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PubMed2004

Dietary versus post-mortem use of oregano oil and/or alpha-tocopherol in turkeys to inhibit development of lipid oxidation in meat during refrigerated storage.

The dietary and post-mortem uses of oregano oil in turkeys to inhibit development of lipid oxidation in breast and thigh meat during refrigerated storage were investigated. Using minced meat, patties were prepared from turkey meat post-mortem added with either 200 mg oregano oil or alpha-tocopherol/kg, meat from turkeys dietary supplemented with either 200 mg oregano oil or alpha-tocopheryl acetate/kg feed, and control meat. All patties were cooked, placed in a refrigerated cabinet at 4 degrees C, and lipid oxidation was assessed by monitoring malondialdehyde formation after 3, 6 and 9 days of storage. Treatments significantly (P<0.05) retarded lipid oxidation in both breast and thigh meat patties at all storage times compared with controls. The dietary supplementation of either oregano oil or alpha-tocopheryl acetate exhibited the highest antioxidative activity compared with the other treatments. Post-mortem addition of either oregano oil or alpha-tocopherol to the minced meat also retarded lipid oxidation in the prepared patties compared with controls; however, this effect was inferior to that of the dietary supplementation even though the post-mortem alpha-tocopherol supplemented meat contained 90-fold more alpha-tocopherol than patties from the dietary supplemented meat. Thigh meat was more susceptible to oxidation than breast meat, although the former contained alpha-tocopherol at markedly higher levels. Supplementing the diet with 200 mg oregano oil/kg, alpha-tocopherol levels in the breast and thigh meat significantly (P<0.05) increased compared with control. This increase could not be attributed to the alpha-tocopherol already present in the oregano oil since post-mortem addition of oregano oil to control breast and thigh meat at the same dose could not actually increase the alpha-tocopherol concentrations.

Animal Nutritional Physiological Phenomena↗
PubMed2005

Airborne exposure to trihalomethanes from tap water in homes with refrigeration-type and evaporative cooling systems.

This study evaluates airborne concentrations of common trihalomethane compounds (THM) in selected living spaces of homes supplied with chlorinated tap water containing >85 ppb total THM. Three small homes in an arid urban area were selected, each having three bedrooms, a full bath, and approximately 1000 square feet; two homes had standard (refrigeration-type) central air conditioning and the third had a central evaporative cooling system ("swamp cooler"). A high-end water-use pattern was used at each home in this exposure simulation. THM were concurrently measured on 4 separate test days in tap water and air in the bathroom, living room, the bedroom closest to the bathroom, and outside using Summa canisters. Chloroform (trichloromethane, TCM), bromodichloromethane (BDCM), and dibromochloromethane (DBCM) concentrations were quantified using U.S. EPA Method TO-14. The apparent volatilization fraction consistently followed the order: TCM > BDCM > DBCM. Relatively low airborne THM concentrations (similar to outdoors) were found in the living room and bedroom samples for the home with evaporative cooling, while the refrigeration-cooled homes showed significantly higher THM levels (three- to fourfold). This differential remained after normalizing the air concentrations based on estimated THM throughput or water concentrations. These findings indicate that, despite higher throughput of THM-containing water in homes using evaporative coolers, the higher air exchange rates associated with these systems rapidly clears THM to levels similar to ambient outdoor concentrations.

Air Conditioning↗
PubMed1999

Effect of dietary conjugated linoleic acid on the quality characteristics of chicken eggs during refrigerated storage.

Twenty-four, 79-wk-old White Leghorn hens were assigned randomly to three diets containing 0, 2.5, or 5.0% conjugated linoleic acid (CLA). The diets were fed for 4 wk to determine the effect of dietary CLA on quality characteristics of eggs. Eggs were collected daily and stored at 4 C for 1, 7, 21, or 49 d. At the designated times, the eggs were processed to evaluate water content, fatty acid composition, color, proportions and pH of yolk and albumen. Firmness of yolk after the eggs were hard-cooked was also determined. The proportions of myristic, palmitic, stearic, CLA (9-cis, 11-trans CLA and 10-trans, 12-cis CLA isomers), and unidentified fatty acids in egg yolk lipids were increased as dietary CLA increased, but those of palmitoleic, oleic, linoleic, linolenic, arachidonic, and docosahexaenoic acid were decreased. Duration of refrigeration increased the proportion of egg yolk but decreased the contents of albumen and yolk lipids after 21 d or longer of storage. Egg yolk pH increased as refrigeration time increased, regardless of dietary treatment, but the increase was greater in the eggs produced by hens fed the CLA diets. Albumen pH increased significantly after 7 d of storage but remained unchanged until 21 d and then decreased by 49 d. Dietary CLA had no effect on the pH of albumen until 49 d of storage. After 49 d storage, egg albumen pH from hens fed CLA diets was lower than that of albumen from hens fed the control diet. Yolk color was not influenced by the dietary CLA and storage, but the egg yolk surface from hens fed CLA diets sometimes had relatively dark color with light spots. Dietary CLA and storage of CLA eggs increased the firmness of hard-cooked egg yolk. The texture of yolks from hard-cooked CLA eggs was rubbery and elastic, and the yolks were more difficult to break using an Instron. It was speculated that the quality changes of CLA eggs were related to the increase of yolk water content, the movement of ions between yolk and albumen through yolk membrane, and the changes of egg yolk pH during storage.

Animal Feed↗
PubMed2004

Effects of dietary conjugated linoleic acid on the productivity of laying hens and egg quality during refrigerated storage.

Five hundred and four 40-wk-old Brown Dwarf hens (1.51 +/- 0.08 kg BW) were fed corn-soybean meal diets containing 0, 1, 2, 3, 4, 5, or 6% conjugated linoleic acid (CLA) for 56 d to measure the effects of dietary CLA on laying hen productivity and egg quality during refrigerated storage. Four hens were placed in 1 cage, and 3 cages were grouped as 1 replicate resulting in 6 replicates per treatment. After feeding the experimental diets for 11 d, eggs were collected to determine the fatty acid composition of egg yolks. From d 12 to 18, eggs from hens fed diets containing 0, 2, 4, and 6% CLA diets were stored at 4 degrees C for up to 28 d. At designated times (1, 14, or 28 d), eggs were taken, broken, and shelled to evaluate water content, pH, and ion concentration. Firmness of hard-cooked egg yolk was also determined. With increased dietary CLA, feed intake, BW gain, rate of egg production, egg weight, and feed efficiency all decreased linearly (P < 0.01). The weight of the yolk, albumen, and shell decreased linearly (P < 0.01) with increasing dietary CLA. Concentration of CLA in the yolk lipids increased quadratically (P < 0.01), with increasing dietary CLA. Concurrent increases (P < 0.01) in the concentration of myristic, palmitic, and stearic acids and decreases (P < 0.01) in oleic, linoleic, linolenic, and archidonic acids in egg yolk lipids were observed. Days of storage and CLA (P < 0.01) increased yolk firmness. Egg yolk water content and pH increased with storage and CLA content (P < 0.01). Corresponding decreases were observed in albumen pH. Regardless of dietary treatment, the concentrations of Na, K, and Mg in egg yolks increased with longer storage time. At 28 d of storage, there was a linear (P < 0.01) increase in Na, K, and Mg content in egg yolks as dietary CLA increased. In contrast to the egg yolk, the concentrations of Na, K, and Mg in egg albumen decreased with storage time. On d 28, there was a linear decrease (P < 0.01) in the Na content of albumen with increasing CLA. This study suggests that the greater firmness of CLA-fed eggs might be related to the change of pH, water content, and ion concentrations during refrigerated storage.

Albumins↗
PubMed2007

Role of the alternative sigma factors sigmaE and sigmaS in survival of Salmonella enterica serovar Typhimurium during starvation, refrigeration and osmotic shock.

