摘要:

The effects of retinol and α‐tocopherol‐deficient and supplemented diets on the cytosolic concentration of thiobarbituric acid reactive substances (TBARS) in rat liver have been studied. Physiological lipoperoxidation (LPO) was observed in liver cytosol of control rats (TBARS = 0.315 ± 0.034 nmol of MDA equivalents/mg of liver cytosolic proteins). In retinol‐deficient diets there was a decrease in retinolaemia and the absence of retinol in liver cytosol while cytosolic TBARS increased significantly(P <0.001).

ISSN:0265-203X    

DOI:10.1080/02652039209374042

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Karl Fischer titration has been used to eliminate the need to humidity‐condition food contact plastics under test for overall migration into olive oil. The water content of the oil is measured before and after the migration test. This direct measure of the loss (or uptake) of water by the test plastic is then used in calculations of the overall migration. The use of Karl Fischer titration gives faster analysis with reduced labour input. The time savings varied from a few days to several weeks depending on the type of plastic. Karl Fischer titration is particularly useful in the high temperature testing of polar plastics where incomplete humidity conditioning can lead to erroneous results. The technique should be equally valuable when employing sunflower oil or the triglyceride HB307 in place of olive oil.

ISSN:0265-203X    

DOI:10.1080/02652039209374043

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Experiments have been carried out with (a) microwave treatment of plastics followed by migration testing using the food simulant, olive oil, and (b) microwave treatment of plastics in direct contact with an organic extractant (iso‐octane). In neither of these complementary approaches was there evidence of any difference in migration from plastics that had been microwave‐treated compared with plastics that had received an equivalent thermal treatment. Five plastics commonly employed in microwave applications were tested and oligomers, plasticizer, antioxidant and volatile contaminants were monitored as representatives of typical migration species.

ISSN:0265-203X    

DOI:10.1080/02652039209374044

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Salted and dried fish(Nemipterus virgatus)acquired from Hong Kong, was treated with 0.43–110 mM nitrite duringin vitrodigestion using gastric enzymes and the volatileN‐nitrosamine content and mutagenicity onSalmonella typhimuriumTA 100 assayed without concentration.N‐Nitrosodimethylamine (NDMA; the only nitrosamine detected) formation was second order in nitrite concentration. When 10 g of fish was treated with 6.96 nM nitrite, 394 nM NDMA was formed. Thiocyanate was catalytic for NDMA formation at nitrite concentration >0·87 mM and when the ratio of thiocyanate to nitrite was > 1. Approximately a 50% inhibition in NDMA formation by ascorbic acid was seen when the ratio of ascorbate to nitrite was approximately 2 or greater and the nitrite concentration was 1.74 mM. Mutagenicity increased with increasing nitrite concentration but the addition of thiocyanante did not increase mutageneicity over nitrite alone. Ascorbate increased mutagenicity even though NDMA formation was inhibited. Even at nitrite concentrations > 100‐fold higher than expectedin vivothere was insufficient NDMA formed to account for the observed mutagenicity. These data do not exclude the possibility that the observed mutagenicity was due to non‐volatileN‐nitroso compounds, however, this possibility seems unlikely given the effects of ascorbate and thiocyanate which would be expected to inhibit and enhance non‐volatileN‐nitroso compound formation.

ISSN:0265-203X    

DOI:10.1080/02652039209374045

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A review of the literature published prior to July 1991 covers the occurrence and formation of non‐volatileN‐nitrosamines occurring in foods and beverages. The presence of identified volatile and non‐volatileN‐nitrosamines accounts for less than 10% of the total apparentN‐nitrosamine concentration.N‐Nitrosoproline andN‐nitrosothiazolidine‐4‐carboxylic acid are the most commonly identified non‐volatileN‐nitrosamines in the diet. Non‐volatileN‐nitrosamines account for 12 of the 21 currently identifiedN‐nitroso compounds in foods and beverages.

ISSN:0265-203X    

DOI:10.1080/02652039209374046

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

To provide a basis for the certification of wheat and maize flour reference materials containing deoxynivalenol, a series of three preliminary intercomparisons of methods was carried out between 1985 and 1988. The first intercomparison, involving 10 laboratories was designed to examine the determinative step and used a solution of deoxynivalenol in ethyl acetate and a spiked wheat extract solution. The second intercomparison involving 13 laboratories established minimum extraction times for naturally contaminated samples, demonstrated the absence of matrix effects in purified extracts and showed that there was no evidence of differences in the use of any of three different end determinations. The third intercomparison involving 15 laboratories used naturally contaminated cereals and acted as a preliminary to the final certification exercise. Over a period of four years there was a steady improvement in the range of results submitted by participants thought to be due to the application of improved analytical methods, increased expertise in the analysis and through experience gained through the intercomparisons.

ISSN:0265-203X    

DOI:10.1080/02652039209374047

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper reports for the first time in smoked foods the presence of three tetrahydro‐ß‐carboline carboxylic acids. One of these, 1‐hydroxymethyl‐tetrahydro‐ß‐carboline‐3‐carboxylic acid, which is derived from the interaction of tryptophan and glycolaldehyde, and which has not previously been reported in foods, was observed in 20 samples at levels up to 444 μg/kg. The corresponding products which are derived from tryptophan and formaldehyde or tryptophan and acetaldehyde were found respectively in 28 samples at levels up to 22 mg/kg and in 16 samples at levels up to 881 μg/kg. Greater concentrations were generally found in those smoked foods having a lower pH value and produced by using a longer fermentation or maturation. Only l‐methyl‐tetrahydro‐ß‐carboline carboxylic acid (156–574 μg/kg) was found in the four unsmoked samples analysed.

ISSN:0265-203X    

DOI:10.1080/02652039209374048

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Groups of rats were fed diets containing marginal levels of Fe and Zn as glycine chelates (tradename ‘Chelazome’, Albion Laboratories, Verona, New Jersey, USA), or the same level of mineral as ferrous sulphate or zinc carbonate. The Fe diets were fed to weanling rats for 4 weeks and the Zn diets to young adult rats for 5 weeks. Blood Hb concentrations were significantly higher in the group fed Fe‐chelazome than ferrous sulphate, 149 and 128 g/l respectively(P <0.001), but PCV and liver Fe concentrations were similar between the two groups. No difference in plasma Zn, pancreas, testes or femur Zn concentrations were observed between the two Zn groups, indicating that Zn‐chelazome has no advantage over zinc carbonate. The results of this preliminary study indicate that Fe‐chelazome has a higher bioavailability than ferrous sulphate and merits further study.

ISSN:0265-203X    

DOI:10.1080/02652039209374049

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Foodborne Pathogens—An Illustrated Text.Edited by A. H. Varnam and M. G. Evans. (Wolfe Publishing Ltd, London, 1991). Pp. 557. Price £70. ISBN 0–7234–1521–8.

ISSN:0265-203X    

DOI:10.1080/02652039209374050

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0265-203X    

DOI:10.1080/02652039209374051

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor