Search

Certain cheeses can be legally produced in the United States using raw milk, but they must be aged for at least 60 d to reduce pathogen risks. However, some varieties, even when aged for 60 d, have been shown to support growth of Listeria monocytogenes or survival of Shiga toxin–producing Escherichia coli (STEC). Thermization, as a subpasteurization heat treatment, has been proposed as a control to reduce the risk of pathogens in raw cheese milk while retaining some quality attributes in the cheese. However, the temperature and time combinations needed to enhance safety have not been well characterized. The objective of this research was to determine and validate decimal reduction values (D-values) for L. monocytogenes and STEC at thermization temperatures 65.6, 62.8, and 60.0°C; a D-value at 57.2°C was also determined for L. monocytogenes only. Nonhomogenized, pasteurized whole-milk samples (1 mL) were inoculated with 8-log cfu/mL L. monocytogenes or STEC (5- or 7-strain mixtures, respectively), vacuum-sealed in moisture-impermeable pouches, and heated via water bath submersion. Duplicate samples were removed at appropriate intervals and immediately cooled in an ice bath. Surviving bacteria were enumerated on modified Oxford or sorbitol MacConkey overlaid with tryptic soy agar to aid in the recovery of heat-injured cells. Duplicate trials were conducted, and survival data were used to calculate thermal inactivation rates. D65.6°C-, D62.8°C-, and D60.0°C-values of 17.1 and 7.2, 33.8 and 16.9, and 146.6 and 60.0 s were found for L. monocytogenes and STEC, respectively, and a D57.2°C-value of 909.1 s was determined for L. monocytogenes. Triplicate validation trials were conducted for each test temperature using 100 mL of milk inoculated with 3 to 4 log cfu/mL of each pathogen cocktail, A 3-log reduction of each pathogen was achieved faster in larger volumes than what was predicted by D-values (D-values were fail-safe). Data were additionally compared with published results from 21 scientific studies investigating L. monocytogenes and STEC in whole milk heated to thermization temperatures (55.0–71.7°C). These data can be used to give producers of artisanal raw-milk cheese flexibility in designing thermal processes to reduce L. monocytogenes and STEC populations to levels that are not infectious to consumers.

Biopreservatives are clean-label ingredients used to control pathogenic and spoilage microorganisms in ready-to-eat foods, including cheese. In a first set of experiments, the efficacies of six commercial biopreservatives in controlling Listeria monocytogenes growth at 4°C were tested in a high-moisture model cheese (pH 6.00, 56% moisture, and 1.25% salt) made of cream, micellar casein, water, salt, lactose, lactic acid, and a single protective culture (PC-1, PC-2, or PC-3 at 106 CFU/g [target]) or bacterial fermentate (CM-1 or CM-2 [cultured milk] or CSV-1 [cultured sugar-vinegar blend], 0.5 or 1.0% target level). Cheeses were inoculated with 3 log CFU/g L. monocytogenes (5-strain cocktail), after which 25-g samples were vacuum sealed and stored at 4°C for 8 weeks. L. monocytogenes populations from triplicate samples were enumerated weekly on modified Oxford agar in duplicate trials. L. monocytogenes growth (≥1-log increase) was observed in approximately 1 week in control cheese and those formulated with 106 CFU of PC-1 or PC-2 per g. Growth was delayed to 2.5 weeks in model cheeses formulated with 106 CFU of PC-3 per g or 0.5% CM-2 and to 3 weeks with 0.5% CM-1 or CSV-1. Growth was further delayed to 6.5 to 7.5 weeks in model cheeses formulated with 1.0% CM-1 or CM-2, while formulation with 1.0% CSV-1 inhibited L. monocytogenes growth for 8 weeks. In a second set of experiments, the combined effects of pH and 0.5% CSV-1 on L. monocytogenes inhibition were investigated. Incorporation of 0.5% CSV-1 delayed L. monocytogenes growth to 3, 6, and >10 weeks in cheeses of pH 6.00, 5.75, and 5.50, respectively, versus growth observed in 1, 1, and 3.5 weeks in control cheeses. These data suggest that certain fermentates have greater antilisterial activity than protective cultures in directly acidified cheeses with direct biopreservative incorporation and refrigerated storage. Further research is needed to optimize the conditions to prevent listerial growth by utilizing protective cultures in fresh, soft cheeses. HIGHLIGHTS

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.

Cooking temperature of poultry meat is typically inadequate to inactivate the heat resistant spores of Clostridium botulinum. The purpose of this study is to develop a predictive model for C. botulinum during cooling of cooked ground chicken. Cooked chicken was inoculated with a cocktail of five strains of proteolytic C. botulinum type A and five strains of proteolytic C. botulinum type B to yield a final spore concentration of approximately 2 log CFU/g. The growth of C. botulinum was determined at constant temperatures from 10 to 46 °C. Dynamic temperature experiments were performed with continued cooling from 54.4 to 4.4 °C or 7.2 °C in mono- or bi-phasic cooling profiles, respectively. The Baranyi primary model was used to fit growth data and the modified Ratkowsky secondary model was used to fit growth rates with respect to temperature. The primary models fitted the growth data well (R2 values ranging from 0.811 to 0.988). The R2 and root mean square error (RMSE) of the modified Ratkowsky secondary model were 0.95 and 0.06, respectively. Out of 11 prediction error values calculated in this study, ten were within the limit of acceptable prediction zone (−1.0 to 0.5), indicating a good fit of the model. The predictive model will assist institutional food service operations in determining the safety of cooked ground chicken subjected to different cooling periods.

Acidification and nutrient depletion by dairy starter cultures is often sufficient to prevent outgrowth of pathogens during post-processing of cultured dairy products. In the case of cottage cheese, however, the addition of cream dressing to the curd and subsequent cooling procedures can create environments that may be hospitable for the growth of Listeria monocytogenes. We report on a non-bacterio-cinogenic Lacticaseibacillus rhamnosus strain that severely limits the growth potential of L. monocytogenes in creamed cottage cheese. The main mechanism underlying Listeria spp. inhibition was found to be caused by depletion of manganese (Mn), thus through competitive exclusion of a trace element essential for the growth of many microorganisms. Growth of Streptococcus thermophilus and Lactococcus lactis that constitute the starter culture, on the other hand, were not influenced by reduced Mn levels. Addition of L. rhamnosus with Mn-based bioprotective properties during cottage cheese production therefore offers a solution to inhibit undesired bacteria in a bacteriocin-independent fashion.

Sodium is an essential nutrient with important functions in regulating extracellular fluid volume and the active transport of molecules across cell membranes. However, recent estimates from NHANES III (Third National Health and Nutrition Examination Survey) data show that over 95% of men and over 75% of women exceed the recommended daily tolerable upper intake of sodium. Since these high levels of dietary sodium are associated with a high prevalence of hypertension, prehypertension and, possibly, other adverse effects on health, many national and international health organizations recommend that sodium intake be significantly decreased. Traditionally, salt (sodium chloride) has been used as a food preservative that kills or limits the growth of foodborne pathogens and spoilage organisms by decreasing water activity. Salt also performs other important functions in foods by adding flavor and masking bitter tastes, controlling growth of yeast and fermentative bacteria, and promoting binding of proteins and other components in foods to achieve desired textures. Many processed foods contain high levels of salt and several countries have developed national programs for significantly reducing the sodium chloride content in many processed foods and encouraging a decrease in discretionary salt use. This review considers published data on the apparent adverse health effects of excess salt intake as well as the important functions of salt in different foods and possible strategies for reducing sodium levels in processed foods while still producing safe foods that consumers find acceptable.

