ISSN:0265-203X    

DOI:10.1080/02652038909373798

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Complementary methods based on three mass spectrometric ionization techniques are presented for the determination of the thermal decomposition products of the α‐dipeptide sweetener aspartame. Thermal decomposition products generated in acidic aqueous model systems were separated by ion‐pair high‐performance liquid chromatography and either (1) isolated and concentrated on solid‐phase extraction columns for determination by direct insertion probe/electron impact mass spectrometry; (2) determined by gas chromatography/mass spectrometry asN‐trifluoroethyl‐O‐trimethylsilyl polyamino alcohol derivatives; or (3) determined directly via Thermospray liquid chromatography/mass spectrometry. These procedures resulted in the elucidation and structural determination of four compounds: (1) β‐aspartame, a non‐sweet constitutional isomer of aspartame; (2) its anhydro analogue, methyl‐3‐phenyl‐2‐(3‐amino‐2,5‐dioxo‐1‐pyrrolidinyl propanoate; (3) the non‐sweet β‐L‐aspartyl‐L‐phenylalanine; and (4) its anhydro analogue, 3‐phenyl‐2‐(3‐amino‐2,5‐dioxo‐1‐pyrrolidinyl)propanoic acid.

ISSN:0265-203X    

DOI:10.1080/02652038909373799

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A method is reported for determination of total free and bound non‐sulphonated aromatic amines (NSAA) in the food colour amaranth. Bound amines are first reduced using sodium dithionite then all NSAA are extracted into chloroform, followed by transfer to aqueous acid solution, diazotization with sodium nitrite and subsequent coupling with 2‐naphthol‐3, 6‐disulphonic acid, disodium salt (R‐salt). The coloured derivatives are then analysed by reversed‐phase ion‐pair liquid chromatography using an absorbance detector at 522 nm. Samples of amaranth were spiked with various amounts of 1‐ and 2‐naphthylamine and recoveries ranged from 80 to 100% with deviations of less than 2%. A survey of commercial amaranth samples indicated that the dye may contain up to 435 μg/g of total 1‐naphthylamine and 214μg/g of total 2‐naphthylamine. The majority of NSAA are bound to R‐salt during the manufacturing process and less than 5% remain in the free state in the dye.

ISSN:0265-203X    

DOI:10.1080/02652038909373800

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Carageenans are a group of high molecular weight sulphated polygalactans which find extensive use in the food industry as thickening, gelling and protein‐suspending agents. Although there is no evidence to suggest that the persorption of small amounts of carageenans across the intestinal barrier poses an acute toxic hazard, they are known to be biologically active in a number of physiological systems and extended oral administration in laboratory animals has been shown to modify bothin vivoandin vitroimmune competence. Whereas this effect could be attributed to carrageenan having a selective toxic effect on antigen‐processing macrophages, additional studies suggest that macrophages can also influence immune responses by the timed release of immunoregulatory mediators. Evidence in support of this comes fromin vitrostudies which demonstrate that carrageenan‐treated macrophages can, depending on conditions and time of administration, release either stimulatory or inhibitory factors. The former is known to be the immunostimulatory agent interleukin 1 (IL‐1). The inhibitory factor, which is produced at an early stage following exposure to non‐toxic doses of carrageenans, has yet to be formally identified but it is believed to be a prostaglandin because of its specific mode of action and short biological half‐life.

ISSN:0265-203X    

DOI:10.1080/02652038909373801

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

It has been demonstrated that on storage of a tightly wound reel of polypropylene packaging film, specially printed for experimental purposes, transfer can occur of components from the ink on the outer surface of the film on to the inner food contact surface. For dicyclohexyl phthalate this transfer amounted to6%of the total amount of plasticizer available in the printing ink system. It was subsequently shown for confectionery and snack food products wrapped in commercially printed polypropylene films that plasticizers only present in the printing ink migrated into the foods. The migration of plasticizer increased with storage time of the wrapped product; for dibutyl phthalate, for example, levels increased from 0.2 to 6.7 mg/kg over the period from 0 to 180 days storage of a chocolate‐coated confectionery product. A small retail survey (47 samples) of confectionery, snack products and biscuits wrapped in printed polypropylene film showed the presence of one or more plasticizers at levels from 0.02 to 14.1 mg/kg for dibutyl phthalate, from <0.01 to 18.6 mg/kg for dicyclohexyl phthalate and from <0.01 to 1.8 mg/kg for di(2‐ethylhexyl) phthalate. In all cases there was a good correlation between the plasticizers found in the printing ink from the film and those in the food. Wide variations were found, however, in the amounts and types of plasticizers used in printed packaging of the same brand of retail food product purchased from different regions of the country.

ISSN:0265-203X    

DOI:10.1080/02652038909373802

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The amounts ofN‐nitrosoproline (NPRO) excreted in the urine of lacto‐vegetarians and subjects eating a free‐choice diet were determined. The study was carried out during four consecutive weeks and specified extra amounts of ascorbic acid were ingested daily during three of them. The average amount of NPRO excreted in the urine of the lacto‐vegetarians (1.33μg/24h) was slighly smaller than that in the urine of the individuals eating a free‐choice diet (2.13 μg/24 h). Intake of as little as 3 x 20 mg of extra ascorbic acid per day reduced the NPRO excretion. Intake of 3 x 1000 mg of ascorbic acid resulted in a statistically significant decrease in NPRO excretion in the urine.

ISSN:0265-203X    

DOI:10.1080/02652038909373803

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The fermented foods yoghurt, bread and cheese were analysed for the presence of apparent totalN‐nitroso compounds (ATNC) by a group‐selective procedure involving direct chemical denitrosation and chemiluminescence detection of the released nitric oxide. The levels of ATNC were below the 20μg(N‐NO)/kg detection limit in all 20 yoghurts, 23 of the 24 bread samples and 28 out of 31 different varieties of cheese analysed. ATNC were detected in most of those cheese samples manufactured with added nitrate, including Edam, Gouda and Havarti, in concentrations ranging from 30 to 210μg(N‐NO)/kg.

ISSN:0265-203X    

DOI:10.1080/02652038909373804

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A survey of the occurrence of aflatoxins B1, B2, G1and G2in Soviet domestic and imported cereals and nuts (totalling 4532 samples) collected in 1985–87, showed that 26.9% of imported peanuts, 2.2% of corn and 28.3% of cotton seeds were contaminated by aflatoxins at levels exceeding the maximum tolerated level established in the USSR (5μg/kg for aflatoxin B1in foodstuffs of all types excluding baby foods); maximum concentrations were 3650, 600 and 153μg/kg, respectively. A highly sensitive normal‐phase high‐performance liquid chromatographic method was developed. The detection limit was 0.1μg/kg and the coefficients of variation were 11% and 8.5% at contamination levels 10 and 100μg/kg of aflatoxin B1, respectively.

ISSN:0265-203X    

DOI:10.1080/02652038909373805

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

A commercial formulation of chloramphenicol and oxytetracycline was administered to dairy cows and bullocks by the intramuscular route. Concentrations of drugs were determined in milk and edible tissues by high‐performance liquid chromatographic and microbiological methods. The data allowed the calculation of withdrawal times for milk (4 and 17 milkings for chloramphenicol and oxytetracycline, respectively) and for tissues (35 days for chloramphenicol, more than 35 days for oxytetracycline, depending on the levels at the injection sites). Hence oxytetracycline residues were the most persistent in these types of foods, according to our dosage scheme.

ISSN:0265-203X    

DOI:10.1080/02652038909373806

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Young male pigs (25–40 kg bw) were treated experimentally with a single 0.4 mg/kg bw, s.c. dose of ivermectin (Ivomec vet. inj., MSD). The disappearance of the drug from the edible tissues 7–21 days after treatment was studied using a sensitive high‐performance liquid chromatographic method. The highest residue levels were found at the injection site (up to 59 and 2.6 mg/kg 7 and 14 days post‐injection, respectively). Among the other tissues studied, the residue levels 7 days post‐injection showed the following order: liver (≤50 /μg/kg) > kidney (≤ 25μg/kg) > muscle (≤ 20 μg/kg). After 21 days only traces of ivermectin (≤ 2 μg/kg) could be detected in the muscle and other edible tissues, including the injection site. Similar residue concentrations were found in slaughterhouse material from sows therapeutically treated with ivermectin for parasite infestation. An ordinary culinary preparation of the minced beef muscle from a bull treated with ivermectin resulted in a 45% (boiling) or 50% (frying) decrease in the drug residue. Based on the known toxic effects of the drug and the results of the present and other residue studies, the suggested withdrawal time for Ivomec in edible tissues of swine and cattle is 21 and 28 days, respectively.

ISSN:0265-203X    

DOI:10.1080/02652038909373807

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor