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Ionizing radiation and antioxidants affect volatile sulfur compounds, lipid oxidation, and color of ready-to-eat Turkey bologna.

Bologna was processed from ground turkey breast meats containing one of four antioxidant treatments (none, rosemary extract, sodium erythorbate, and sodium nitrite). After it was cooked, the bologna was sliced, sealed in gas impermeable bags, exposed to 0, 1.5, and 3.0 kGy gamma-radiation, and then stored at 5 degrees C for up to 8 weeks. Thiobarbuturic acid reactive substances (TBARS), color, and volatile sulfur compounds were measured every 2 weeks during storage. Irradiation had no consistent effect on TBARS values. The rosemary extract and sodium nitrite inhibited, while erythorbate increased, TBARS values, independent of radiation dose or storage time. Irradiation promoted redness and reduced yellowness of the control (no antioxidant) bologna at weeks 0 and 2. The use of nitrite and rosemary extract inhibited the changes in color due to irradiation. Several volatile sulfur compounds (hydrogen sulfide, methanethiol, methyl sulfide, and dimethyl disulfide), measured using a pulsed flame photometric detector, increased with radiation dose. However, none of the antioxidants had any substantial effect on volatile sulfur compounds induced by irradiation. Our results suggest that antioxidants did not consistently affect irradiation-induced volatile sulfur compounds of turkey bologna although they did significantly impact color and lipid oxidation.

Animals↗

Formation of cholesterol oxides in irradiated raw and cooked chicken meat during storage.

The objective of this study was to determine the effect of electron-beam irradiation on the oxidation of cholesterol in raw and cooked chicken meats with different packaging and storage times. Patties were prepared with skinless chicken breasts and legs. Half of the patties were used for raw meat study and the other half for cooked meat work. For cooked samples, patties were cooked in an electric oven to an internal temperature of 70 C. Raw and cooked meat patties were either aerobically or vacuum-packaged before irradiation. Irradiated patties were stored at 4 C up to 2 wk, and the amounts of cholesterol oxides in the patties were analyzed at 0, 7, and 14 d of storage. In raw chicken meat with vacuum packaging, 7beta-hydroxycholesterol and beta-epoxide were the only two cholesterol oxides present in significant amounts. In raw chicken meat with aerobic packaging, 7alpha-hydroxycholesterol and 7-keiocholesterol, which were not detected in vacuum-packaged raw chicken meat, were found. 7beta-Hydroxycholesterol in raw chicken meat was increased by irradiation and storage time, regardless of packaging. The kinds of cholesterol oxides found in cooked meat were basically the same as those found in raw chicken, but the levels in cooked meats at all storage time were higher than those of the raw meats. With vacuum packaging, irradiation had no consistent effect on the amount of beta-epoxide, 7alpha-hydroxycholesterol, or 7-ketocholesterol, but storage significantly influenced the amount of 7-ketocholesterol, 7beta-hydroxycholesterol, and total cholesterol oxides in cooked chicken meat. With aerobic packaging, irradiation significantly increased the formation of 7alpha-hydroxycholesterol, 7beta-hydroxycholesterol, and 7-ketocholesterol in cooked meat stored for 0 and 7 d. After 14 d of storage, however, irradiation had minor effects on the formation of cholesterol oxides in aerobically packaged cooked chicken.

Animals↗

Effects of dietary functional ingredients and packaging methods on sensory characteristics and consumer acceptance of irradiated turkey breast meat.

Raw and cooked breast patties from turkeys fed 8 different diets [control; 200 IU/kg of vitamin E (VE); 0.3 mg/kg of Se; 2.5% conjugated linoleic acids (CLA); 200 IU/kg of VE + 0.3 mg/kg of Se; 200 IU/kg of VE + 2.5% CLA; 0.3 mg/kg of Se + 2.5% CLA; and 200 IU/kg of VE + 0.3 mg/kg of Se + 2.5% CLA] were treated with 2 irradiation doses (0 and 1.5 kGy) and 2 packaging methods (vacuum and aerobic). Raw and cooked samples from 32 treatments were tested by 8 trained sensory panelists for turkey aroma and irradiation off-aroma. Based on the sensory scores, the 3 dietary treatments producing the most and the least off-aroma were selected and used for a consumer acceptance study. Sensory results of raw meat showed that turkey aroma was intense in aerobically packaged meat, whereas irradiation off-aroma was intense with vacuum packaging. Raw meats from dietary treatments containing CLA (CLA, VE + CLA, Se + CLA, VE + Se + CLA) had greater turkey aroma scores, whereas those containing VE (VE and VE + Se) had lower scores than the control. Dietary treatments containing VE (VE, VE + Se, VE + Se + CLA) significantly lowered (P < 0.05) irradiation off-aroma in raw turkey breast meat, whereas CLA increased it, especially when the meats were packaged aerobically. In cooked meat, however, irradiation and packaging had no effect on turkey meat aroma and irradiation off-aroma. Cooked meat from turkeys supplemented with VE (VE and VE + Se) had less (P < 0.05) irradiation off-odor than other dietary treatments. Dietary CLA increased the irradiation off-aroma in cooked meat, which could not be reduced, even when VE and Se were combined in the diet. Irradiation off-aroma of raw meat was not pleasant for most consumers, and dietary supplementation of VE and VE + Se improved consumer acceptance of irradiated raw meat. For cooked meat samples, consumers preferred both color and flavor of irradiated meat to nonirradiated meat.

Animals↗

Irradiation as a phytosanitary treatment for white peach scale (Homoptera: Diaspididae).

Irradiation was examined as a potential phytosanitary treatment to control white peach scale, Pseudaulacaspis pentagona (Targioni-Tozzetti) (Homoptera: Diaspididae), a serious quarantine pest of papaya, Carica papaya L., in Hawaii. Dose-response tests were conducted with second-stage nymphs, adult females without eggs, and adult females with eggs at a series of irradiation doses between 60 and 150 Gy to determine the most tolerant stage. The adult female with eggs was the most tolerant stage. In large-scale validation tests 35,424 adult female scales with and without eggs irradiated at a dose of 150 Gy produced no F1 generation adults with eggs. Irradiation treatment with a minimum absorbed dose of 150 Gy should provide quarantine security for white peach scale on exported papaya and other commodities.

Animals↗

Microbial and sensory quality of marinated and irradiated chicken.

Chicken legs were subjected to two pretreatments (packaged in air or marinated in natural plant extracts and then packaged in air) followed by irradiation (0, 3, or 5 kGy). The control and irradiated chicken legs were stored at 4 degrees C and underwent microbial analysis (mesophilic aerobic plate counts and Salmonella detection) and sensory evaluation at predetermined intervals. Microbial analysis indicated that irradiation had a significant effect (P < or = 0.05) on the mesophilic aerobic plate counts of the poultry. For each treatment, the bacterial growth decreased with an increase of irradiation dose. The marinade had an additive effect with irradiation in reducing bacterial growth and controlling proliferation during storage at 4 +/- 1 degree C. No Salmonella was observed until day 12 in marinated chicken irradiated at 3 kGy and for all experiments with chicken legs stored under air or marinated at 5 kGy. However, Salmonella was found in chicken legs irradiated at 3 kGy in air and in nonirradiated samples. The sensory evaluation indicated a significant (P < or = 0.05) difference in odor and flavor intensities between the irradiated chicken at 5 kGy and the control. No significant difference was found (P > 0.05) between the marinated chicken irradiated at 5 kGy and the control.

Animals↗

Effect of gamma irradiation on the microbiological quality of minimally processed vegetables.

The initial microflora of minimally processed celery and cabbage packaged under a modified atmosphere was determined. The samples came from the same producer and were sold in a supermarket chain of Santiago, Chile. Although neither E. coli nor Salmonella spp. were detected, initial total plate and Enterobacteriaceae counts were high (= 10(5) cfu/g), not meeting in most cases the specifications of the Chilean legislation. The D10 value for two strains of E. coli (ATCC 8739 and a wild type) inoculated as indicator microorganisms was determined. After irradiating with 5 D10 doses (1kGy), the variation of the microbial population and sensory quality during a 7 days storage period at 5 degrees C was studied. In irradiated celery, a reduction of 4.7 and 3.8 logs for total plate and Enterobacteriaceae counts respectively was observed. There was a decrease of 3.8 and 3.6 logs in cabbage for total plate and Enterobacteriaceae counts respectively. In both irradiated and non-irradiated vegetables, neither E. coli nor Salmonella spp. were detected. An increase of 1.6 - 1.7 logs in both microbiological parameters in non-irradiated samples was observed during storage. In irradiated products, only celery showed an increase of 1.2 log in total plate count. Both Enterobacteriaceae count in the two vegetables and Total plate count in cabbage presented essentially no variation in time. No significant differences (p = 0.05) were detected in sensory total quality between the control and the irradiated vegetable and between days of storage.

Apium↗

Microbiological analyses of Merluccius merluccius hubbsi (Marini, 1933) fillets treated with Co-60 ionizing radiation.

Fillets of a hake, Merluccius merluccius hubbsi, were exposed to 2 kGy, 6 kGy, and 10 kGy of ionizing radIation from a Cobalt 60 source and were subsequently stored frozen at 0 degree C. Both these irradiated samples and control samples were examined to determine their bacterial counts and organoleptic qualities (texture, elasticity odor, color, and drip loss) for a period of seven weeks following the irradiation. The irradiated fillets showed an initial marked decrease in the total number of bacteria--amounting to roughly one order of magnitude for those exposed to 2 kGy and roughly three orders of magnitude for those exposed to 6 kGy and 10 kGy as compared to the controls. The samples irradiated with 6 and 10 kGy had bacterial counts well below the minimum acceptable level of 0.8 x 10(6) bacteria per gram for the entire seven-week study period. Regarding organoleptic quality, the fillets exposed to 2 kGy and 6 kGy were found to retain acceptable qualities for an average of about six weeks, somewhat longer than the controls and other irradiated samples. Considering both bacterial counts and organoleptic qualities, the most effective of the three radiation doses employed was 6 kGy.

Animals↗

Oil quality and sensory evaluation of almond (Prunus amygdalus) stored after electron beam processing.

The changes in the lipid fraction and the deterioration of its quality were studied in almonds (Prunus amygdalus) of the variety Guara after treatment with accelerated electrons at doses of 3, 7, and 10 kGy, during a storage period of 5 months. In almond oil, the most significant difference from the nutritional point of view was seen in the fatty acid linolenic (18:3), which shows at 3 kGy a maintenance of the initial content during the whole storage period, whereas, at 7 and 10 kGy, the content in 18:3 disappears from the first moment. The quality indices of the oil (K(232), K(270)) decreased at all doses and remained stable during the time of storage. The peroxide value did not show changes at the doses of 3 and 7 kGy, in non-irradiated samples, but significantly increased when the maximum dose of 10 kGy was applied. These changes were reflected in the sensory analysis, in which the tasters did not find sensory differences between the controls and those irradiated at doses of 3 or 7 kGy, whereas almonds irradiated at 10 kGy exhibited a rancid flavor and a significant decrease in general quality.

Aflatoxins↗

Double-packaging is effective in reducing lipid oxidation and off-odor volatiles of irradiated raw turkey meat.

The effects of double packaging on lipid oxidation, color, and volatile production were determined to establish a modified packaging method to improve quality changes in irradiated raw turkey meat. Sliced raw turkey breast and thigh meats were aerobically, vacuum- or double (vacuum and aerobic)-packaged, electron beam irradiated at 2.5 kGy, and then stored under refrigerated temperature. For the double-packaged samples, the outer vacuum bags were removed after 5, 7, or 9 d of refrigerated storage. 2-Thiobarbituric acid-reactive substances (TBARS) values, volatile compounds, and color values of the samples were determined after 10 d of storage. Irradiation and aerobic packaging promoted production of aldehydes (propanal and hexanal) related to lipid oxidation in turkey breast and thigh meats. Vacuum-packaged irradiated samples retained S-volatile compounds (methanethiol, dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide), mainly responsible for the irradiation off-odor, during storage. Exposure of double-packaged irradiated turkey meats to aerobic conditions by removing outer vacuum bags a few days before the test was effective in controlling both lipid oxidation-dependent (aldehydes) and radiolytic off-odor (S-compounds) volatiles. The a* values of raw turkey breast and thigh meats increased by irradiation regardless of packaging conditions. The a* value of double-packaged meats was lower than that of the vacuum-packaged meats but was not significant. Thus, the use of double-packaging alone was not enough to reduce the pink color of irradiated raw turkey meat. When lipid oxidation and irradiation off-odor should be minimized without any additional additives, however, double packaging is an excellent method to be used for turkey meats.

Animals↗

Effect of freezing, irradiation, and frozen storage on survival of Salmonella in concentrated orange juice.

Six strains of Salmonella (Anatum F4317, Dublin 15480, Enteritidis 13076, Enteritidis WY15159, Stanley H0588, and Typhimurium 14028) were individually inoculated into orange juice concentrate (OJC) and frozen to -20 degrees C. The frozen samples were treated with 0 (nonirradiated), 0.5, 1.0, or 2.0 kGy of gamma radiation and held frozen for 1 h, and the surviving bacterial population was assessed. The strains showed significant variability in their response to freezing and to freezing in combination with irradiation. The response was dose dependent. Relative to the nonfrozen, nonirradiated control, the reduction following the highest dose (2.0 kGy) ranged from 1.29 log CFU/ml (Salmonella Typhimurium) to 2.17 log CFU/ml (Salmonella Stanley). Samples of OJC inoculated with Salmonella Enteritidis WY15159 and irradiated were stored at -20 degrees C for 1, 2, 7, or 14 days, and the surviving population was determined. Relative to the nonfrozen, nonirradiated control, after 14 days, the population was reduced by 1.2 log CFU/ml in the nonirradiated samples and by 3.3 log CFU/ml following treatment with 2.0 kGy. The combination of frozen storage plus irradiation resulted in greater overall reductions than either process alone.

Beverages↗

Radiation (gamma) resistance and postirradiation growth of Listeria monocytogenes suspended in beef bologna containing sodium diacetate and potassium lactate.

Listeria monocytogenes, a psychrotrophic foodborne pathogen, is a frequent postprocessing contaminant of ready-to-eat (RTE) meat products, including frankfurters and bologna. Ionizing radiation can eliminate L. monocytogenes from RTE meats. When they are incorporated into fine-emulsion sausages, sodium diacetate (SDA) and potassium lactate (PL) mixtures inhibit the growth of L. monocytogenes. The radiation resistance of L. monocytogenes, and its ability to proliferate during long-term refrigerated storage (9 degrees C), when inoculated into beef bologna that contained 0% SDA-0% PL, 0.07% SDA-1% PL, and 0.15% SDA-2% PL, were determined. The radiation doses required to eliminate 90% of the viable L. monocytogenes cells were 0.56 kGy for bologna containing 0% SDA-0% PL, 0.53 kGy for bologna containing 0.07% SDA-1% PL, and 0.46 kGy for bologna containing 0.15% SDA-2% PL. L. monocytogenes was able to proliferate on bologna containing 0% SDA-0% PL during refrigerated storage, but the onset of proliferation was delayed by the addition of the SDA-PL mixtures. An ionizing radiation dose of 3.0 kGy prevented the proliferation of L. monocytogenes and background microflora in bologna containing 0.07% SDA-1% PL and in bologna containing 0.15% SDA-2% PL over 8 weeks of storage at 9 degrees C. Little effect on lipid oxidation and color of the control bologna, or bologna containing SDA-PL mixtures, was observed upon irradiation at either 1.5 or 3.0 kGy.

Animals↗

Effect of gamma radiation and oregano essential oil on murein and ATP concentration of Escherichia coli O157:H7.

This study was carried out to evaluate the effects of gamma radiation alone or in combination with oregano essential oil on the murein composition of Escherichia coli O157:H7 and on the intracellular and extracellular concentrations of ATP. The bacterial strain was treated with three radiation doses: 0.4 kGy to induce cell damage, 1.1 kGy to obtain a viable but non-culturable state, and 1.3 kGy to cause cell death. Oregano essential oil was used at 0.006 and 0.025% (wt/vol), which is the MIC. All treatments had a significant effect (P < or = 0.05) on the murein composition, although some muropeptides did not seem to be affected by the treatment. Each treatment had a different effect on the relative percentage and number of muropeptides. There was a significant correlation (P < or = 0.05) between the decrease in intracellular ATP and the increase in extracellular ATP following treatment of the cells with oregano oil. The reduction of intracellular ATP was even more important when oregano oil was combined with irradiation, but irradiation alone at a high dose (< or = 1.1 kGy) significantly decreased (P < or = 0.05) the internal ATP without affecting the external ATP. Transmission electron microscopic examination revealed that oregano oil and irradiation have an effect on cell wall structure.

Adenosine Triphosphate↗

Incidence of aflatoxin B1 in the Egyptian cured meat basterma and control by gamma-irradiation.

In the present studies trials have been carried out to investigate the occurrence of aflatoxin B1 in the Egyptian cured meat basterma and to control such contamination by gamma-rays. Basterma was prepared from fresh salted meat coated with spice paste and stored at room temperature. The total mould counts of basterma samples varied from 10(3) to 10(6) cfu/g in summer months and from 10(2) to 10(5) cfu/g in winter months. Aspergillus, Penicillium, Mucor, Rhizopus, Fusarium and Cladosporium were the most common fungal genera isolated from basterma samples and its components. Basterma samples contained total aflatoxins at levels from 2.8 to 47 microg x kg(-1). Aflatoxins were determined in the spice paste at levels from 9.6 to 120 microg x kg(-1) and in pepper (285.6 microg x kg(-1)), garlic (224.4 microg x kg(-1)), fenugreek (194.2 microg x kg(-1)), coriander (16 and capsicum (42.4 microg x kg(-1)). At an irradiation dose level of 3 kGy, only one sample each of pepper, fenugreek, and spice paste were contaminated with aflatoxins and all basterma samples and its components were free from aflatoxins at an irradiation dose level of 5 kGy.

Aflatoxin B1↗

Effect of gamma irradiation on shelf life and bacterial and viral loads in hard-shelled clams (Mercenaria mercenaria).

The feasibility of using 60Co gamma irradiation to inactivate total coliforms, fecal coliforms, Escherichia coli, Clostridium perfringens, and F-coliphage in hard-shelled clams, Mercenaria mercenaria, was investigated. The results of three trials indicated average D10 values of 1.32 kGy for total coliforms, 1.39 kGy for fecal coliforms, 1.54 kGy for E. coli, 2.71 kGy for C. perfringens, and 13.50 kGy for F-coliphage. Irradiation doses of > 0.5 kGy were significantly lethal to the shellfish.

Animals↗

Reduction and survival of Listeria monocytogenes in ready-to-eat meats after irradiation.

