Dimitrios Fletouris

The effect of dietary oregano essential oil on lipid oxidation in raw and cooked chicken during refrigerated storage.

The antioxidative effect of dietary supplementation with oregano essential oil on susceptibility of raw and cooked breast and thigh muscle meat of chickens to lipid oxidation during refrigerated storage for 9 days was investigated. Day-old chickens (n=80) were randomly divided into four 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) feed, or basal diet plus 50 or 100 mg oregano essential oil kg(-1) for 38 days prior to slaughter. Lipid oxidation was assessed by monitoring malondialdehyde (MDA) formation in raw and cooked meat during 0, 3, 6 and 9 days of refrigerated storage, using the thiobarbituric acid (TBA) assay and third-order derivative spectrophotometry. Results showed that dietary oregano essential oil supplementation exerted antioxidative effects, the supplementation being most effective in retarding lipid oxidation in stored raw and cooked meat at the 100 mg oregano essential oil kg(-1) feed. However, dietary α-tocopheryl acetate supplementation at 200 mg kg(-1) feed displayed greater antioxidant activity than oregano treatments. Thigh muscle was more susceptible to oxidation compared to breast muscle in all treatments, although the former tissues contained α-tocopherol at markedly higher levels.

Drug Residues in Foods : Pharmacology: Food Safety, and Analysis

Part 1 Drugs in food-producing animals: a general view of drug usage some pharmacokinetic considerations antibacterial drugs anthelminthic drugs anticoccidial and other antiprotozoal drugs antimicrobial growth promoters anabolic hormonal-type growth promoters other drugs benefits and risks of drug usage. Part 2 Residues in food: drug residues and public health safety assessment and control of residues global harmonization of regulatory requirements incidence of violative residues in food factors influencing the occurrence of residues in food costs of residues in the livestock industry residue avoidance management stability of residues during food processing consumer perceptions and concerns. Part 3 Analysis of drug residues: the analytical challenge sample preparation derivatization separation detection confirmation validation analytical strategy microbiological methods immunochemical methods physicochemical methods future trends.

Determination of the marker residue of albendazole in milk using ion-pair liquid chromatography and fluorescence detection

Abstract A simple, rapid, and sensitive ion-pair liquid Chromatographic (LC) method for the determination of the sulphoxide, sulphone and 2-aminosulphone metabolites that comprise the marker residue of albendazole in milk has been developed. Samples are made alkaline with sodium hydroxide solution and extracted with ethyl acetate, and the extracts are cleaned-up by partition with water. Chromatographic separation of the analytes is performed isocratically in presence of both positive and negative pairing ions, while detection is carried out fluorometrically using excitation and emission wavelengths of 290 and 320 nm, respectively. The method shows accuracy and precision figures well within acceptable limits. Overall recoveries were 85.3 ± 9.0%, 96.4 ± 6.2% and 83.4 ± 7.5% for the sulphoxide, sulphone and 2-aminosulphone metabolites, respectively, while precision data, based on within- and between-days variation, suggested overall relative standard deviation values ranging from 2.9% to 6.0%. The good analytical characteristics of the method could allow limits of detection in the low ng ml −1 range to be realised. The method was successfully applied to determine total residues in milk of a dairy cow treated with albendazole and, also, to study the stability of the residues with storage.

Effect of olive leaf (Olea europea L.) extracts on protein and lipid oxidation in cooked pork meat patties enriched with n-3 fatty acids

BACKGROUND The effect of olive leaf extracts on lipid and protein oxidation of cooked pork patties refrigerated stored for 9 days was evaluated. Patties were prepared from longissimus dorsi muscle of pigs, and dietary supplemented with linseed oil. RESULTS Results showed that dietary linseed oil modified the fatty acid composition of pork patties by increasing (P ≤ 0.05) n-3 (α-linolenic acid) and decreasing (P ≤ 0.05) n-6 (linoleic acid) fatty acids. Olive leaf extracts at supplementation levels of 200 and, especially, of 300 mg gallic acid equivalents kg⁻¹ meat, delayed lipid oxidation by reducing (P ≤ 0.05) both primary (conjugated dienes and hydroperoxides) and secondary (malondialdehyde) oxidation products. They also inhibited protein oxidation in a concentration-dependent manner by reducing (P ≤ 0.05) protein carbonyls and increasing (P ≤ 0.05) protein sulfhydryls. In addition, they improved sensory attributes of the n-3 enriched patties. CONCLUSION Results suggested that olive leaf extracts might be useful to the meat industry as an efficient alternative to synthetic antioxidants.

Lipid and protein oxidation of α-linolenic acid-enriched pork during refrigerated storage as influenced by diet supplementation with olive leaves (Olea europea L.) or α-tocopheryl acetate.

