In this study, we examined 78 powdered spice products for wheat contamination, using enzyme-linked immunosorbent assay (ELISA) to detect wheat proteins and polymerase chain reaction (PCR) to detect wheat DNA, as notified by the Japanese Ministry of Health, Labour and Welfare. Wheat protein was detected in 22 of the 78 samples, and wheat DNA was detected in 2 of these 22 samples. In addition, to ascertain the influence of PCR inhibitors, we screened the 22 samples for plant DNA. Plant DNA was not detected in 11 of the 22 samples. Therefore, we assumed that polysaccharides and/or phenolic compounds in the spice samples were responsible for inhibiting the PCR amplifications. Subsequently, using a modified PCR procedure, Ampdirect® plus, plant DNA was detected in all 22 samples, while wheat DNA was detected in 15 samples. These results suggest that commercial powdered spice products are contaminated with wheat. Ampdirect® plus can overcome the probable PCR inhibition, which is caused by the presence of other contaminants in the extracted DNA solution, and can easily be applied in food testing. Therefore, this method can be used to detect the presence of wheat and other allergens in processed food.

View full abstract

A simple, rapid, and precise method for the determination of cyclopiazonic acid (CPA) in liquid seasoning was developed, which uses liquid chromatography with ultraviolet and photodiode array detection LC/UV(PDA) and liquid chromatography with time-of-flight mass spectrometry (LC/TOF-MS). CPA in liquid seasoning was subjected to ethyl acetate extraction, and solid-phase extraction using Oasis® HLB. LC/UV(PDA) was used for qualitative and quantitative analysis, and LC/TOF-MS was used as the confirmatory method. The limit of detection (S/N = 3) and the limit of quantification (S/N > 10) of CPA in LC/UV(PDA) were 0.01 μg/mL and 0.03 μg/mL, respectively. Standard materials were prepared for quality control samples (a low concentration of 0.2 μg/mL and a high concentration of 2.0 μg/mL), and internal quality control was performed. As a result, the trueness of the low concentration sample and the high concentration samples was 80.3% and 81.6%, respectively. The relative standard deviation (RSD) of repeatability was 5.3% or less, whereas that of intermediate precision was less than 10.1%. The results suggest that the developed method is useful for the determination of CPA in liquid seasoning.

View full abstract

2-(5-Benzyl-3,6-dioxopiperazin-2-yl)acetic acid (DKP) is one of the degradation products of aspartame (APM). The Joint FAO/WHO Expert Committee on Food Additives (JECFA), USA, EU, and Japan has set 1.5 wt% as the maximum level of DKP in APM. In this study, we developed and validated a high-performance liquid chromatography (HPLC) method to determine the content of DKP in APM, based on the approach recommended in the Food Chemical Codex (FCC) from USA. For the separation of analyte, the column was investigated with 5 and 10 μm particle size. In the recovery test, the developed method gave satisfactory recoveries (99.1% and 99.5%) and repeatabilities (0.4%) from APM spiked with two concentrations (viz. 0.15 and 1.5 wt%). The limits of detection and quantification for DKP are estimated to be 0.0005 and 0.002 wt%, respectively. In the analyses of ten commercial APM samples, the DKP contents determined using the developed method are all in good agreement with those obtained using the conventional FCC method. This developed method is therefore applicable for the determination of DKP contents in commercial-grade APM.

View full abstract

The effect of mung bean tripsin inhibitor (MBTI) on "himodori" kamaboko was analyzed by rheological and histological methods. Normal and himodori kamaboko were prepared from surimi of lizardfish (Saurida wanieso) by two step heating: preheating at 40℃ for 30, 120 min (normal) or 60℃ for 30, 60, 90, 120 min (himodori), and then 90℃ for 30 min. MBTI and E-64 were added in surimi before heating, respectively. Decreased breaking strength caused by himodori was improved by the addition of MBTI or E-64 even in long preheating time. Although himodori kamaboko showed the disturbed structure, its structure was recovered by treatment with MBTI at intermediate structural levels between normal and himodori kamaboko in light microscope. The electron micrographs showed an equal distribution of black and gray areas in the normal kamaboko. Although the addition of E-64 showed particle aggregation and unstained area as found in himodori kamaboko, MBTI failed to detect these phenomena. These results suggest that the addition of MBTI during making procedure may inhibit himodori occurrence.

View full abstract

Daily intakes of food additives such as colors, preservatives, sweeteners and food manufacturing agents for children (1-6 years) in Japan were estimated using market basket method. A list of daily consumption of processed foods was prepared based on the National Nutrition Survey (2001-2002) and National Health and Nutrition Survey (2003). The food additives with the highest daily intake was orthophosphoric acid (9.4 mg/kg bw/day, expressed as phosphorus), followed by condensed phosphoric acid (0.76 mg/kg bw/day, expressed as phosphorus), and propylene glycol (0.47 mg/kg bw/day). Acceptable daily intake (ADI) and maximum tolerable daily intake (MTDI) set by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) or Food Safety Commission of Japan were compared with the estimated daily intake of food additives in children. The ratio to ADI of the colors, preservatives, sweeteners and propylene glycol were 0〜1.9%. The ratio to the MTDI of phosphorus compounds was 15%.

View full abstract

Daily intakes of food additives such as colors, preservatives, sweeteners and food manufacturing agents for children (1-6 years) in Japan were estimated using market basket method in 2014. A list of daily consumption of processed foods was prepared based on the special survey study (2011). The food additives with the highest daily intake was orthophosphoric acid (11 mg/kg bw/day, expressed as phosphorus), followed by condensed phosphoric acid (1.0 mg/kg bw/day, expressed as phosphorus), and propylene glycol (0.73 mg/kg bw/day). The estimated daily intake of food additives in children was compared with acceptable daily intake (ADI) and maximum tolerable daily intake (MTDI) set by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) or Food Safety Commission of Japan. The ratio of the estimated daily intake to ADI for the colors, preservatives, sweeteners and propylene glycol were 0-2.9%. The ratio to the estimated daily intake to MTDI for phosphorus compounds was 18%.

View full abstract

Total plate count, Escherichia coli or coliform bacteria on the surface of dried horse mackerel produced by cold-air or hot-air drying were tested. These organisms on the surface of dried-horse mackerel available on the market were considerably more than those of the fish produced by cold-air or hot-air drying. Twenty minutes soak in 1%NaCl and reduction of water activity by cold-air drying of the fish contributed to repress these bacteria. These results suggested that a strict hygienic management in preservation, transport and over-the-counter is required.

View full abstract

In order to evaluate the applicability of combustion method to the measurement of maturity index of cheese, the method was compared with the Kjeldahl method that had been applied to the test. Soluble and total nitrogen content in seven kinds of cheeses with different maturity and physical property were determined by each method. The resulting nitrogen content and maturity index calculated from the both content of nitrogen were analyzed statistically. Repeatability and intermediate precision of soluble nitrogen by the combustion method are somewhat lower those of Kjeldahl method. Significant differences (P < 0.05) were observed between mean values of soluble nitrogen content by the two methods in some samples. However, the maturity indexes of each method agreed well in all samples, and the coefficient of correlation between the indexes by the two methods was over 0.999, suggesting that the combustion method is applicable to the measurement of maturity index of cheese as an alternative to Kjeldahl method.

View full abstract