The ability of Salmonella enterica serovar Typhimurium to survive environmental stress requires specific, coordinated, responses, which induce resistance to the stress condition. This study investigated the relative contribution of sigmaE and sigmaS, the sigma factors regulating extracytoplasmic and general stress response functions, respectively, to survival at low temperature and also in media of differing osmotic strength, conditions relevant to food preservation. To determine if low-temperature storage is a signal for sigmaE- and sigmaS-mediated survival, the ability of S. Typhimurium rpoE, rpoS and rpoE/rpoS mutants to survive in a saline starvation-survival model at a refrigeration temperature (4.5 degrees C) was examined. Under these conditions, the rpoE mutant was significantly (P<0.05) compromised compared to the parent and to an rpoS mutant. The double mutant in rpoE and rpoS displayed a cumulative defect in survival. In hyperosmotic environments (low aw) containing 6 % NaCl and at refrigeration temperature, both sigma factors were important for maximum survival but sigmaS played the dominant role. Analysis of the metabolic activity of starved populations at 4.5 and 37 degrees C revealed significantly (P<0.001) elevated electron-transport system activity in mutants in rpoE and rpoS, indicating a role for sigmaE- and sigmaS-regulated genes in maintaining energy homeostasis. Together these data demonstrate that sigmaE and sigmaS are important for survival of S. Typhimurium in conditions encountered during food processing and that the relative contribution of sigmaE and sigmaS is critically dependent on the precise nature of the stress.

Bacterial Proteins↗
PubMed2005

Effect of Lactobacillus-protective cultures with bacteriocin-like inhibitory substances' producing ability on microbiological, chemical and sensory changes during storage of refrigerated vacuum-packaged sliced beef.

AIMS: To investigate the effect of applying two different Lactobacillus-protective cultures, with bacteriocin-like inhibitory substances' (BLIS) producing ability, individually or in combination, on microbiological, chemical and sensory changes during storage of refrigerated vacuum-packaged sliced beef meat. METHODS AND RESULTS: Lactobacillus sakei CECT 4808 and Lactobacillus curvatus CECT 904(T), which were shown to be producers of BLIS, were inoculated individually or in combination on slices of beef M. semitendinosus. The samples were vacuum packaged and stored at 4 +/- 1 degrees C and were assessed during a 28-day storage period for microbiological [Enterobacteriaceae, Pseudomonas spp., lactic acid bacteria (LAB), Brochothrix thermosphacta and yeasts and moulds], chemical (pH, protein hydrolysis degree, lipid oxidation), sensory (abnormal odour) parameters and instrumental colour. Samples inoculated with the Lact. sakei strain and samples inoculated with the combination of the two strains had significantly (P < 0.05) lower spoilage microbial counts than those inoculated with the Lact. curvatus strain alone or the controls, while both chemical parameters (including lipid oxidation) and abnormal odour scores were also significantly (P < 0.05) improved by the former. Moreover, Lact. sakei alone showed a better preserving effect (P < 0.05) than the combination of both strains in the majority of the parameters tested. Instrumental colour measurements changed with storage time, but no treatment effects (P >or= 0.05) were observed during the whole 28-day storage period. CONCLUSIONS: The BLIS producer Lact. sakei CECT 4808 strain may be used for improving preservation of vacuum-packaged beef slices, as regards spoilage microbial counts and the chemical parameters tested in this study. SIGNIFICANCE AND IMPACT OF THE STUDY: Inoculation with the BLIS producer Lact. sakei CECT 4808 strain would provide an additional hurdle to improve storage life of refrigerated vacuum-packaged sliced beef. Furthermore, this strain demonstrated limited antioxidative ability, which could make a contribution to the prevention of lipid oxidation in meat and meat products.

Animals↗
PubMed1991

Effect of the lactoperoxidase system on Listeria monocytogenes behavior in raw milk at refrigeration temperatures.

Activity of raw milk lactoperoxidase-thiocyanate-hydrogen peroxide (LP) system on four Listeria monocytogenes strains at refrigeration temperatures after addition of 0.25 mM sodium thiocyanate and 0.25 mM hydrogen peroxide was studied. The LP system exhibited a bactericidal activity against L. monocytogenes at 4 and 8 degrees C; the activity was dependent on temperature, length of incubation, and strain of L. monocytogenes tested. D values in activated-LP system milk for the four strains tested ranged from 4.1 to 11.2 days at 4 degrees C and from 4.4 to 9.7 days at 8 degrees C. The lactoperoxidase level in raw milk declined during a 7-day incubation, the decrease being more pronounced at 8 degrees C than at 4 degrees C and in control milk than in activated-LP system milk. The thiocyanate concentration decreased considerably in activated-LP system milk at both temperatures during the first 8 h of incubation. LP system activation was shown to be a feasible procedure for controlling development of L. monocytogenes in raw milk at refrigeration temperatures.

