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PubMed1981

[Development of a grain irradiator--relation between dimension of the irradiator and grain flow in irradiation region (author's transl)].

A grain irradiator was devised for the radiation disinfestation of rice. In this irradiator, dose of rice was varried through regulation of rice velocity in irradiation region. The velocity was regulated by variation of opening area and time of an annular gate valve setted at the bottom of the region. For the irradiator design, experiments of rice flow in the region were conducted by a pilot plant of the irradiator. The main results are as follows: (1) Flow rate of rice from slits of the valve independed on curvature of arrangement of the slits, (2) The flow rate was controlled within 2.7%, (3) Standard diviation of the velocity of a rice grain in an irradiation region was 1.8%, (4) Distribution of the velocity was uniform within 10% with no inclination of shutter of the valve to the slit, (5) Rice were not damaged by mechanical action of the irradiator.

Food Irradiation↗
PubMed1966

Microbial flora of irradiated Dungeness crabmeat and Pacific oysters.

The microorganisms in Dungeness crabmeat (Cancer magister) and Pacific oysters (Crassostrea gigas) were identified by the replica-plating and computer analysis method. The initial flora of the shellfish and the flora change during storage at 7 C were determined. The microbial flora shifts in both shellfish were also determined after irradiation at 0.1 and 0.4 Mrad and during subsequent storage at 7 C. The Achromobacter species predominated in the initial flora of crabmeat (77.0%). The predominant position of this group increased to 99.2% after 0.1 Mrad and 100% after 0.4 Mrad. A large percentage of Lactobacillus was detected in oysters (55.0%). The Lactobacillus species were the predominant survivors after 0.1 Mrad (92.4%) but the predominant survivors after 0.4 Mrad were Achromobacter species (99.3%).

Alcaligenes↗
PubMed2004

Effect of gamma-radiation and microwave heating of wheat grain on some starch properties in irradiated grain as well as in grain of the next generation crops.

Grains of the Polish winter wheat variety Begra were subjected to gamma-radiation (grain harvested in 1996) within the dose range of 0.05-10 kGy and microwave heating (grain harvested in 1997) from 28 degrees C to 98 degrees C. Later the grains were divided into two parts, the first was used for direct analyses after treatment. The second part was sown on the experimental fields. The obtained crop was described as the first generation and divided into two parts. One part was destined to determination of starch properties and the second part was sown in order to obtain the second generation crop. The same pattern was conducted in order to achieve the third generation crop. gamma-Irradiation directly applied on the wheat grain reduced statistically significant falling number values and gelatinisation enthalpy (deltaH) of the grain treated by 5 and 10 kGy. Calculated linear regression correlation coefficient between the falling number values and the gelatinisation enthalpy was equal to 0.94 (p < or = 0.001) and showed that these two starch characteristics are well correlated in the case of directly irradiated wheat grain. The falling number values, peak temperatures (Tp) and gelatinisation enthalpy (deltaH), in three generations of wheat grain crop studied, did not show any statistically significant differences as a result of indirect effect of gamma-irradiation. Microwave direct heating of wheat grain to 98 degrees C caused a statistically significant increase in the falling number value and decrease in starch gelatinisation power expressed by the enthalpy of gelatinisation (deltaH). The statistically significant changes in the falling number values, slight changes in the peak temperatures (Tp) and enthalpy of gelatinisation (deltaH) were found in all three generation crops as an indirect effect of microwave heating.

Animals↗
PubMed2004

Influence of early postmortem protein oxidation on beef quality.

The objective of this study was to examine the effect of early postmortem protein oxidation on the color and tenderness of beef steaks. To obtain a range of oxidation levels, the longissimus lumborum muscles (LM) from both strip loins of 20 steers fed either a finishing diet with vitamin E (1,000 IU per steer daily, minimum of 126 d [VITE]; n = 10 steers) or fed the same finishing diet without vitamin E (CON; n = 10 steers) were used. Within 24 h after slaughter, the LM muscle from each carcass was cut into 2.54-cm-thick steaks and individually vacuum packaged. Steaks from each steer were assigned to a nonirradiated group or an irradiated group. Steaks were irradiated within 26 h postmortem, and were aged at 4 degrees C for 0, 1, 3, 7, and 14 d after irradiation. Steaks from each diet/irradiation/aging time treatment were used to determine color, shear force, and degree of protein oxidation (carbonyl content). Steaks from steers fed the VITE diet had higher (P < 0.01) alpha-tocopherol contents than steaks from steers fed the CON diet. Immediately following irradiation, steaks that had been irradiated had lower (P < 0.05) L* values regardless of diet. Irradiated steaks, regardless of diet, had lower a* (P < 0.05) and b* (P < 0.01) values than nonirradiated steaks at all aging times. Carbonyl concentration was higher (P < 0.05) in proteins from irradiated steaks compared to nonirradiated steaks at 0, 1, 3, and 7 d postirradiation. Immunoblot analysis showed that vitamin E supplementation decreased the number and extent of oxidized sarcoplasmic proteins. Protein carbonyl content was positively correlated with Warner-Bratzler shear force values. These results indicate that increased oxidation of muscle proteins early postmortem could have negative effects on fresh meat color and tenderness.

