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PubMed2003

Stability of ethanol in postmortem blood and vitreous humor in long-term refrigerated storage.

Ethanol concentrations in postmortem blood and vitreous humor samples collected at the Miami-Dade Medical Examiner Department over 5-6 years ago were reexamined to assess whether vitreous humor is a more reliable specimen for the analysis of ethanol in samples stored long term. The average change in 50-mL polypropylene tubes containing blood was 0.06 gm/dL (35% loss). On the other hand, vitreous humor samples collected in 10-mL gray-top Vacutainer tubes yielded an average change of 0.01 gm/dL (6.1% loss). This study demonstrates that vitreous humor may be a reliable matrix for ethanol analysis following prolonged refrigerated storage of the samples.

Chromatography, Gas↗
PubMed1997

Effects of gamma irradiation on the survival of Listeria monocytogenes and on its growth at refrigeration temperature in poultry and red meat.

Gamma irradiation sensitivity of a strain of Listeria monocytogenes was determined in trypticase soy broth supplemented with yeast extract (TSB-YE), in a slurry of chicken breast meat and in raw ground beef. D10 values in these different media were 0.364, 0.599, and 0.699 kGy, respectively. This organism appeared most sensitive in TSB-YE, more resistant in minced fresh chicken breast meat, and most resistant in fresh minced beef. It was found that irradiation at 2.5 kGy prior to refrigeration is an efficient way for the preservation of meat products contaminated at 10(3) to 10(4) per gram initial load of L. monocytogenes for about 7 d. However, with this initial load, the injured cells might repair themselves and cause a health hazard during storage at 4 C in the presence of air after 7 d.

Animals↗
PubMed2000

Comparison of autologous fat transfer in fresh, refrigerated, and frozen specimens: an animal model.

The rising popularity of autologous fat transfer (AFT) has raised the questions whether cryopreserved adipocytes are a suitable substrate for soft-tissue augmentation, and which storage techniques may be most suitable for a maximally successful surgical result. An animal model of AFT was conceived using isogeneic Sprague-Dawley rats. Suction harvesting of fat and subcutaneous implantation was performed with specimens stored at -16 degrees C or 1 degrees C for a period of 1 or 2 weeks, as well as a group that underwent immediate implantation. A histological comparison of the experimental and control groups clearly demonstrated a decrease in viable adipocytes and an increase in signs of inflammation and fat cell necrosis in those animals that received stored fat instead of immediate fat implantation. These changes became more severe with increased length of storage and the use of refrigeration over freezing. The authors conclude that the practice of storing harvested adipocytes for later injection is not supported by the experimental evidence and should be avoided.

Adipose Tissue↗
PubMedDate not supplied

Antimicrobial mixtures used to store harvested skin: antimicrobial activities tested at refrigerator (4 degrees C) temperatures.

Tissue culture media used by skin and tissue banks to store tissue were tested, with and without antimicrobial mixtures, for their ability to inhibit the growth of bacteria during incubation at refrigerator temperatures. Reductions in bacterial load were found after incubation at 4 degrees C in both the basal tissue culture media with and without the addition of antimicrobial mixtures. The presence of antimicrobials enhanced the degree and rapidity of reduction. Variations occurred among the different formulations, with or without added antimicrobials. No one formulation for either the basal tissue culture medium or antimicrobial mixture was ideal. Methods described in this study can be used to establish optimum basal medium and antimicrobial mixture formulations for general use by skin and tissue banks.

Anti-Bacterial Agents↗
PubMed2002

Lactobacillus fuchuensis sp. nov., isolated from vacuum-packaged refrigerated beef.

Four strains of a hitherto unknown bacterium isolated from vacuum-packaged refrigerated beef were characterized by using phenotypic and phylogenetic methods. The novel strains were Gram-positive, catalase-negative, psychrophilic, rod-shaped bacteria with lactic acid-homofermentative mechanism. Comparative 16S rDNA gene sequencing demonstrated that the unknown strains represent a novel subline within the genus Lactobacillus, close to but distinct from Lactobacillus curvatus and Lactobacillus sakei. The unknown strains were readily distinguished from all currently described members of the genus Lactobacillus by biochemical properties and SDS-PAGE whole-cell protein profiles. Based on phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium be classified as Lactobacillus fuchuensis sp. nov. The type strain is strain B5M10T (= JCM 11249T = DSM 14340T).

