Development and single-laboratory validation of an HPLC method for the determination of cyclamate sweetener in foodstuffs.

A method for the determination of cyclamate has been developed and single-laboratory validated for a range of foodstuffs including carbonated and fruit-juice drinks, fruit preserves, spreads, and dairy desserts. The method uses the peroxide oxidation of cyclamate to cyclohexylamine followed by derivatization with trinitrobenzenesulfonic acid and analysis by a modified reversed-phase high-performance liquid chromatography-ultraviolet light (HPLC-UV). Cycloheptylamine is used as an internal standard. The limits of detection were in the range 1-20 mg kg(-1) and the analysis was linear up to 1300 mg kg(-1) cyclamic acid in foods and up to 67 mg l(-1) in beverages. Analytical recovery was between 82% and 123%, and results were recovery corrected. Precision was within experimentally predicted levels for all of the matrices tested and Horrat values for the combined standard uncertainty associated with the measurement of cyclamate between 0.4 (water-based drinks) and 1.7 (spreads). The method was used successfully to test three soft drink samples for homogeneity before analytical performance assessment. The method is recommended for use in monitoring compliance and for formal testing by collaborative trial.

Factors affecting the analysis of furan in heated foods.

Various experimental factors, which could affect the measurement of furan by automated headspace gas chromatography/mass spectrometry, have been investigated. It was established that furan was not lost during sample heating through leakage or decomposition. Deuterium-labelled furan, used as an internal standard, was stable with respect to incubation in the presence of food and stable in model food systems at raised temperature. Saturation of the aqueous phase of the sample with ammonium sulphate improved the partitioning of furan from samples into the headspace. There was a very small decrease in the peak areas of both d0-furan and d4-furan when heated at acid pH. For food samples heated at normal headspace incubation temperature (50 degrees C), the level of furan was highest at the most acidic conditions used (pH 2.4) and did not differ significantly between pH 5 and 10. Under strong heating, production of furan decreased markedly at very high pH. Quantification based on standard additions or on external calibration gave comparable results for foods containing furan at relatively low, moderate and high levels.

Some factors affecting the formation of furan in heated foods.

Levels of furan in various foods were measured before and after heating under heating and laboratory conditions. The effect of contact with can coatings, sealing gaskets and the epoxidized oils used in gasket manufacture on furan formation was studied. The objective was to identify factors affecting furan formation. Furan present in heat-processed food samples persisted during cooking. Furan was shown to form in foods on heating, although it did not accumulate to a significant degree on heating in an open vessel. There were no interactions between foods and cans, can coatings or gaskets that had a significant influence on furan formation. Furan accumulated particularly in heat-processed canned and jarred foods because they are sealed containers that receive a considerable thermal load. Heating epoxidized oils used in sealing gaskets formed furan. At the levels used in gaskets, however, epoxidized oils should not affect the formation of furan in foods.

Effects of storage time and temperature on the concentration of ethyl carbamate and its precursors in wine.

A 3-year study was carried out on the effects of time and temperature on the concentration of ethyl carbamate in wine. The study monitored the changing concentration of ethyl carbamate and of urea and citrulline, which are two major precursors of ethyl carbamate in wine. In addition to the formation of ethyl carbamate, both urea and citrulline decayed in other reactions. Kinetic analysis was carried out to model the formation of ethyl carbamate and its dependence on the concentrations of ethanol, urea and citrulline. This led to the development of an equation that can be used to predict the concentration of ethyl carbamate in wine at the point of consumption, resulting from any given storage time and temperature profile. The results were in good agreement with data obtained from similar studies.

Survey of chloropropanols in soy sauces and related products purchased in the UK in 2000 and 2002.

The results of surveys to investigate the levels of 3-monochloropropane-1,2-diol (3-MCPD) and 1,3-dichloropropanol (1,3-DCP) in UK retail samples of soy sauces and similar products are reported. The products, sampled in 2000 and 2002, were analysed for 3-MCPD using an established solvent extraction technique with a reporting limit of 0.01 mg kg(-1), which also detected 2-monochloropropane-1,2-diol (2-MCPD), and for 1,3-DCP by an automated headspace method with a reporting limit of 0.005 mg kg(-1), which also detected 2,3-dichloropropanol (2,3-DCP). In the 2000 survey, 3-MCPD was quantified in 32 of 100 samples. After normalization to 40% dry matter, it was quantified at or above 0.02 mg kg(-1) in 25 of the samples and in excess of 1 mg kg(-1) in 16 samples, the highest containing 82.8 mg kg(-1). 2-MCPD was found in 26 samples, at up to 17.6 mg kg(-1) after normalization to 40% dry matter. The presence of 1,3-DCP was detected in 17 of the samples, at levels between 0.006 and 0.345 mg kg(-1). 1,3-DCP was only detected where 3-MCPD was present, but the levels of 1,3-DCP and 3-MCPD were not correlated. 2,3-DCP was detected in 11 samples at levels ranging from 0.006 to 0.043 mg kg(-1). In the 2002 survey, 3-MCPD was quantified (> 0.01 mg kg(-1)) in only eight of 99 samples and 2-MCPD in three samples. After normalization to 40% dry matter, 3-MCPD was present at or above 0.02 mg kg(-1) in seven of these, the maximum level being 35.9 mg kg(-1). 1,3-DCP was detected in this sample alone, at 0.017 mg kg(-1).