Animal Feed↗
PubMed1993

Proteolysis and amino acid breakdown of heated and irradiated poultry byproducts and muscle tissue.

As a result of intensification and centralization of poultry slaughtering, the amount of slaughter byproducts produced at a single location is increasing. These byproducts are rich in protein, fat, and vitamins and, therefore, constitute a potentially useful raw material for use as animal feed. To maintain the nutritive value of these byproducts they should be processed to minimize or eliminate degenerative changes that reduce the feed value of the product. In this paper amino acid breakdown in slaughter-fresh poultry viscera, heads, and breast meat is studied as a model. Initial amino acid breakdown in viscera was observed (also when bacterial growth was excluded by gamma-irradiation), which resulted in high levels of total volatile N and cadaverine. Putrescine was produced only in viscera after bacterial proliferation. In heads and breast meat, no production of metabolites of amino acid degradation was observed as a result of initial enzymatic activity. It is concluded that during preservation of poultry byproducts not only bacterial proliferation, but also enzymatic breakdown of amino acids, must be prevented.

Amino Acids↗
PubMed1996

Spoilage and shelf-life extension of fresh fish and shellfish.

Fresh fish and shellfish are highly perishable products due to their biological composition. Under normal refrigerated storage conditions, the shelf life of these products is limited by enzymatic and microbiological spoilage. However, with increasing consumer demands for fresh products with extended shelf life and increasing energy costs associated with freezing and frozen storage, the fish-processing industry is actively seeking alternative methods of shelf life preservation and marketability of fresh, refrigerated fish and at the same time economizing on energy costs. Additional methods that could fulfill these objectives include chemical decontamination, low-dose irradiation, ultra-high pressure, and modified atmosphere packaging (MAP). This review focuses on the biochemical and microbiological composition of fresh fish/shellfish, the spoilage patterns in these products, factors influencing spoilage, and the combination treatments that can be used in conjunction with refrigeration to extend the shelf life and keeping quality of fresh fish/shellfish. The safety concerns of minimally processed/MAP fish, specifically with respect to the growth of Clostridium botulinum type E, is also addressed.

Animals↗
PubMed2006

Radioresistance of Anisakis simplex third-stage larvae and the possible role of superoxide dismutase.

The radioresistance of Anisakis simplex third-stage larvae and the possible role of sublethal radiation on superoxide dismutase (SOD) were investigated. Larvae were isolated from the viscera of the sea eel Anago anago; irradiated with 10, 100, 200, 500, or 1,000 Gy; and then given orally to rats. Worms were recovered at 16 hr postinoculation. Most larvae were found to have invaded the gastric wall, omentum, and abdominal cavity, suggesting that their viability and infectivity were not controlled by irradiation with the doses used. To determine the relationship between SOD activities in parasites and their radiosensitivities, the larvae of A. simplex and the metacercariae of Neodiplostomum seoulense (a radiosensitive control) were irradiated with 0, 30, 100, or 500 Gy, and parasite SOD levels were measured. In nonirradiated A. simplex larvae, the average SOD level was 38.9 U/mg, and this increased to 51.3 U/mg at 500 Gy. However, at all radiation doses applied, SOD activities of N. seoulense metacercariae were significantly (P < 0.05) lower than those of A. simplex larvae. Our results demonstrate that A. simplex third-stage larvae are radioresistant, and suggest that SOD plays a role in this radioresistance.

Animals↗
PubMed2006

Nalidixic acid resistance influences sensitivity to ionizing radiation among Salmonella isolates.

Nalidixic acid (Nal) resistance has been used as a selective marker for studies of pathogen-inoculated fruits and vegetables. A collection of 24 Salmonella isolates were screened for natural resistance to Nal (50 microg/ml). The resistance to ionizing radiation was determined and compared for i) three naturally Nal-resistant (Nal(R)) strains, ii) three naturally Nal-sensitive (Nal(S)) strains, and iii) three strains derived from Nals strains that were made resistant to Nal (Nal(Ri)) by successive culturing and selection in Nal-amended broth. The radiation D10-values (the radiation dose required to achieve a 1-log reduction in population) were determined in buffer solution and in orange juice. D10-values were significantly (P < 0.05) different among the Salmonella isolates tested. When considered as a group, Nal(R) isolates were significantly more sensitive to ionizing radiation than Nals isolates in both media tested. In buffer, D10 of Nal(R) was 0.210 kGy versus 0.257 kGy for Nals. In orange juice, D10 of Nal(R) was 0.581 versus 0.764 for Nals. Inducing resistance to Nal altered the response to irradiation. D10-value of Nal(Ri) was 0.234 kGy in buffer, a 9% reduction relative to Nals parents. In orange juice, the D10-value of Nal(Ri) was 0.637 kGy, a reduction of 17% relative to Nals parents. These results suggest that natural and/or induced resistance to Nal may predispose Salmonella isolates to greater sensitivity to ionizing radiation,and that this effect is influenced by the suspending medium and by the nature of the isolates evaluated.

Colony Count, Microbial↗
PubMed1998

Effects of dietary vitamin E supplementation on lipid oxidation and volatiles content of irradiated, cooked turkey meat patties with different packaging.

A study was conducted to determine the effects of dietary vitamin E supplementation on the storage stability and volatiles production in irradiated cooked turkey meat. Turkeys, raised with diets containing 25, 50, 75, or 100 IU of dl-alpha-tocopheryl acetate (TA)/kg diet from 1 to 105 d of age, were fed with diets containing 25, 200, 400, or 600 IU of TA/kg diet from 105 to 122 d of age. Breast and leg meat patties were prepared, irradiated at 0 or 2.5 kGy dose, cooked to an internal temperature of 78 C, and stored in either vacuum or aerobic packaging. Thiobarbituric acid reactive substance (TBARS) values gradually decreased as the dietary TA increased and > 200 IU TA/kg diet treatments were helpful in maintaining low TBARS values in irradiated breast and leg meat patties during the 7-d storage period. With vacuum-packaging, irradiated cooked breast patties developed more oxidation than nonirradiated patties but the prooxidant effect of irradiation in cooked leg meat patties was not consistent. In aerobic-packaged cooked meat, irradiated patties had lower TBARS than nonirradiated patties in both breast and leg meat stored in oxygen permeable bags for 7 d. Propanal, pentanal, hexanal, 1-pentanol, and total volatiles were highly correlated with the TBARS values of meat. However, hexanal represented the lipid oxidation status of cooked meat better than any other volatiles component. The amount of hexanal and total volatiles in cooked breast and leg meat shows decreasing trends as dietary TA increased. In vacuum packaging, irradiated breast and leg meat had higher hexanal and total volatiles content than nonirradiated meat at both 0 and 7 d of storage. In aerobic packaging, the amount of hexanal and total volatiles greatly increased in both irradiated and nonirradiated meat patties during the 7-d storage periods. The results illustrated that the antioxidant effect of TA was not strong enough to control lipid oxidation and off-odor generation in cooked meat stored under aerobic conditions because the progress of lipid oxidation in cooked meat under aerobic condition is very rapid. However, the combination of dietary TA and vacuum packaging of cooked meat immediately after cooking could be a good strategy to minimize oxidation and volatiles production in cooked meat.

Animal Feed↗
PubMed2004

Irradiation to kill Escherichia coli O157:H7 and Salmonella on ready-to-eat radish and mung bean sprouts.

A study was carried out to evaluate the effectiveness of ionizing radiation in eliminating Escherichia coli O157:H7 and Salmonella on commercial ready-to-eat radish and mung bean sprouts and to assess the chemical and physical quality of these sprouts. The use of ionizing radiation was investigated as a means of reducing or totally inactivating these pathogens, if present, on the sprouts. Treatment of mung bean and radish sprouts with a dose of 1.5 and 2.0 kGy, respectively, significantly reduced E. coli O157:H7 and Salmonella to nondetectable limits. The total vitamin C content was gradually reduced with the increase in irradiation dose (P < 0.0001). However, the effect of storage interval on the loss of vitamin C was nonsignificant for radish sprouts and significant for mung bean sprouts (P < 0.04). The color, firmness, and overall visual quality of the tested sprouts were acceptable when effective doses were applied to both radish and mung bean sprouts. Therefore, ionizing radiation could be useful in reducing the population of pathogens on sprouts and yet retain acceptable quality parameters.

