The alkylresorcinol (AR) content of 8 commonly consumed cereals, 125 Triticum cultivars, milling fractions of wheat and rye, bread, and other cereal products was analyzed. ARs were found in wheat (489-1429 microgram/g), rye (720-761 microgram/g), triticale (439-647 microgram/g), and barley (42-51 microgram/g), but not in rice, oats, maize, sorghum, or millet. One durum wheat variety was found to have an exceptionally low level of ARs (54 microgram/g) compared to other durum wheat varieties (589-751 microgram/g) and Triticumspecies analyzed. The AR content of milling fractions closely followed the ash content and could be used as a marker of the presence of bran in flour. Using hot 1-propanol extraction, all ARs could be extracted from bread, contrary to previous studies which suggested that ARs were destroyed during baking. Cereal products varied greatly in AR content, with those containing wheat bran or whole rye having the highest content.

A method was established for fast and easy analysis of 5-n-alkylresorcinols in rye grains, considering effects of milling (intact grains versus¯our), extraction solvent (ethyl acetate, methanol and acetone), extraction volume per gram of sample (20 and 40 ml) and extraction time (3, 6, 18 and 24 h). For intact kernels, extraction of 1 g samples with ethyl acetate (40 ml, 24 h) is recommended. The ease of extraction is consistent with the presence of alkylresorcinols in the outer layers of the kernel and their absence in the endosperm. The extracts were analysed (without further puri®cation or derivatisation) by gas chromatography using methyl behenate (C22:0, fatty acid methyl ester) as internal standard. Alkylresorcinols were identi®ed by gas chromatography/mass spectrometry, and the major homologues were found to contain alkyl chains of C17:0, C19:0, C21:0, C23:0 and C25:0. The methodology was then applied to analyse the alkylresorcinol content in 15 rye cultivars grown at two locations in Sweden. Total alkylresorcinol contents varied within the range 549±1022 mg g À1, and the average percentages of the different alkylresorcinols were: 17:0, 23%; 19:0, 32%; 21:0, 26%; 23:0, 11%; and 25:0, 8%.

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.

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Alkylresorcinols (AR) are amphiphilic 1,3-dihydroxy-5-alkyl phenolic lipids. AR in food are only found in the outer layers of wheat and rye grains, and in whole grains are present at concentrations of 500-1000 mg/g. In wheat and rye, there are five main homologues, differing in the length of the odd-numbered alkyl chain (from seventeen to twenty-five C atoms long). Because AR may be bioactive, and might serve as biomarkers for these cereals, their absorption was investigated in model experiments with pigs and rats. Pigs with a cannula in the terminal ileum were fed four diets containing rye fractions with different levels of AR and the ileal effluents were analysed. The ileal recovery of AR was found to vary between 21 and 40 %, with no major difference between different chain-length homologues. The absorption of AR by rats was investigated by feeding 14 C-labelled heneicosylresorcinol (C 21 : 0 ). Of the total activity, about 34 % was recovered in the urine, showing that the labelled AR was absorbed and metabolised by rats. AR were mostly cleared from rats by 60 h. It is concluded that AR are absorbed in the small intestine of single-stomached animals and excreted in metabolised form in the urine, and might contribute to the nutritional qualities of wholegrain wheat and rye diets.

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Tracking circuits are available for positioning the linear delay trigger exactly halfway between these markers automatically.

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