ISSN:0265-203X    

DOI:10.1080/026520300283531

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH3CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH2PO4-20.6 mm Na2b4O7buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of ‘true’ positives and the elimination of ‘false’ positives.

ISSN:0265-203X    

DOI:10.1080/026520300283540

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Fresh cod fillets (Gadus morhua) were sprayed with a 10% acetate buffer (pH 5.6), packed with an industrial gas-flushing packaging machine under modified atmospheres (50% CO2-45% O2-5% N2, 2cm3/1g gas/ product ratio) and stored at 7°C for 12 days. Control cod fillets were directly packed and stored under the same conditions. A reduction of the aerobic plate counts was observed immediately after the cod fillets had been sprayed. During storage under modified atmospheres, there was complete inhibition of H2S-producing bacteria and Enterobacteriaceae in the treated cod fillets. Production of total volatile bases and trimethylamine (TMA) was inhibited in treated fillets for 10 days' storage under modified atmospheres. Inhibition of TMA production can be attributed to growth inhibition of H2S-producing bacteria, inhibition of the trimethylamine oxide (TMAO)-dependent metabolism of TMAO-reducing bacteria and the stable pH during storage. The shelf-life, at 7°C, of treated cod fillets, based on cooked flavour score, was almost 12 days, ca 8 days more than shelf-life of the control fillets.

ISSN:0265-203X    

DOI:10.1080/026520300283559

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The effectiveness of the steps of a general method, which includes alkaline treatment of the samples, extraction, clean-up and analysis, for the determination of polycyclic aromatic hydrocarbons in liquid smoke flavourings and smoked foods have been studied, by using mixtures of pure polycyclic aromatic hydrocarbons and of smoke flavouring compounds. All these products were applied to samples of liquid smoke flavourings in order to test the effectiveness of each step of the method, as well as to investigate its effect on real samples, and thus obtain a suitable procedure for the study of polycyclic aromatic hydrocarbons in liquid smoke flavourings. The alkaline treatment has been proved to be necessary because of its capability for removing some smoke components. Both cyclohexane and dichloromethane are able to extract polycyclic aromatic hydrocarbons with high recovery percentages; however, cyclohexane is more adequate due to its lower ability to extract other smoke flavourings components. It is important to note that the elution sequence of polycyclic aromatic hydrocarbons during the clean-up step is quite different depending on the solvent used to dissolve the extract, which determines the ability of this process to isolate polycyclic aromatic hydrocarbons for their accurate identification and quantification by gas chromatography-mass spectrometry in selected ion monitoring mode. Finally, the PAHs present in a liquid smoke flavouring and their concentrations were determined; it was observed that, despite the different extraction solvents and clean-up procedures used, the results were very similar.

ISSN:0265-203X    

DOI:10.1080/026520300283568

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A survey was carried out with the aim to assess the levels of some toxic (cadmium, lead) and essential (copper, zinc) trace metals in wheat grown in Italy. A total of 178 samples of soft wheat grain and 239 samples of durum wheat grain from all the Italian wheat-growing regions were pooled into 35 and 38 representative samples respectively. After dry ashing, cadmium and lead were determined by graphite furnace atomic absorption spectrometry (GFAAS), whereas copper and zinc were determined by flame atomic absorption spectrometry (FAAS). In soft wheat the mean and median contents of all samples were (on a dry weight basis) 40 and 33 µg kg-1for cadmium, 16 and 14 µg kg-1for lead, 3.4 and 3.2 mg kg-1for copper, 33 and 32 mg kg-1for zinc. Similar levels were found in durum wheat. In this latter case the mean and median were 42 and 39 µg kg-1for cadmium, 15 and 14 µg kg-1for lead, 3.5 and 3.2 mg kg-1for copper, 34 and 34 mg kg-1for zinc. Significant differences were detected for some metals in relation to geographical provenance and variety. The average intake of the four selected elements from wheat-based products was estimated for the Italian population.

ISSN:0265-203X    

DOI:10.1080/026520300283577

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Fumonisins B1(FB1) and B2(FB2) were determined in 35 samples of corn flour and corn grits destined for human consumption and purchased directly from Buenos Aires food shops and supermarkets from October 1996 to January 1997 and during the month of January 1998. During the first period of sample collecting, 16 out of 19 samples were found to be contaminated. Considering all 19 samples, contamination levels were between not detected and 1860 ng/g FB1, and from not detected to 768 ng/g FB2. During the second period all 16 samples were found to be contaminated with levels ranging from 75 to 4987 ng/g FB1, and from not detected to 1818 ng/g FB2. The levels of FB1and FB2in the samples collected during January 1998 were significantly higher than the samples collected during the period from October 1996 to January 1997. No significant difference was found in terms of fumonisin levels between the branded and unbranded samples.

