摘要:

A gas chromatographic‐mass spectrometric technique is described for the simultaneous determination of sorbates, benzoates and other lipophilic preservatives in foods and beverages. The selected ions monitoring (SIM) technique allowed unambiguous identification of the compounds under study. This methodology eliminated all kinds of interferences from the complex food matrices which affect most routinely‐used techniques, HPLC included. A very simple and time‐saving extraction procedure was therefore employed, since subsequent purification steps were unnecessary, even for detection of trace levels of preservatives. The detection limits fell within the range of 100–200 pg. With this analytical technique, we have conducted a survey on sorbic acid, benzoic acid, methyl, ethyl, and propyl 4‐hydroxybenzoate levels in 249 samples of foods and beverages on sale in markets in the Rome area. Samples were chosen from among those currently preserved by these additives. All compounds were also determined by a routinely‐used HPLC technique for method comparison.

ISSN:0265-203X    

DOI:10.1080/02652039509374273

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Utilizing solvents such as ethanolic aqueous ammonia, petroleum ether, hexane and chloroform, annatto components α‐ and β‐norbixin and α‐ and β‐bixin were extracted from cheese, butter, margarine and hard candy. After transferring the extract into a solution of aqueous acetic acid in methanol, bixin and norbixin were determined quantitatively using high‐performance liquid chromatography (HPLC) and an absorbance detector set at 500 nm. Recovery of norbixin from spiked cheese samples averaged 92.6% over a range of 1 to 110μg/g. Commercial cheese samples were found to contain 1.1–68.8μg/g total norbixin, and two samples also contained 5.1–5.6μg/g total bixin. Samples of uncoloured butter were spiked with bixin and recovery averaged 93.2% over a range of 0.1 to 445μg/g. Levels of 0.2μg/g total bixin and 0.91μg/g total norbixin were found in one commercial butter sample; the others contained trace levels of both compounds. Hard candies were prepared in the laboratory and recovery studies conducted. Recovery of norbixin averaged 88%.

ISSN:0265-203X    

DOI:10.1080/02652039509374274

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A survey of free glutamic acid levels in a variety of foods was conducted. The foods were analysed by high‐performance liquid chromatography (HPLC). Free glutamic acid was extracted from the food with 0.02m potassium phosphate with subsequent precipitation of other food components with acetone. Impurities were removed by passing the extract through a C‐8 or C‐18 reversed‐phase solid‐phase extraction column. The free glutamic acid was derivatized with phenylisothiocyanate, and the derivative was separated by HPLC with detection at 254 nm. Free glutamic acid levels ranged from not found (<20ppm) in some spices to as high as 89% in another spice.

ISSN:0265-203X    

DOI:10.1080/02652039509374275

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Ochratoxin A (OA), fumonisin B1(FB1) and fumonisin B2(FB2) were added to wort at levels of 0.19, 0.95 and 0.95μg/ml, respectively, and fermented for up to 8 days by three strains ofSaccharomyces cerevisiae.Decreases of OA in the beer over this period were estimated from straight line slopes to be 2–13%. Losses of FB1and FB2were estimated to be 3–28% and 9–17% respectively. Some OA was taken up by the yeast, up to 21% in a detailed study with one strain. In contrast, uptake of fumonisins by yeast was negligible (< 1% FB1and < 2% FB2). In control experiments, OA, FB1and FB2were found to be stable when added to yeast‐free wort and kept for up to 8 days at 25°C. In addition, spiking experiments with blank day 0–8 fermenting wort samples showed method recoveries averaging 87–91%. None of the mycotoxins was detected in control fermentations where they were not added to the wort.

ISSN:0265-203X    

DOI:10.1080/02652039509374276

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The fusarial toxicosis induced by trichothecenes is characterized by common syndromes such as vomiting, inflammation, haemorrhages, diarrhoea and haematological changes. Subchronic ingestion of trichothecenes causes a decrease in circulating white cells. This leukopenic change of animals is reported as a characteristic feature in the best known human disorder: Alimentary Toxic Aleukia (ATA). The aim of the present study was to evaluate whether the haematologic disorders imputed to trichothecenes were a result of myelotoxicity by investigating in anin vitromodel. Rat haematopoietic progenitors, Colony Forming Units‐Granulocytes and Macrophages (CFU‐GM), were cultured in the presence of several concentrations of four trichothecenes; T‐2 toxin, HT‐2 toxin, diacetoxyscirpenol (DAS) and deoxynivalenol (DON). All these trichothecenes were cytotoxic to rat haematopoietic progenitor cells. It is concluded that haematological disorders observed during trichothecene intoxication of animals are caused by the destruction of haematopoietic progenitors such as CFU‐GM cells.

