgers (≤1.2-log decrease), after 21 days at 10°C. For L. monocytogenes, levels increased by ca. 1.3 and 2.6 log CFU/g in plant burgers after 21 days at 4 and 10°C, respectively, whereas pathogen levels decreased slightly (≤0.9-log decrease) in beef burgers during storage at 4 and 10°C. Regarding cooking, burgers (ca. 114 g each) were inoculated with ca. 7.0 log CFU/g STEC, Salmonella, or L. monocytogenes and cooked in a sauté pan. Cooking plant- or beef-based burgers to 62.8°C (145°F), 68.3°C (155°F), or 73.9°C (165°F) delivered reductions ranging from ca. 4.7 to 6.8 log CFU/g for STEC, ca. 4.4 to 7.0 log CFU/g for L. monocytogenes, and ca. 3.5 to 6.7 log CFU/g for Salmonella. In summary, the observation that levels of all three pathogens increased by ca. 1.0 to ca. 2.5 log CFU/g in plant-based burgers when stored at an abusive temperature (10°C) highlights the importance of proper storage (4°C) to lessen risk. However, because all three pathogens responded similarly to heat in plant-based as in beef-based burgers, well-established cooking parameters required to eliminate STEC, Salmonella, or L. monocytogenes from ground beef should be as effective for controlling cells of these same pathogens in a burger made with plant-sourced protein., (Published 2020 by the International Association for Food Protection. Not subject to U.S. Copyright.)

This study was conducted to validate a commercial nut muffin baking process and to compare the survival of a 7-serovar Salmonella cocktail when contaminated via inoculated flour or walnuts. Enriched wheat flour or walnut pieces were mist inoculated with the Salmonella cocktail and dried back to the pre-inoculation weight, resulting in a Salmonella population level of 6.9 and 8.4 log CFU/g, respectively. Nut muffin batters were prepared separately using inoculated flour or walnuts, followed by baking at 375 °F (190.6 °C) oven temperature for 21 min and post-bake ambient air-cooling (B + C). During baking, >5-log CFU/g reductions in the Salmonella population in nut muffins was achieved in 17 min, and Salmonella was not detected by direct plating (<0.2 log CFU/g detection limit) but was recovered by enrichment at the end of 21 min of baking and B + C. In a separate baking study using an extended baking time (24 min) at 375 °F, Salmonella was detected after 24 and 22 min using enrichment plating of nut muffins prepared from inoculated flour and walnuts, respectively. The D-values of the Salmonella cocktail in nut muffin batters prepared from inoculated flour were 24.0, 4.0 and 0.6 min at 60, 65 and 70 °C; whereas, corresponding D-values in batters prepared from inoculated walnuts were 22.0, 3.6 and 1.7 min. The z-values of the Salmonella cocktail in nut muffin batters were 6.1 and 9.0 °C for inoculated flour and walnuts, respectively. This simulated commercial nut muffin baking study utilizing an oven temperature of 190.6 °C for at least 17 min validates that the process will eliminate Salmonella populations by ≥5 log CFU/g if pre-baking contamination occurs via flour or walnut ingredients., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

Salmonella in low-moisture foods is an emerging challenge due to numerous food product recalls and foodborne illness outbreaks. Identification of suitable surrogate is critical for process validation at industry level due to implementation of new Food Safety Modernization Act of 2011. The objective of this study was to evaluate Enterococcus faecium NRRL B-2354 as a surrogate for Salmonella during the extrusion of low-moisture food. Oat flour, a low-moisture food, was adjusted to different moisture (14% to 26% wet basis) and fat (5% to 15% w/w) contents and was inoculated with E. faecium NRRL B-2354. Inoculated material was then extruded in a lab-scale single-screw extruder running at different screw speeds (75 to 225 rpm) and different temperatures (75, 85, and 95 °C). A split-plot central composite 2nd order response surface design was used, with the central point replicated six times. The data from the selective media (m-Enterococcus agar) was used to build the response surface model for inactivation of E. faecium NRRL B-2354. Results indicated that E. faecium NRRL B-2354 always had higher heat resistance compared to Salmonella at all conditions evaluated in this study. However, the patterns of contour plots showing the effect of various product and process parameters on inactivation of E. faecium NRRL B-2354 was different from that of Salmonella. Although E. faecium NRRL B-2354 may be an acceptable surrogate for extrusion of low-moisture products due to higher resistance than Salmonella, another surrogate with similar inactivation behavior may be preferred and needs to be identified., Practical Application: Food Safety Modernization Act requires the food industry to validate processing interventions. This study validated extrusion processing and demonstrated that E. faecium NRRL B-2354 is an acceptable surrogate for extrusion of low-moisture products. The developed response surface model allows the industry to identify process conditions to achieve a desired lethality for their products based on composition., (© 2018 Institute of Food Technologists®.)

Thermal inactivation of Salmonella is a critical component of the calculated thermal process to ensure the safety of cooked human and animal products. However, lethality performance standards for meat processing by-products that may harbor Salmonella have not been properly set under the actual conditions of rendering processes. The goal of this study was to evaluate the thermal inactivation parameters for Salmonella in high-fat beef trimmings as a model system for animal food products treated under simulated "worst-case scenario" commercial rendering conditions. Ground high-fat beef trimmings (50% fat) were artificially inoculated with a 10 8 CFU/g Salmonella cocktail containing human outbreak strains including the highly thermotolerant serotype Salmonella Senftenberg. The meat samples were packaged and immersed in either water or silicon oil at predetermined temperatures ranging from 60 to 121°C (from 140 to 250°F). D-values of Salmonella at each temperature were calculated from the negative inverse slope of the log CFU per gram versus time plot. The z-values were determined from the negative inverse slope of the log D versus temperature plot. The D-values in thermal death curves for low-fat (20%) content materials (between 60 and 95°C) were 2.175, 0.658, 0.237, 1.563, 0.356, 0.284, 0.264, and 0.201 min, whereas materials with 50% fat (between 100 to 121°C) were 0.277, 0.286, 0.159, 0.143, 0.137, and 0.087 min. The z-values for low- and high-temperature schedules were 43.7 and 42.9°C, respectively. Thermal lethality data for Salmonella inactivation in high-fat rendering raw materials will help animal food processors design adequate thermal processing schedules and support critical control points to ensure the safety of final beef-based rendered products.