USDA, FSIS thermal processing guidelines (e.g. Appendix A for cooked beef, roast beef, and cooked corned beef, and Time-Temperature Tables for Cooking Ready-to-Eat Poultry Products) are widely used as validation support for cooking processes, but these procedures were developed and validated only for Salmonella in a limited number of products. To determine the extent to which Appendix A can safely be applied to other pathogens and products, a study was conducted to compare the thermal-death times of Salmonella, Listeria monocytogenes, and shiga toxin-producing E. coli (STEC) in model products representing roast beef, turkey breast, and boneless ham. Raw batter for each of the 3 products was inoculated with 8 log CFU/g of a multi-strain mixture of L. monocytogenes, Salmonella, or STEC. One-gram portions of inoculated roast beef, turkey breast, or ham batter were flattened into a thin film in moisture-impermeable pouches, vacuum-packaged, and heated at 54.4, 60.0, 65.6, or 71.1°C in a water bath. Triplicate samples were removed at predetermined time points and enumerated for surviving pathogens. The time needed to yield a 6.5-log reduction of Salmonella and STEC at 60.0, 65.6, or 71.1°C for the three product types was comparable to the times prescribed by USDA, FSIS Appendix A for Salmonella inactivation; however, at 54.4°C similar inactivation levels were not observed. L. monocytogenes showed greater thermotolerance than Salmonella and STEC for all 3 product types. These data suggest that current USDA, FSIS thermal processing guidelines are acceptable tools for ensuring the safety of cooking processes at 60.0°C or higher to inactivate Salmonella and STEC in the product types, but longer dwell times may be necessary to yield comparable log reduction of L. monocytogenes.

The 1986 Food Research Institute-Tanaka et al. model predicts the safety of shelf-stable process cheese spread formulations using the parameters of moisture, pH, NaCl, and disodium phosphate (DSP) to inhibit toxin production by Clostridium botulinum. Although this model is very reliable for predicting safety for standard-of-identity spreads, the effects of additional factors have not been considered. The objective of this study was to create a predictive model to include the interactive effect of moisture, pH, fat, sorbic acid, and potassium-based replacements for NaCl and DSP to reflect modern reduced-sodium recipes. Eighty formulations were identified using a central composite design targeting seven factors: 50 to 60% moisture, pH 5.4 to 6.2, 0 to 0.2% sorbic acid, 10 to 30% fat, 1.7 to 2.4% NaCl, 0.8 to 1.6% DSP, and 0 to 50% potassium replacement for sodium salts. Samples were inoculated with proteolytic C. botulinum spores at 3 log spores per g, hot filled into sterile vials, and stored anaerobically at 27°C. Samples were assayed at 0, 1, 2, 3, 4, 8.5, 17.5, 26, and 40 weeks for the presence of botulinum toxin using the mouse bioassay. A parametric survival model was fit to the censored time-to-toxin data. All linear, quadratic, and pairwise effects were considered for model fit. As hypothesized, the effects of pH, sorbate, moisture, DSP, and NaCl were highly significant (P < 0.001). Fat concentration and potassium replacement effects were significant at P < 0.021 and P < 0.057, respectively. The model consistently predicted the safety failure of the toxic samples, but it also predicted failure for some samples that were not toxic. This model is an adjunct to existing models by adding the factors of potassium salts, fat, and sorbic acid to predict the botulinal safety of prepared process cheese products but is not intended to be a substitute for formulation evaluation by a competent process authority.

Clostridium botulinum may be of concern in prepared refrigerated meals, for which strict cold chain management cannot be guaranteed. This study evaluated the effect of temperature, product composition, and cultured celery juice powder (CCJP) as a source of nitrite on the inhibition of botulinum toxin formation in two experimental (meat- and vegetable-based) prepared meals. Data obtained from the challenge study were compared with a published mathematical model to determine whether the model is fail-safe with regard to the tested meals. Treatments were inoculated with proteolytic C. botulinum, vacuum packaged, cooked at 90°C for 10 min, and assayed for botulinum toxin at appropriate intervals in samples stored at 10, 15, or 20°C for up to 8 weeks. None of the treatments stored at 10°C for 8 weeks supported toxin production by proteolytic C. botulinum. The addition of CCJP delayed toxin production by 1 and 3 weeks in cauliflower potatoes and in Dijon pork, respectively, stored at 15°C. Toxin production was delayed by 1 week at 20°C when CCJP was added to the cauliflower potatoes. This study found that the predictive model was fail-safe but was overly conservative for the experimental meals described. Finally, this study confirms that product composition, the addition of nitrite via CCJP, storage time, and temperature play important roles in the inhibition of toxin formation by proteolytic C. botulinum.

Clostridium botulinum is a foreseeable biological hazard in prepared refrigerated meals that needs to be addressed in food safety plans. The objective of this study was to evaluate the effect of product composition and storage temperature on the inhibition of botulinum toxin formation in nine experimental meals (meat, vegetable, or carbohydrate based). Treatments were inoculated with proteolytic C. botulinum, vacuum packaged, cooked at 90°C for 10 min, and assayed for botulinum toxin in samples stored at 25°C for up to 96 h for phase 1, or at 25°C for 12 h and then transferred to 12.5°C for up to 12 and 6 weeks in phases 1 and 2, respectively. For phase 1, none of the treatments (equilibrated pH 5.8) supported toxin production when stored at 25°C for 48 h, but toxin production was observed in all treatments at 72 h. For the remaining experiments with storage at 12.5°C, toxin production was dependent on equilibrated pH, storage time, and growth of indigenous spoilage microorganisms. In phase 1, no gross spoilage and no botulinum toxin was detected for any treatment (pH ≤5.8) stored at 12.5°C for 12 weeks. In phase 2, gross spoilage varied by commodity, with the brussels sprouts meal with pH 6.5 showing the most rapid spoilage within 2 weeks and botulinum toxin detected at 5 and 6 weeks for the control and cultured celery juice treatments, respectively. In contrast, spoilage microbes decreased the pH of a pH 5.9 beef treatment by 1.0 unit, potentially inhibiting C. botulinum through 6 weeks at 12.5°C. None of the other treatments with pH 5.8 or below supported toxin production or spoilage. This study provides validation for preventive controls in refrigerated meals. These include equilibrated product pH and storage temperature and time to inhibit toxin formation by proteolytic C. botulinum, but the impact of indigenous microflora on safety and interpretation of challenge studies is also highlighted.

High-moisture, low-acid cheeses have been shown to support Listeria monocytogenes growth during refrigerated storage. Prior studies suggest that organic acids vary in their antilisterial activity and that cheeses of lower pH delay growth longer than those of higher pH; however, no standard pH value for Listeria control in cheese exists. The objective of this research was to create a predictive model to include the effects of acid type, pH, and moisture on the growth of L. monocytogenes in a model cheese system. Cream, micellar casein, water, lactose, salt, and acid (citric, lactic, acetic, or propionic) were combined in 32 formulations targeting 4 pH values (5.25, 5.50, 5.75, and 6.00) and two moisture levels (50 and 56%). Each was inoculated with 3 log CFU/g L. monocytogenes (five-strain mixture) after which 25-g samples were vacuum sealed and stored 8 weeks at 4°C. Triplicate samples were enumerated on modified Oxford agar weekly in duplicate trials. Model cheeses formulated with acetic and propionic acids inhibited growth (i.e., no observed increase in L. monocytogenes populations over 8 weeks) at pH ≤5.75, while those formulated with lactic acid inhibited growth at pH 5.25 only. In contrast, all model cheeses formulated with citric acid supported growth. Resulting growth curves were fitted for lag phase and growth rate before constructing models for each. The pH and acid type were found to significantly affect both growth parameters (P0.05), while moisture (50 to 56%) was not statistically significant in either model (P ≥ 0.05). The effects of acetic and propionic acid were not significantly different. In contrast, model cheeses made with citric acid had significantly shorter lag phases than the other acids tested, but growth rates after lag were statistically similar to model cheeses made with lactic acid. These data suggest propionic ∼ aceticlacticcitric acids in antilisterial activity within the model cheese system developed and can be used in formulating safe high-moisture cheeses.

The antilisterial activity of sodium diacetate and a commercial shelf-life extender (ALTA™ 2341) were monitored at 25°C in slurries prepared with turkey breast meat. In slurries prepared without either ingredient, populations of Listeria monocytogenes increased about 5-log10 units in 7 d. The addition of 0.3% diacetate extended the generation time (7 h) compared to the control (no food additives; 1.7 h), whereas 0.5% inhibited the pathogen somewhat (0.4-log10 unit decrease in 7 d compared to the control). Slurries containing ALTA (0.25, 0.5, or 0.75%) and 0.3% diacetate extended the lag phase of L. monocytogenes to a greater extent than slurries with 0.3% diacetate alone. In contrast, 0.5% diacetate in combination with all three levels of ALTA tested was listericidal (ca. 2-log10 unit decrease after 7 d compared to the control). These data confirm the efficacy of diacetate for inhibiting L. monocytogenes in turkey meat and indicate that multiple barriers such as diacetate with ALTA may further lessen the likelihood of food-related listeriosis.