ISSN:0265-203X    

DOI:10.1080/02652039509374277

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

It was shown that the ability of three different strains ofPenicillium expansum(NRRL 2034, NRRL 6069, and CBS 481.84) to grow and to produce patulin in pears (cv. Spadona) and apples (cv. Starking) varied under the different temperatures tested (0, 3, 6, 17 and 25°C). Strain NRRL 2034 did not produce patulin at 0 or 25°C while the two other strains produced the toxin at all temperatures, the maximum production occurring at 25°C (for pears) and 17°C(for apples). No significant differences in pathogenicity, as determined by lesion diameter, was recorded among the strains. Patulin production was totally inhibited when the fungi were grown in apples stored under 3% CO2/2% O2(25ˆC). The weight of infected tissue in apples contaminated with any of the strains and stored at that modified atmosphere was 70% that of the control. Under 3% CO2/10% O2or 3% CO2/20% O2, strain NRRL 2034 did not produce patulin while the two other strains produced the toxin in different amounts.

ISSN:0265-203X    

DOI:10.1080/02652039509374278

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A method using immunoaffinity as a purification step for the determination of aflatoxin M1in cheese is described. A simple solvent extraction with dichloromethane followed by a washing step with N‐hexane gives a prepurified extract. A comparison between two ways of aflatoxin M1purification, by solid‐phase extraction clean‐up and by immunoaffinity, was carried out. The use of immunoaffinity columns containing monoclonal antibodies against aflatoxin M1gives the best result, i.e. a very clean preparation containing purified aflatoxin M1. The quantification of aflatoxin M1is then performed by high performance liquid chromatography using fluorometric detection. This method was successfully carried out on naturally‐contaminated and spiked cheeses. Recoveries are about 75%. The limit of quantification is 0.020 μg of aflatoxin M1per kg of cheese. This method seems suitable for use in monitoring programmes for aflatoxin M1contamination in dairy products such as cheese.

ISSN:0265-203X    

DOI:10.1080/02652039509374279

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The heat stability of clenbuterol was investigated. The drug was shown to be stable in boiling water at 100°C. In cooking oil at 260°C, losses were observed, indicating a half‐life of about 5 min. The effect of a range of cooking processes (boiling, roasting, frying, microwaving) on clenbuterol residues in fortified and incurred tissue was studied. No net change in the amount of clenbuterol was observed in any of the cooking processes investigated except for deep frying using extreme conditions. There was little observed migration from the tissue into the surrounding liquid or meat juices. Clenbuterol residues were found not to be evenly distributed in the incurred raw tissue used for the investigation. The findings of this investigation show that data obtained from measurements on raw tissue are applicable for use in consumer exposure estimates and dietary intake calculations.

ISSN:0265-203X    

DOI:10.1080/02652039509374280

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A one‐plate screening method is described for the microbiological detection of antibiotic residues by growth inhibition ofBacillus subtilisin agar medium, at pH 7, which contains trimethoprim for better detection of sulphonamides.β‐Glucuronidase is added to the samples to enable the detection of chloramphenicol residues. The sensitivity was determined for 16 antimicrobial substances frequently used in animal husbandry. A comparison was made with the sensitivity of the EEC four‐plate test and existing maximum residue levels. The method has been used in Belgium for 5 years for the monitoring of antimicrobial residues in kidney tissue and meat of slaughter animals.

ISSN:0265-203X    

DOI:10.1080/02652039509374281

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Polyclonal antibodies against the coccidiostat, lasalocid, were raised in sheep. The antisera were applied in an enzyme‐linked immunosorbent assay (ELISA) for lasalocid, which was validated for chicken serum, liver and muscle. Bridge homology in the ELISA was overcome by absorbing unspeciflc antisera onto a conjugate between salinomycin and chicken serum albumin, which was immobilized onto Biosilon beads. The described assay is highly specific for lasalocid, and is capable of detecting lasalocid at concentrations of less than 015 ng/g, depending on the tissue. Residual concentrations of lasalocid in broilers fed medicated feed containing 90 mg/kg lasalocid were measured during a 7 day withdrawal period. The half‐life of lasalocid was 11, 36 and 41 h in serum, liver and muscle, respectively. Lasalocid concentrations in liver were approximately 10 ng/g 7 days withdrawal of the medicated feed.

ISSN:0265-203X    

DOI:10.1080/02652039509374282

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor