Four fungal strains, namely, AspergiUus niger, Eurotium herbariorum, a Rhizopus sp., and non-aflatoxin (AF)-producing Aspergillus flavus, which could convert AF-B1 to aflatoxicol (AFL), could also reconvert AFL to AF-B1. The interconversion of AF-B1 to AFL and of AFL to AF-B1 was ascertained to occur during proliferation of the fungi. These reactions were distinctly observed in cell-free systems obtained from disrupted mycelia of A. flavus and the Rhizopus sp., but they were not observed in culture filtrates from intact (nondisrupted) mycelia of the same strains. The interconversion activities of AF-B1 and AFL were not observed when the cell-free systems were preheated at 100°C. These findings strongly suggest that the interconversion of AF-B1 and AFL is mediated by intracellular enzymes of A. flavus and the Rhizopus sp. In addition, the isomerization of AFL-A to AFL-B observed in culture medium was also found to occur by the lowering of the culture pH. Aflatoxicol (AFL) is formed by reduction of the cyclopentenone carbonyl of aflatoxin (AF)-B, and has two types of stereoisomers, AFL-A and AFL-B, determined by the stereoconfiguration of the OH group in the cyclopentenol ring (2) (Fig. 1). AFL is well known (1) as a main in vitro metabolite produced from AF-B, by reductase in the supernatant of liver homogenates of several avian and mammalian species. It has also been reported that AFL is produced from the biological reduction of AF-B, by microorganisms such as Rhizopus spp. (3), Dactylium dendroides (4-6), Absidia repens (5), Mucor griseo-cyanus (5), Aspergillus niger (8, 9), Mucor ambiguus (8, 9), Trichoderma viride (8, 9), Streptococcus lactis (10), and Tetrahymena pyriformis (14). These facts suggest the possibility of detecting AFL in foods and feeds contaminated with AF-Bl. Saito et al., in this laboratory (16), reported the simultaneous contamination of commercial pistachio nuts and corn with AFL and AF-B, in 1984, in the first report on natural contamination of food with AFL. To elucidate the cause of natural AFL contamination, we reported the abilities of various species of non-AF-Blproducing fungi which were isolated from AFL-contaminated corn to convert AF-B, to AFL. As a result, it was found (11) that A. niger, Eurotium herbariorum, the Rhizopus sp., etc., had fairly potent conversion abilities. It was also found (12) that several strains of AF-Bl-producing Aspergillus flavus isolated from AFL-contaminated corn showed a fairly high AFL-producing ability. As mentioned above, the conversion of AF-B, to AFL by microorganisms has already been demonstrated, but little is known about the reverse conversion, namely, that from AFL to AF-Bl. This paper deals with the metabolic interconversion of AFL and AF-B, by non-AF-producing fungi isolated from AFL-contaminated corn. * Corresponding author. MATERIALS AND METHODS Organisms. The fungal strains used in this study were the following: A. niger C-41-i, E. herbariorum C-41-f, Rhizopus sp. C-40-m, and non-AF-producing A. flavus C-40-d, which were isolated from AFL-...

Azodicarbonamide ADA is used in some countries as a flour bleaching agent and a dough conditioner. However, ADA is prohibited for use as a food additive in Japan. Therefore, it is necessary to establish an efficient and sensitive method to determine ADA in wheat flour. A simple and practical procedure to analyze ADA in wheat flour and prepared flour mixes was developed. ADA was extracted from samples by ultrasonication with acetone. ADA in the solution was derivatized with triphenylphosphine TPP . The ADA-TPP derivative was concentrated and cleaned up using a reversed-phase solid-phase extraction cartridge, and the ADA-TPP derivative was analyzed using HPLC for determination and LC-MS/MS for identification. Good linearity was achieved over the concentration range of 0.25-100 ppm ADA in wheat flour and prepared flour mixes. The mean recoveries from wheat flour and prepared flour mixes fortified at the levels of 1 and 10 ppm ranged from 86.9 to 101.0 , and the coefficients of variation ranged from 1.9 to 3.4 .

No abstract

A method for the determination of sucralose in various foods by RI-HPLC and ion chromatography with a pulsed amperometric detector (PAD-IC) was developed.Chopped or homogenized samples were packed into cellulose tubing with 0.01 mol/L hydrochloric acid containing 10ΐ sodium chloride and were dialyzed against 0.01 mol/L hydrochloric acid for 24 hours. The dialyzate was passed through a Bond Elut ENV cartridge, and the cartridge was washed with 0.2 mol/L NaOH and water. Sucralose was eluted from the cartridge with methanol. The extract was taken to dryness in an evaporator and the residue was re-dissolved in water.Sucralose was separated on an Inertsil ODS-3V column with a mobile phase of acetonitrileῌ water (15 : 85) and an RI detector. It was also determined on a CarboPak PA1 column with a mobile phase of 100 mmol/L NaOHῌ75 mmol/L CH 3 COONa, using a PAD detector.The recoveries of sucralose from various kinds of foods spiked at 50 mg/g and 200 mg/g ranged from 88ῐ105ΐ. The detection limit in samples was 10 mg/g for RI-HPLC and 1 mg/g for PAD-IC.

No abstract