Two new varieties of commercial low-calorie mayonnaise, i.e., cholesterol-free, reduced-calorie (CFM) and reduced-calorie (RCM), made with different levels of acetic acid, were evaluated to determine the survival characteristics of Salmonella or Listeria monocytogenes . Two formulations of CFM, made with 0.3 or 0.7% acetic acid in the aqueous phase, and four formulations of RCM, made with 0.1, 0.3, 0.5, or 0.7% acetic acid in the aqueous phase, were evaluated. The initial pH of the products after equilibration ranged from 3.9 to 4.3, which was adjusted by addition of HCl. Products were inoculated with an eight- or six-strain mixture of Salmonella sp. or L. monocytogenes , respectively, at ca. 106 CFU per gram and held at 23.9°C for up to 2 weeks. L. monocytogenes survived longer than Salmonella in equivalent preparations of mayonnaise. No Salmonella (per 100 g) was detected at 48 h in either variety of mayonnaise made with 0.7% acetic acid in the aqueous phase. Salmonella levels in mayonnaise made with lower levels of acetic acid decreased during storage, and at 2 weeks the organism was not detectable in samples containing 0.3% acetic acid in the aqueous phase. No L. monocytogenes (per 100 g) was detected at 14 or 10 d postinoculation in CFM or RCM, respectively, made with 0.7% acetic acid in the aqueous phase. Results indicate these new varieties of mayonnaise, when formulated with 0.7% acetic acid in the aqueous phase, will inactivate >107 Salmonella and >104 L. monocytogenes per gram within the 72-h holding time required for regular mayonnaise made with unpasteurized eggs. Hence, properly acidified (pH

Listeria monocytogenes may survive the typical process used to produce sausage such as pepperoni and hard salami that is made from uncooked meat. Studies were done to identify heat treatments that could be applied during sausage-making to inactivate the organism to undetectable levels. Initial studies with beaker sausage revealed that heat treatments of 51.7°C for 8 h or 57.2°C for 4 h reduced L. monocytogenes counts by >2 log10 CFU/g, but for each treatment the organism was detected by enrichment in one of two samples. Heating beaker sausage to an internal temperature of 62.8°C inactivated listeriae to undetectable levels. Studies with pepperoni revealed that heating sausage at 51.7°C for 4 h after fermentation but before the drying cycle killed most L. monocytogenes , but the organism was occasionally detected in samples during drying. Heating pepperoni at 51.7°C for 4 h after the drying cycle completely inactivated L. monocytogenes in all samples. An additional study done to determine the fate of L. monocytogenes in beaker sausage made with and without lactic starter culture revealed that the organism could grow at 32.2°C in sausage batter during the fermentation period if the lactic starter culture was not added. The organism did not grow, but was reduced by about 1 to 2 log10 CFU/g during fermentation, in sausage made with lactic starter culture.

A dynamic model to predict the germination and outgrowth of Clostridium botulinum spores in cooked ground beef was presented. Raw ground beef was inoculated with a ten-strain C. botulinum spore cocktail to achieve approximately 2 log spores/g. The inoculated ground beef was vacuum packaged, cooked to 71 °C to heat shock the spores, cooled to below 10 °C, and incubated isothermally at temperatures from 10 to 46 °C. C. botulinum growth was quantified and fitted into the primary Baranyi Model. Secondary models were fitted to maximum specific growth rate and lag phase duration using Modified Ratkowsky equation (R2 0.96) and hyperbolic function (R2 0.94), respectively. Similar experiments were also performed under non-isothermal (cooling) conditions. Acceptable zone prediction (APZ) analysis was conducted on growth data collected over 3 linear cooling regimes from the current study. The model performance (prediction errors) for all 22 validation data points collected in the current work were within the APZ limits (−1.0 to +0.5 log CFU/g). Additionally, two other growth data sets of C. botulinum reported in the literature were also subjected to the APZ analysis. In these validations, 20/22 and 10/14 predictions fell within the APZ limits. The model presented in this work can be employed to predict C. botulinum spore germination and growth in cooked uncured beef under non-isothermal conditions. The beef industry processors and food service organizations can utilize this predictive microbial model for cooling deviations and temperature abused situations and in developing customized process schedules for cooked, uncured beef products.

The antimicrobial impact of purified and natural sources of both nitrite and ascorbate were evaluated against Clostridium perfringens during the postthermal processing cooling period of deli-style turkey breast. The objective of phase I was to assess comparable concentrations of nitrite (0 or 100 ppm) and ascorbate (0 or 547 ppm) from both purified and natural sources. Phase II was conducted to investigate concentrations of nitrite (50, 75, or 100 ppm) from cultured celery juice powder and ascorbate (0, 250, or 500 ppm) from cherry powder to simulate alternative curing formulations. Ground turkey breast (75% moisture, 1.2% salt, pH 6.2) treatments were inoculated with C. perfringens spores (three-strain mixture) to yield 2.5 log CFU/g. Individual 50-g portions were vacuum packaged, cooked to 71.1°C, and chilled from 54.4 to 26.7°C in 5 h and from 26.7 to 7.2°C in 10 additional hours. Triplicate samples were assayed for growth of C. perfringens at predetermined intervals by plating on tryptose-sulfite-cycloserine agar; experiments were replicated three times. In phase I, uncured, purified nitrite, and natural nitrite treatments without ascorbate had 5.3-, 4.2-, and 4.4-log increases in C. perfringens, respectively, at 15 h, but

To control the growth of Clostridium perfringens in cured meat products, the meat and poultry industries commonly follow stabilization parameters outlined in Appendix B, "Compliance Guidelines for Cooling Heat-Treated Meat and Poultry Products (Stabilization)" ( U.S. Department of Agriculture, Food Safety and Inspection Service [USDA-FSIS], 1999 ) to achieve cooling (54.4 to 4.4°C) within 15 h after cooking. In this study, extended cooling times and their impact on C. perfringens growth were examined. Phase 1 experiments consisted of cured ham with 200 mg/kg ingoing sodium nitrite and 547 mg/kg sodium erythorbate following five bilinear cooling profiles: a control (following Appendix B guidelines: stage A cooling [54.4 to 26.7°C] for 5 h, stage B cooling [26.7 to 4.4°C] for 10 h), extended stage A cooling for 7.5 or 10 h, and extended stage B cooling for 12.5 or 15 h. A positive growth control with 0 mg/kg nitrite added (uncured) was also included. No growth was observed in any treatment samples except the uncured control (4.31-log increase within 5 h; stage A). Phase 2 and 3 experiments were designed to investigate the effects of various nitrite and erythorbate concentrations and followed a 10-h stage A and 15-h stage B bilinear cooling profile. Phase 2 examined the effects of nitrite concentrations of 0, 50, 75, 100, 150, and 200 mg/kg at a constant concentration of erythorbate (547 mg/kg). Results revealed changes in C. perfringens populations for each treatment of 6.75, 3.59, 2.43, -0.38, -0.48, and -0.50 log CFU/g, respectively. Phase 3 examined the effects of various nitrite and erythorbate concentrations at 100 mg/kg nitrite with 0 mg/kg erythorbate, 100 with 250, 100 with 375, 100 with 547, 150 with 250, and 200 with 250, respectively. The changes in C. perfringens populations for each treatment were 4.99, 2.87, 2.50, 1.47, 0.89, and -0.60 log CFU/g, respectively. Variability in C. perfringens growth for the 100 mg/kg nitrite with 547 mg/kg erythorbate treatment was observed between phases 2 and 3 and may have been due to variations in treatment pH and NaCl concentrations. This study revealed the importance of nitrite and erythorbate for preventing growth of C. perfringens during a much longer (25 h) cooling period than currently specified in the USDA-FSIS Appendix B.

