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PubMed1971

Isolation of psychrophilic bacteriophage-host systems from refrigerated food products.

Thirty-eight bacteriophage-host systems were isolated from 22 of 45 refrigerated food products examined under psychrophilic conditions. Isolates were obtained from ground beef, pork sausage, chicken, raw skim milk, and oysters, whereas no isolations were made from liquid egg whites and processed meat products. Thirty of the 38 psychrophilic bacterial hosts were gram-negative rods, and 27 of these were classified within the genus Pseudomonas; three were members of the family Enterobacteriaceae. The remaining eight were gram-positive cocci, which were tentatively classified as Leuconostoc. Plate counts of psychrophilic bacteria were greater than 2.2 x 10(5)/ml (g) in all but one sample which contained phage, whereas phage titers ranged from less than 100 to 6.3 x 10(6) plaque-forming units/ml (g). Phage isolates showed limited host ranges usually attacking only those hosts upon which they were isolated. Of eight phages tested against 13 cultures of known identity, one showed lytic action, and this was against strains of P. fragi.

Animals↗
PubMed1974

Survival of Vibrio parahaemolyticus in cooked seafood at refrigeration temperatures.

The growth and survival of two strains of Vibrio parahaemolyticus isolated during food-borne gastroenteritis outbreaks in Japan and surface inoculated on cooked shrimp, shrimp with sauce, or cooked crab were tested at various refrigeration temperatures during a 48-h holding period. On cooked shrimp and crab, the vibrios grew well at 18.3 C, but their numbers declined gradually at 10 C and below. At 12.8 C, vibrios remained static for the most part. Thus, it appeared that 12.8 C was the borderline temperature for growth of the organism on cooked seafood. When cocktail sauce was added to surface-inoculated shrimp at a ratio of 2:1, the vibrio die-off rate was accelerated. In the shrimp and sauce few cells remained after 48 h, but in the sauce alone die-off was complete at 6 h.

Brachyura↗
PubMed1985

Comparison of the effect of refrigerated versus room temperature media on the isolation of Neisseria gonorrhoeae from genital specimens.

We evaluated the effect of medium temperature at the time of inoculation on the isolation of Neisseria gonorrhoeae from urethral and cervical swabs. There were no major differences in the isolation rates of 176 positive cultures on cold or warm media. Colonies tended to be larger and more numerous on room temperature plates after 24 h; however, colonies on most refrigerated plates were easily recognized at 24 h, and growth was essentially the same on both plates after 48 h.

Cervix Uteri↗
PubMed2000

Survival of the human granulocytic ehrlichiosis agent under refrigeration conditions.

The human granulocytic ehrlichiosis (HGE) agent in infected blood specimens remained viable during refrigeration at 4 degrees C for up to 18 days. These findings suggest that blood specimens submitted for culture may withstand transportation to a remote laboratory. HGE should be added to the list of infections potentially transmitted by blood transfusion.

Adult↗
PubMedDate not supplied

Stability of amiodarone in an oral suspension stored under refrigeration and at room temperature.

OBJECTIVE: Amiodarone is currently available in a tablet dosage form, which cannot be used in young pediatric patients. The objective of our study was to determine the stability of amiodarone in an oral suspension stored at two temperatures. METHODS: Commercially available amiodarone tablets (200 mg each) were dissolved in purified water and a suspension prepared in methylcellulose 1% and syrup to yield a concentration of 5 mg/mL. The dosage form was stored in 10 glass and 10 plastic prescription bottles. One-half of the bottles were stored at 4 degrees C and the others at 25 degrees C. Three samples were taken from each bottle at 0, 7, 14, 28, 42, 56, 70, and 91 days (n = 15). Amiodarone concentrations were measured by a validated and stability-indicating HPLC method; the pH was also determined in each sample. The drug was considered stable if its concentration exceeded 90% of the original concentration. RESULTS: The mean concentration of amiodarone was 90% or more at 4 degrees C for 91 days and at 25 degrees C for 42 days. The concentration was not affected by the type of storage container. Over 91 days, the pH did not change at 4 degrees C; it decreased slightly from 4.4 to 4.3 at 25 degrees C. CONCLUSIONS: Amiodarone was stable in an oral suspension for 3 months under refrigeration and for 6 weeks at room temperature.

Amiodarone↗
PubMed1997

Some preliminary studies on the ability of Africanized honey bees (Apis mellifera L.) to tolerate cold temperatures when placed inside a refrigerator.

Cold is often suggested as an ecological mechanism to prevent the migration of Africanized honey bees. The ability of Africanized honey bees to tolerate cold temperatures was investigated. In one study an observation hive was placed inside a refrigerator at 25 degrees C. The study was conceptualized as a choice experiment in which the colony could remain in a cold environment or leave for a warm environment. Analysis indicated that the bees remained at 9 +/- 1 degrees C for 14 days before leaving. In a second series of studies, testing the tolerance to 0 degree C, 280 bees were placed individually in small metal tubes. The data gathered included survival rate, time to regain consciousness, and ability to feed. Analysis indicated that Africanized bees can survive for up to 3 hr. at 0 degree C with few ill effects. At 4 hr., however, the survival rate is low. Limitations of the study, the use of cold as a possible deterrent to honey bee mites, and suggestions for additional research are discussed.

Animals↗
PubMed2000

Viability of microencapsulated bifidobacteria in set yogurt during refrigerated storage.

Bifidobacteria are probiotic organisms that improve the microbial balance in the human gut. They can be incorporated as live cultures in fermented dairy foods, including yogurt, for transmission to humans. Because bifidobacteria are sensitive to high acidity, their viability in yogurt is limited. The objective of the present study was to investigate the effect of microencapsulation on the viability of bifidobacteria in yogurt during refrigerated storage for 30 d. Live bifidobacterial cells were encapsulated in kappa-carrageenan. Cell enumeration, determination of titratable acidity and pH, quantitation of lactic and acetic acids, and sensory evaluation (consumer test) were carried out on the yogurt samples. Microbiological results showed a decline of 78 and 70.5% in the population of Bifidobacterium longum B6 and B. longum ATCC 15708, respectively, for the treatments containing nonencapsulated cells. No difference in bifidobacterial population was observed in the encapsulated treatments. The acetic acid content in the yogurt with nonencapsulated bifidobacteria was higher than that in the plain yogurt (control) and encapsulated treatments. The increase in lactic acid content during storage was not different among the various treatments for B. longum B6, but was greater for nonencapsulated than encapsulated B. longum 15708 and the control. Consumers judged the nonencapsulated treatment as the most sour, which was likely due to the higher acetic acid content. Consumers preferred the control and nonencapsulated treatments over the encapsulated treatment. Microencapsulation appears to increase the viability of bifidobacteria in yogurt. This technique can be used to transmit bifidobacteria via fermented products provided that sensory characteristics of the product are improved or maintained.

Acetic Acid↗
PubMed1997

Monoclonal antibodies and an indirect ELISA for detection of psychrotrophic bacteria in refrigerated milk.

Monoclonal antibodies generated against live cells of Pseudomonas fluorescens have been used in an indirect ELISA format for the detection of Pseudomonas spp. and related psychrotrophic bacteria in refrigerated milk. The immunorecognition of monoclonal antibodies adsorbed to bacteria bound to the wells of a microtiter plate was performed with rabbit anti-mouse immunoglobulins conjugated to horseradish peroxidase. Subsequent enzymic conversion of the substrate resulted in distinct absorbance differences when assaying milk samples containing psychrotrophic bacteria in the range 10(5) to 10(9) CFU ml(-1) . The detection threshold for the ELISA assay developed in this work is 10(5) CFU ml(-1).

Animals↗
PubMed1998

Long-term bacterial profile of refrigerated ground beef made from carcass tissue, experimentally contaminated with pathogens and spoilage bacteria after hot water, alkaline, or organic acid washes.

The effects of 2% (vol/vol) lactic acid (LA), 2% (vol/vol) acetic acid (AA), 12% (wt/vol) trisodium phosphate (TSP), 72 degrees C water (HW), and 32 degrees C water (W) washes on bacterial populations which were introduced onto beef carcass surfaces after wash treatments were determined up to 21 days of storage at 4 degrees C of packaged ground beef prepared from the treated and inoculated carcasses. Beef carcass necks were collected from cattle immediately after harvest and subjected to the above treatments or left untreated (control). Neck meat was then inoculated with low levels (ca. <2 log10) of Listeria innocua, Salmonella typhimurium, Escherichia coli O157:H7, and Clostridium sporogenes contained in a bovine fecal cocktail. In general, growth of these four bacteria, aerobic bacteria, lactic acid bacteria, and pseudomonads was suppressed or not observed in the ground beef when LA, AA, or TSP treatments were used as compared to the untreated control. HW or W washes offered little suppression of growth of pathogens during subsequent storage of ground beef when these bacteria were introduced onto beef tissue posttreatment. Of the treatments used, a final LA or AA wash during the processing of beef carcasses offers the best residual efficacy for suppression of pathogen proliferation in ground beef during long-term refrigerated storage or short-term abusive temperature storage if these bacteria contaminate the carcass immediately after carcass processing.

Abattoirs↗
PubMed1998

Long-term effect of alkaline, organic acid, or hot water washes on the microbial profile of refrigerated beef contaminated with bacterial pathogens after washing.

The effect of 2% (vol/vol) lactic acid, 2% (vol/vol) acetic acid, 12% (wt/vol) trisodium phosphate, water at 72 degrees C and water at 32 degrees C washes on bacterial populations introduced onto beef carcass surfaces after treatment was determined for up to 21 days at 4 degrees C storage in vacuum packaging. Beef carcass short plates were collected from cattle immediately after slaughter and subjected to the above treatments or left untreated (C). Short plates were then inoculated with low levels (ca. < 2 log10) of Listeria innocua Salmonella typhimurium, Escherichia coli O157:H7, and Clostridium sporogenes cells contained in a bovine fecal cocktail. In general, growth of these four bacteria and of aerobic bacteria, lactic acid bacteria, and pseudomonads was suppressed or not observed when lactic acid or acetic acid treatments were used. Bacteria introduced to trisodium phosphate-treated tissue underwent some growth suppression, but to a lesser extent than on acid-treated tissue, and in some cases grew as well as on untreated beef surfaces. Water washes at 72 or 32 degrees C offered little growth suppression of pathogens during subsequent storage when these bacteria were introduced to beef tissue after treatment. The use of a final lactic or acetic acid wash during the processing of beef carcasses offers some residual efficacy in suppressing pathogen proliferation during the refrigerated storage, should these bacteria be introduced immediately after carcass processing.

Abattoirs↗
PubMed1998

Salmonella penetration through eggshell associated with freshness of laid eggs and refrigeration.

Effects of egg age after laying and refrigeration on penetration of the eggshell by Salmonella enteritidis (SE) and Salmonella typhimurium (ST) were examined. Eggs 0.25 to 3 h, 3.25 to 6 h, 1 day, and 7 days old held at two temperatures were immersed in SE or ST suspensions containing 10(3) or 10(6) CFU/ml at 25 degrees C for 10 min. After holding at 25 degrees C for 2 h, the inner eggshell and egg contents were examined for Salmonella cells. The recovery rates of Salmonella cells from both the inner eggshell and egg contents of the 0.25- to 3-h-old eggs were significantly higher than those of other groups, especially at the high-exposure dose. There was no significant difference noted between SE and ST in ability to penetrate through eggshell. Salmonella penetration was significantly decreased by cooling the eggs at 4 degrees C for 15 min prior to immersing them in SE or ST suspension. The data suggested that Salmonella cells readily penetrated through the shell of freshly laid eggs, but that this penetration was suppressed by cooling the eggs before they were exposed to Salmonella suspensions.

Animals↗
PubMed1998

Fate of gamma-irradiated Listeria monocytogenes during refrigerated storage on raw or cooked turkey breast meat.

The radiation resistance and ability of Listeria monocytogenes ATCC 7644, 15313, 43256, and 49594 to multiply on irradiated, air-packed, refrigerated raw or cooked turkey breast meat nuggets (ca. 25 g) and ground turkey breast meat was investigated. Gamma-radiation D values for L. monocytogenes were significantly different on raw and cooked nuggets, 0.56 +/- 0.03 kGy and 0.69 +/- 0.03 kGy, respectively; but they were not significantly different (P < or = 0.05) on raw and cooked ground turkey meat. High populations (approximately 10(9) CFU/g) of L. monocytogenes declined during 14 days of storage at 4 degrees C in both irradiated and nonirradiated samples of raw but not of cooked ground turkey breast meat. A moderate inoculum (approximately 10(3) CFU/g) did not survive a radiation dose of 3 kGy. The population increased in cooked but not in raw samples of irradiated ground turkey meat stored at either 2 or 7 degrees C for 21 days. The D value changed significantly from 0.70 +/- 0.04 to 0.60 +/- 0.02 kGy when the product was cooked to an internal temperature of 80 degrees C before irradiation. Growth on either raw or cooked turkey meat did not alter the radiation resistance of L. monocytogenes. Analyses were performed for pH, aw, moisture, and reducing potential of raw and cooked turkey meat and for pH, amino acid profile, thiamine, and riboflavin contents of aqueous extracts of raw and cooked turkey meats without identifying the factor or factors involved in differences in the survival and multiplication of L. monocytogenes on raw and cooked meat.

Animals↗
PubMed1999

Starter culture activity in refrigerated fermented soymilk.

The refrigerated shelf life of soymilk fermented with single cultures of Lactobacillus fermentum, L. casei, Streptococcus salivarius subsp. thermophilus, and Bifidobacterium longum was evaluated. During storage at 4 degrees C for 28 days, the stability of the microflora differed markedly among the starter cultures. After 28 days, the average numbers of S. salivarius subsp. thermophilus decreased by two log cycles to 6.0 x 10(7) CFU/ml, whereas those of L. casei increased gradually by more than two log cycles to 4.6 x 10(9) CFU/ml. Numbers of B. longum and L. fermentum remained moderately high (8.7 x 10(8) CFU/ml and 3.7 x 10(8) CFU/ml, respectively) even after 28 days of storage. S. salivarius subsp. thermophilus and L. casei continued to metabolize sucrose during the storage period, but the pattern of consumption was different among the strains. The other starter cultures did not seem to have significant activity (P > 0.05) on the residual sugars. In most cases, L(+)-lactate predominated.