A five-strain Listeria monocytogenes culture was inoculated onto six different types of ready-to-eat (RTE) meats (frankfurters, ham, roast beef, bologna, smoked turkey with lactate, and smoked turkey without lactate). The meats were vacuum packed and stored at 4 degrees C for 24 h prior to irradiation. Populations of L. monocytogenes were recovered by surface plating on nonselective and selective media. The margins of safety studied include 3-log (3D) and 5-log (5D) reduction of pathogenic bacteria to achieve an optimal level of reduction while retaining organoleptic qualities of the meats. A 3-log reduction of L. monocytogenes was obtained at 1.5 kGy when nonselective plating medium was used. The dosages for 3-log reduction were 1.5 kGy for bologna, roast beef, and both types of turkey and 2.0 kGy for frankfurters and ham on the basis of use of selective medium. The D10-values ranged from 0.42 to 0.44 kGy. A 5-log reduction of L. monocytogenes was obtained at 2.5 kGy with nonselective medium. With selective medium, the dosages were 2.5 kGy for bologna, roast beef, and both types of turkey and 3.0 kGy for frankfurters and ham. Survival of L. monocytogenes in the same RTE meat types after irradiation was also studied. Meats were inoculated with 5 log L. monocytogenes per g and irradiated at doses of 2.0 and 4.0 kGy. Recovery of the surviving organisms was observed during storage at temperatures of 4 and 10 degrees C for 12 weeks. Preliminary results showed no growth in meats irradiated at 4.0 kGy. Survivors were observed for irradiated meats at 2.0 kGy stored at 10 degrees C after the second week. No growth was observed in samples irradiated at 2.0 kGy stored at 4 degrees C until the fifth week.

Colony Count, Microbial↗

Radiation resistance and virulence of Listeria monocytogenes Scott A following starvation in physiological saline.

The influence of starvation on the resistance of Listeria monocytogenes Scott A to electron beam irradiation in 0.85% (wt/vol) NaCl (saline) and in ground pork was investigated. Exponential- or stationary-phase cells (control) were grown at 35 degrees C in tryptic soy broth supplemented with 0.6% yeast extract. Washed cells were starved for 12 days in saline, and virulence of the pathogen was evaluated at 0, 8, and 12 days during starvation. Samples of saline and irradiation-sterilized ground pork, inoculated with control or starved cells, were irradiated at doses ranging from 0.0 to 2.5 kGy. L. monocytogenes survivors were determined by plating diluted samples of saline or pork on tryptic soy agar supplemented with 0.6% yeast extract and counting bacterial colonies following incubation (35 degrees C, 48 h). Virulence of starved cells and control was not significantly different (P > 0.05). Cells exhibited the highest radiation resistance at 8 days of starvation. Irradiation (0.5 kGy) in saline resulted in approximately 7.14, 5.55, and 2.38 log reduction in exponential, stationary, and starved cells, respectively. Irradiation of ground pork at 2.5 kGy reduced controls by approximately 6.0 log, whereas starved cells were reduced by only 3.8 log. Starved cells consistently exhibited higher irradiation D10-values than controls (P < 0.05). D10-values for exponential, stationary, and starved cells were 0.07, 0.09, and 0.21 kGy and 0.35, 0.42, and 0.66 kGy in saline and ground pork, respectively. These results indicate that starvation cross-protects L. monocytogenes Scott A against radiation inactivation and should be considered when determining this pathogen's irradiation D-value.

Adaptation, Physiological↗

INACTIVATION OF THE RADIATION-RESISTANT SPOILAGE BACTERIUM MICROCOCCUS RADIODURANS. II. RADIATION INACTIVATION RATES AS INFLUENCED BY MENSTRUUM TEMPERATURE, PREIRRADIATION HEAT TREATMENT, AND CERTAIN REDUCING AGENTS.

The R(1) strain of Micrococcus radiodurans, previously determined to be more resistant than three other strains exposed to gamma radiation, was studied further to determine the influence of certain environmental factors on resistance to radiation inactivation. The frozen state offered insignificant protection to the organisms irradiated in raw puréed beef. Resistance was reduced by higher menstruum temperatures (40 and 50 C) during irradiation. Preirradiation heat treatment was found to lower resistance to subsequent irradiation. When the cells were irradiated in buffer at pH 5, 7, or 9, no differences in resistance were noted. Cell suspensions in buffer were protected to some extent by cysteine but not by thioglycolate. Ascorbate enhanced radiation inactivation.

Animals↗