A Cheddar cheese model system, Cheddar cheese extract, was used to examine how different levels of known microbial hurdles (NaCl, pH, and lactic acid) in Cheddar cheese contribute to inhibition of bacterial pathogens. This knowledge is critical to evaluate the safety of Cheddar varieties with altered compositions. The range of levels used covered the lowest and highest level of these factors present in low-sodium, low-fat, and traditional Cheddar cheeses. Four pathogens were examined in this model system at 11°C for 6 wk, with the lowest levels of these inhibitory factors that would be encountered in these products. The 4 pathogens examined were Salmonella enterica , Staphylococcus aureus , Listeria monocytogenes , and Shiga toxin-producing Escherichia coli (STEC). None of these organisms were capable of growth under these conditions. The STEC exhibited the highest survival and hence was used to examine which of these inhibitory factors (NaCl, pH, and lactic acid) was primarily responsible for the observed inhibition. The STEC survival was examined in Cheddar cheese extract varying in NaCl (1.2 vs. 4.8%), lactic acid (2.7 vs. 4.3%), and pH (4.8 vs. 5.3) at 11°C for 6 wk. The microbial hurdle found to have the greatest effect on STEC survival was pH. The interactions between pH and levels of protonated lactic acid and anionic lactic acid with STEC survival was also evaluated; only the concentration of protonated lactic acid was determined to have a significant effect on STEC survival. These results indicate that, of the pathogens examined, STEC is of the greatest concern in Cheddar varieties with altered compositions and that pH is the microbial hurdle primarily responsible for controlling STEC in these products.

Fermentation-derived nitrite (NO2) from vegetable sources is increasingly used as a "clean label" alternative to conventional NaNO2. Previous results suggested that processed meats cured with NO2 derived from a "natural" source had lower antimicrobial activity than did meats produced with chemical NaNO2; however, the differences were likely due to NO2 concentration rather than source. The objective of this study was to compare the antilisterial properties of traditional and clean label alternative curing approaches when combined with antimicrobials in deli-style turkey. Listeria monocytogenes inhibition by NO2 from synthetic and natural sources was validated in deli-style turkey (73 to 74% moisture, 1.8% salt, pH 6.4). Products were prepared with 0, 80, or 120 mg/kg NO2 using purified NaNO2 or cultured celery powder. Additional treatments were supplemented with 3.8% lactate-diacetate blend (LD) or 1% cultured sugar-vinegar blend (DF). Sliced cooked products were surface inoculated with L. monocytogenes at 3 log CFU/g, vacuum packaged, and stored at 4°C for 12 weeks. Results revealed an average 2.4-log increase in L. monocytogenes at 3 weeks in the control without antimicrobials, a 1.3-log increase at 4 weeks for both 80 mg/kg NO2 treatments, and a 1.5-log increase at 6 weeks for the 120 mg/kg NO2 treatments. No significant difference (P > 0.05) in growth inhibition was found between NO2 sources when equivalent concentrations were added. In uncured turkey with 3.8% LD or 1% DF, growth was delayed until 6 weeks, whereas supplementation with LD or DF and 80 mg/kg NO2 from either source delayed listerial growth through 12 weeks. This study confirmed that the concentration of NO2, rather than the source, is a primary factor in enhancing the safety of ready-to-eat meats. Both conventional NO2 treatments and a clean label solution consisting of a fermentation-derived antimicrobial combined with 80 mg/kg naturally derived NO2 inhibited L. monocytogenes through 12 weeks of storage at 4°C.

Listeria monocytogenes growth can be controlled on ready-to-eat meats through the incorporation of antimicrobial ingredients into the formulation or by postlethality kill steps. However, alternate approaches are needed to provide options that reduce sodium content but maintain protection against pathogen growth in meats after slicing. The objective of this study was to determine the inhibition of L. monocytogenes by propionic acid-based ingredients in high-moisture, cured turkey stored at 4 or 7°C. Six formulations of sliced, cured (120 ppm of NaNO2 ), deli-style turkey were tested, including control without antimicrobials, 3.2% lactate-diacetate blend (LD), 0.4% of a liquid propionate-benzoate-containing ingredient, or 0.3, 0.4, and 0.5% of a liquid propionate-containing ingredient. Products were inoculated with 5 log CFU L. monocytogenes per 100-g package (3 log CFU/ml rinsate), vacuum-sealed, and stored at 4 or 7°C for up to 12 weeks; and populations were enumerated by plating on modified Oxford agar. As expected, the control without antimicrobials supported rapid growth, with2 log average per ml rinsate increase within 4 weeks of storage at 4°C, whereas growth was observed at 6 weeks for the LD treatment. For both replicate trials, all treatments that contained liquid propionate or propionate-benzoate limited L. monocytogenes growth to an increase of1 log through 9 weeks storage at 4°C. Sporadic growth (1-log increase) was observed in individual samples for all propionate-containing treatments at weeks 10, 11, and 12. As expected, L. monocytogenes grew more rapidly when products were stored at 7°C, but trends in relative inhibition were similar to those observed at 4°C. These results verify that propionate-based ingredients inhibit growth of L. monocytogenes on sliced, high-moisture, cured turkey and can be considered as an alternative to reduce sodium-based salts while maintaining food safety.

The objective of this study was to identify ingredients that inhibit Listeria monocytogenes in natural, organic, or clean-label ready-to-eat meat and poultry products. Fourteen ingredients were screened in uncured (no-nitrate-or-nitrite-added), traditional-cured (156 ppm of purified sodium nitrite), cultured (alternative cured, natural nitrate source, and Staphylococcus carnosus), or preconverted (alternative cured, natural nitrite source) turkey slurries. Slurries were cooked, cooled, inoculated to yield 3 log CFU/ml L. monocytogenes, stored at 4°C, and tested weekly for 4 weeks. Three antimicrobial ingredients, 1.5 % vinegar-lemon-cherry powder blend, 2.5 % buffered vinegar, and 3.0 % cultured sugar-vinegar blend, were incorporated into alternative-cured ham and uncured roast beef and deli-style turkey breast. Controls included all three meat products without antimicrobial ingredients and a traditional-cured ham with 2.8 % sodium lactate-diacetate. Cooked, sliced products were inoculated with 3 log CFU/g L. monocytogenes, vacuum packed, and stored at 4 or 7°C, for up to 12 weeks. For control products without antimicrobial agents stored at 4°C, a 2-log L. monocytogenes increase was observed at 2 weeks for ham and turkey and at 4 weeks for roast beef. Growth (>1-log increase) in the sodium lactate-diacetate was delayed until week 6. Compared with the control, the addition of either vinegar-lemon-cherry powder blend or buffered vinegar delayed L. monocytogenes growth for an additional 2 weeks, while the addition of cultured sugar-vinegar blend delayed growth for an additional 4 weeks for both ham and turkey. The greatest L. monocytogenes delay was observed in roast beef containing any of the three antimicrobial ingredients, with no growth detected through 12 weeks at 4°C for all the treatments. As expected, L. monocytogenes grew substantially faster in products stored at 7°C than at 4°C. These data suggest that antimicrobial ingredients from a natural source can enhance the safety of ready-to-eat meat and poultry products, but their efficacy is improved in products containing nitrite and with lower moisture and pH.

Sodium nitrite has been identified as a key antimicrobial ingredient to control pathogens in ready-to-eat (RTE) meat and poultry products, including Listeria monocytogenes. This study was designed to more clearly elucidate the relationship between chemical factors (ingoing nitrite, ascorbate, and residual nitrite) and L. monocytogenes growth in RTE meats. Treatments of cooked, cured pork sausage (65% moisture, 1.8% salt, pH 6.6, and water activity 0.98) were based on response surface methodology with ingoing nitrite and ascorbate concentrations as the two main factors. Concentrations of nitrite and ascorbate, including star points, ranged from 0 to 352 and 0 to 643 ppm, respectively. At one of two time points after manufacturing (days 0 and 28), half of each treatment was surface inoculated to target 3 log CFU/g of a five-strain L. monocytogenes cocktail, vacuum packaged, and stored at 7°C for up to 4 weeks. Growth of L. monocytogenes was measured twice per week, and enumerations were used to estimate lag time and growth rates for each treatment. Residual nitrite concentrations were measured on days 0, 4, 7, 14, 21, and 28, and nitrite depletion rate was estimated by using first-order kinetics. The response surface methodology was used to model L. monocytogenes lag time and growth rate based on ingoing nitrite, ascorbate, and the residual nitrite remaining at the point of inoculation. Modeling results showed that lag time was impacted by residual nitrite concentration remaining at inoculation, as well as the squared term of ingoing nitrite, whereas growth rate was affected by ingoing nitrite concentration but not by the remaining residual nitrite at the point of inoculation. Residual nitrite depletion rate was dependent upon ingoing nitrite concentration and was only slightly affected by ascorbate concentration. This study confirmed that ingoing nitrite concentration influences L. monocytogenes growth in RTE products, yet residual nitrite concentration contributes to the antimicrobial impact of nitrite as well.