Ascorbic Acid↗
PubMed2006

Biocontrol of aflatoxins B1, B2, G1, G2, and fumonisin B1 with 6,7-dimethoxycoumarin, a phytoalexin from Citrus sinensis.

Phytoalexins (stress-induced compounds) from Citrus sinensis cultivar Valencia were screened for antifungal and antimycotoxic activity against a test organism (Cladosporium cladosporoides) and mycotoxin-producing fungi Fusarium verticillioides and Aspergillus parasiticus. The active compound, a member of the coumarin family of compounds, has antifungal and antimycotoxic activities and was chemically identified. High-performance liquid chromatography results indicated that Valencia oranges contain a trace amount (0.36 microg/g) of scoparone in untreated fruit, but concentrations increased in UV-irradiated fruit (15.2 microg/g). Infection with Penicillium digitatum, a natural spoilage mold of citrus fruit, caused a 35.51-microg/g increase in the phytoalexin. UV absorption, infrared absorption, and 1H nuclear magnetic resonance spectroscopy revealed that this phytoalexin is identical to 6,7-dimethoxycoumarin. This is the first report indicating that the stress-induced compound, 6,7-dimethoxycoumarin, isolated from P. digitatum-infected Valencia fruit confers resistance against the mycotoxigenic fungi A. parasiticus and F. verticillioides and causes a reduction in production of fumonisin B1 and aflatoxins G1, G2, B1, and B2.

Aflatoxin B1↗
PubMed2004

Prediction of fungal growth and ochratoxin A production by Aspergillus ochraceus on irradiated barley grain as influenced by temperature and water activity.

Ochratoxin A (OTA) is a secondary metabolite of Aspergillus and Penicillium species, including Aspergillus ochraceus, a species that can be found in stored cereal grains such as barley. The objective of this study was to determine the effects of water activity (a(w), 0.80-0.99), temperature (10, 20, 30 degrees C), and A. ochraceus isolate differences on radial growth and OTA production in irradiated barley grains. The three isolates showed optimal conditions for growth and ochratoxin A production at 0.99 a(w) and 30 degrees C, with a marked decrease of growth rates and OTA production at the lowest levels of a(w) and temperature assayed. The minimum a(w) level for growth, observed in this study, was 0.85 and 0.90 a(w) for OTA production. Significant differences among the isolates were found. Lag phases prior to fungal growth and OTA production values were modelled by multiple linear regression and response surface models. These models could provide an approximate prediction of growth and OTA production.

Aspergillus ochraceus↗
PubMed1976

[Organoleptic changes in beef and pork fats following gamma-ray irradiation].

Studied were bovine and swine fats that had been treated with gamma-rays at the rates of 0.10 to 2.00 Mrad, in the presence of oxygen and in an atmosphere containing no oxygen as well as under storage conditions at 2 to 4degreesC, and -- 18 and up to --20degreesC, for 45 and 90 days, respectively. When doses of 0.25 Mrad were used no changes in the organoleptic properties were observed. Fats that were treated at the rate of more than 0.25 Mrad in the presence of oxygen assumed 'side' smell and taste. If irradiation was carried out in the absence of oxygen no such deviations from the normal taste and odor were noted--at rates of up to 0.70 Mrad for the swine fats, and at rates of more than 0.50 Mrad for the bovine fats. Destruction of the yellow pigment in the bovine fats was observed at treatment with doses higher than 0.70 Mrad. The changes in the organoleptic properties corresponded to the changes taking place with the peroxides, the water soluble fatty acids, and the epihydrinaldehyde. Changes in the organoleptic properties (odor and taste) in the bovine fats took place at lower doses of iradiation than in the swine fats.

Animals↗
PubMed2003

Zearalenone in maize: stability testing and matrix characterisation of a certified reference material.

Within the certification process of a reference material for the determination of the mycotoxin zearalenone (ZON) in maize, short- and long-time stability tests of naturally contaminated maize have been performed. The short-term stability of ZON in the maize was evaluated under four different conditions (4, 25, 40 and 70 degrees C) in preliminary studies. Four storage times of 0, 1, 2 and 4 weeks were investigated using HPLC. The long-term stability study was conducted with measurements after 0, 3, 6, 12, 24 and 36 months under three storage conditions (4, 25 and 40 degrees C) in preliminary studies using HPLC. Stability data gained under two different conditions (4 and 25 degrees C) with five storage times of 0, 1, 6, 12 and 18 months were further evaluated for the contaminated maize in the certification process. Before the certification, the maize matrix had been characterized with respect to dry residue, ash content, fat content, protein content, ergosterol content and total dietary fibre, and the efficiency of gamma-irradiation on the fungal flora was investigated. The stability of the maize matrix was evaluated by monitoring UV absorption and ergosterol content under four different storage conditions (4, 25, 35 and 70 degrees C) with five storage times of 0, 1, 6, 12 and 24 months. Other possibly occurring mycotoxins (deoxynivalenol, nivalenol, 3-acetyl deoxynivalenol, 15-acetyl deoxynivalenol, fusarenon X and moniliformin) have been quantified. On the basis of the stability measurements, which showed no significant trends for both short- and long-term stabilities, it can be recommended to store the samples at temperatures < 4 degrees C and ship the samples at ambient temperatures.

