Kobayashi Kazuhiro, Tanaka Masaharu, Yatsukawa Yoichi, Tanabe Soichi, Tanaka Mitsuru, Ohkouchi Naohiko
Global Food Safety Institute, Nissin Foods Holdings Co., Ltd.
Global Innovation Research Center, Nissin Foods Holdings Co., Ltd.
Anal Sci. 2018;34(5):571-574. doi: 10.2116/analsci.17P450.
Recent growing health awareness is leading to increasingly conscious decisions by consumers regarding the production and traceability of food. Stable isotopic compositions provide useful information for tracing the origin of foodstuffs and processes of food production. Plants exhibit different ratios of stable carbon isotopes (δC) because they utilized different photosynthetic (carbon fixation) pathways and grow in various environments. The origins of glutamic acid in foodstuffs can be differentiated on the basis of these photosynthetic characteristics. Here, we have developed a method to isolate glutamic acid in foodstuffs for determining the δC value by elemental analyzer-isotope-ratio mass spectrometry (EA/IRMS) without unintended isotopic fractionation. Briefly, following acid-hydrolysis, samples were defatted and passed through activated carbon and a cation-exchange column. Then, glutamic acid was isolated using preparative HPLC. This method is applicable to measuring, with a low standard deviation, the δC values of glutamic acid from foodstuffs derived from C3 and C4 plants and marine algae.
近期，消费者对健康的关注度不断提高，这使得他们在食品生产和可追溯性方面做出了越来越谨慎的决策。稳定同位素组成可为追溯食品来源和食品生产过程提供有用信息。植物呈现出不同的稳定碳同位素比率（δC），因为它们利用不同的光合（碳固定）途径并生长在各种环境中。基于这些光合特性，可以区分食品中谷氨酸的来源。在此，我们开发了一种从食品中分离谷氨酸的方法，以便通过元素分析仪 - 同位素比率质谱仪（EA/IRMS）测定δC值，且不会产生意外的同位素分馏。简而言之，经过酸水解后，样品进行脱脂处理，然后通过活性炭和阳离子交换柱。接着，使用制备型高效液相色谱法分离谷氨酸。该方法适用于以低标准偏差测量来自C3和C4植物以及海藻的食品中谷氨酸的δC值。