The objective of this study was to identify concentrations of sorbate, benzoate, and propionate that prevent the growth of Listeria monocytogenes on sliced, cooked, uncured turkey breast and cured ham. Sixteen test formulations plus a control formulation for each product type were manufactured to include potassium sorbate, sodium benzoate, or sodium propionate, used alone and combined (up to 0.3% [wt/wt]), or with sodium lactate-sodium diacetate combinations. Products were inoculated with L. monocytogenes (5 log CFU/100-g package) and stored at 4, 7, or 10 degrees C for up to 12 weeks, and triplicate samples per treatment were assayed biweekly by plating on modified Oxford agar. Data showed that 0.1% benzoate, 0.2% propionate, 0.3% sorbate, or a combination of 1.6% lactate with 0.1% diacetate prevented the growth of L. monocytogenes on ham stored at 4 degrees C for 12 weeks, compared with greater than a 1-log increase at 4 weeks for the control ham without antimicrobials. When no nitrite was included in the formulation, 0.2% propionate used alone, a combination of 0.1% propionate with 0.1% sorbate, or a combination of 3.2% lactate with 0.2% diacetate was required to prevent listerial growth on the product stored at 4 degrees C for 12 weeks. Inhibition was less pronounced when formulations were stored at abuse temperatures. When stored at 7 degrees C, select treatments delayed listerial growth for 4 weeks but supported significant growth at 8 weeks. All treatments supported more than a 1-log increase in listerial populations when stored at 10 degrees C for 4 weeks. These results verify that antimycotic agents inhibit the growth of L. monocytogenes on ready-to-eat meats but aremore effective when used in combination with nitrite.

A 2014 multistate listeriosis outbreak was linked to consumption of caramel-coated apples, an unexpected and previously unreported vehicle for Listeria monocytogenes. This outbreak was unanticipated because both the pH of apples (3 log10 in apples with sticks, whereas only a 1-log10 increase was observed even after 1 week for caramel-coated apples without sticks. When stored at 7°C, apples with sticks exhibited an approximately 1.5-log10 increase in L. monocytogenes levels at 28 days, whereas no growth was observed in apples without sticks. We infer that insertion of a stick into the apple accelerates the transfer of juice from the interior of the apple to its surface, creating a microenvironment at the apple-caramel interface where L. monocytogenes can rapidly grow to levels sufficient to cause disease when stored at room temperature., IMPORTANCE Neither caramel nor apples are a food where the pathogenic bacterium Listeria monocytogenes should grow, as caramel does not contain enough free water and apples are too acidic. Caramel-coated apples, however, were recently linked to a deadly outbreak of listeriosis. We hypothesized that inserting a stick into the apple releases juice to the interface between the apple and caramel, providing a more hospitable environment than either component alone. To test this hypothesis, apples were inoculated with L. monocytogenes prior to caramel dipping. Some apples had sticks inserted into them before dipping, while others did not. No growth of L. monocytogenes occurred on refrigerated caramel apples without sticks, whereas slow growth was observed on refrigerated caramel apples with sticks. In contrast, significant pathogen growth was observed within 3 days at room temperature on caramel apples with sticks inserted. Food producers should consider interfaces between components within foods as potential niches for pathogen growth.

Shelf-stable, ready-to-eat meat and poultry products represent a large sector of the meat snack category in the meat and poultry industry. Determining the physiochemical conditions that prevent the growth of foodborne pathogens, namely, Staphylococcus aureus postprocessing, is not entirely clear. Until recently, pH and water activity (a(w)) criteria for shelf stability has been supported from the U.S. Department of Agriculture training materials. However, concern about the source and scientific validity of these critical parameters has brought their use into question. Therefore, the objective of this study was to evaluate different combinations of pH and aw that could be used for establishing scientifically supported shelf stability criteria defined as preventing S. aureus growth postprocessing. Snack sausages were manufactured with varying pH (5.6, 5.1, and 4.7) and a(w) (0.96, 0.92, and 0.88) to achieve a total of nine treatments. The treatments were inoculated with a three-strain mixture of S. aureus, with populations measured at days 0, 7, 14, and 28 during 21 °C storage. Results revealed treatments with a pH ≤ 5.1 and a(w) ≤ 0.96 did not support the growth of S. aureus and thus could be considered shelf stable for this pathogen. The results provide validated shelf stability parameters to inhibit growth of S. aureus in meat and poultry products.

Organic acids and sodium nitrite have long been shown to provide antimicrobial activity during chilling of cured meat products. However, neither purified organic acids nor NaNO2 is permitted in products labeled natural and both are generally avoided in clean-label formulations; efficacy of their replacement is not well understood. Natural and clean-label antimicrobial alternatives were evaluated in both uncured and in alternative cured (a process that uses natural sources of nitrite) deli-style turkey breast to determine inhibition of Clostridium perfringens outgrowth during 15 h of chilling. Ten treatments of ground turkey breast (76% moisture, 1.2% salt) included a control and four antimicrobials: 1.0% tropical fruit extract, 0.7% dried vinegar, 1.0% cultured sugar-vinegar blend, and 2.0% lemon-vinegar blend. Each treatment was formulated without (uncured) and with nitrite (PCN; 50 ppm of NaNO2 from cultured celery juice powder). Treatments were inoculated with C. perfringens spores (three-strain mixture) to yield 2.5 log CFU/g. Individual 50-g portions were vacuum packaged, cooked to 71.1°C, and chilled from 54.4 to 26.7°C in 5 h and from 26.7 to 7.2°C in an additional 10 h. Triplicate samples were assayed for growth of C. perfringens at predetermined intervals by plating on tryptose-sulfite-cycloserine agar. Uncured control and PCN-only treatments allowed for 4.6- and 4.2-log increases at 15 h, respectively, and although all antimicrobial treatments allowed less outgrowth than uncured and PCN, the degree of inhibition varied. The 1.0% fruit extract and 1.0% cultured sugar-vinegar blend were effective at controlling populations at or below initial levels, whether or not PCN was included. Without PCN, 0.7% dried vinegar and 2.0% lemon-vinegar blend allowed for 2.0- and 2.5-log increases, respectively, and ∼1.5-log increases with PCN. Results suggest using clean-label antimicrobials can provide for safe cooling following the study parameters, and greater inhibition of C. perfringens may exist when antimicrobials are used with nitrite.

Interest in natural/organic meat products has resulted in the need to validate the effectiveness of clean label antimicrobials to increase safety and shelf life of these products. A Response Surface Methodology (RSM) was used to investigate the effects of varying levels of moisture, pH, and a commercial "clean-label" antimicrobial (cultured sugar-vinegar blend; CSVB) on the growth rate of Listeria monocytogenes and Leuconostoc mesenteroides in uncured turkey stored at 4 °C for 16 wk. Twenty treatment combinations of moisture (60% to 80%), pH (5.8 to 6.4), and CSVB (2.5% to 5.0%) were evaluated during phase I to develop growth curves for both microbe types, whereas the interactive effects of pH (5.8 to 6.4) and CSVB (0.0 to 4.75) were tested in 16 treatment combinations during Phase II at a single moisture level using L. monocytogenes only. CSVB inhibited L. monocytogenes growth in 14 of the 20 treatments tested in Phase I and in 12 of the 16 treatments in Phase II through 16 and 8 wk, respectively. In contrast, CSVB had little effect on L. mesenteroides, with growth inhibited in only 4 of 20 treatments in Phase I and was therefore not tested further in Phase II. Significant interactions of the RSM design coefficients yielded a predictive model for L. mesenteroides growth rate, but due to lack of growth, no growth rate model was developed for L. monocytogenes. CSVB was found to be an effective antilisteral antimicrobial, while having little effect on a spoilage microorganism.