Animals↗
PubMed1969

Aerobic and facultative microflora of fresh and spoiled refrigerated dough products.

The microbial flora of fresh, unsterile, dough products held at refrigeration temperatures was compared with the microbial flora of the same products that had spoiled spontaneously. Various methods based on selective media were used to determine molds, yeasts, and bacteria present. Except for two special cases in which a yeast and Penicillium roqueforti induced spoilage, all of the samples deteriorated because of bacterial growth. A total of 1,132 bacterial isolates was subjected to further classification. In the spoiled products, 92% of the isolates belonged to the Lactobacillaceae. More than one-half of these (53%) belonged to the genus Lactobacillus, and an additional 36% were in the genus Leuconostoc. In the genus Leuconostoc almost all of the strains (94%) were L. mesenteroides. The third most common genus present was Streptococcus, represented by 3% of the total isolates. A preliminary taxonomic study of the microflora of refrigerated dough products revealed none of the isolates to be indicators of fecal contamination and none to be forms known to produce toxins. The highest counts encountered in the moist, fresh products were up to 200 million lactic acid bacteria per g in buttermilk biscuits, with a psychrophilic count as high as 4.8 million. In the spoiled samples, the highest total counts were 820 million in buttermilk biscuits. Mold counts were no higher than 1,800, except in the sample ruined by P. roqueforti where the count was 130,000 mold colonies.

Bacteria↗
PubMed1981

Effect of refrigeration on inoculated Micro-ID strips.

Since reading results after 4 h with the Micro-ID system is not always convenient, a study of 500 isolates indicated that identification at the species level is essentially unchanged when inoculated strips are refrigerated overnight and then incubated or incubated and then refrigerated overnight before reading.

Bacteriological Techniques↗
PubMed1988

Safety of refrigerated storage of admixed parenteral fluids.

Many hospital pharmacies are reluctant to store admixed parenteral fluids longer than 24 to 48 h because of concern about possible microbial contamination. We evaluated the safety of prolonged refrigerated storage of admixtures by culturing mixtures in 471 bags prepared routinely in a hospital pharmacy and stored at 4 degrees C for up to 15 days. Low-level contamination (1 CFU per bag) was found in 3 of 253 solutions of saline and/or glucose into which nonantibiotic additives had been injected. None of 171 saline and/or glucose solutions with antibiotic additives or 47 parenteral nutrition fluids was culture positive. The risk of contamination did not increase with duration of storage, and none of 107 bags stored greater than or equal to 5 days was culture positive. Laboratory studies to measure growth of bacteria and fungi in glucose infusate and parenteral nutrition solutions confirmed that storage at 4 degrees C suppresses growth. Eight of twelve bacterial isolates grew in glucose solutions at 25 degrees C, while none grew at 4 degrees C. Of 13 species of bacteria and fungi inoculated in parenteral nutrition fluids, 8 proliferated at 25 degrees C and none proliferated at 4 degrees C. We conclude that refrigerated storage of parenteral fluids for up to 1 week following admixture, as permitted by Centers for Disease Control guidelines, does not appear to increase the risk of microbial contamination when standard aseptic procedures for admixing and storage are followed.

Bacteria↗
PubMed2003

Processing sputum specimens in a refrigerated centrifuge does not increase the rate of isolation of Mycobacterium tuberculosis.

A total of 1,047 sputum samples from pulmonary tuberculosis patients was collected in cetyl pyridinium chloride-sodium chloride solution. Each sample was divided into two parts and randomly allocated for the isolation of Mycobacterium tuberculosis, with one part to be processed by the standard method and the other by a modified method. In the standard method, the samples were processed by using nonrefrigerated centrifuges, while in the modified method, they were processed by using a refrigerated centrifuge. Fifty-seven samples that yielded contaminants were excluded, and the remaining 990 samples were taken up for analysis. The rates of isolation of M. tuberculosis with the standard and modified methods were 48.6 and 48.1%, respectively, and the difference was not statistically significant (McNemar's test; P > 0.5). However, 51% of the positive cultures were isolated within 2 weeks with the modified method compared to 37% with the standard method (chi-square test; P < 0.001). The results of the study reveal that processing of sputum samples in a refrigerated centrifuge does not improve the rate of isolation but will result in rapid isolation of M. tuberculosis.

