Certain types of goat's cheeses are produced using unpasteurized milk, which increases the food safety concerns for these types of products. Popularity and consumption of goat's milk products have increased, and the niche market includes gourmet goat's cheeses. The U.S. Code of Federal Regulations and the Pasteurized Milk Ordinance both address the possibility for processing alternatives to heat treatment, and the use of UV light treatment may be a viable alternative that still ensures the safety of the product. Fresh goat's milk was inoculated with Listeria monocytogenes (L-2289) at 10 7 CFU/ml and exposed to UV light using the CiderSure 3500 apparatus (FPE Inc., Macedon, NY). Inoculated milk was exposed to a UV dose range between 0 and 20 mJ/cm 2 to determine the optimal UV dose. A greater than 5-log reduction was achieved ( P < 0.0001) when the milk received a cumulative UV dose of 15.8 ± 1.6 mJ/cm 2 . The results of this study indicate that UV irradiation could be used for the reduction of L. monocytogenes in goat's milk.

The top surface of the raw eye of round steaks was inoculated with either green fluorescent protein (GFP)-labeled Escherichia coli ( E. coli -GFP) or rifampin-resistant E. coli ( E. coli -rif). Cryostat sampling in concert with laser scanning confocal microscopy (LSCM) or plating onto antibiotic selective agar was used to determine if hydrodynamic shock wave (HSW) treatment resulted in the movement of the inoculated bacteria from the outer inoculated surface to the interior of intact beef steaks. HSW treatment induced the movement of both marker bacteria into the steaks to a maximum depth of 300 μm (0.3 mm). Because popular steak-cooking techniques involve the application of heat from the exterior surface of the steak to achieve internal temperatures ranging from 55 to 82°C, the extent of bacterial penetration observed in HSW-treated steaks does not appear to pose a safety hazard to consumers.

This study examined the efficacy of UV light for reducing Escherichia coli O157:H7 in unpasteurized cider. Cider containing a mixture of acid-resistant E. coli O157:H7 (6.3 log CFU/ml) was treated using a thin-film UV disinfection unit at 254 nm. Dosages ranged from 9,402 to 61,005 μW-s/cm 2 . Treatment significantly reduced E. coli O157:H7 ( P ≤ 0.0001). Mean reduction for all treated samples was 3.81 log CFU/ml. Reduction was also affected by the level of background microflora in cider. Results indicate that UV light is effective for reducing this pathogen in cider. However, with the dosages used in this experiment, additional reduction measures are necessary to achieve the required 5-log reduction.

The heat resistance of Listeria monocytogenes was determined in infant formula for all possible combinations of temperature (50, 55, and 60°C), pH level (5, 6, and 7), and NaCl concentration (0, 2, and 4%). Survival curves were fit using nonlinear regression with a Gompertz equation. The Gompertz equation was flexible enough to fit the three most commonly observed survival curves: linear curves, those with an initial lag region followed by a linear region, and sigmoidal shaped. Parameter estimates obtained by the method of nonlinear least squares were used to describe the effect(s) of different heating treatments on the lag region, death rate, and tailing region of survival curves. These estimates were further used to predict single and interactive effects of temperature, pH, and percentage of NaCl on the log of the surviving fraction (LSF) of bacteria. Interactions among these variables significantly ( P ≤ .05) affected the LSF. Generally, increased pH or NaCl concentration lead to an increased LSF, whereas increased time or temperature lead to a decreased LSF. All multiple-factor interactions significantly ( P ≤ .05) affected the LSF. The correlation of observed LSF versus predicted LSF ( R 2 = .92) indicated that the estimated Gompertz equation was in close agreement with the observation. This study demonstrated that the Gompertz equation and nonlinear regression can be used as an effective means to predict survival curve shape and response to heat of L. monocytogenes under many different environmental conditions.