Growth and inactivation regression equations were developed to describe the effects of temperature on Salmonella concentration on chicken meat for refrigerated temperatures (⩽10°C) and for thermal treatment temperatures (55-70°C). The main objectives were: (i) to compare Salmonella growth/inactivation in chicken meat versus laboratory media; (ii) to create regression equations to estimate Salmonella growth in chicken meat that can be used in quantitative risk assessment (QRA) modeling; and (iii) to create regression equations to estimate D-values needed to inactivate Salmonella in chicken meat. A systematic approach was used to identify the articles, critically appraise them, and pool outcomes across studies. Growth represented in density (Log10CFU/g) and D-values (min) as a function of temperature were modeled using hierarchical mixed effects regression models. The current meta-analysis analysis found a significant difference (P⩽0.05) between the two matrices - chicken meat and laboratory media - for both growth at refrigerated temperatures and inactivation by thermal treatment. Growth and inactivation were significantly influenced by temperature after controlling for other variables; however, no consistent pattern in growth was found. Validation of growth and inactivation equations against data not used in their development is needed., (Copyright © 2012 Ministry of Health, Saudi Arabia. Published by Elsevier Ltd. All rights reserved.)

The objective of this study was to validate a simulated commercial baking process for traditional crust pepperoni pizza to inactivate Salmonella when contamination was introduced through inoculated flour and pepperoni slices. The unbleached flour and pepperoni slices were inoculated (separate studies) with a 3‐serovar Salmonella cocktail and dried back to their respective pre‐inoculation water activity level to achieve 6.14 and 6.84 log CFU/g, respectively. The inoculated traditional crust pizza was baked at 260°C (500 °F) for 12 min followed by 15 min of ambient cooling. In both cases, a >6 log CFU/g reduction in Salmonella population was achieved by the first 8 min of baking. The pH (5.23–5.25) and water activity (0.958 ± 0.001–0.938 ± 0.005) of the pizza in this study did not change significantly. The D‐values of 3‐serovar Salmonella cocktail in traditional crust pepperoni pizza dough were 23.2 ± 1.82, 7.50 ± 0.32, and 2.0 ± 0.15 min at 56°C, 59°C, and 62°C, respectively, with a z‐value of 5.7°C. The study validated that traditional crust pepperoni pizzas when baked at 260°C (500 °F) for at least 12 min will reduce Salmonella populations by ≥5 log CFU/g if prebaking contamination occurs via flour and/ or pepperoni. [ABSTRACT FROM AUTHOR]

The laboratory inoculation techniques should ideally mimic the real‐life environment to reliably estimate the decimal reduction time (D‐value) of bacteria for process validation. This study aims at investigating the influence of the inoculation method on the D‐value of Salmonella in black pepper powder. Whole black peppercorns were either inoculated prior to grinding (pre‐grinding procedure) or ground and then inoculated (post‐grinding procedure). The ground black pepper was thermaly treated at 80°C for 0‐30 min. The D80°C values of Salmonella inoculated by pre‐grinding and post‐grinding procedures were 5.5 ± 0.8 and 3.9± 0.3, respectively. Salmonella and E. faecium were significantly (p⟨0.05) more thermally resistant in ground black pepper when inoculated pre‐ rather than post‐grinding. Therefore, inoculation protocol must be considered by spice industries while validating the pasteurization process. E. faecium is a suitable surrogate for Salmonella because of its higher decimal reduction time for both inoculation methods. [ABSTRACT FROM AUTHOR]

Salmonella spp. is a significant foodborne pathogen present in raw meat products and in the processing environment. It can be eliminated by thermal processes such as cooking. Time and temperature in the thermal process play an important role in eliminating this pathogen. The objective of this study is to determine the D- and z-values of Salmonella spp. in whole-muscle beef using the isothermal inactivation method in four temperatures at designated time intervals. Whole-muscle beef was inoculated with 7 to 8 log10 CFU/mL of Salmonella Typhimurium and Salmonella Enteritidis. The inoculated meat samples were heat treated at 58 °C, 60 °C, 62 °C, and 64 °C. At each temperature, Salmonella spp. survival rate was plotted and the D- and z-values were obtained by linear regression of the survival curve. The D-values for the thermal inactivation of whole-muscle beef are D58 °C=5.41 min, D60 °C=2.03 min, D62 °C=0.46 min, and D64 °C=0.18 min, while the z-value obtained was 3.94 °C. These findings will assist food processors in designing the critical limits on the critical control points of the cooking process that ensure safety against Salmonella spp. in cooked whole-muscle beef. [ABSTRACT FROM AUTHOR]

Chicken wings are among the most popular poultry products for home and foodservice consumption. Poultry products must be handled and cooked safely to decrease the risk of foodborne salmonellosis for consumers. This study aims to validate the use of domestic appliances (convection and air fryer ovens) for the thermal inactivation of Salmonella on chicken wings. Wings (n = 3, 46.5 ± 4.3 g) were inoculated with a five‐strain cocktail of Salmonella (ca. 8 log10 CFU/wing) and cooked in a convection oven (179.4°C) or an air fryer (176, 190, or 204°C) for 2, 5, 10, 15, 20, 22, or 25 min. Thermocouples recorded temperature profiles of wings and appliances. Salmonella counts were determined on XLD agar for rinsates (100 ml/sample), and rinsates were enriched to recover bacteria below the limit of quantification. The recommended internal cooking temperature (73.8°C) was achieved after a range of 7.5 to 8.5 min in both appliances. Salmonella counts were reduced by 6.5 log10 CFU/wing when this temperature was achieved. Cumulative lethality (F‐value) calculations predicted a 9‐log reduction after 7.0 to 8.1 min of cooking. However, sample enrichments tested positive for Salmonella for all cooking times below 22 min. Ultimately, cooking at the temperature–time combinations recommended by manufacturers and online recipes helped achieve complete microbial elimination in both appliances. This study contributes to the validation of home cooking methods to ensure consumer safety. [ABSTRACT FROM AUTHOR]