ISSN:0265-203X    

DOI:10.1080/026520300283586

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The occurrence of aflatoxin M1(AFM1)in pasteurized milk and dairy products was investigated by using direct competitive enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). The recoveries of AFM1from the samples spiked at levels between 5 and 500 pg/ml were 88.0–106.5% for pasteurized milk and 84.0–94.0% for yoghurt by ELISA. By HPLC, the recoveries were 103–120% for pasteurized milk and 87.0–93.0% for yoghurt. The limits of detection were found to be 2 pg/ml by ELISA and 10 pg/ml by HPLC. Among a total of 180 samples collected in Seoul, Korea, the incidence of AFM1in pasteurized milk, infant formula, powdered milk and yoghurt was 76, 85, 75, and 83%, respectively, with a mean concentration of 18, 46, 200, and 29 pg/g, respectively, when determined by ELISA. These results obtained by ELISA were closely related to those by HPLC for AFM1(r2= 0.9783).

ISSN:0265-203X    

DOI:10.1080/026520300283595

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Two methods for the determination of aflatoxin B1(AFB1) in olive oil were tested and compared. In method A the oil sample was mixed with methanol + water (60 + 40), extracted with hexane and then with chloroform. Chloroform was evaporated and the residue was dissolved with dichloromethane which was then transferred for clean-up onto a silica ‘Sep-Pak’ cartridge. The cartridge was pre-washed with hexane, ethyl ether and dichloromethane. AFB1was eluted with chloroform + acetone (9 + 1) and evaporated to dryness. In method B, the oil sample was mixed with methanol + water (80 + 20), shaken and centrifuged. The supernatant was diluted 1:10 with water and 10ml of the diluted mixture transferred to an ‘Aflaprep’ immunoaffinity column for the clean-up step. AFB1was eluted with acetonitrile and evaporated to dryness. AFB1from both methods was derivatized to its hemiacetal (AFB2a) and then quantitated by HPLC using a C18(60 A 4.6 x 250 mm) column with fluorescence detection. Both methods are simple, reliable and efficient, but method A showed a lower detection limit (2.8 ng/kg) than method B (56 ng/kg). With a 95% confidence level there was no significant difference in recovery between the two methods, which was 87.2% for method A and 84.8% for method B. In addition, application of a two-tailed F-test to the variances within spiked samples at concentrations 1, 2, 5 and 10 µg/kg separately showed that there was no significant difference in the precisions of the two methods. Fifty samples of olive oil of Greek origin produced between 1995 and 1998 were examined with both methods for the presence of AFB1. When analysing the samples with method B, the presence of AFB1was not detected. The use of method A revealed the presence of AFB1in 72% of the samples. The range of contamination was generally found to be very low (2.8–15.7 ng/kg), however one sample was contaminated with 46.3 ng/kg.

ISSN:0265-203X    

DOI:10.1080/026520300283603

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The use of furazolidone in food-producing animals has been banned in the EU. The ban can most effectively be enforced by monitoring for bound residues containing the 3-amino-2-oxazolidinone (AOZ) moiety. Unlike the parent drug, AOZ residues are stable and can be detected for prolonged periods after cessation of treatment. However, AOZ can be passed from pig-to-pig following brief exposure of unmedicated animals to housing that previously contained medicated pigs. We describe criteria by which a distinction may be drawn between pigs treated illegally with the drug and pigs that contain detectable AOZ residues as a result of exposure to contaminated housing. These criteria are that illegally treated pigs will have a concentration ratio of AOZ in bile: kidney of less than 0.3; while unmedicated pigs will have a concentration ratio of AOZ in bile: kidney of greater than 3.0. Using this criteria, 12 pigs, either treated with the drug or exposed to contaminated housing were analysed in a blind study. The pigs were classified as ‘Treated’ or ‘Contaminated’ on the basis of the criteria described above. All 12 pigs were assigned to the correct group. This shows that it is possible to differentiate between furazolidone abuse and contamination.

ISSN:0265-203X    

DOI:10.1080/026520300283612

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.

ISSN:0265-203X    

DOI:10.1080/026520300283621

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor