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.

The composition of the two major lipidic organelles of the tapetum of Brassica napus L. has been determined. Elaioplasts contained numerous small (0.2-0.6 micron) lipid bodies that were largely made up of sterol esters and triacylglycerols, with monogalactosyldiacylglycerol as the major polar lipid. This is the first report in any species of the presence of non-cytosolic, sterol ester-rich, lipid bodies. The elaioplast lipid bodies also contained 34- and 36-kDa proteins which were shown by N-terminal sequencing to be homologous to fibrillin and other plastid lipid-associated proteins. Tapetosomes contained mainly polyunsaturated triacylglycerols and associated phospholipids plus a diverse class of oleosin-like proteins. The pollen coat, which is derived from tapetosomes and elaioplasts, was largely made up of sterol esters and the C-terminal domains of the oleosin-like proteins, but contained virtually no galactolipids, triacylglycerols or plastid lipid-associated proteins. The sterol compositions of the elaioplast and pollen coat were almost identical, consisting of stigmasterol > campestdienol > campesterol > sitosterol >> cholesterol, which is consistent with the majority of the pollen coat lipids being derived from elaioplasts. These data demonstrate that there is substantial remodelling of both the lipid and protein components of elaioplasts and tapetosomes following their release into the anther locule from lysed tapetal cells, and that components of both organelles contribute to the formation of the lipidic coating of mature pollen grains.

Four varieties of green bean (Phaseolus vulgaris) were analyzed for flavonol composition and content. Two flavonol conjugates, not previously reported in green bean, were found in three of the varieties. These are quercetin 3-O-(2G-β-d-xylopyranosylrutinoside) (1), (1.0−2.0 μg/g of fresh weight) and the corresponding kaempferol analogue (2) (0.3−0.7 μg/g). The major flavonol component in all of the varieties was quercetin 3-O-glucuronopyranoside (3) (3.5−15.1 μg/g) with lesser amounts of quercetin 3-O-rutinoside (4) (0.2−4.3 μg/g) and kaempferol 3-O-glucuronopyranoside (5) (0.5−1.3 μg/g). Kaempferol rutinoside (6) was detected in only one variety (0.8 μg/g). Commercial processing, such as canning, did not result in chemical breakdown of the conjugates, although between 8.8 and 24.4%, depending on the conjugate, was leached into the cooking water. Keywords: Phaseolus; green bean; HPLC; flavonol; glycoside

The composition and content of flavonol glycosides (FGs) have been measured in infusions of a range of black tea and black tea products. Tea contains a mixture of glycosides of quercetin, kaempferol, and myricetin and the total level of these glycosides, in infusions prepared in a normal domestic manner, for the leaf teas varied from 36.5 to 88.3 mg/L, although greater variation was observed for the tea products, from 7.0 to 428.1 mg/L. Altogether seven quercetin, five kaempferol, and two myricetin glycosides were detected; their relative amounts varied significantly in the different samples. The significance of these differences in relation to the bioavailability and potential bioactivity of these compounds is discussed. Keywords: Tea; flavonol; glycoside; HPLC; quercetin; kaempferol; myricetin