ABSTRACT: This study compares kinetic parameters of Salmonella and surrogate Enterococcus faecium in mash broiler feed during thermal inactivation. Two-gram samples of mash broiler feed were added into a filtered sample bag and inoculated with nalidixic acid (NaL, 200 ppm) resistant S. Typhimurium or Enterococcus faecium, followed by vacuum-packaging and heating in a circulated thermal water bath at 75°, 85°, and 95°C for 0 to 180 s. Counts of bacterial survival were analyzed on tryptic soy agar and bile esculin agar plus 200 ppm of NaL. Microbial data and thermal kinetic parameters (n = 8, Global-Fit and United States Department of Agriculture [USDA]-Integrated-Predictive-Modeling-Program software) were analyzed by JMP software. Heating mash broiler feed at 75°, 85°, and 95°C decreased (P < 0.05) Salmonella cell counts by >6 log10CFU/g after 180, 60, and 50 s, respectively. Heating E. faecium in feed at 75°, 85°, and 95°C for 180, 120, and 70 s achieved reductions of 3, 6, and >6.5 log10CFU/g, respectively. D-values of linear, Weibull models, and z-value of Salmonella at 75°, 85°, and 95°C were 1.8 to 11.2, 4.2 to 21.8, and 28.6 s, respectively, which were lower (P < 0.05) than those of E. faecium (3.7–18.1, 8.5–34.4, and 34.1 s). Linear with Tail, Linear with Tail and Shoulder, and Weibull with tail equations revealed that E. faecium were more resistant (P < 0.05) to heat than Salmonella as shown by longer “Shoulder-time” (26.5 vs. 16.2 s) and greater “Tail” effect (4.4–4.5 vs. 2.5–2.6 log10CFU/g). Results clearly suggested that E. faecium can be used as a surrogate for Salmonella to validate thermal inactivation during feed manufacture.

Featured Application: Radio frequency (RF) heating is a promising novel technology for food pasteurisation and sterilisation applications. However, knowledge on the (thermal) inactivation mechanisms of RF against foodborne pathogens (e.g., bacteria) is limited thus far. Therefore, in the current study, a small-scale laboratory RF setup that is appropriate for fundamental studies towards RF inactivation mechanisms was developed. The developed setup is more suited for fundamental research topics than existing commercial RF setups, which are both expensive and inconvenient for treatments of small sample sizes. A lab-scale low-power free-running radio frequency (RF) oscillator operating at a frequency of 27.12 ± 0.50 MHz was developed to be suitable for fundamental microbiological research topics. Calibration and validation were conducted for two common foodborne pathogens in relevant microbiological growth media, i.e., Salmonella Typhimurium and Listeria monocytogenes in Tryptic Soy Broth and Brain–Heart Infusion broth, respectively. The evolution of temperature, frequency, and power consumption was monitored during treatments, both with and without bacterial cells. The setup operated within the predefined frequency range, reaching temperatures of 71–76 °C after 15 min. The average power consumption ranged between 12 and 14 W. The presence of bacteria did not significantly influence the operational parameters. The inactivation potential of the RF setup was validated, demonstrating the absence of viable cells after 8 and 10 min of treatment, for S. Typhimurium and L. monocytogenes, respectively. In future studies, the setup can be used to conduct fundamental microbiological studies on RF inactivation. The setup can provide added value to the scientific field, since (i) no consensus has been reached on the inactivation mechanisms of RF inactivation of pathogens in foods and (ii) most commercial RF setups are unsuitable to adopt for fundamental studies. [ABSTRACT FROM AUTHOR]

SUMMARY: Feed hygienics is of increasing concern for poultry producers. This project included 2 studies to investigate kinetic parameters for inactivation of Salmonella Typhimurium in mash broiler feed heated at various temperatures. In study one, 2- and 5-g feed samples, contained in a sample bag, were inoculated with S. Typhimurium and submerged in a water bath heated to 90°C until internal temperatures of 75°, 80°, and 85°C were reached. In study two, 2-g of sample were inoculated with S. Typhimurium and submerged into a water bath set at 75°, 80°, 85°, 90°, and 95°C heated for 0 to 180 s. Feed sample and water bath temperature were monitored by thermocouples. Thermocouple data demonstrated 2- and 5-g samples achieved a 5-log reduction of S. Typhimurium when internal temperature of feed reached 80°C and 85°C, respectively. D-values for linear and Weibull models were calculated for the 5 temperatures. D-values of the linear model were 6.70, 8.83, 12.05, 13.91, and 24.40 s, and D-values for the Weibull model were 2.27, 3.67, 3.95, 4.68, and 7.63 s when heated to 95°, 90°, 85°, 80°, and 75°C. Individual temperature datasets were further analyzed using GinaFit software. As heating temperature decreased, Double-Weibull and Biphasic models fit all the thermal data, indicating that Salmonella could have generated 2 subpopulations with different thermoresistance. Similar to other thermal inactivation models, this study demonstrates that linear, Weibull, Double-Weibull, and Biphasic models could be used to predict thermal inactivation of Salmonella in mash broiler feed. These data may contribute to establishing feed mill microbiological safety standards and reducing Salmonella contamination in broiler feed.

This study investigated the effectiveness of cooking processes that incorporated hydrated surface lethality (HSL) steps for ensuring the reduction of Salmonella on the surfaces of small-dimension meat and poultry products cooked using short-duration, high-temperature impingement oven processes. Whole-muscle chicken tenders (3% fat), beef patties (10% and 30% fat), pork patties (10% and 30% fat), and chicken patties (10% and 20% fat) were surface inoculated with a 5-strain mixture of Salmonella to yield 8 log colony-forming units/g, then cooked in a two-zone impingement oven using either dry heat or steam-humidified HSL processes. The HSL steps used steam injection to control the wet-bulb temperature at either 71.1°C or 82.2°C. Dry-heat cooking processes using a dry-bulb temperature of 204.4°C and no steam-injected HSL steps failed to consistently achieve a 6.5 log reduction of Salmonella on chicken tenders and the low-fat patty products (≤10% fat). In contrast, processes incorporating an HSL step using an 82.2°C wet-bulb temperature in one or both zones resulted in ≥6.5 log reductions of Salmonella for all products. Sufficient reductions were achieved regardless of whether this 82.2°C wet-bulb HSL step was incorporated before or after a dry-cook step. Processes that incorporated an HSL step using a 71.1°C wet-bulb temperature in both zones also resulted in reductions ≥6.5 log for all products. Processes using a 71.1°C wet-bulb HSL step in only one zone delivered ≥ 6.5 log reduction for all of the patty products. However, the one-zone 71.1°C HSL step achieved ≥6.5 log reduction in chicken tenders only if used in the first zone of the two-zone oven. When the 71.1°C HSL step was used in the second zone for chicken tenders after using dry heat in the first zone, the target reduction of 6.5 log was not achieved. This research successfully validated approaches to ensure ≥6.5 log reduction of Salmonella on product surfaces.

