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Suzuki Y.,Japan National Food Research Institute | Isshiki M.,Food Agricultural Materials Inspection Center | Sato R.,SI Science CO. | Nakashita R.,Japan Forestry and Forest Products Research Institute
Bunseki Kagaku | Year: 2014

In previous studies, stable carbon, nitrogen and oxygen isotope analyses were probably a useful tool for tracing the geographical origin of processed eels. However, the lack of a reliable technique for isotope ratio measurements is significantly regrettable, and should be improved immediately. Here, we present results of an inter-laboratory test on the EA-IRMS determination of stable carbon, nitrogen and oxygen isotopic compositions (δ13C, δ15N and δ18O) in processed eel samples. The processed eel samples were distributed and analyzed by a total of 5 laboratories. The variations of the standard deviations for δ13C (- 18.7 ‰ ± 0.2 ‰) and δ15N (+13.4 %o ± 0.3 ‰) among laboratories were not very large compared to the instrument uncertainties. The δ18O values (+ 16.5 %o ± 3.1 ‰) in processed eel samples showed a large variation among laboratories. This may have been caused by much the contamination of N2 to the CO peak on the EA-IRMS chromatogram, and may be improved by using a longer GC column or Purge & trap columns for chromatographic separation. © 2014 The Japan Society for Analytical Chemistry. Source


Isshiki M.,Food Agricultural Materials Inspection Center | Nakamura S.,Food Agricultural Materials Inspection Center | Suzuki Y.,Japan National Agriculture and Food Research Organization
Nippon Shokuhin Kagaku Kogaku Kaishi | Year: 2015

Simultaneous multielement analysis in acacia honey samples was performed in order to determine their geographic origin. We investigated a total of 165 samples collected from two countries; 100 samples from Japan and 65 samples from China. Thirteen elements (Li, Mg, P, K, Ca, Mn, Fe, Rb, Sr, Y, Cd, Ba and La) were measured by inductively coupled plasma mass spectrometry (ICP-MS). Principal component analysis (PCA) of the obtained data revealed good separation between the Japanese and Chinese samples, and indicated the ability to distinguish between samples. Therefore, we performed two statistical analyses : support vector machine (SVM) and linear discriminant analysis (LDA), and compared their results. Consequently, the LDA model, using log10 ([Ca]/[P]), log10 ([Mn]/[P]), log10 ([Rb]/[P]), and log10 ([Sr]/[P]), where [E] is the concentration of element E, was selected as the most appropriate model. This model correctly predicted 97% of the Japanese samples and 100% of the Chinese samples. It was concluded that the simultaneous multielement analysis can be useful in discriminating the geographic origin of acacia honey. Copyright © 2015, Japanese Society for Food Science and Technology. Source


Isshiki M.,Food Agricultural Materials Inspection Center | Nakamura S.,Food Agricultural Materials Inspection Center | Takashima Y.,Food Agricultural Materials Inspection Center | Terada S.,Food Agricultural Materials Inspection Center | Suzuki Y.,Japan National Agriculture and Food Research Organization
Nippon Shokuhin Kagaku Kogaku Kaishi | Year: 2014

Stable isotope analysis of carbon, nitrogen, and oxygen ( 13C/12C, 15N/14N and 18O/16O) was evaluated as a potential tool for discriminating the geographical origin of eel products. We investigated a total of 244 samples collected from two countries; 139 samples from Japan and 105 samples from China. We also developed method to minimize N2 contamination of 18O/16O measurements, and confirmed the absence of oxygen-exchange during ultrasonic cleaning of the samples. The isotope ratios of carbon, nitrogen, and oxygen were significantly different between the Japanese and Chinese samples. The difference in the isotope ratio between collection years (i.e., 2010 and 2011) was significant for carbon and nitrogen, but negligible for oxygen. Based on these results, we established a linear discriminant model and tested its predictive accuracy by leave-one-out cross validation. Consequently, 97.8% of the Japanese samples and 83.8% of the Chinese samples were correctly identified. We concluded that stable isotope analysis is useful for discriminating the geographic origin of eel products. © 2014, Japanese Society for Food Science and Technology. Source

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