Ochratoxin A in dried vine fruit: method development and survey.

A method is described for the determination of concentrations of the mycotoxin ochratoxin A in dried vine fruits (currants, raisins and sultanas) using acidic methanolic extraction, immunoaffinity chromatography clean-up and HPLC determination. The limit of detection was estimated as 0.2 microgram/kg, and recoveries of 63-77% were achieved at 5 micrograms/kg. HPLC-mass spectrometric confirmation of the identity of ochratoxin was obtained. Ochratoxin A and aflatoxins were determined in 60 samples of retail dried vine fruits purchased in the United Kingdom. Ochratoxin A was found in excess of 0.2 microgram/kg in 19 of 20 currant, 17 of 20 sultana and 17 of 20 raisin samples examined, an overall incidence of 88%. The maximum level found was 53.6 micrograms/kg. No aflatoxin was found in any sample analysed, using a method with a detection limit of 0.2 microgram/kg for each of aflatoxin B1, B2, G1 and G2.

Food plant toxicants and safety Risk assessment and regulation of inherent toxicants in plant foods.

The ADI as a tool for risk management and regulation of food additives and pesticide residues is not readily applicable to inherent food plant toxicants: The margin between actual intake and potentially toxic levels is often small; application of the default uncertainty factors used to derive ADI values, particularly when extrapolating from animal data, would prohibit the utilisation of the food, which may have an overall beneficial health effect. Levels of inherent toxicants are difficult to control; their complete removal is not always wanted, due to their function for the plant or for human health. The health impact of the inherent toxicant is often modified by factors in the food, e.g. the bioavailability from the matrix and interaction with other inherent constituents. Risk-benefit analysis should be made for different consumption scenarios, without the use of uncertainty factors. Crucial in this approach is analysis of the toxicity of the whole foodstuff. The relationship between the whole foodstuff and the pure toxicant is expressed in the `product correction factor' (PCF). Investigations in humans are essential so that biomarkers of exposure and for effect can be used to analyse the difference between animals and humans and between the food and the pure toxicant. A grid of the variables characterising toxicity is proposed, showing their inter-relationships. A flow diagram for risk estimate is provided, using both toxicological and epidemiological studies.

Survey of ethnic foods for mycotoxins.

A survey has been carried out in the UK to determine the levels of mycotoxins in a range of ethnic foods. The survey involved analysis of 121 samples of ethnic foods, purchased from specialist shops, for aflatoxins, ochratoxin A and the Fusarium mycotoxins (fumonisins, zearalenone and trichothecenes). The samples were of cereal and cereal product, fats and oils, nuts and nut products, seeds, spices and herbs, pickles, sauces and a variety of canned vegetable and/or pickle products. Low concentrations of mycotoxins were present in many samples analysed. The types and levels of mycotoxins present varied with the type of sample. The most common contaminants were the trichothecenes and ochratoxin A. Trace levels of aflatoxins, ochratoxin A, zearalenone, fumonisins and trichothecenes were detected in samples containing cereal, such as rice, noodles, corn flour and pitta bread. Trace levels of aflatoxins and zearalenone were detected in a sample of chili oil and ochratoxin A in a sample of sesame oil. Only one sample of nut (almond) contained aflatoxin while aflatoxins, ochratoxin A, zearalenone and deoxynivalenol (a trichothecene) were detected in various seeds. Aflatoxins, ochratoxin A and fumonisins were found in chili paste and zearalenone and ochratoxin A in curry pastes. The highest mycotoxin levels and frequency of occurrence were in chili powder, curry powder and ginger.