Risky home canning techniques are still performed for food preservation due to limited science-based recommendations. This study aimed to evaluate the inactivation of Shiga toxin-producing Escherichia coli O157:H7, Salmonella enterica (ser. Typhimurium, Enteritidis, and Infantis) and Listeria monocytogenes during home canning with a household dishwasher. The 450 mL of blended tomato (acidic liquid food) and potato puree (non-acidic solid food) were prepared with 1.5 % salt and 25 mL vinegar as model foods in glass jars (660 mL). The two model foods were sterilized, then inoculated with separate cocktails of each pathogen at 106–107 CFU/g. The prepared jars were placed in the bottom rack of a dishwasher and subjected to the following cycles: economic (50 °C, 122 min), express (60 °C, 54 min), and intensive (70 °C, 96 min). Temperature changes in jars were monitored by using thermocouples during heat treatment. Within the center of the jars, temperatures were measured as 45 to 53 °C in blended tomato and 44 to 52 °C in potato puree during all tested dishwasher cycles, respectively. The economic cycle treatment reduced S. enterica , E. coli O157:H7, and L. monocytogenes populations by 3.1, 4.6, and 4.2 log CFU/g in blended tomato (P ≤ 0.05), where a <1.0 log reduction was observed in potato puree (P > 0.05). All pathogens showed similar heat resistance during the express cycle treatment with a log reduction ranging from 4.2 to 5.0 log CFU/g in blended tomato and 0.6 to 0.7 log CFU/g in potato puree. Reduction in L. monocytogenes population was limited (0.6 log CFU/g) compared to E. coli O157:H7 (2.0 log CFU/g) and S. enterica (2.7 log CFU/g) in blended tomato during the intensive cycle treatment (P ≤ 0.05). Dishwasher cycles at manufacturer defined settings failed to adequately inactivate foodborne pathogens in model foods. This study indicates that home-canned vegetables may cause foodborne illnesses when dishwashers in home kitchens are used for heat processing. [Display omitted] • Home canning with dishwasher is proven as an unsafe food preservation technique. • Temperature in dishwasher may not reach to manufacturer defined settings. • Heat transfer is affected by food matrix during treatment with dishwasher cycles. • Heat treatment with dishwasher cycles is not effective to inactivate pathogens. [ABSTRACT FROM AUTHOR]

Pathogens, such as Salmonella and Listeria monocytogenes, can survive under the dry environment of flour for extended periods of time and could multiply when flour is hydrated to prepare batter or dough. Therefore, inactivation of these pathogens during the cooking/baking step is vital to ensure the microbiological safety of bakery products such as brownies. The aim of this research was to validate a simulated commercial baking process as a kill‐step for controlling Salmonella and L. monocytogenes in brownies and to determine thermal inactivation parameters of these pathogens in brownie batter. Independent studies were conducted in a completely randomized design for each pathogen. All‐purpose flour was inoculated with a 5‐serovar Salmonella and 3‐strain L. monocytogenes cocktails. For baking validation, brownie batters were prepared from inoculated flour, and cooked in the oven set at 350°F (176.7°C) for 40 min followed by 15 min of ambient air cooling. For calculating D‐values, brownie batter was transferred into thermal‐death‐time disks, sealed, and placed in hot‐water baths. The samples were held for pre‐determined time intervals in hot‐water baths and immediately transferred to cold‐water baths. Microbial populations were enumerated using injury‐recovery media. At the end of baking, Salmonella and L. monocytogenes populations decreased by 6.3 and 5.9 log CFU/g, respectively. D‐values of Salmonella and L. monocytogenes cocktails were 53.4 and 37.5 min at 64°C; 27.2 and 16.9 min at 68°C; 10.7 and 9.1 min at 72°C; and 4.6 and 7.3 min at 76°C; respectively. The z‐values of Salmonella and L. monocytogenes cocktails were 11.1 and 16.4°C, respectively. This study can be used as a supporting document for the validation of similar brownie baking processes to control Salmonella and L. monocytogenes. The data from this study can also be employed for developing basic prediction models for the survival and thermal resistance of these pathogens during brownie baking step. [ABSTRACT FROM AUTHOR]

A lab-scale low-power free-running radio frequency (RF) oscillator operating at a frequency of 27.12 ± 0.50 MHz was developed to be suitable for fundamental microbiological research topics. Calibration and validation were conducted for two common foodborne pathogens in relevant microbiological growth media, i.e., Salmonella Typhimurium and Listeria monocytogenes in Tryptic Soy Broth and Brain–Heart Infusion broth, respectively. The evolution of temperature, frequency, and power consumption was monitored during treatments, both with and without bacterial cells. The setup operated within the predefined frequency range, reaching temperatures of 71–76 °C after 15 min. The average power consumption ranged between 12 and 14 W. The presence of bacteria did not significantly influence the operational parameters. The inactivation potential of the RF setup was validated, demonstrating the absence of viable cells after 8 and 10 min of treatment, for S. Typhimurium and L. monocytogenes, respectively. In future studies, the setup can be used to conduct fundamental microbiological studies on RF inactivation. The setup can provide added value to the scientific field, since (i) no consensus has been reached on the inactivation mechanisms of RF inactivation of pathogens in foods and (ii) most commercial RF setups are unsuitable to adopt for fundamental studies.

Salmonella enterica is a major cause of foodborne pathogen contamination in the United States. The heat resistance of Salmonella increases as a w decreases, leading to a significant challenge in the design of thermal processes. The aluminum thermal death time (TDT) cell is a common experimental tool to study the isothermal resistance of Salmonella and other pathogenic bacteria in foods. However, the TDT cell has the problem of a relatively long come-up time, and it is difficult to seal. This research improved the previous design of aluminum TDT cells and evaluated the performance of the improved design by using the thermal inactivation data of Salmonella enterica cocktail and Enterococcus faecium in brown rice flour. The come-up time of brown rice flour was reduced significantly, from 2.33 min in the previous design to 0.67 min (40 s) in the improved design of test cells when immersed in an 85 °C glycol bath. With the increase of the cavity diameter of the cell, it was easy to load and unload food samples. Additional new features of the improved design included the wrench flats on the outer surface of cell wall. The D -values for Salmonella in the a w 0.45 (measured at 25 °C) brown rice flour were 42.70, 17.51, 8.11, and 2.27 min at 70, 75, 80, and 85 °C, respectively. The D -values for Enterococcus faecium were 65.82, 22.28, 6.05, and 1.86 min at 70, 75, 80, and 85 °C, respectively. This research shows that the improved design of test cells is a reliable experimental tool to study the thermal resistance of microorganisms in low-a w foods. Accurate detection of microbial survival under isothermal conditions will provide reliable data for modeling and pathogen control during thermal processing to help ensure food safety and quality. • This research improved the previous design of aluminum test cell. • The new design has short come-up time, it is easy to load and unload food samples. • Custom tightening fixtures are applied for better opening and closing the cell. • The improved design is reliable to study the thermal resistance of bacteria. [ABSTRACT FROM AUTHOR]