Chromatography, High Pressure Liquid↗
PubMed1991

A numerical taxonomic study of lactic acid bacteria isolated from irradiated pork and chicken packaged under various gas atmospheres.

Ninety-four Gram-positive, catalase-negative bacteria, isolated from pork and chicken that had been packed in modified atmospheres and irradiated to 1.75 and 2.5 kGy respectively, were studied. The majority of the strains were Lactobacillus saké. Numerical taxonomy, with the group average clustering strategy, revealed the existence of six clusters at the 85% similarity level. The largest, Cluster 1, contained 78 (83%) of the test strains along with three Lact. sak'e strains. Cluster 2 contained three test strains and the type strains of Carnobacterium piscicola and Carn. divergens. Cluster 3 contained two chicken strains and Lact. curvatus. Cluster 4 contained a pork strain and Leuconostoc dextranicum. Clusters 5 and 6 contained four pork and two chicken strains respectively and no type strains. Four test strains remained unclustered as did the other reference strains included in the study.

Animals↗
PubMed2006

Influence of antimicrobial compounds and modified atmosphere packaging on radiation sensitivity of Listeria monocytogenes present in ready-to-use carrots (Daucus carota).

Radiosensitization of Listeria monocytogenes was determined in the presence of trans-cinnamaldehyde, Spanish oregano, winter savory, and Chinese cinnamon on peeled minicarrots packed under air or under a modified atmosphere (60% O2, 30% CO2, and 10% N2). Samples were inoculated with L. monocytogenes HPB 2812 serovar 1/2a (106 CFU/g) and were coated separately with each active compound (0.5%, wt/wt) before being packaged under air or the modified atmosphere and irradiated at doses from 0.07 to 2.4 kGy. Results indicated that the bacterium was more resistant to irradiation under air in the absence of active compound. The dose required to reduce L. monocytogenes population by 1 log CFU (D10) was 0.36 kGy for samples packed under air and 0.17 kGy for those packed under the modified atmosphere. The active compounds evaluated in this study had an effect on the radiation sensitivity of L. monocytogenes on carrots. The most efficient compound was trans-cinnamaldehyde, where a mean 3.8-fold increase in relative radiation sensitivity was observed for both atmospheres compared with the control. The addition of winter savory and Chinese cinnamon produced a similar increase in relative radiation sensitivity but only when samples where packed under modified atmosphere conditions.

Anti-Bacterial Agents↗
PubMed2005

Combined effect of carvacrol and packaging conditions on radiosensitivity of Escherichia coli and Salmonella Typhi in ground beef.

This study was undertaken to evaluate the effect of 1.0% carvacrol and 0.1% tetrasodium pyrophosphate on the radiation D10 of Escherichia coli and Salmonella Typhi added to ground beef at a concentration of 10(5) CFU/g. The ground beef was then packaged under four different atmosphere conditions: air (78.1% N2, 20.9% O2, 0.036% CO2), 100% CO2, modified atmosphere (60% O2, 30% CO2, 10% N2) and vacuum. Samples were irradiated at doses of 0.1 to 0.6 kGy for E. coli and 0.5 to 2.0 kGy for Salmonella Typhi. Radiation D10-values of 0.126 and 0.526 kGy were observed for E. coli and Salmonella Typhi, respectively, when meat was packed under air. When meat was packed under modified atmosphere conditions, the radiation D10-values for E. coli and Salmonella Typhi were 0.086 and 0.221 kGy, respectively. The addition of carvacrol and tetrasodium pyrophosphate and the use of modified atmosphere packaging reduced the radiation D10-value from 0.126 to 0.046 kGy for E. coli and from 0.526 to 0.053 kGy for Salmonella Typhi. Under vacuum and 100% CO2 conditions, the radiation D10 reduction was not as great as that for the modified atmosphere regardless of the presence or absence of carvacrol and tetrasodium pyrophosphate.

Animals↗