Distinguishing glutamic acid in foodstuffs and monosodium glutamate used as seasoning by stable carbon and nitrogen isotope ratios
Kazuhiro Kobayashi,
Masaharu Tanaka,
Soichi Tanabe,
Yoichi Yatsukawa,
Mitsuru Tanaka,
Takuya Suzuki
Affiliations
Kazuhiro Kobayashi
Global Food Safety Institute, Nissin Foods Holdings Co., Ltd., 2100 Tobuki-machi, Hachioji, Tokyo 192-0001, Japan; Corresponding author.
Masaharu Tanaka
Global Food Safety Institute, Nissin Foods Holdings Co., Ltd., 2100 Tobuki-machi, Hachioji, Tokyo 192-0001, Japan
Soichi Tanabe
Global Innovation Research Center, Nissin Foods Holdings Co., Ltd., 2100 Tobuki-machi, Hachioji, Tokyo 192-0001, Japan
Yoichi Yatsukawa
Global Food Safety Institute, Nissin Foods Holdings Co., Ltd., 2100 Tobuki-machi, Hachioji, Tokyo 192-0001, Japan
Mitsuru Tanaka
Global Food Safety Institute, Nissin Foods Holdings Co., Ltd., 2100 Tobuki-machi, Hachioji, Tokyo 192-0001, Japan; Global Innovation Research Center, Nissin Foods Holdings Co., Ltd., 2100 Tobuki-machi, Hachioji, Tokyo 192-0001, Japan
Takuya Suzuki
Graduate School of Biosphere Science, Hiroshima Univ. Kagamiyama, Higashihiroshima, Hiroshima 739-8528, Japan
Recently, a number of consumers have begun to appreciate more natural ingredients and have become less willing to consume monosodium glutamate (MSG) as a seasoning. By measuring stable isotope ratios (δ13C and δ15N) of glutamic acid contained in foodstuffs and MSG used as seasoning, we attempted to distinguish between both using elemental analyzer-isotope-ratio mass spectrometry (EA/IRMS) and gas chromatography/combustion/IRMS (GC/C/IRMS). As a result, seasoning MSG was observed to have a lower δ15N value than glutamic acid in foodstuffs. We statistically analyzed the stable isotope ratio data using canonical discriminant analysis, thereby differentiating seasoning MSG from foodstuff-derived glutamic acid at an accuracy of 96.7%. This method is effective for distinguishing glutamic acid in foodstuffs from seasoning MSG.