The enhanced thermal resistance of Salmonella in low-moisture foods (LMFs) presents a challenge when validating pathogen control processes. Product water is recognized as a controlling factor in thermal inactivation of Salmonella in or on LMFs, such as almonds. Water activity (aw) describes the state of water in a product; however, aw is temperature dependent and characterized by hysteresis between sorption states. Moisture content (%MC) describes the amount of water in a product; it is not temperature dependent and might be a more convenient metric than aw to account for water in thermal inactivation processes. To test these two metrics independently, Salmonella-inoculated almonds were equilibrated to two %MC levels but the same aw and to two aw levels but the same %MC. Equilibrated products were vacuum packaged and thermally treated in a water bath at 80°C. Survivors were recovered and enumerated. The resulting inactivation curves were used to fit the log-linear inactivation model, and the inactivation kinetics were compared. D-values ranged from 15.7 to 18.0 min, and the root mean square error was 0.25 to 0.69 log CFU/g. No differentiated (P > 0.05) effect attributable preferentially to aw or %MC was seen in the inactivation kinetics. The separate effects of aw and %MC on the inactivation kinetics of Salmonella in LMFs remain inconclusive, but analyses of data from prior studies strongly suggested an effect of sorption state. Further analysis is needed to identify which metric is best for modeling and validating thermal inactivation processes. [ABSTRACT FROM AUTHOR]

Recent recalls and outbreaks due to foodborne pathogens in thermally processed low-moisture foods highlight the need for the food industry to validate their thermal process. The purpose of this study was to validate baking as an adequate lethality step in controlling Salmonella and Listeria monocytogenes during the production of peanut butter (PB)–filled pretzels and whole wheat (WW) pita chips. Two dough types, PB-filled pretzel and WW pita chip with varying water activities (0.96 to 0.98), were inoculated (target level, ∼108 to 109 CFU/g) with a multistrain cocktail of Salmonella and L. monocytogenes in separate trials and were baked at 300°F (148.9°C) and 350°F (176.6°C) for 0, 5, 10, 17, 25, and 30 min. Following baking, samples were rapidly cooled and analyzed for Salmonella and L. monocytogenes by the pour plate method. Uninoculated samples were analyzed for total viable aerobic plate count (APC) and Enterobacteriaceae counts. Water activity analysis was also performed. The experiment was replicated three times. Nonlinear regression was used to estimate the baking times required to achieve a minimum of 4- and 5-log reduction in APC, Salmonella, and L. monocytogenes. A 4- and 5-log reduction in APC was predicted following a treatment at 350°F for 3.3 and 5.6 min in WW pita chip product, respectively. Following a treatment of 350°F for 10 and 25 min, Enterobacteriaceae and APC counts were below the detection limit (<1 log CFU/g), respectively, in all of the PB-filled pretzel samples. Salmonella and L. monocytogenes counts decreased with increasing baking time regardless of the temperature used. Significant reductions (≥5-log reduction) were estimated in Salmonella and L. monocytogenes in product baked at 350°F for 15.5 and 17.5 min in WW pita chip dough and PB-filled pretzel dough, respectively. Both pathogens were below the detection limit (<1 log CFU/g) in PB-filled pretzel and WW pita chip products under baking conditions of 350°F for 25 and 30 min, respectively. This study demonstrates that PB-filled pretzel and WW pita chip products, when baked to saleable quality, will not present a public health risk from the standpoint of Salmonella or L. monocytogenes. [ABSTRACT FROM AUTHOR]

Salmonella can survive in low-moisture, high-protein, and high-fat foods for several years. Despite nationwide outbreaks and recalls due to the presence of Salmonella in low-moisture foods, information on thermal inactivation of Salmonella in these products is limited. This project evaluated the impact of water activity (aw), temperature, and food composition on thermal inactivation of Salmonella enterica serovar Agona in defined high-protein and high-fat model food matrices. Each matrix was inoculated with Salmonella Agona and adjusted to obtain a target aw, ranging from 0.50 to 0.98. Samples were packed into aluminum test cells and heated (52 to 90°C) under isothermal conditions. Survival of Salmonella Agona was detected on tryptic soy agar with 0.6% yeast extract. Complex influences by food composition, aw, and temperature resulted in significantly different ( P < 0.05) thermal resistance of Salmonella for the conditions tested. It was estimated that the same point temperatures at which the D-values of the two matrices at each aw (0.63, 0.73, 0.81, and 0.90) were identical were 79.48, 71.28, 69.62, and 38.42°C, respectively. Above these temperatures, the D-values in high-protein matrices were larger than the D-values in high-fat matrices at each aw. Below these temperatures, the inverse relationship was observed. A correlation between temperature and aw existed on the basis of the level of fat or protein in the food, showing that these compositional factors must be accounted for when predicating thermal inactivation of Salmonella in foods. [ABSTRACT FROM AUTHOR]

On 10 August 2016, the Maricopa County Department of Public Health identified culture-confirmed Salmonella enterica serotype Javiana isolates from two persons who reported eating at a seafood restaurant; seven additional cases were reported by 15 August. We investigated to identify a source and prevent further illness. We interviewed persons with laboratory-reported Salmonella Javiana infection. Pulsed-field gel electrophoresis (PFGE) and whole genome sequencing of isolates were performed. A case was defined as diarrheal illness in a person during July to September 2016; confirmed cases had Salmonella Javiana isolate yielding outbreak-related PFGE patterns; probable cases had diarrheal illness and an epidemiologic link to a confirmed case. Case finding was performed (passive surveillance and identification of ill meal companions). A case-control study assessed risk factors for Salmonella Javiana infection among restaurant diners; control subjects were chosen among meal companions. No restaurant workers reported illness. Foods were reportedly cooked according to the Food Code. Food and environmental samples were collected and cultured; Salmonella Javiana with an indistinguishable PFGE pattern was isolated from portioned repackaged raw shrimp, halibut, and a freezer door handle. We identified 50 Salmonella Javiana cases (40 confirmed and 10 probable); illness onset range was from 22 July to 17 September 2016. Isolates from 40 patients had highly related PFGE patterns. Thirty-three (73%) of 45 patients interviewed reported eating at the restaurant. Among 21 case patients and 31 control subjects, unfried cooked shrimp was associated with illness (odds ratio, 6.7; 95% confidence interval, 1.8 to 24.9; P ¼ 0.004). Among restaurant diners, laboratory and case-control evidence indicated shrimp as the possible outbreak source; poor thermal inactivation of Salmonella on shrimp is theorized as a possible cause. Cross-contamination might have prolonged this outbreak; however, the source was not identified and highlights limitations that can arise during these types of investigations. [ABSTRACT FROM AUTHOR]