The heat resistance of Listeria monocytogenes was determined in 0.1 M KH 2 PO 4 buffer at three temperatures (50, 55, and 60°C), three pH levels (5, 6, and 7), and three NaCl concentrations (0, 2, and 4%). Survival curves were fit using nonlinear regression with a modified Gompertz equation. The Gompertz equation is capable of fitting survival curves which are linear, those which display an initial lag region followed by a linear region, and those which are sigmoidal. Parameter estimates were used to describe the lag region, death rate, and the tailing region of a survival curve. These estimates were also used to predict single and interactive effects of temperature, pH, and percentage of NaCl on the log surviving fraction (LSF) of bacteria. Interactions among these variables significantly ( P < .05) affected the LSF. Generally, increased pH or NaCl concentration lead to an increased ( P < .05) LSF, where as increased time or temperature lead to a decreased ( P < .05) LSF. All multiple factor interactions significantly ( P < .05) affected the LSF. These interactions differed depending on the heating medium and the region of the survival curve. The correlation of observed LSF and predicted LSF ( R 2 = .89) indicated that the Gompertz equation was in close agreement with the observations. This study demonstrated that the Gompertz equation and nonlinear regression can be used as an effective means to predict survival curve shape and response to heat of L. monocytogenes in many different environmental conditions.

Log phase cells of Listeria monocytogenes Scott A were heat shocked in Trypticase Soy + 0.6% yeast extract (TSYE) broth at 48°C for 10 min, followed by heating at 55°C for up to 50 min. Heat resistance was determined using nonselective (TSYE) and selective (McBride Listeria ) enumeration media which were incubated under aerobic and anaerobic environments. D 55 °C-values for heat shocked cells were 2.1-fold higher than nonheat shocked cells (18.7 min vs. 8.89 min) when cells were enumerated on TSYE agar aerobically and 2.2-fold higher (26.4 min vs. 12.0 min) for cells enumerated anaerobically on TSYE agar. When cells were enumerated aerobically on McBride Listeria (ML) agar, D 55 °C-values for heat shocked cells were 1.4-fold higher than nonheat shocked cells (9.55 min vs. 6.69 min). No growth was observed on ML agar anaerobically. The physiological condition of the microorganism, the enumeration medium, and the growth environment greatly affected the heat resistance of logphase cells of Listeria monocytogenes Scott A.

Log phase cells of Listeria monocytogenes Scott A were heat shocked in trypticase soy + 0.6% yeast extract broth at 40, 44, and 48°C for 3, 10, and 20 min, followed by heating at 55°C for 50 min in order to determine an optimum heat shock response. Most heat shocking temperatures significantly increased thermal resistance (p ≤ 0.05). Increasing heat shock temperature and time allowed the organism to survive much longer than nonheat shocked cells at 50 to 65°C. The optimal heat shock condition was 48°C for 20 min where D-values at 55°C increased 2.3-fold in nonselective agar and 1.6-fold in selective agar. However, cells heat shocked at 48°C for 10 min gave more consistent results; these cells were heat processed at 50, 55, 60, and 65°C to determine a z-value. Although D-values notably increased due to heat shocking, z-values remained constant. Heat shocking at 48°C significantly increased D-value ratios for cells enumerated on nonselective vs. selective media. Heat shocking conditions may be created in pasteurization or minimal thermal processing of food allowing increased heat resistance of pathogenic and spoilage microorganisms.

Inhibition of Clostridium botulinum (strains A, B, and E) growth and toxin production by various concentrations of origanum oil and sodium nitrite was studied for both TYG broth and a model meat system. At concentrations of 100 and 200 ppm, origanum oil was effective in inhibiting C. botulinum growth in TYG broth. In addition, origanum oil acted synergistically with sodium nitrite in inhibiting C. botulinum growth in TYG broth. The inhibitory effect of origanum oil in the meat system was dramatically reduced and had a significant (p≤ 0.05) effect only when used at 400 ppm in combination with 50–100 ppm sodium nitrite.

The oils of clove, thyme, black pepper, pimenta, origanum, garlic, onion, and cinnamon were tested for their activity on germination, outgrowth, and vegetative growth of Clostridium botulinum 67B in broth media. Garlic, onion, cinnamon, thyme, origanum, and black pepper oils at a concentration of 100 ppm prevented germination of C. botulinum 67B spores. Clove and pimenta oils at a concentration of 150 ppm prevented germination. The effect of spice oils on spore germination was reversible. The oils of black pepper and clove had a greater inhibitory effect on vegetative growth than the other oils. None of the oils had a significant effect on outgrowth.

Efforts to find a suitable sparing agent for nitrite in cured meat products have brought sodium hypophosphite (SHP) to the attention of the scientific community. Hypophosphites were introduced in the mid 1800s as a cure for tuberculosis, but recent reports have suggested SHP could possess antibotulinal and antimicrobial properties. Sodium hypophosphite has good potential as an antimicrobial food ingredient and it is Generally Recognized As Safe (GRAS). This review summarizes SHP chemistry, history, toxicology, regulatory status, applications, and antimicrobial properties.