Prospective epidemiologic studies aid in identifying genetic variants associated with diseases, health risks, and physiologic traits. These genetic variants may eventually be measured clinically for purposes of diagnosis, prognosis, and treatment. As evidence of the potential clinical value of such information accrues, research studies face growing pressure to report these results to study participants or their physicians, even before sufficient evidence is available to support widespread screening of asymptomatic persons. There is thus a need to begin to develop consensus on whether and when genetic findings should be reported to participants in research studies. The National Heart, Lung, and Blood Institute (NHLBI) convened a Working Group on Reporting Genetic Results in Research Studies to discuss if, when, and how genetic information should be reported to study participants. The Working Group concluded that genetic test results should be reported to study participants when the associated risk for the disease is significant; the disease has important health implications such as premature death or substantial morbidity or has significant reproductive implications; and proven therapeutic or preventive interventions are available. Finally, the Working Group recommended procedures for reporting genetic research results and encouraged increased efforts to create uniform guidelines for this activity.

Some authors argue that the ethics of medical care and the ethics of research differ, and that it is a mistake to conflate the two. They propose “that medical research and medical treatment are two distinct forms of activities, governed by different ethical principles.” This raises the question of whether physicians who are also clinical investigators may separate their role as physician from that of researcher when they are involved in clinical trials, thereby avoiding the obligations required in the physician-patient relationship. Miller and Brody suggest that medical training is to blame for what they believe is the physicians’ tendency to confound the obligations of research and practice. “Physician-investigators, after all, went to medical school” they explain. They believe that considering research with patients outside the ethical framework of the physician-patient relationship may be “difficult and threatening” to physicians who have “psychological needs” to consider the ethical obligations flowing from their relationship with their patients.

Ingredients used in the manufacture of reduced-fat process cheese products were screened for their ability to inhibit growth of Clostridium botulinum serotypes A and B in media. Reinforced clostridial medium (RCM) supplemented with 0, 0.5, 1, 2, 3, 5, or 10% (wt/vol) of various ingredients, including a carbohydrate-based fat replacer, an enzyme-modified cheese (EMC) derived from a Blue cheese, sweet whey, modified whey protein, or whey protein concentrate, did not inhibit botulinal growth and toxin production when stored at 30 degrees C for 1 week. In contrast, RCM supplemented with 10% soy-based flavor enhancer, 10% Parmesan EMC, or 5 or 10% Cheddar EMC inhibited botulinal toxin production in media for at least 6 weeks of storage at 30 degrees C. Subsequent trials revealed that the antibotulinal effect varied significantly among 13 lots of EMC and that the antimicrobial effect was not correlated with the pH or water activity of the EMC.

The inhibition of Listeria monocytogenes by sodium lactate and sodium diacetate was evaluated for wieners containing pork, turkey, and beef and for cooked bratwurst containing beef and pork. Both products were supplied by commercial manufacturers. Treated products were surface-inoculated with 10(5) CFU of L. monocytogenes per package and vacuum-packed in gas-impermeable pouches. Wieners were stored for 60 days at 4.5 degrees C, and bratwurst were stored for 84 days at 3 and 7degrees C. A surface treatment that consisted of dipping wieners into solutions containingor = 6% lactate andor = 3% diacetate for 5 s did not delay pathogen growth compared with that for untreated wieners. In additional trials, the antilisterial activity of lactate and diacetate in wiener and bratwurst formulations was evaluated. Lactate levels ranged from 1.32 to 3.4%, and diacetate was evaluated at 0.1 and 0.25%. The growth of L. monocytogenes was delayed for 4 and 12 weeks at 7 and 3 degrees C, respectively, on uncured, unsmoked bratwurst formulated with 3.4% lactate/0.1% diacetate, compared with 1 and 2 weeks, respectively, for the formulation containing 2% lactate. L. monocytogenes grew byor = 1 log unit after 4 weeks' storage at 3 or 7 degrees C on cured, smoked bratwurst without lactate or diacetate, but growth was inhibited for 12 weeks on cured, smoked bratwurst formulated with 3.4% lactate and 0.1% diacetate. Sodium lactate levels ofor = 3% and combinations ofor = 1% lactate plusor = 0.1% diacetate prevented listerial growth on wieners stored for 60 days at 4.5 degrees C. These results indicate that dipping wieners in lactate-diacetate solutions is not an efficient way to apply these antimicrobial agents to wieners. However, the inclusion of combinations of sodium lactate and sodium diacetate in wiener or bratwurst formulations inhibits the growth of L monocytogenes ator = 7 degrees C, and an additional margin of safety was observed for products that are cured and smoked.

Public debate over the use of techniques that result in heritable changes to human germ cells (i.e., sperm and ova), called germ-cell gene interventions, lags far behind the development of such therapies. Such a debate is particularly needed now because the first steps in somatic-cell, or non-heritable, gene therapy have taken place and may accelerate the beginning of germ-cell gene therapy trials. Because germ-cell therapy affects future generations, its moral status differs considerably from that of somatic-cell therapy. To stimulate and inform public discussion, the authors review the major ethical arguments for and against germ-cell therapy that are found in the literature. (These arguments include the dangers of "playing God," of moving on the "slippery slope" to germ-cell manipulations for enhancement rather than therapy, and of causing irreversible changes to the genomes of future generations.) They demonstrate that these arguments do not apply uniquely to such therapy, since most of the properties of germ-cell therapy are present in other medical interventions or elsewhere in social interactions. For example, there are many examples of human activities that are irreversible and have effects on future generations. However, this lack of uniqueness does not necessarily imply that the moral status of germ-cell gene therapy is unique, or that it should be banned forever. The public, and especially health policymakers, researchers, and clinicians, must reflect on and discuss the issues outlined in this article before efforts are made to introduce changes into the germ cells of human beings.

The U.S. Department of Agriculture's Food Safety and Inspection Service compliance guideline known as Appendix B specifies chilling time and temperature limits for cured and uncured meat products to inhibit growth of spore-forming bacteria, particularly Clostridium perfringens. Sodium lactate and potassium lactate inhibit toxigenic growth of Clostridium botulinum, and inhibition of C. perfringens has been reported. In this study, a cocktail of spores of three C. perfringens strains (ATCC 13124, ATCC 12915, and ATCC 12916) were inoculated into 100-g samples of ground skinless, boneless turkey breast formulated to represent deli-style turkey breast. Three treatment groups were supplemented with 0 (control), 1, or 2% potassium lactate (pure basis), cooked to 71 °C, and assayed for C. perfringens growth during 10 or 12 h of linear cooling to 4 °C. In control samples, populations of C. perfringens increased 3.8 to 4.7 log CFU/g during the two chilling protocols. The 1% potassium lactate treatment supported only a 2.5- to 2.7-log increase, and the 2% potassium lactate treatment limited growth to a 0.56- to 0.70-log increase. When compared with the control, 2% potassium lactate retarded growth by 2.65 and 4.21 log CFU/g for the 10- and 12-h cooling protocols, respectively. These results confirm that the addition of 2% potassium lactate inhibits growth of C. perfringens and that potassium lactate can be used as an alternative to sodium nitrite for safe extended cooling of uncured meats.

Botulism is a severe neuroparalytic disease, caused by consumption of minute quantities of botulinum neurotoxin (BoNT) in a contaminated food, or by development of toxin by toxigenic spores in the intestine of susceptible infants and adults. The severity, onset time, and duration of botulism are largely dependent upon dose and BoNT type, and because of its rarity, symptoms may be misdiagnosed. BoNTs formed by Clostridium botulinum and rare strains of C. baratii and C. butyricum are responsible for the majority of human botulism cases. C. botulinum presents a particular challenge to food safety because of its ability to form highly stable endospores; their distribution and prevalence vary by geographical region. Primary factors contributing to foodborne botulism include inadequate thermal processing, inadequate storage temperature-time control, food formulations with pH and water activity within growth range of C. botulinum, reduced-oxygen environment, inadequate levels of antimicrobial food ingredients, and lack of competitive microflora.

