Distribution and stability of aflatoxin M1 during processing, ripening and storage of Telemes cheese

Telemes cheeses were produced using milk that was artificially-contaminated with aflatoxin M1 at the levels of 0.050 and 0.100 microg/l. The cheeses produced in the two cheese-making trials were allowed to ripen for 2 months and stored for an additional 4 months to simulate commercial production of Telemes cheese. Concentrations of aflatoxin M1 in whey, curd, brine, and the produced cheeses were determined at intervals by liquid chromatography and fluorometric detection coupled with immunoaffinity column extraction. Concentrations of aflatoxin M1 in the produced curds were found to be 3.9 and 4.4 times higher than those in milk, whereas concentrations in whey were lower than those in curd and milk. Aflatoxin M1 was present in cheese at higher concentrations at the beginning than at the end of the ripening/storage period, and it declined to concentrations 2.7 and 3.4 times higher than those initially present in milk by the end of the sixth month of storage. Concentrations of aflatoxin M1 in brine started low and increased by the end of the ripening/storage period but only a portion of the amounts of aflatoxin M1 lost from cheese was found in the brine. Results showed that Telemes cheeses produced from milk containing aflatoxin M1 at a concentration close to either the maximum acceptable level of 0.05 microg/l set by the European union (EU) or at double this value, will contain the toxin at a level that is much lower or slightly higher, respectively, than the maximum acceptable level of 0.250 microg of aflatoxin M1/kg cheese set by some countries.     

The inhibitory potential of feed supplementation with rosemary and/or α-tocopheryl acetate on microbial growth and lipid oxidation of turkey breast during refrigerated storage

Twenty-four 12-week-old female turkeys divided into four equal groups were fed a basal diet (CONT) or basal diet supplemented with 300 mg α-tocopheryl acetate/kg (TOC), or 5 g rosemary/kg (ROS5), or 10 g rosemary/kg (ROS10), for 4 weeks. Following slaughter, fillets from breast were stored at 4 °C in the dark for 12 days, and lipid oxidation was assessed on the basis of the malondialdehyde formed, whereas microbial growth on the basis of total viable counts (TVC), lactic acid bacteria (LAB), Enterobacteriaceae (ENB) and psychrotrophic (PSY) bacteria. Results showed that incorporation of dried rosemary in turkey diets delayed lipid oxidation in raw breast meat during refrigerated storage. Dietary rosemary at the level of 1 g/100 g was significantly (P<0.05) more effective in delaying lipid oxidation compared to 0.5 g/100 g but inferior to the dietary supplementation of 300 mg α-tocopheryl acetate/kg. TVC, LAB, ENB and PSY bacterial counts were all significantly increased (P<0.05) in breast samples of all groups throughout the refrigerated storage. The TOC and CONT groups presented TVC, LAB, ENB and PSY counts that did not differ (P>0.05) among each other, during the whole storage period. However, the rosemary-supplemented groups presented bacterial counts that were significantly lower (P<0.05) than the CONT and TOC groups, at day 2 of storage period and thereafter. During this period, the ROS5 group presented TVC, LAB, ENB and PSY counts that were significantly higher (P<0.05) than the ROS10 group.     

Effect of long‐term dietary administration of oregano and rosemary on the antioxidant status of rat serum,liver, kidney and heart after carbon tetrachloride‐induced oxidative stress

