Studies were conducted to determine the effectiveness of allyl isothiocyanate (AIT) vapor treatment with a commercial mustard seed extract (Wasaouro®) in controlling aflatoxin-producing fungi on stored corn. The concentration of AIT in the closed container peaked at 54.6 ng/mL on the 14th day and remained at 21.8 ng/mL on the 42nd day. AIT inhibited visible growth of aflatoxigenic molds in unsterilized corn and in sterilized corn inoculated with various aflatoxigenic fungi. However, fungi such as Aspergillus glaucus group, A. penicillioides and A. restrictus were detected by means of culture methods.
A method using liquid chromatography coupled with mass spectrometry (LC-MS) was developed for the simultaneous determination of colorants in foods. Twenty-five colorants were extracted from foods with water or methanol and ammonia water, and cleaned up with a solid-phase extraction column. Recovery rates were between 71 and 113%, and relative standard deviations were less than 10%. The detection limits of the colorants were 0.2–0.8 μg/g. The analytical method using LC-MS established in this study is suitable for the detection of colorants in processed foods.
A simple method using HPLC and LC-MS/MS was developed for the determination of ultra-high-intensity sweetener, advantame, in processed foods. Advantame was extracted by dialysis, and cleaned up on a Sep-Pak Plus C18 cartridge, then determined by HPLC and LC-MS/MS. The recoveries from 5 kinds of processed foods fortified at the levels of 0.001 g/kg and 0.01 g/kg were 64.1–89.9% (RSD 0.9–6.9%) by HPLC and 68.8–99.9% (RSD 0.8–4.9%) by LC-MS/MS. The quantitation limit was 0.0004 g/kg by HPLC and 0.00004 g/kg by LC-MS/MS.
We performed a single-laboratory validation study of a simple and simultaneous determination method for pesticide residues in meat using LC-MS/MS. Water was added to the sample and the mixture was homogenized. Next, pesticides were extracted with acetonitrile containing 1 vol% formic acid using a homogenizer, and salted out with magnesium sulfate, trisodium citrate and sodium chloride. After centrifugation, the acetonitrile layer was made up to standard volume and analyzed by LC-MS/MS. This method was assessed by performing recovery tests in retail bovine, swine and chicken muscle samples spiked with the 132 pesticides at the levels of 0.01 and 0.04 μg/g. Among them, 125 pesticides satisfied the Japanese method validation guideline criteria in bovine, 120 in swine and 127 in chicken.
An improved method for analysis of Malachite green (MG) and its metabolite, Leucomalachite green (LMG), in broiled eels without using dichloromethane was developed. This method was evaluated by means of recovery tests according to the guideline for validation of analytical methods by the Ministry of Health, Labour and Welfare of Japan. MG and LMG were extracted from spiked samples with acetonitrile and citric acid/disodium hydrogen phosphate buffer solution, and were salted-out with sodium chloride. The acetonitrile layer was dried over anhydrous sodium sulfate and purified on C18 and strongly acidic cation exchange columns. MG and LMG in the purified solution were determined quantitatively using LC-MS/MS by the internal standard method with surrogates, MG and LMG labeled with deuterium (MG-d5, LMG-d6). The recovery rates of MG and LMG were 99.2% and 93.6%, respectively. The relative standard deviations of repeatability were 2.2% for MG and 4.4% for LMG, and the relative standard deviations of within-laboratory reproducibility were 3.5% for MG and 5.1% for LMG.