Water activity (a w ) influences the thermal resistance (D-value) of pathogens in low-moisture foods (LMF). However, the influence of food matrices on a w at elevated temperatures is complicated. A recent study reported that a novel thermal water activity cell (TAC) could be used to control a w of LMF using LiCl solution (select molality) during the isothermal determination of D-values of Salmonella . This research proposed a new version of TAC (TAC II) that could significantly reduce the time to establish the moisture-equilibrium between LMF and LiCl solutions during D-value measurements. Wheat flour (WF) samples inoculated with Salmonella (a w at room temperature = 0.45) were treated in TAC II at 80 °C under controlled relative humidity (RH) (50%) provided by LiCl solution (9.37 mol kg −1 ). Results showed that the moisture-equilibrium was established to the controlled RH condition at 80 °C in <4 min for tests with TAC II, as opposed to >14 min for TAC. The D-value of Salmonella PT30 in WF (80 °C, RH 50%) tested with TAC II (20.7 ± 1.1 min) was significantly higher ( p  < 0.05) than the reported result obtained from TAC. TAC II provides more accurate estimation of D value for giving relative humidity at high temeprature, and it offers to improve our understanding of the isolated effect of a w (corresponding RH) at high temperatures on the D-values of Salmonella in LMF. [ABSTRACT FROM AUTHOR]

Little research exists on Salmonella inactivation during extrusion processing, yet many outbreaks associated with low water activity foods since 2006 were linked to extruded foods. The aim of this research was to study Salmonella inactivation during extrusion of a model cereal product. Oat flour was inoculated with Salmonella enterica serovar Agona, an outbreak strain isolated from puffed cereals, and processed using a single-screw extruder at a feed rate of 75 kg/h and a screw speed of 500 rpm. Extrudate samples were collected from the barrel outlet in sterile bags and immediately cooled in an ice-water bath. Populations were determined using standard plate count methods or a modified most probable number when populations were low. Reductions in population were determined and analyzed using a general linear model. The regression model obtained for the response surface tested was Log ( NR/ NO) = 20.50 + 0.82 T − 141.16aw - 0.0039 T2 + 87.91 aw2 ( R2 = 0.69). The model showed significant ( p < 0.05) linear and quadratic effects of aw and temperature and enabled an assessment of critical control parameters. Reductions of 0.67 ± 0.14 to 7.34 ± 0.02 log CFU/g were observed over ranges of aw (0.72 to 0.96) and temperature (65 to 100 °C) tested. Processing conditions above 82 °C and 0.89 aw achieved on average greater than a 5-log reduction of Salmonella. Results indicate that extrusion is an effective means for reducing Salmonella as most processes commonly employed to produce cereals and other low water activity foods exceed these parameters. Thus, contamination of an extruded food product would most likely occur postprocessing as a result of environmental contamination or through the addition of coatings and flavorings. [ABSTRACT FROM AUTHOR]

In 2011, EFSA assessed the risk posed by the possible use of dead-in-shell chicks for the production of processed pet food. In 2014, the European Commission asked for an update on the risk posed by the same material but as raw material for the production of biogas and compost according to standard transformation parameters normally used for Category 3 material. According to current European Union legislation, the following processing method was considered: maximum particle size before entering the processing unit: 12 mm; minimum temperature in all material in the unit: 70°C; and minimum time in the unit without interruption: 60 minutes. A list of pathogens potentially present in the material to be treated was compiled and available literature data were used to assess the ability of the processing methods to inactivate the most resistant pathogens identified. Spores of Clostridium botulinum were identified as the most resistant hazard potentially present in the material to be processed. Circovirus and parvovirus and Enterococcus faecium were considered the most heat-resistant viruses and non-sporulating bacterium, respectively. Moreover, depending on storage conditions, the formation of bacterial toxins is possible. The processing methods considered were therefore assessed for their ability to inactivate those hazards. The probability of survival of pathogens related to the use of dead-in-shell chicks subjected to the treatment process was considered to be extremely low for the heat-sensitive pathogens that could be present in the material, which include bacteria such as Salmonella and avian influenza virus. However, this treatment is unable to sufficiently inactivate other relevant hazards (e.g. bacterial spores, thermoresistant viruses and certain bacterial toxins). [ABSTRACT FROM AUTHOR]

Abstract: Peanut butter has been implicated in multi-state outbreaks of salmonellosis in recent years. Studies have shown that Salmonella exhibited increased thermal resistance in peanut butter. However, little is known about the effect of product formulation on the kinetics of survival of Salmonella during thermal treatment. Therefore, the objective of this research was to compare the thermal resistance of Salmonella in four commercially available peanut butter and spread products, and evaluate the effect of product formulation on the survival of this pathogen during heating. Four peanut butter and spread samples, including Omega 3 (A), regular fat (B), reduced sugar (C), and reduced fat (D), inoculated with a 6-strain cocktail of Salmonella spp., were heated at 70, 75, 80, 85, and 90 °C. Experimental results showed that the highest thermal resistance of Salmonella was found in the samples with reduced fat, while the least in the samples with Omega 3 formulation. No significant difference in the bacterial thermal resistance was observed in the regular fat and reduced sugar formulations. The Weibull survival model was used to describe the survival curves. Results showed that the average exponent (shape factor) of the model ranged from 0.38 to 0.662, suggesting progressively decreased rate of inactivation during heating. The scale (rate) coefficients of the model increased linearly with temperature. The calculated minimum lethal temperature for Salmonella was 54.8, 59.8, 59.5, and 63.9 °C in samples A, B, C, and D, respectively. No tail effect was observed. The results of this study suggest that proper formulation of peanut butter and spread may enhance thermal inactivation of Salmonella. [Copyright &y& Elsevier]