Centrifugation↗
PubMed1990

Cardiac arrhythmia in refrigerator repairmen exposed to fluorocarbons.

A field study of 89 refrigerator repairmen was carried out to ascertain whether occupational exposure to fluorocarbons induces cardiac arrhythmia. The concentrations of fluorocarbons in the breathing zones and the heart activity were recorded simultaneously. Most cooling systems contained FC 12 or FC 22. The highest level recorded in one minute was 14,000 ppm and the highest time weighted level during eight hours was 280 ppm. Two types of arrhythmia were recorded, ectopic beats and sudden bradycardia. A within subject comparison design was applied and the main parameter was the difference in arrhythmia frequencies between exposed and unexposed periods. No appreciable differences between exposed and unexposed periods and no consistent dose effect relations were observed, although subjects in the medium exposure category showed a difference of borderline significance (Wilcoxon's test: p = 0.05, one tailed). The frequencies of arrhythmia when unexposed were somewhat higher than previously reported. Misclassification of the exposure and the possible confounding effect of physical workload and psychological strain may have obscured a causal relation and therefore a minor effect cannot be ruled out. The results do not support the notion that fluorocarbons induce cardiac arrhythmia in occupationally exposed refrigerator repairmen.

Adult↗
PubMed1982

A refrigerated treadmill apparatus for exercising dogs.

To prevent overheating and panting in exercising dogs, a refrigerated enclosure was constructed on a standard laboratory treadmill to regulate skin and body temperature of exercising beagles. The enclosure temperature is controlled by a computer software algorithm that analyzes the exercising dog's skin and rectal temperatures and stabilizes rectal temperature to within +/- 0.1 degree C of a preselected resting level. Refrigeration is activated depending on the skin and rectal temperature dynamics lowering enclosure temperature as skin temperature and rectal temperature increase. The system has been used extensively to inhibit panting in exercising beagles, maintaining a mean and standard deviation respiratory frequency of 32 +/- 5 breaths/min during exercise at 5 km/h, 0% grade. These respiratory rates can be compared with reported respiratory frequencies of 95 +/- 57 breaths/min for beagles exercising at the same work load but at room temperature (Mauderly and Pickrell, Research Animals in Medicine, DHEW Publ. 72-333, 1973). This reduction in respiratory frequency is also accompanied by a reduced and repeatable expired minute ventilation and O2 consumption of 9.40 +/- 1.0 1/min (BTPS) and 0.331 +/- 0.031 1/min (STPD), respectively, and can be compared with 24.84 +/- 6.44 1/min (BTPS) and 0.440 +/- 0.0831 1/min (STPD) reported for beagles exercising at room temperature.

Animals↗
PubMed2006

Influence of dietary alpha-tocopheryl acetate supplementation on cholesterol oxidation in retail packed chicken meat during refrigerated storage.

This study examined the effect of dietary alpha-tocopheryl acetate on lipid and cholesterol oxidation in retail packed chicken meat during refrigerated storage. Male broiler chicks were randomly assigned to five pens containing 30 chicks each, which was subjected to one of five dietary treatments (0, 50, 100, 200, or 400 IU of alpha-tocopheryl acetate/kg diet). Five different levels of alpha-tocopherol were supplied to the chicks from 3 to 6 weeks. After 42 d of feeding all the broilers were slaughtered, and the carcasses were packed in polyethylene bags individually, bags similar to those used in the retail trade, and stored for 12 d at 4 degrees C. Growth performance and fatty acid composition were not affected by the dietary alpha-tocopherol levels. The alpha-tocopherol content in breast and thigh muscles increased as the level of dietary alpha-tocopherol increased. The supplementation with 200 or 400 IU of alpha-tocopherol was more effective in reducing the level of lipid oxidation (P<0.05) and total cholesterol oxidation products (P<0.05). Therefore, an increase in the dietary alpha-tocopherol level from 200 to 400 IU/kg feed causes major improvements in the oxidative stability of chicken meat during refrigerated storage.