Increased awareness of the morbidity and mortality attributed to diarrheal disease among children under 5 years of age in developing countries has led to a variety of approaches aimed toward prevention. In this review, foods and food ingredients which appear to be most effective in prevention of diarrheal disease in infants are considered. The effect of each of the following potential food or food ingredient categories on the control or prevention of diarrheal disease is discussed: human milk components, antibodies, probiotics, and fermented foods.

The influence of medium composition, pH, incubation time and gaseous atmosphere during incubation on enumeration of H 2 S-producing bacteria from anaerobically packaged pork was determined. Samples of anaerobically packaged pork were plated and H 2 S-producing bacteria isolated. Stock cultures of these isolates were prepared, diluted and pour-plated with Lead Acetate Agar (LAA) containing various concentrations of cysteine (0.001 to 0.005%) at different pH values (5.0 to 8.0). The inoculated plates were incubated at 21°C for various periods (3 to 6 d) under different gaseous atmospheres (N 2 , CO 2 or mixtures of both). The conditions resulting in optimized recovery and enumeration of H 2 S-producing bacteria from anaerobically packaged pork consisted of pour-plating the isolates with LAA to which 0.003 to 0.005% cysteine was added and pH adjusted to 7.5–8.0 plus incubation in an atmosphere of 5%CO 2 –95%N 2 for 5 to 6 d at 21°C.

Nine cooperating laboratories, distributed throughout the United States, determined the interlaboratory reproducibility of a sensitive, selective method for isolation of Campylobacter jejuni and Campylobacter coli from foods, and determined the prevalence and distribution of the organism in retail meats. A double-blind inoculated/recovery experiment demonstrated the ability to detect two cells of C. jejuni and C. coli per g of meat at a rate of 96% among the cooperating laboratories. However, a 7.5% false-positive rate for the presumptive detection of the organism was also reported. Samples of ground beef, beef flank steak, lamb stew meat, broiler chicken, pork sausage (without antimicrobials), and pork chops were selected to assess the presence of campylobacters. Each cooperator purchased five of each of the above samples from the refrigerated case of two retail outlets at quarterly intervals throughout the year. A total of 2,160 retail samples were analyzed for the presence of C. jejuni and C. coli . Results indicated that about 30% of the 360 chickens sampled yielded the organism. Analysis of 1,800 red meat products yielded campylobacters at a rate of about 5.1%. Pork samples yielded C. coli and other meats yielded C. jejuni . Higher numbers of isolations from the red meats were made during June and September (8.6%) as compared with December and March (4.2%). These results provide a baseline, for the prevalence of campylobacters in these selected foods, and also support epidemiologic data associating mishandled foods of animal origin as a potential vehicle in human gastroenteritis.

Nitrite plays a major role in the curing of meats. However, the potential problem of nitrosamine formation has been responsible for reduction or elimination of nitrate and nitrite in curing. Reduced amounts of nitrite in curing can provide less protection against botulism, and subsequent investigations have examined solutions to this situation. Residual nitrite has been reduced by limiting the ingoing nitrite and by introducing curing substances, i.e., phosphates, lactobacillus cultures, and phenolic smoke compounds, to lower the pH. Ascorbates, alpha-tocopherol and other blocking agents have been used with nitrite in an attempt to devise a curing system that can provide a safe product with the color and flavor associated with nitrite-cured products while retarding nitrosopyrrolidine formation. This review focuses on the efficacy of various curing methods using nitrites that have the goal of reducing formation of nitrosamines.

Inhibition of Salmonella typhimurium and Staphylococcus aureus in Trypticase Soy Broth by the propyl ester of p-hydroxybenzoic acid (propyl paraben, 0 to 500 ppm) and butylated hydroxyanisole (BHA, 0 to 400 ppm) alone and in combination was studied. A concentration of 200 ppm of BHA was bactericidal to S. aureus , while up to 400 ppm of BHA was only restrictive to the growth of S. typhimurium . A gradual decline in viable cell numbers of S. aureus was noted with addition of 500 ppm of propylparaben while an initial reduction of S. typhimurium and subsequent growth occurred at a level of 300 ppm of propylparaben. A combination of 50 ppm of BHA-propylparaben was needed to produce a gradual reduction in viable cells of S. aureus and 150 ppm of each additive caused S. typhimurium to exhibit an apparent decrease in cell numbers and then limited growth.

Butylated hydroxyanisole (BHA) was inhibitory to growth of three proteolytic strains of Clostridium botulinum in prereduced thiotone yeast-extract glucose medium (TYG) (pH 7.0) at 37 C. There was outgrowth and toxin production by strain 10755A spores when 25 ppm of BHA was present in the medium, whereas growth was inhibited by 50 ppm of BHA. Strains 62A and 213B were inhibited by 25 ppm of BHA throughout an incubation period of 7 days. Butylated hydroxytoluene (BHT) and propyl gallate (PG) were less effective in inhibiting outgrowth of C. botulinum spores than was BHA. Spore outgrowth and toxin production were inhibited in the presence of 200 ppm of BHT in the TYG. PG exhibited the least inhibitory activity of the antioxidants tested. None of the levels (25 to 200 ppm) of PG tested delayed outgrowth or toxin formation for more than 24 h.

The influence of potassium sorbate on growth of Staphylococcus aureus in bacon was determined. Bacon was manufactured to contain 0 and 40 ppm sodium nitrite with 0.13 and 0.26% potassium sorbate, 40 and 120 ppm sodium nitrite, or neither nitrite nor sorbate. The bacon was inoculated with approximately 1,000 cells of a mixed suspension of five strains of Staphylococcus aureus per gram, vacuum packaged, and stored at 27 and 13 C. Bacon with 0.13 and 0.26% potassium sorbate and no nitrite was most effective in suppressing growth of S. aureus through 14 days of storage at 27 C. When stored at 13 C, bacon containing nitrite and potassium sorbate exhibited lower numbers of staphylococci after 7 days than did the bacon containing potassium sorbate alone.

Single and multiple stage air samplers were evaluated under commercial conditions for enumerating airborne microbial particles in a plant in which swine were slaughtered and pork was further processed. Three volumes of air, 0.014, 0.028, (1 ft 3 ), and 0.057 cu M were sampled in duplicate on each of 2 days (for airborne molds, yeasts, coliforms, and aerobic bacteria) in eight rooms where pork carcasses were handled and further processed. Unexpectedly, the microbial counts were low during this winter sampling. The single and multiple samplers yielded mean (log 10 ) counts (n = 94) of 0.15 and 0.42; −0.23 and −0.36; 1.18 and 1.29; and −0.63 and −0.91 per 0.028 cm M; for molds, yeasts, aerobes and coliforms, respectively. The multiple sampler detected slightly greater numbers of molds and aerobic bacteria, but did not define the differences in aerobic bacterial numbers from among the various processing rooms as readily as the single stage sampler. Counts of coliforms were higher from the single than from the multiple stage sampler. The single stage sampler required only one petri dish per sample, as compared with six for the multiple stage sampler, so it required less medium and time for evaluating air for microorganisms.

Vibrio parahaemolyticus (04:K11) was grown at 35 C in trypicase soy broth containing an additional 2.5% NaCl (TSBS; pH 7.0) and in a homogenate of blue crab meat ( Callinectes sapidus ) (pH 7.0) containing various amounts of butylated hydroxylanisole (BHA). Growth in TSBS was inihibited by 50 ppm of BHA while 400 ppm BHA was required to inhibit growth in the crab meat homogenate.

Survival of Vibrio parahaemolyticus in various diluents was investigated. 100 mM potassium phosphate buffers (pH 6, 7, and 8) without added NaCl were extremely deleterious to V. parahaemolyticus 04:Kll in comparison to the same diluent with either 0.5, 3, or 6% NaCl. Maximum counts were obtained when phosphate buffers containing 3% NaCl were used as diluents. There were no significant differences among survivor counts of cells exposed for 20 min to 100 mM potassium phosphate 3% NaCl buffer at either pH 6, 7, or 8. Greater than 99.9% of the cell population was destroyed within 20 min in 0.1% peptone diluent without NaCl when compared to 0.1% peptone with either 0, 5, 3, or 6% NaCl. Cell counts using 0.1% peptone diluents containing 3 and 6% NaCl were not significantly different; however, both were superior to 0.1% peptone containing 0.5% NaCl. Survival data for V. parahaemolyticus 04: Kll in distilled water containing 0, 0.5, 3. and 6% added salt were similar to data for the 0.1% peptone diluents. Culture age (4, 10, and 24 h) and time of exposure to the diluents also significantly affected survival of V. parahaemolyticus 04:Kll and 17802.