Animals↗
PubMed2000

Viability of bifidobacteria in commercial dairy products during refrigerated storage.

Commercial milk and two brands of yogurt containing bifidobacteria were obtained from retail outlets. All products were evaluated for viability of bifidobacteria and lactic acid bacteria during refrigerated storage at 4 degrees C. Milk was evaluated at 9, 6, and 3 days prior and past its expiration date. The yogurts were evaluated at 3, 2, and 1 week prior and past their expiration. Viability of bifidobacteria and lactic acid bacteria in milk and yogurt remained above 10(6) CFU/ml or g until the expiration date of the respective products. This microbial concentration is the recommended minimum dose to receive the health benefits of these organisms.

Animals↗
PubMed2001

Acid tolerance and survival of Escherichia coli O157:H7 inoculated in fruit pulps stored under refrigeration.

The adaptation of Escherichia coli O157:H7 cells to acid conditions has been reported. This study showed the behavior of three strains of E. coli O157:H7 in two different physiological stages (acid shocked and control cells), inoculated in five fruit pulps stored at 4 degrees C for up to 30 days. The three strains of E. coli O157:H7 inoculated in grape pulp could be recovered up to day 30. E. coli O157:H7 strains survived for 4 days in all fruit pulps tested with different pH values (2.51 to 3.26), with the exception of acid-shocked cells of E. coli O157:H7 strain 933, which did not survive in "cajá" (Spodias lutea L.) pulp. The results clearly indicated that acid resistance can persist for long periods during storage at 4 degrees C. The protection conferred by acid adaptation suggests that acid-resistant organisms will be better equipped to outlast these acid challenges. The survival of E. coli O157:H7 in fruit pulps with a low pH, stored under refrigeration, is of extreme importance due to the high virulence of this microorganism. The viability of microorganisms was dependent on the viscosity index of fruit pulps. Less viscous pulps supported the bacteria survival longer than more viscous fruit pulps.

Acids↗
PubMed2003

Impact of cooking, cooling, and subsequent refrigeration on the growth or survival of Clostridium perfringens in cooked meat and poultry products.

In January 1999, the Food Safety and Inspection Service (FSIS) finalized performance standards for the cooking and chilling of meat and poultry products in federally inspected establishments. More restrictive chilling (stabilization) requirements were adopted despite the lack of strong evidence of a public health risk posed by industry practices employing the original May 1988 guidelines (U.S. Department of Agriculture FSIS Directive 7110.3). Baseline data led the FSIS to estimate a "worst case" of 10(4) Clostridium perfringens cells per g in raw meat products. The rationale for the FSIS performance standards was based on this estimate and the assumption that the numbers detected in the baseline study were spores that could survive cooking. The assumptions underlying the regulation stimulated work in our laboratory to help address why there have been so few documented outbreaks of C. perfringens illness associated with the consumption of commercially processed cooked meat and poultry products. Our research took into account the numbers of C. perfringens spores in both raw and cooked products. One hundred ninety-seven raw comminuted meat samples were cooked to 73.9 degrees C and analyzed for C. perfringens levels. All but two samples had undetectable levels (<3 spores per g). Two ground pork samples contained 3.3 and 66 spores per g. Research was also conducted to determine the effect of chilling on the outgrowth of C. perfringens spores in cured and uncured turkey. Raw meat blends inoculated with C. perfringens spores, cooked to 73.9 degrees C, and chilled according to current guidelines or under abuse conditions yielded increases of 2.25 and 2.44 log10 CFU/g for uncured turkey chilled for 6 h and an increase of 3.07 log10 CFU/g for cured turkey chilled for 24 h. No growth occurred in cured turkey during a 6-h cooling period. Furthermore, the fate of C. perfringens in cooked cured and uncured turkey held at refrigeration temperatures was investigated. C. perfringens levels decreased by 2.52, 2.54, and 2.75 log10 CFU/g in cured turkey held at 0.6, 4.4, and 10 degrees C, respectively, for 7 days. Finally, 48 production lots of ready-to-eat meat products that had deviated from FSIS guidelines were analyzed for C. perfringens levels. To date, 456 samples have been tested, and all but 25 (ranging from 100 to 710 CFU/g) of the samples contained C. perfringens at levels of <100 CFU/g. These results further support historical food safety data that suggest a very low public health risk associated with C. perfringens in commercially processed ready-to-eat meat and poultry products.

Animals↗