The behavior of Listeria monocytogenes was evaluated during storage of a queso blanco type of cheese produced with acidulants (citric, malic, or acetic acids) and a commercial lactic acid bacterium fermentation product, ALTA TM 2341 (ALTA). The cheese was prepared by direct acidification (final pH 5.2), with and without 0.6% ALTA, inoculated with 10 6 CFU/g of L. monocytogenes, and stored at 4 or 20°C for 42 and 7 days, respectively. Levels of L. monocytogenes increased in cheese coagulated with citric or malic acids and stored at 4°C, but decreased slightly in cheese coagulated with acetic acid At 20°C, counts of L. monocytogenes increased in cheeses acidified with citric or malic acid, but counts did not increase appreciably in cheese acidified with acetic acid When cheese was stored at 4°C, the presence of 0.6% ALTA resulted in lower counts of L. monocytogenes compared with counts in cheese that did not contain ALTA. However, at 20°C populations of L. monocytogenes increased in cheese containing ALTA regardless of acid type. Additional studies compared the effects of acetic acid, alone or in combination with 0.6 or 2.5% ALTA, against low (10 2 CFU/g) and high (10 6 CFU/g) inoculum levels. When inoculum levels were low, pathogen counts decreased by >1.1 log 10 CFU/g in all formulations at 4°C. After 7 days at 20°C, pathogen counts increased in the queso blanco type of cheese prepared with acetic acid alone. In contrast, in the presence of 0.6 or 2.5% ALTA, 7-day counts were less than the initial inoculum. With high inoculum levels at 4°C, counts of L. monocytogenes were less than the initial inoculum in the acetic acid-coagulated queso blanco type of cheese with or without ALTA. At 20°C, counts increased in the queso blanco type of cheese prepared with 0.6% ALTA, but decreased appreciably in cheese prepared with 25% ALTA. These results demonstrate that acetic acid is significantly more effective than malic or citric acids for controlling L. monocytogenes in queso blanco, and that inclusion of ALTA can provide added protection against the pathogen.

The objective of this study was to compare the survival of non-O157 Shiga toxin-producing Escherichia coli (STEC) with E. coli O157:H7 during pepperoni production. Pepperoni batter was inoculated with 7 log CFU/g of a seven-strain STEC mixture, including strains of serotypes O26, O45, O103, O111, O121, O145, and O157. Sausages were fermented to pH ≤4.8, heated at 53.3°C for 1 h, and dried for up to 20 days. STEC strains were enumerated at designated intervals on sorbitol MacConkey (SMAC) and Rainbow (RA) agars; enrichments were completed in modified EC (mEC) broth and nonselective tryptic soy broth (TSB). When plated on SMAC, total E. coli populations decreased 2.6 to 3.5 log after the 1-h heating step at 53.3°C, and a 4.9- to 5-log reduction was observed after 7 days of drying. RA was more sensitive in recovering survivors; log reductions on it were 1.9 to 2.6, 3.8 to 4.2, and 4.6 to 5.3 at the end of cook, and at day 7 and day 14 of drying, respectively. When numbers were less than the limit of detection by direct plating on days 14 and 20 of drying (representing a 5-log kill), no more than one of three samples in each experiment was positive by enrichment with mEC broth; however, STEC strains were recovered in TSB enrichment. Freezing the 7-day dried sausage for 2 to 3 weeks generated an additional 1- to 1.5-log kill. Confirmation by PCR revealed that O103 and O157 had the greatest survival during pepperoni productions, but all serotypes except O111 and O121 were occasionally recovered during drying. This study suggests that non-O157 STEC s trains have comparable or less ability than E. coli O157 to survive the processing steps involved in the manufacture of pepperoni. Processes suitable for control of E. coli O157 will similarly inactivate the other STEC strains tested in this study.

The involvement of the pathogenic Shiga-toxin-producing Escherichia coli (STEC; also called verocytotoxic-producing E. coli or VTEC) in sporadic cases and disease outbreaks is presently increasing. Infrequent cases are due to ingestion of milk and dairy products. As ruminants are healthy carriers of STEC and most dairy products may provide these bacteria with favourable conditions for their growth, milk and dairy products are a potential source of STEC. But not all STEC serotypes are pathogens; only relatively small numbers in the entire family of STEC are pathogenic. This review focuses on the recent advances in understanding of STEC and their significance in milk and dairy products. It is intended to gather the information that is needed to understand how these bacteria are described, detected and characterised, how they contaminate milk and grow in dairy products, and how the dairy industry can prevent them from affecting the consumer.

In January 1992, the IMAGE Project extended the establishment of its registry of familial Alzheimer cases to all areas of the province of Quebec, for collection of epidemiological and clinical data, as well as biological samples. The aim is to study genetic transmission patterns of Alzheimer's disease (AD) and to provide a sampling framework for further etiologic and risk factor studies. The IMAGE registry already includes data of a population-based study in the Saguenay-Lac-St-Jean area; the project to collect data on familial AD (FAD) cases across the province of Quebec is known as the ALGENE Initiative. The registry is thus a collection of "AD families" for both familial and sporadic cases. The establishment of the registry involves several steps in the field work: recruitment and selection of families; collection of information on family medical history; selection of informative families and genetic testing for AD/FAD by linkage analysis. As AD is not homogeneous in its etiology and since we do not know if, in the event that genetics is involved in AD whether or not penetrance of the gene(s) is high, we must be aware of the "genetic horizons" of AD in collecting and conserving data on families of cases, and in the genetic testing for AD/FAD by linkage analysis. Families who choose genetic testing must be aware of the implications of our undertaking, assured of the confidentiality of the test and, at the same time, they must understand its limitations. The experimental nature of our research project raises ethical dilemmas. This article examines these initial considerations of the field work involved in developing a registry pertaining to genetic testing for AD/FAD by linkage analysis and offers some preliminary observations on the experience of the first year of this project.

Bookman et al . write to correct the impression given in the Commentary by Kohane and Taylor that the recommendations of the National Heart, Lung, and Blood Institute (NHLBI) Working Group “Reporting Genetic Results in Research Studies” included advice to return genetic information to research subjects only in cases where there is a proven or preventative intervention for the identified disorder. In fact, the report does recommend that genetic information be returned to subjects when there is an intervention available, but it does not recommend against giving this kind of information to subjects if there is no available intervention.

Two formulations of chicken summer sausages [100% hand deboned chicken meat (HDCM) and 85% HDCM and 15% chicken hearts (HDCM-CH)] were prepared with a nonpediocin-producing (PED-) Pediococcus acidilactici starter culture and inoculated with 10(4) or 10(7) cfu of a five-strain mixture of Listeria monocytogenes/g of batter. Sausages were fermented to pH 5.0 (11 h), cooked to an internal temperature of 66.5 C, cold-showered, and stored at 4 C (60 days) and 30 C (7 days). For both formulations and inoculation levels, L. monocytogenes populations decreased 1.3 to 1.8 log10 cfu/g by the end of fermentation. No L. monocytogenes organisms were recovered from sausages (by enrichment) following the cook and shower or storage at 4 or 30 C. In contrast, P. acidilactici increased .7 to 1.2 log10 cfu/g during fermentation, and < 10(2) cfu/g remained after the cook and shower and storage at 4 and 30 C. In a second set of experiments, sausages (HDCM) were prepared with a PED- or a pediocin-producing (PED+) P. acidilactici starter culture and challenged with the L. monocytogenes mixture (10(7) cfu/g). The PED- culture reduced numbers of L. monocytogenes 1.2 log10 cfu/g during fermentation, whereas L. monocytogenes numbers declined 2.6 log10 cfu/g in the presence of the PED+ culture. Although acid production by both starter cultures was equivalent, greater inhibition of L. monocytogenes by the PED+ compared with the PED- starter culture was attributed to in situ production of pediocin. Pediococcal starter cultures and proper cooking eliminated L. monocytogenes from sausages and established that PED+ cultures provide an additional hurdle against poultry-related listeriosis.