BACKGROUND: This study was performed on female Wistar rats allocated to eight groups of six animals each. Groups 1 and 2 were fed the basal diet, groups 3 and 4 were fed the basal diet supplemented with ground oregano at 20 g kg^?1 level, groups 5 and 6 were fed the basal diet supplemented with ground rosemary at 20 g kg^?1 level, while groups 7 and 8 were fed the basal diet supplemented with both oregano and rosemary, each at 20 g kg^?1 level. Following 6 weeks feeding, groups 2, 4, 6 and 8 were injected with CCl₄ at 1 mL kg^?1 body weight, and 6 h thereafter all animals were sacrificed. RESULTS: Administration of CCl₄ to the control rats enhanced (P < 0.05) aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP) activities, decreased cholesterol and triglycerides content in serum, increased (P < 0.05) lipid peroxidation and decreased (P < 0.05) the ABTS radical cation, the hydroxyl anion radical, the superoxide anion radical, and the hydrogen peroxide scavenging activities in all tested tissues, as compared to the control. Feeding oregano, rosemary or both before CCl₄ treatment resulted in decline (P < 0.05) of the increase in AST, ALT and ALP activities, increase (P < 0.05) of cholesterol and triglycerides in serum, decrease (P < 0.05) of lipid peroxidation, and increase (P < 0.05) of the ABTS radical cation, hydroxyl anion radical, superoxide anion radical and hydrogen peroxide scavenging activity. CONCLUSION: The results of this study suggest that long‐term dietary administration of oregano and rosemary has the potential to quench free radicals and alleviate CCl₄‐induced oxidative stress in rats. Copyright © 2009 Society of Chemical Industry     

The effects of dietary oregano essential oil and α-tocopheryl acetate on lipid oxidation in raw and cooked turkey during refrigerated storage

The effects of dietary oregano essential oil and α-tocopheryl acetate supplementation on the susceptibility of raw and cooked turkey breast and thigh meat to lipid oxidation during refrigerated storage for 9 days were examined. Thirty 12-week-old turkeys were divided into five groups and fed a basal diet containing 30 mg α-tocopheryl acetate kg(-1) feed as control, or basal diet plus 200 mg α-tocopheryl acetate kg(-1), or basal diet plus 100 mg oregano oil kg(-1), or basal diet plus 200 mg oregano oil kg(-1), or basal diet plus 100 mg oregano oil and 100 mg α-tocopheryl acetate kg(-1), for 4 weeks prior to slaughter. Lipid oxidation was assessed by monitoring malondialdehyde formation in raw and cooked meat at 0, 3, 6 and 9 days of refrigerated storage, through use of a third-order derivative spectrophotometric method. Results showed that all dietary treatments significantly (P<0.05) increased the stability of both raw and cooked turkey meat to lipid oxidation compared with the control. Oregano oil at 200 mg kg(-1) was significantly (P<0.05) more effective in delaying lipid oxidation compared to the level of 100 mg kg(-1), equivalent to α-tocopheryl acetate at 200 mg kg(-1), but inferior (P<0.05) to oregano oil plus α-tocopheryl acetate at 100 mg kg(-1) each, which in turn was superior (P<0.05) to all dietary treatments, indicating a synergistic effect. Thigh muscle was more susceptible to oxidation compared with breast muscle in all treatments, although it contained α-tocopherol at significantly (P<0.05) higher levels.     

Occurrence of aflatoxin M1 in raw and market milk commercialized in Greece

From December 1999 to May 2000, 114 samples of pasteurized, ultrahigh temperature-treated (UHT) and concentrated milk were collected in supermarkets, whereas 52 raw milk samples from cow, sheep and goat were obtained from different milk producers all over Greece. Sample collection was repeated from December 2000 to May 2001 and concerned 54 samples of pasteurized milk, 23 samples of bulk-tank raw milk and 55 raw milk samples from cow, sheep and goat. The total number of samples analysed for aflatoxin M₁ (AFM₁) contamination by immunoaffinity column extraction and liquid chromatography was 297. In the first sampling, the incidence rates of AFM 1 contamination in pasteurized, UHT, concentrated and cow, sheep and goat raw milk were 85.4, 82.3, 93.3, 73.3, 66.7 and 40%, respectively, with only one cow raw milk and two concentrated milk samples exceeding the EU limit of 50 ng l^-1. In the second sampling, the incidence rates of AFM 1 contamination in pasteurized, bulk-tank and cow, sheep and goat raw milk were 79.6, 78.3, 64.3, 73.3 and 66.7%, respectively, with only one cow and one sheep raw milk samples exceeding the limit of 50 ng l^-1. The results suggest that the current regulatory status in Greece is effective.     