Animals↗
PubMed2002

Carnobacterium viridans sp. nov., an alkaliphilic, facultative anaerobe isolated from refrigerated, vacuum-packed bologna sausage.

A facultatively anaerobic, non-spore-forming, psychrophilic, gram-positive, non-aciduric but alkaliphilic, rod-shaped bacterium (MPL-11T) was found to be responsible for green discoloration of refrigerated vacuum-packaged bologna upon opening of the package. Although Aerococcus viridans, which had been implicated earlier in causing the same problem, was also found, this is the first report of discoloration caused by an organism shown to be a species of Carnobacterium. Bacterial discoloration was caused by H2O2 production upon exposure of the meat to air. Strain MPL-11T is catalase- and oxidase-negative. It is not motile and does not reduce nitrate to nitrite or produce ammonia from arginine. It does not grow in acetate-containing broth or agar (Rogosa) or produce H2S. The peptidoglycan is of the meso-diaminopimelic acid type and it produces predominantly L(+)-lactic acid from glucose. It grows from at least 2 to 30 degrees C over a pH range from 5.5 to 9.1. Ribotyping suggested that strain MPL-11T could be a species of either Lactobacillus or Carnobacterium, but analysis using DNA sequences from the 16S rRNA gene showed conclusively that the organism belonged to the genus Carnobacterium. Since acid is not produced from amygdalin, inulin, mannitol, methyl alpha-D-glucoside or D-xylose, the organism differs from the seven described species of Carnobacterium. In addition, strain MPL-11T is the first member of the genus found that does not produce acid from ribose. It is capable of acid production/growth on galactose, glucose, fructose, mannose, N-acetylglucosamine, aesculin, cellobiose, maltose, lactose, sucrose, trehalose and tagatose. Although extremely salt tolerant, it does not grow in > or = 4% NaCl. On the basis of phenotypic and genotypic data, it is concluded that this isolate represents a separate, novel species. Accordingly, the name Carnobacterium viridans sp. nov. is proposed. The type strain is strain MPL-11T (= ATCC BAA-336T = DSM 14451T).

DNA, Bacterial↗
PubMed2004

Evaluation of refrigerated platelet concentrates supplemented with low doses of second messenger effectors.

With the goal of producing haemostatically effective platelet concentrates (PCs) with a longer shelf-life, we aimed to identify a simple combination of platelet inhibitors, with a low pharmacological load, which could avoid the unacceptable loss of platelets stored under refrigerated conditions. PCs stored with different combinations of second messenger effectors were analysed at days 5, 10 and 15 of storage and compared with those supplemented with ThromboSol--a combination of six platelet inhibitors that protects cells from cold damage. The following parameters were analysed: platelet counts, biochemical parameters (glucose, pH, bicarbonate, lactate), cell lysis (lactic dehydrogenase, LDH), membrane glycoproteins (GPs), platelet aggregation, fibrinogen binding and hypotonic shock response. We characterized the combination of amiloride and sodium nitroprusside (at 1/2 the dose included in ThromboSol). This was found to be similar to ThromboSol and superior to nontreated units in the prevention of cold-induced platelet aggregation at day 15 of storage (maintenance of 78% and 80% of initial platelet counts, respectively), preservation of GPIbalpha (11% and 12% better maintenance of mean fluorescence intensity compared with control units, respectively), and reduced cell lysis (13% and 11% decrease in supernatant LDH, respectively). The reduced pharmacological load with the identified solution compared with ThromboSol is an argument in favour of the potential use of these agents when designing strategies to improve PC storage.

Blood Platelets↗
PubMed1990

Growth of Listeria monocytogenes at refrigeration temperatures.