This study explored the thermal characteristics (D- and z-values) of Salmonella Typhimurium in raw chicken shawirma. Marinated and non-marinated chicken breasts with skin were inoculated with S. Typhimurium 112 or S. Typhimurium 144. Inoculated samples were ground, packed in sterile bags and submerged in a water bath at 54, 56, 58 and 60°C for 2.5 to 72min. The mean D-values of S. Typhimurium strains in inoculated, non-marinated, ground raw chicken breast, as well as those of S. Typhimurium 15h after exposure to the marinade (inoculated before marinating, IBM) or after brief exposure (30min) to the marinade (inoculated after marinating, IAM) ranged from 9.15 to 12.44, 2.89 to 3.92, 1.06 to 1.30 and 0.32 to 0.52min at 54, 56, 58 and 60°C, respectively. Generally, no significant differences (P >0.05) were found among the D-values of S. Typhimurium in all chicken samples. However, the D-values of S. Typhimurium in raw ground chicken shawirma IBM were the lowest. The z-values of S. Typhimurium in all products ranged from 3.78 to 4.58°C. It was concluded that thorough cooking of the outside of the shawirma meat cylinder or cone before removal of slices at foodservice counters can enhance the safety of the product. [ABSTRACT FROM AUTHOR]

Aims: The purpose of this study was to determine the effect of moisture on thermal inactivation of Salmonella spp. in poultry litter under optimal composting conditions. Methods and Results: Thermal inactivation of Salmonella was studied in fresh poultry compost by simulating early phase of composting process. A mixture of three Salmonella serotypes grown in Tryptic soy broth with rifampin (TSB-R) was inoculated in fresh compost with 40 or 50% moisture at a final concentration of c. 7 log CFU g−1. The inoculated compost was kept in an environmental chamber which was programmed to rise from room temperature to target composting temperatures in 2 days. In poultry compost with optimal moisture content (50%), Salmonella spp. survived for 96, 72 and 24 h at 50, 55 and 60°C, respectively, as compared with 264, 144 and 72 h at 50, 55 and 60°C, respectively, in compost with suboptimal moisture (40%). Pathogen decline was faster during the come-up time owing to higher ammonia volatilization. Conclusions: Our results demonstrated that Salmonella spp. survived longer in fresh poultry compost with suboptimal moisture of 40% than in compost with optimal moisture of 50% during thermophilic composting. High nitrogen content of the poultry compost is an additional factor contributing to Salmonella inactivation through ammonia volatilization during thermal exposure. Significance and Impact of the Study: This research validated the effectiveness of the current composting guidelines on Salmonella inactivation in fresh poultry compost. Both initial moisture level and ammonia volatilization are important factors affecting microbiological safety and quality of compost product. [ABSTRACT FROM AUTHOR]

Abstract: The fate of manure-borne pathogen surrogates (gfp-labeled Escherichia coli O157:H7 and Listeria innocua and avirulent Salmonella Typhimurium) in the field was monitored at both sub-surface (30cm from surface) and surface sites of static composting piles (3.5-m base diameter) composed of chicken litter and peanut hulls. Despite exposure to elevated temperatures, Salmonella was detected by enrichment culture in sub-surface samples following 14days of composting. In surface samples, pathogen surrogates were detected in the summer after 4days of composting by enrichment culture only, whereas E. coli O157:H7 and L. innocua remained detectable by direct plating (>2log10 cfu/g) up to 28days in piles composted during the fall and winter. All three types of bacteria remained detectable by enrichment culture in surface samples composted for 56days during the winter. [Copyright &y& Elsevier]

We assessed the heat resistance of Salmonella in raw ground beef in both the absence and presence of sodium lactate, oregano oil, and in combinations of these 2 GRAS-listed ingredients, and determined their bactericidal or bacteriostatic activities during postthermal treatment storage at 15 °C. A cocktail of 8 serotypes of Salmonella spp. was inoculated into ground beef supplemented with sodium lactate (NaL) (1.5% and 3%) and/or oregano oil (0.5% and 1%) to obtain approximately 8 log CFU/g. The ground beef samples (3 g) were vacuum-packed and heated at 60, 65, or 71 °C in a circulating water bath for selected times to inactivate approximately 5 to 6 log CFU/g of the pathogen, and then stored at 15 °C for 15 and 30 d. Results show that especially at the lower cooking temperatures, addition of oregano oil increased the inactivation rate of Salmonella spp., whereas addition of NaL alone exhibited a protective effect against lethality and decreased the rate. Addition of combinations of oregano oil and NaL overcame this protective effect. During subsequent posttreatment storage for 15 d, Salmonella populations in the controls and in samples containing 0.5% oregano (60 and 65 °C) or 1% oregano oil (60 °C) increased to 4.5 to 6 log CFU/g. The values for all other samples were at or near undetectable levels. Results from the 30-d storage study were similar. These findings indicate that lactate and oregano oil may be used to render Salmonella spp. more susceptible to the lethal effect of heat and to inhibit growth of Salmonella spp. that survive heat treatments. [ABSTRACT FROM AUTHOR]

Abstract: Aerobic composting is a common management practice to inactivate pathogens in manure; however, additional research on the role of compost composition in pathogen inactivation is needed. The objective of this study was therefore to determine the effect of the carbon:nitrogen (C:N) ratio and the presence of ammonium sulfate on inactivation of Salmonella spp. in cow manure-based mixtures composted in a bioreactor under controlled conditions. Compost preparations with an initial C:N ratio of 20:1 required a maximum of 4days of storage before Salmonellae were inactivated by 7log10, whereas preparations with C:N ratios of 30:1 and 40:1 C:N required more than 5 and 7days of storage, respectively. The pH values of both the 20:1 and 30:1 C:N preparations decreased during the onset of composting before increasing to >8. In contrast, pH values of 40:1 C:N preparations increased immediately to >8, generally within the first day of storage. Maximum temperatures observed in 20:1 C:N preparations for inactivation of pathogens were less than 50°C, and the cumulative heat exposure required for pathogen inactivation in 20:1 C:N preparations was 15-fold less than in 40:1 C:N preparations. Supplementation of compost mixtures with 0.08% ammonium sulfate resulted in slightly higher temperatures; however, these higher temperatures did not translate into more rapid rates of pathogen inactivation. [Copyright &y& Elsevier]