Animals↗
PubMed2002

Possible effect of refrigeration of warfarin on the international normalized ratio.

A 43-year-old African-American woman taking warfarin for prevention of ischemic stroke experienced fluctuating international normalized ratio (INR) values over 8.5 months; no cause could be identified. After reading a pharmacy information sheet that accompanied a warfarin refill, she reported that she had been refrigerating her warfarin because her other drugs had been "sticking together." She then was instructed to store her warfarin at room temperature. During the 8.5 months she had been refrigerating her warfarin, 80% of her INR values had been outside her goal range versus 37.5% during 9 months of storage at room temperature. A MEDLINE search and communication with the drug's manufacturer provided no information regarding storage of warfarin outside the temperature range of 59-86 degrees F and resultant changes in potency of the drug. Because of potential fluctuation in anticoagulation control, patients should be reminded to store their warfarin at room temperature.

Adult↗
PubMed1998

Inhibition of Listeria monocytogenes and Aeromonas hydrophila by plant extracts in refrigerated cooked beef.

Refrigerated ready-to-eat foods are becoming increasingly popular but are often vulnerable to contamination and subsequent growth by psychrotrophic foodborne pathogens. Consequently, there is a need for additional methods to assure the safety of these foods. Beef slices prepared from roasted whole sirloin tips were used in the study. Nine plant extracts were evaluated for ability to inhibit the growth of two psychrotrophic pathogens (Aeromonas hydrophila and Listeria monocytogenes) in refrigerated cooked beef. Results indicated that only eugenol (clove extract) and pimento extract significantly inhibited the growth of A. hydrophila and L. monocytogenes. However, L. monocytogenes was not as sensitive as was A. hydrophila to both treatments, especially to pimento extracts. These results suggest that plant extracts might be useful as an antimicrobial in cooked ready-to-eat meat.

Aeromonas hydrophila↗
PubMed1998

Growth of inoculated psychrotrophic pathogens on refrigerated fillets of aquacultured rainbow trout and channel catfish.

Aquacultured rainbow trout (Oncorhynchus mykiss) and channel catfish (Ictalurus punctatus) fillets were inoculated with the psychrotrophic pathogens Listeria monocytogenes and Aeromonas hydrophila: cell populations were monitored during refrigerated storage at 2 to 4 degrees C. Fillets of both species were placed individually in sterile plastic bags and inoculated with cell suspensions (10(4.7) CFU/100 g of fish) of either A. hydrophila or L monocytogenes or of both A. hydrophila and L. monocytogenes, for a total of three treatments for each species of fish. Each inoculum and fillet were mixed to ensure uniform distribution and then stored at 2 to 4 degrees C. A. hydrophila, L. monocytogenes, and aerobic cell populations were determined on days 1, 3, 6, 8, 10, 13, and 15. Individually inoculated A. hydrophila and L. monocytogenes grew on catfish and trout fillets during the 15-day study. There was no inhibition of either pathogen by the natural flora on the fillets. Both psychrotrophic pathogens grew equally well in catfish and trout fillets inoculated with a combination of A. hydrophila and L. monocytogenes. In all three treatments, the counts of the psychrotrophic pathogens were lower than the aerobic plate counts. The growth of the psychrotrophic pathogens L. monocytogenes and/or A. hydrophila during refrigerated storage on aquacultured fish fillets could increase the food hazard risk, particularly where there is a possibility of cross-contamination with ready-to-eat food products.

Aeromonas hydrophila↗
PubMed1991

Walk-in refrigerators are key to proper cold storage.

Often overlooked as an important kitchen design element, properly sized refrigeration and freezing equipment is an important contributor to a kitchen's functionality. In many operations, particularly large-volume units, walk-in refrigerators are the anchors of a good cold-storage system. A walk through three different foodservice operations--a college, a hotel and a hospital--finds walk-ins at work.

Equipment Design↗