The antilisterial effects of sodium diacetate (0.1, 0.3 and 0.5%) alone or in combination with sodium nitrite (30 ppm), sodium lactate (2.5%) or pediocin (5000 arbitrary units/ml) were evaluated in slurries (25% meat in sterile deionized H2O) prepared from vacuum-packaged, ready-to-eat turkey breast meat and challenged with Listeria monocytogenes. In the absence of food additives, counts of L. monocytogenes increased from 4.5 log10 cfu/ml to ca. 8 log10 cfu/ml within 1 day at 25 degrees C and within 14 days at 4 degrees C. Similarly, the pathogen grew to ca. 8 log10 cfu/ml within 1 d at 25 degrees C and within 28 days at 4 degrees C in slurries containing nitrite or lactate. In the presence of pediocin, after an initial decrease of 0.9 log10 cfu/ml, numbers of the pathogen reached ca. 8 log10 cfu/ml within 5 days at 25 degrees C and within 28 days at 4 degrees C. However, 0.3 and 0.5% diacetate in turkey slurries were listericidal at 4 and 25 degree C, respectively. In the presence of nitrite with diacetate, there was no appreciable difference in growth of L. monocytogenes compared with diacetate alone. Antilisterial activity was potentiated in treatments containing lactate with 0.3% diacetate at 25 degrees C and lactate with 0.1% diacetate at 4 degrees C, compared to similar treatments containing diacetate or lactate alone. A listericidal effect (ca. 7 log10 cfu/ml difference compared to slurries without additives) was observed in treatments containing pediocin with 0.5% diacetate at 25 degrees C and pediocin with 0.3% diacetate at 4 degrees C. The pH of slurries containing 0.3 or 0.5% diacetate was 5.5 and 5.2, respectively, whereas nitrite (pH 6.2), lactate (pH 6.3) or pediocin (pH 6.2) in slurries had a negligible effect on pH compared to the control (pH 6.2). The increased antilisterial activity in slurries with diacetate in combination with other additives was due to synergistic effects and not just pH. Thus, sodium diacetate alone can be used to delay growth of L. monocytogenes in turkey, and an additional level of safety can be achieved using diacetate in combination with sodium lactate or pediocin.

Medical research is frequently regarded as not only laudable, but even obligatory. However, the moral foundation for such an obligation is far from clear. Lively debate concerning the viability of an obligation to conduct and support medical research is transpiring among a small number of scholars speaking from a variety of backgrounds, yet the current discussion is predominantly situated within several discrete academic and professional circles, allowing only sporadic engagement within and between scholarly disciplines and the medical realm. We aim to lay the groundwork for a focused critique of the "research imperative" by examining (1) its commitments within ideologies of science, medicine, and progress: and (2) its normative theoretical underpinnings. Our analysis finds no solid grounding for the research imperative and exposes problems in the attitudes and arguments supporting it. We believe these concerns present compelling reasons for devoting greater critical attention to the research imperative and to the morality of the medical research enterprise as a whole.

The answer to the question of “Why not?” would seem relatively straightforward: substituting placebo for established, effective therapy is always ethically questionable and usually ethically inappropriate, and therefore we should not do it. That position finds support in numerous guidelines

The influence of pH adjusted with lactic acid or HCl or sodium chloride concentration on survival or growth of Escherichia coli O157:H7 in Trypticase soy broth (TSB) was determined. Studies also determined the fate of E. coli O157:H7 during the production and storage of fermented, dry sausage. The organism grew in TSB containing less than or equal to 6.5% NaCl or at a pH of 4.5 to 9.0, adjusted with HCl. When TSB was acidified with lactic acid, the organism grew at pH 4.6 but not at pH 4.5. A commercial sausage batter inoculated with 4.8 x 10(4) E. coli O157:H7 per g was fermented to pH 4.8 and dried until the moisture/protein ratio was less than or equal to 1.9:1. The sausage chubs were then vacuum packaged and stored at 4 degrees C for 2 months. The organism survived but did not grow during fermentation, drying, or subsequent storage at 4 degrees C and decreased by about 2 log10 CFU/g by the end of storage. These studies reveal the importance of using beef containing low populations or no E. coli O157:H7 in sausage batter, because when initially present at 10(4) CFU/g, this organism can survive fermentation, drying, and storage of fermented sausage regardless of whether an added starter culture was used.

Clinical equipoise and not the uncertainty principle is the moral underpinning of the randomised controlled trial {#article-title-2} The ethical basis for entering patients in randomised controlled trials is under debate. Some doctors espouse the uncertainty principle whereby randomisation to treatment is acceptable when an individual doctor is genuinely unsure which treatment is best for a patient. Others believe that clinical equipoise, reflecting collective professional uncertainty over treatment, is the soundest ethical criterion. Here doctors from two Canadian centres discuss their positions. # For {#article-title-3} On what ethical grounds may a physician offer trial participation to his or her patient? The answer seems to depend greatly on which side of the Atlantic you reside. In the United Kingdom, the uncertainty principle is widely endorsed. 1 2 However, in North America, clinical equipoise—reflecting collective uncertainty—is the dominant ethical basis.3 Which of these principles offers the preferred moral underpinning for the randomised controlled trial? It is widely acknowledged that physicians have a primary duty to promote their patients' welfare. When physicians become investigators, however, other ends such as recruiting enough subjects and retaining them in the trial may conflict with this duty.4 How can the physician maintain fidelity to the patient and further the ends of a randomised controlled trial? The uncertainty principle offers an appealing solution to this problem. Physicians who are convinced that one treatment is better than another for a particular patient cannot ethically choose at random which treatment to give, they must do what they think best for the patient. For this reason, physicians who feel they already know the answer cannot enter their patients into a trial. If they think, whether for a wise or silly reason, that they know the answer before the trial starts, they should not enter any patients.2 On the other hand, if the physician is uncertain about which treatment is best for a patient, offering the patient randomisation to equally …

Contemporary research ethics review committees (RECs) are heavily influenced by the established academic or health care institutional frameworks in which they operate, sharing a cultural, methodological and ethical perspective on the conduct of research involving humans. The principle of autonomous choice carries great weight in what is a highly individualistic decision-making process in medical practice and research. This assumes that the best protection lies in the ability of patients or research participants to make competent, voluntary, informed choices, evaluating the risks and benefits from a personal perspective. Over the past two decades, North American and international indigenous researchers, policy makers and communities have identified key issues of relevance to them, but ignored by most institutional or university-based RECs. They critique the current research review structure, and propose changes on a variety of levels in an attempt to develop more community sensitive research ethics review processes. In doing so, they have emphasized recognition of collective rights including community consent. Critics see alternative policy guidelines and community-based review bodies as challenging the current system of ethics review. Some view them as reflecting a fundamental difference in values. In this paper, we explore these developments in the context of the political, legal and ethical frameworks that have informed REC review. We examine the process and content of these frameworks and ask how this contrasts with emerging Aboriginal proposals for community-based research ethics review. We follow this with recommendations on how current REC review models might accommodate the requirements of both communities and RECs.

Four types of fresh pasta (meat- or cheese-filled tortellini and flat noodle linguine or fettucine) were prepared with different water activities, inoculated with proteolytic Clostridium botulinum spores, packaged under a modified atmosphere, and stored at either 4 or 30°C for 8 to 10 weeks. Products were assayed for botulinal toxin at appropriate sampling times. No toxin was detected in any fresh pasta held at 4°C for up to 8 weeks. However, toxin was detected in meat tortellini with aw of 0.99 and 0.95 at 2 and 6 weeks, respectively, when held at 30°C. Toxin was not detected in tortellini with an aw of 0.94 or below held at 30°C for 10 weeks. Toxin was produced at 2 weeks in linguine at aw 0.96 and held at 30°C, whereas no linguine or fettucine at aw 0.93 or 0.95 and held at 30°C was toxic during 10 or 8 weeks, respectively. The aw of fresh pasta is a principal factor in preventing botulinal toxin production by proteolytic C. botulinum in temperature-abused products. A survey of commercially available fresh pasta revealed that most flat noodles were below the aw limit for botulinal toxin production, whereas most of the filled pasta had aw values which permitted toxin production if temperature abuse occurred.