Thermal inactivation of a four-strain mixture of Salmonella spp. was determined in chicken breast and thigh meat. Inoculated meat was packaged in bags and then completely immersed in a circulating water bath and held at 55, 57.5, 60 and 62.5 °C for pre-determined lengths of time. When the surviving bacteria were enumerated on tryptic soya agar supplemented with 0.6% yeast extract and 1% pyruvate (non-selective medium), D-values (time to inactivate 90% of bacteria) in chicken breast meat were 6.08, 4.77, 3.00 and 0.66 min at 55, 57.5, 60 and 62.5 °C, respectively; the values in thigh meat ranged from 11.48 min at 55 °C to 0.84 min at 62.5 °C. As expected, the measured heat resistance was lower when the recovery medium was selective (xylose lysine deoxycholate agar). Thermal death time values from this study will assist food processors in designing the HACCP plans to effectively eliminate Salmonella spp. in cooked chicken breast and thigh meat. [ABSTRACT FROM AUTHOR]

Abstract: Four food borne pathogens (Listeria monocytogenes CA and Ohio2, Salmonella enteritidis FDA and Salmonella typhimurium E21274, Escherichia coli O157:H7 931 and 933, Staphylococcus aureus 485 and 765) were inactivated under mild temperature (60°C) and their survival curves determined at selected time intervals. Tailing was observed in all survival curves as a monotonic upward concavity. The resulting survival curves were either described by the Weibull or traditional first-order model and goodness of fit of these models was investigated. Regression coefficients (R 2 ), root mean square error (RMSE) and correlation plots suggested that Weibull model produced a better fit to the data than the traditional model. Hazard plots suggested that the Weibull model was fully appropriate for the data being analysed. Although more studies should be carried out to evaluate the applicability of the nonlinear models, the present study has shown that thermal process calculations should most probably be reconsidered. This could lead to a reduction in under- and over-processing of thermally treated foods [Copyright &y& Elsevier]

Decimal reduction times ( D-values) and thermal resistance constants ( z-values) for 3 foodborne pathogenic bacteria in formulated ready-to-eat breaded pork patties were determined with thermal inactivation studies. Meat samples, inoculated with Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes cultures or uninoculated controls, were packaged in sterile bags, immersed in circulated water bath, and held at 55, 57.5, 60, 62.5, 65, 67.5, and 70 °C for different durations of time. The D- and z-values were determined by using a linear regression model. Average calculated D-values for E. coli O157:H7, Salmonella, and L. monocytogenes at a temperature range of 55 to 70 °C were 32.11 to 0.08 min, 69.48 to 0.29 min, and 150.46 to 0.43 min, respectively. Calculated z-values for E. coli O157:H7, Salmonella, and L. monocytogenes were 5.4, 6.2, and 5.9 °C, respectively. The results of this study will be useful to food processors to validate thermal lethality of the studied foodborne pathogens in ready-to-eat breaded pork patties. [ABSTRACT FROM AUTHOR]

Inactivation rates of a cocktail of Salmonella spp. in sous vide cooked beef exposed to varied ‘come-up’ heating times of zero (control), and 1–3 h from 10 °C to the processing temperature of 58 °C were examined. The observed survival curves, determined for 58 °C, displayed a slight ‘shoulder’ followed by a non-zero asymptotic D-values. Comparisons of the survival curves confirm that the rate of heating can substantially influence the heat resistance of Salmonella spp. While there was no significant difference between the estimated asymptotic D-values for the control and 1-h come-up heating time survival curves, the estimated D-values were significantly larger for the 2- and 3-h come-up heating times curves. The estimated averages of the asymptotic D-values for the control and 1-h come-up time survival curves are approximately 5.7 min; for the 2-h come-up time curves, 7 min; and for the 3-h come-up time curves, 8 min. These findings could have substantial practical importance to food processors in sous vide cooked beef that are processed by slow heating rate/long come-up times and low heating temperatures. [Copyright &y& Elsevier]

The quantitative risk assessment (QRA) approach recommended by the Codex Alimentarius Commission was used to assess the risk of human salmonellosis from the consumption of ‘cordon bleu’, a specific turkey product, in collective catering establishments (CCEs) of a French department. The complete process was modeled and simulated, from the initial storage in the CCE freezer to the consumption, using a Monte Carlo simulation software. Data concerning the prevalence of contaminated ‘cordon bleu’, the level of contamination of Salmonella, the cooking and storage process were collected from 21 CCEs and 8 retailers of ‘cordon bleu’ in the selected department. Thermal inactivation kinetics for Salmonella were established to estimate the effect of heat treatment on the concentration in the product and to calculate the dose that could be ingested by the consumer. The Beta-Poisson dose-response model of Rose and Gerba [Water Science and Technology 24 (1991) 29] with the specific parameters for Salmonella was used to estimate the probability of infection related to the ingestion of a particular dose and a factor was applied to estimate the probability of illness from ingestion. The individual risk of salmonellosis, the risk of outbreak and the number of cases were calculated using Monte Carlo simulation method. The risk of salmonellosis was close to zero when the ‘cordons bleus’ were cooked in the oven. Therefore, the risk was calculated for the fryer cooking since the insufficient cooking time observed was, sometimes, at the origin of low temperatures (37–89 °C). The influence of both the initial concentration of Salmonella in the product and the heat storage before consumption on the final risk was studied. For a high initial concentration of Salmonella in the product, when the ‘cordons bleus’ are fryer cooked, the average risk of salmonellosis was equal to 3.95×10−3 without storage before consumption and 2.8×10−4 if the product is consumed after storage.This paper presents the results of the QRA and discusses risk management options to minimize the risk of salmonellosis. [Copyright &y& Elsevier]

In 19.1% fat ground beef, Escherichia coli O157:H7 was less heat-resistant at ≥58 °C than the Salmonella typhimurium DT104 and Salmonella senftenberg, but at 55 °C the D value was similar to DT104 strains and higher than an eight-strain Salmonella cocktail. Inactivation of E. coli O157:H7 was more temperature-dependent than the cocktail and DT104 strains. E. coli and DT104 strains were more heat-resistant in beef containing 19% fat than 4.8% fat. The cocktail was more thermally stable in stationary as compared to log phase. Freezing of inoculated raw meat decreased heat resistance of the cocktail. The pathogenic strain, growth phase of the organism, state of the meat (fresh or frozen) and meat composition must be considered when designing protocols to verify thermal processes. [ABSTRACT FROM AUTHOR]