The objective of this study was to evaluate the effect of diet supplementation with olive leaves or α-tocopheryl acetate on lipid and protein oxidation of raw and cooked n-3 enriched-pork during refrigerated storage. Enrichment of pork with α-linolenic acid through diet supplementation with linseed oil enhanced (p≤0.05) lipid oxidation in both raw and cooked chops but had no effect (p>0.05) on protein oxidation during refrigerated storage while decreasing (p≤0.05) the sensory attributes of cooked pork. Diet supplementation with olive leaves or α-tocopheryl acetate had no effect (p>0.05) on the fatty acid composition of pork but decreased (p≤0.05) lipid oxidation while exerting no effect (p>0.05) on protein oxidation in both raw and cooked α-linolenic acid-enriched chops stored and chilled for 9 days. Moreover, olive leaves and α-tocopheryl acetate supplemented at 10 g/kg and 200mg/kg diet, respectively, exerted (p≤0.05) a beneficial effect on the sensory attributes of cooked α-linolenic acid-enriched pork chops.

Effect of olive leaf (Olea europea L.) extracts on protein and lipid oxidation of long-term frozen n-3 fatty acids-enriched pork patties.

Our previous study has demonstrated the protective effects of olive leaf extracts on the oxidation of pork patties from n-3 fatty acid-enriched meat during refrigerated storage. The target of the present study was to examine these effects during frozen storage. Results showed that frozen storage accelerated (P=0.05) both lipid and protein oxidation in pork patties, but an addition of olive leaf extract at 200mg gallic acid equivalent/kg improved sensory attributes by delaying oxidation of lipids (reduction (P=0.05) of conjugated dienes, hydroperoxides and malondialdehyde), and of proteins (reduction (P=0.05) of protein carbonyls and inhibition (P=0.05) of the decrease of protein sulfhydryls).

Trace analysis of albendazole and its sulphoxide and sulphone metabolites in milk by liquid chromatography

Analytical methodology for determination of albendazole and its sulphoxide and sulphone metabolites in milk at levels down to 2-5 ng/ml has been developed. Extraction was carried out with ethyl acetate under alkaline conditions, and extracts were analyzed on a silica-based C18 column in the presence of positively-charged pairing ions. Accuracy data showed overall recoveries ranged from 78.4% to 100%, whereas precision data, based on within and between-day variation, suggested overall precision values better than 4.9%. The method was successfully applied to determine residues in milk of a dairy cow orally given albendazole.

Liquid Chromatographic Analysis of Multiple Sulfonamide Residues in Chicken Muscle Using Pre-Column Derivatization and Fluorescence Detection

Abstract A rapid liquid chromatographic (LC) method is described for the quantitation of sulfadiazine, sulfamethazine, sulfadimethoxine, and sulfaquinoxaline residues in chicken muscle. The sulfonamides are extracted with chloroform, partitioned into hydrochloric acid, and submitted to pre-column derivatization with fluorescamine. LC analysis of the fluorescent derivatives is performed on a C18 column using a mobile phase of acetonitrile /20 mM phosphate buffer pH 4, (34/66, v/v), containing 20 mM octanesulfonate sodium salt. Owing to the sensitivity and selectivity of the fluorescence detection, residue levels of as low as 3 ng/g for sulfadiazine, 4 ng/g for sulfamethazine, 9 ng/g for sulfadimethoxine, and 40 ng/g for sulfaquinoxaline could be readily determined in chicken muscle. Overall recoveries were found to be 77.7±4.8% for sulfadiazine, 84.6±4.2% for sulfamethazine, 92.3±4.1% for sulfadimethoxine, and 82.5±7.0% for sulfaquinoxaline. The linearity of the method was quite acceptable in the range exa...

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 200mg 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.

Albendazole-related drug residues in milk and their fate during cheesemaking, ripening, and storage.

The level and nature of the albendazole residues in milk of treated cows were determined as a function of the time of milking (12-h intervals), and the fate of those residues during cheesemaking, ripening, and storage was examined when the obtained milk was used for making Teleme cheese. Ion-pair liquid chromatographic analysis with fluorescence detection showed that the albendazole sulfoxide metabolite reached its maximum (523 +/- 199 micrograms/kg) at the 1st milking and declined below the detection limit by the 4th milking. The sulfone metabolite attained its highest level (812 +/- 99 micrograms/kg) more slowly (at the 2nd milking) and declined below detection limit by the 13th milking. The 2-aminosulfone metabolite, which was present in the milk obtained at the 1st milking, reached its maximum (128 +/- 36 micrograms/kg) at the 3rd milking, and slowly declined to a level below detection limit by the 15th milking. Whey and cheese analysis revealed that about 70% of each major metabolite initially present in milk could be distributed in the whey. The remaining 30% occurred in the cheese at residue levels higher than those initially present in the milk of the 1st or 2nd milking (688 versus 445 or 450 versus 230 micrograms/kg for albendazole sulfoxide; 890 versus 608 or 1502 versus 783 micrograms/kg for albendazole sulfone; 19 versus 15 or 161 versus 105 micrograms/kg for albendazole 2-aminosulfone). Ripening and storage of the cheeses made from milks from the 1st or 2nd milkings results in a decrease of the sulfoxide metabolite (to 225 or 206 micrograms/kg), an increase of the sulfone metabolite (to 1,181 or 1,893 micrograms/kg), and no effect on the 2-aminosulfone metabolite.