The growth of three strains of Listeria monocytogenes at refrigeration temperatures (-0.5 to 9.3 degrees C) in chicken broth and/or UHT milk was determined using a rocking temperature gradient incubator. Minimum growth temperatures ranged from -0.1 to -0.4 degree C for the three strains. Lag times of 1-3 d and 3 to greater than 34 d were observed with incubation at 5 and 0 degrees C respectively. Corresponding generation times ranged from 13-24 h at 5 degrees C and 62-131 h at 0 degree C. The type of culture medium had an influence on both the rate and extent of growth. Incubation of cultures at 4 degrees C before inoculation caused a marked reduction in the lag time when compared with cultures which had been previously incubated at 30 degrees C.

Animals↗
PubMed1993

A sandwich enzyme-linked immunosorbent assay (ELISA) for detection of Pseudomonas fluorescens and related psychrotrophic bacteria in refrigerated milk.

A sandwich ELISA (enzyme-linked immunosorbent assay) was developed for detection of Pseudomonas fluorescens and related psychrotrophic bacteria in refrigerated milk. Polyclonal antibodies were raised in rabbits against protein F from the cell envelope of Pseudomonas fluorescens AH-70. The anti-protein F antibodies (anti-PF) bound to the wells of a microtitre plate were used to capture this protein from the micro-organisms on milk samples. Further immunorecognition of the captured antigen was attained with the same anti-PF antibodies conjugated to biotin. ExtrAvidin-peroxidase was used to detect the biotinylated antibodies bound to their specific antigens. Subsequent enzymic conversion of substrate gave clear absorbance differences when assaying milk samples containing Ps. fluorescens strains of different origin as well as related psychrotropic micro-organisms.

Animals↗
PubMed2006

Mammalian sperm energy resources management and survival during conservation in refrigeration.

The present review has as its main aim to present an overview regarding the mechanisms utilized by mammalian sperm to manage its intracellular energy levels. This management will strongly influence the sperm's ability to maintain its overall function during its entire life span. Thus, the precise knowledge of these mechanisms will be of the utmost interest to optimize the systems utilized to conserve mammalian sperm for a medium-to-long time-lapse. Briefly, utilization of hexoses as energy substrates by mammalian sperm is very finely regulated from the very first step of its metabolization. Furthermore, the equilibrium among the separate, monosaccharide metabolization pathways in mammalian sperm depends on many factors. This prevents the possibility to draw a general vision of sperm energy utilization, which explains the results of all mammalian species in all points of the sperm life-cycle. To complicate the matter further, there are separate energy phenotypes among mammalian spermatozoa. The precise knowledge of these phenotypes is of the greatest importance in order to optimize the design of new extenders for sperm conservation in refrigerated conditions. Moreover, sugars can act on sperm not only as passive metabolic substrates, but also as direct function activators through mechanisms like specific changes in the tyrosine phosphorylation status of distinct proteins. Finally, mammalian sperm utilizes non-glucidic substrates like citrate and lactate to obtain energy in a regular form. This utilization is also finely regulated and of importance to maintain overall sperm function. This implies that the exact proportion of glucidic and non-glucidic energy substrates could be very important to optimize the survival ability of these cells in conservation.

Animals↗
PubMed2005

Growth of Bifidobacterium longum BB536 in medida (fermented cereal porridge) and their survival during refrigerated storage.

AIMS: To develop medida, a Sudanese fermented thin porridge as a probiotic dietary adjunct with high total solids. METHODS AND RESULTS: Fifteen per cent brown rice flour of 2-day-old malted paddy and skim milk were used for formulation. Levels of 2.25, 4.5 and 10% of added skim milk were studied. The initial pH was 6.7 and fermentation was run to a final pH of 4.4 using culture of Bifidobacterium longum BB 536. The highest count of 9.9 +/- 0.07 log CFU ml(-1) was obtained with 10% of added skim milk. The total solids at this level was 21%, 11.1 times more compared with the traditionally prepared medida using un-malted brown rice. The viscosity was low and the flowing characteristic was stable. The final productions of lactic and acetic acids were 56.8 +/- 0.80 and 56.3 +/- 2.00 mumol ml(-1) respectively. The high ratio of acetate to lactate decreased as fermentation continues due to the increase in the rate of lactate production. Under refrigerated storage the count of B. longum BB 536 remained relatively stable during the first week (9.7 +/- 0.10 log CFU ml(-1)) then subsequently decreased by 0.9 log CFU ml(-1) in the following week. CONCLUSIONS: The results of this study demonstrated that fermented medida made from malted brown rice is a suitable food system for the delivery of B. longum BB 536 with a relatively stable shelf life. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study is the first attempt to prepare fermented medida from malted flour with bifidobacteria having the highest total solids while still maintaining the flowing characteristics. Previous studies on medida did not go beyond the use of alpha amylase enzyme and pure lactic acid bacteria isolates from spontaneously fermented dough.

Acetic Acid↗
PubMed2003

Thermal modeling and performance analysis of a thermoacoustic refrigerator.

A heat-driven thermoacoustic refrigerator has been designed and tested. A detailed thermal model of the device is presented. Energy balances within the system are discussed using external, heat exchanger, and stack control volumes in order to clarify the relationships of work and heat fluxes below and above onset. Thermal modeling is discussed as a tool for performance analysis as well as for determining system heat losses and finding input heat flows required by a thermoacoustic code. A method of using the control volume balance equations to find stack work and device efficiencies is presented. Experimental measurements are compared to DELTAE thermoacoustic modeling predictions. Modeling results show that viscous losses within the system have a significant impact on the device performance as well as on the ability of DELTAE to accurately predict performance. Modeling has led to an understanding of system performance and highlighted loss sources that are areas for improvement in a redesign.

Acoustics↗
PubMed2006

Changes in the spoilage-related microbiota of beef during refrigerated storage under different packaging conditions.

The microbial spoilage of beef was monitored during storage at 5 degrees C under three different conditions of modified-atmosphere packaging (MAP): (i) air (MAP1), (ii) 60% O2 and 40% CO2 (MAP2), and (iii) 20% O2 and 40% CO2 (MAP3). Pseudomonas, Enterobacteriaceae, Brochothrix thermosphacta, and lactic acid bacteria were monitored by viable counts and PCR-denaturing gradient gel electrophoresis (DGGE) analysis during 14 days of storage. Moreover, headspace gas composition, weight loss, and beef color change were also determined at each sampling time. Overall, MAP2 was shown to have the best protective effect, keeping the microbial loads and color change to acceptable levels in the first 7 days of refrigerated storage. The microbial colonies from the plate counts of each microbial group were identified by PCR-DGGE of the variable V6-V8 region of the 16S rRNA gene. Thirteen different genera and at least 17 different species were identified after sequencing of DGGE fragments that showed a wide diversity of spoilage-related bacteria taking turns during beef storage in the function of the packaging conditions. The countable species for each spoilage-related microbial group were different according to packaging conditions and times of storage. In fact, the DGGE profiles displayed significant changes during time and depending on the initial atmosphere used. The spoilage occurred between 7 and 14 days of storage, and the microbial species found in the spoiled meat varied according to the packaging conditions. Rahnella aquatilis, Rahnella spp., Pseudomonas spp., and Carnobacterium divergens were identified as acting during beef storage in air (MAP1). Pseudomonas spp. and Lactobacillus sakei were found in beef stored under MAP conditions with high oxygen content (MAP2), while Rahnella spp. and L. sakei were the main species found during storage using MAP3. The identification of the spoilage-related microbiota by molecular methods can help in the effective establishment of storage conditions for fresh meat.

Animals↗
PubMed1978

Effect of prior refrigeration on botulinal outgrowth in perishable canned cured meat when temperature abused.

Perishable canned cured meat inoculated with Clostridium botulinum spores was placed at 4.4 or 10 degrees C after manufacture. Spore germination occurred at 10 degrees C. The germinated cell count remained stable over a period of 16 to 18 weeks. During that time period the inhibitory system and residual nitrite descreased. These factors combine to make perishable canned cured meats more prone to spoilage and potential hazard if they are temperature abused after a period of refrigerated storage.

Clostridium botulinum↗
PubMed1988

A method to assess the bacterial content of refrigerated meat.

A new method has been developed to estimate the levels of gram-negative bacteria on refrigerated meat. The method is based on the aminopeptidase activity of these bacteria, which cleaves L-alanine-p-nitroanilide to yield p-nitroaniline, which is easily determined spectrophotometrically. This method allows the determination of levels around 10(6) to 10(7) CFU cm-2 in about 3 h. Because of the yellow color of p-nitroaniline, bacterial loads around 10(7) CFU cm-2 develop a color intense enough to be detected with the naked eye.

Aminopeptidases↗
PubMed1989

Fate of Listeria monocytogenes in processed meat products during refrigerated storage.

The fate of Listeria monocytogenes during refrigerated storage was determined on several processed meat products, including ham, bologna, wieners, sliced chicken, sliced turkey, fermented semidried sausage, bratwurst, and cooked roast beef. The meats were surface inoculated with a five-strain mixture of less than or equal to 200 or ca. 10(5) L. monocytogenes cells per package, vacuum packaged, and stored at 4.4 degrees C. Survival or growth of listeriae was determined for up to 12 weeks of storage or until the product was spoiled. The organism survived but did not grow on summer sausage, grew only slightly on cooked roast beef, grew well on some wiener products but not on others, grew well (10(3) to 10(5) CFU/g increase within 4 weeks) on ham, bologna, and bratwurst, and grew exceptionally well (10(3) to 10(5) CFU/g increase within 4 weeks) on sliced chicken and turkey. The rate of growth depended largely upon the type of product and the pH of the product. Growth was most prolific on processed poultry products. The organism generally grew well on meats near or above pH 6 and poorly or not at all on products near or below pH 5. These results indicate the importance of preventing postprocessing contamination of L. monocytogenes in a variety of ready-to-eat meat products.

Animals↗
PubMed1993

Inhibition of Listeria monocytogenes by Lactobacillus bavaricus MN in beef systems at refrigeration temperatures.

The ability of Lactobacillus bavaricus, a meat isolate, to inhibit the growth of three Listeria monocytogenes strains was examined in three beef systems: beef cubes, beef cubes in gravy, and beef cubes in gravy containing glucose. The beef was minimally heat treated, inoculated with L. bavaricus at 10(5) or 10(3) CFU/g and L. monocytogenes at 10(2) CFU/g, vacuum sealed, and stored at 4 or 10 degrees C. The meat samples were monitored for microbial growth, pH, and bacteriocin production. The pathogen was inhibited by L. bavaricus MN. At 4 degrees C, L. monocytogenes was inhibited or killed depending on the initial inoculum level of L. bavaricus. At 10 degrees C, at least a 10-fold reduction of the pathogen occurred, except in the beef without gravy. This system showed a transient inhibition of the pathogen during the first week of storage followed by growth to control levels by the end of the incubation period. Bacteriocin was detected in the samples, and inhibition could not be attributed to acidification. Low refrigeration temperatures significantly (P < or = 0.05) enhanced L. monocytogenes inhibition. Moreover, the addition of glucose-containing gravy and the higher inoculum level of L. bavaricus were significantly (P < or = 0.05) more effective in reducing L. monocytogenes populations in most of the systems studied.

Animals↗
PubMed2004

Raw cow milk bacterial population shifts attributable to refrigeration.

We monitored the dynamic changes in the bacterial population in milk associated with refrigeration. Direct analyses of DNA by using temporal temperature gel electrophoresis (TTGE) and denaturing gradient gel electrophoresis (DGGE) allowed us to make accurate species assignments for bacteria with low-GC-content (low-GC%) (<55%) and medium- or high-GC% (>55%) genomes, respectively. We examined raw milk samples before and after 24-h conservation at 4 degrees C. Bacterial identification was facilitated by comparison with an extensive bacterial reference database ( approximately 150 species) that we established with DNA fragments of pure bacterial strains. Cloning and sequencing of fragments missing from the database were used to achieve complete species identification. Considerable evolution of bacterial populations occurred during conservation at 4 degrees C. TTGE and DGGE are shown to be a powerful tool for identifying the main bacterial species of the raw milk samples and for monitoring changes in bacterial populations during conservation at 4 degrees C. The emergence of psychrotrophic bacteria such as Listeria spp. or Aeromonas hydrophila is demonstrated.

Animals↗