According to Japanese food allergen labeling regulations, an ELISA screening test is used for detection of crustacean proteins in food and a shrimp/crab-PCR confirmation test is used to confirm a positive ELISA screening test and to exclude false positives. Forty-six kinds of processed foods labeled as containing shrimp/crab were subjected to ELISA screening test and PCR confirmation test and the usefulness of the shrimp/crab-PCR was evaluated. Twenty-seven of the 46 samples contained total crustacean protein levels of 10 ppm or more in the ELISA screening test. All of the samples were positive in the shrimp/crab-PCR confirmation test. The results of the confirmation test were consistent with the declaration in the list of ingredients and with the results of the ELISA screening test. The shrimp/crab-PCR confirmation test was demonstrated to be applicable to various kinds of foods, including powder, extract, seasoning paste, prepared frozen food, snack food, retort food and canned food.
A simple and rapid dialysis method was developed for the extraction and purification of four artificial sweeteners, namely, sodium saccharin (Sa), acesulfame potassium (AK), aspartame (APM), and dulcin (Du), which are present in various foods. Conventional dialysis uses a membrane dialysis tube approximately 15 cm in length and is carried out over many hours owing to the small membrane area and owing to inefficient mixing. In particular, processed cereal products such as cookies required treatment for 48 hours to obtain satisfactory recovery of the compounds. By increasing the tube length to 55 cm and introducing efficient mixing by inversion at half-hour intervals, the dialysis times of the four artificial sweeteners, spiked at 0.1 g/kg in the cookie, were shortened to 4 hours. Recovery yields of 88.9–103.2% were obtained by using the improved method, whereas recovery yields were low (65.5–82.0%) by the conventional method. Recovery yields (%) of Sa, AK, APM, and Du, spiked at 0.1 g/kg in various foods, were 91.6–100.1, 93.9–100.1, 86.7–100.0 and 88.7–104.7 using the improved method.
We developed a method for simultaneous analysis of nine trichothecenes (nivalenol, deoxynivalenol, fusarenon-X, neosolaniol, 3-acetyldeoxynivalenol, 15-acetyldeoxynivalenol, diacetoxyscirpenol, HT-2 toxin, and T-2 toxin). Trichothecenes in samples were extracted with acetonitrile–water (1 : 1) and purified using a QuEChERS kit and a multi-functional cartridge. Then they were quantified by LC-MS/MS using internal standards. LC with a pentafluorophenyl column and a mobile phase containing methanol enabled complete separation and highly sensitive quantification of the nine trichothecenes. Method validation with powdered corn soup samples demonstrated high linearity (>0.99) and accuracy ranging from 95% to 111% with good repeatability of 0.9% to 6.6% and reproducibility of 0.6% to 11.6%. The limits of detection and quantification were 0.01 to 0.75 μg/kg and 0.04 to 2.50 μg/kg, respectively. When 15 samples from powdered corn soups on the market were analyzed with this method, deoxynivalenol was detected in two samples (20.7 and 22.5 μg/kg, respectively), and 3-acetyldeoxynivalenol was concomitantly detected in one of them (13.5 μg/kg).
To improve the efficiency of DNA analysis of foods and agricultural products, we investigated a direct real-time PCR based on the real-time monitoring of DNA amplification directly from crude cell lysates of analytical samples. We established a direct real-time PCR system comprising sample pretreatment with a specified lysis buffer and real-time PCR using the developed master mix reagent. No PCR inhibition was observed in the analysis of crude cell lysates from 50 types of samples, indicating that the direct real-time PCR system is applicable to a wide range of materials. The specificity of the direct real-time PCR was evaluated by means of a model assay system for single nucleotide discrimination. Even when crude cell lysates coexisted in the reaction mixtures, the primer selectivity was not affected, suggesting that the sequence specificity of the direct real-time PCR was equivalent to that of PCR from purified DNA templates. We evaluated the sensitivity and quantitative performance of the direct real-time PCR using soybean flour samples including various amounts of genetically modified organisms. The results clearly showed that the direct real-time PCR system provides sensitive detection and precise quantitation.
We developed a method for the identification of 18 illegal adulterants in dietary supplements for erectile dysfunction by using high-performance liquid chromatography-mass spectrometry. The separation was achieved on a Cosmosil 3C18-EB column. The mobile phase consisted of 0.1% formic acid solution and 0.1% formic acid in acetonitrile, with gradient elution at a flow rate of 0.15 mL/min. The proposed method may be useful for the identification of illegal adulterants and for quality control of dietary supplements.
We have carried out a study (2009–2012) on processed seafood products in order to determine the level of contamination with shrimp and crab. In 2010–2012, after the Allergy Labeling Regulation went into effect, the detection rate of crustacean protein in processed seafood products including small fish, such as niboshi, tukudani and so on (both boiled and dried), was 63%. Detection rates for processed seafood products in which crustacean protein levels were below 1 μg/g were 36% with and 58% without advisory labels, allowing us to conclude that 60% of labels were adequate. On the other hand, the detection rate for processed seafood products with crustacean protein levels higher than the baseline of 10 μg/g was 9%, of which 60% carried no advisory labels. The rate of shrimp DNA detection using the Akiami primer in processed foods containing shrimp and crab was high (73%). This suggests that it is necessary to test these products using the Akiami primer for supplemental analyses of shrimp DNA. The PCR analysis for crab DNA detection failed due to combined detection of mantis shrimp DNA, which accounted for 8% of the total detected.
In the present study, we reviewed food poisoning data published by the Ministry of Health, Labour and Welfare of Japan from 1961 to 2010 in Japan to analyze the trends of plant toxin food poisonings (PTFPs). The annual number of incidents of PTFPs has gradually increased since 1995. PTFPs were predominantly caused by Datura spp., Veratrum spp. and Aconitum spp. Although PTFPs frequently occurred in April and May, poisonings caused by some plants occurred in all seasons, e.g. Datura spp. The major location of PTFPs was “at home”, and most of the patients had accidentally harvested poisonous plants. During the past decade, the numbers of incidents of PTFPs caused by Veratrum spp., Narcissus spp., Solanum tuberosum and Alocasia odora were especially increased. Consumer advice to prevent PTFPs associated with certain plants that are cultivated in gardens and contain toxic substances is needed, because PTFPs caused by such plants are increasing. In addition, education of elementary school teachers and children about the potential risks of natural toxins in plants, particularly Solanum tuberosum, is desirable.