Antibacterial activity of oregano and thyme essential oils against Listeria monocytogenes and Escherichia coli O157:H7 in feta cheese packaged under modified atmosphere

The antibacterial activity of the essential oils (EO) of oregano and thyme added at doses of 0.1 or 0.2 and 0.1 ml/100 g, respectively, to feta cheese inoculated with Escherichia coli O157:H7 or Listeria monocytogenes was investigated during cheese storage under modified atmosphere packaging (MAP) of 50% CO₂ and 50% N₂ at 4 °C. Compositional analysis showed that the predominant phenols were carvacrol and thymol for both EO. In control feta inoculated with the pathogens and stored under MAP, results showed that E. coli O157:H7 and L. monocytogenes strains survived up to 32 and 28 days of storage. However, in feta cheese treated with oregano EO at the dose of 0.1 ml/100 g, E. coli O157:H7 or L. monocytogenes survived up to 22 and 18 days, respectively, whereas at the dose of 0.2 ml/100 g up to16 or 14 days, respectively. Feta cheese treated with thyme EO at 0.1 ml/100 g showed populations of E. coli O157:H7 or L. monocytogenes not significantly different (P > 0.05) than those of feta cheese treated with oregano at 0.1 ml/100 g. Although both essential oils exhibited equal antibacterial activity against both pathogens, the populations of L. monocytogenes decreased faster (P < 0.05) than those of E. coli O157:H7 during the refrigerated storage, indicating a stronger antibacterial activity of both essential oils against the former pathogen.     

Effect of processing and storage on the fatty acid composition of n‐3 or n‐6 fatty acid‐enriched eggs

Fresh eggs from hens fed diets supplemented with 4% linseed oil (LO) or sunflower oil (SO) were either directly submitted to pasteurisation, hard‐boiling or scrambling processing, or first submitted to refrigerated storage at 4 °C for 60 day and then to processing. Fresh LO eggs showed higher (P ≤ 0.05) proportions of monounsaturated fatty acids (MUFAs) and n‐3 polyunsaturated fatty acids (PUFAs), but lower (P ≤ 0.05) proportions of saturated fatty acids (SFAs), PUFAs and n‐6 PUFAs than the SO eggs. Storage decreased (P ≤ 0.05) the proportion of PUFAs and increased (P ≤ 0.05) that of MUFAs in egg yolks from both treatments. The pasteurisation process had no effect on the fatty acid composition of fresh eggs from both treatments, but increased (P ≤ 0.05) n‐6 PUFAs and decreased (P ≤ 0.05) n‐3 PUFAs in stored LO eggs. Hard‐boiling and scrambling modified the fatty acid composition of fresh and stored eggs from both treatments by decreasing (P ≤ 0.05) the proportion of PUFAs, particularly of the very long‐chain n‐3 eicosapentaenoic, docosapentaenoic and docosahexaenoic PUFAs. LO eggs showed a higher susceptibility to fatty acid modification upon processing as compared to the SO eggs.     

Lipid oxidation of stored eggs enriched with very long chain n−3 fatty acids,as affected by dietary olive leaves (Olea europea L.) or α-tocopheryl acetate supplementation

The antioxidant potential of dietary olive leaves or α-tocopheryl acetate supplementation on lipid oxidation of refrigerated stored hen eggs enriched with very long-chain n−3 fatty acids, was investigated. Ninety-six brown Lohmann laying hens, were equally assigned into three groups. Hens within the control group were given a typical diet containing 3% fish oil, whereas other groups were given the same diet further supplemented with 10 g ground olive leaves/kg feed or 200 mg α-tocopheryl acetate/kg feed. Results showed that α-tocopheryl acetate or olive leaves supplementation had no significant effect on the fatty acid composition and malondialdehyde (MDA) levels of fresh eggs but reduced their lipid hydroperoxide levels compared to controls. Storage for 60 d decreased the proportions of polyunsaturated fatty acids (PUFAs) but increased those of monounsaturated fatty acids (MUFAs) in eggs from the control group, while had no effect on the fatty acid composition of the eggs from the other two groups, which showed decreased levels of lipid hydroperoxides and MDA. Therefore, the very long chain n−3 PUFAs in eggs were protected from undergoing deterioration partly by olive leaves supplementation and totally by α-tocopheryl acetate supplementation. In addition, incorporating tocopherols into eggs might also provide a source of tocopherols for the human diet.