Jeong Ji Young, Bae Minseo, Kim Min Ji, Jang Ha-Young, Jung Sera, Lee Jong-Hee, Hwang In Min
Fermentation Regulation Research Group, World Institute of Kimchi, Gwangju 61755, Republic of Korea.
ACS Omega. 2023 Jan 17;8(4):3896-3904. doi: 10.1021/acsomega.2c06303. eCollection 2023 Jan 31.
Kimchi is a traditional Korean salted spontaneous lactic acid bacteria (LAB)-fermented food made using various vegetables. Organic acids, free sugars, and amino acids are key metabolites produced during LAB fermentation that determine the taste and quality of kimchi. However, each metabolite is typically analyzed using an independent analytical method, which is time-consuming and expensive. Therefore, in this study, we developed a method based on LC-Q-Orbitrap MS using which 20 types of representative fermented kimchi metabolites were selected and simultaneously analyzed within 10 min. The established method was validated, and its detection and quantification limits, linearity, precision, and accuracy were found to satisfy the Association of Official Agricultural Chemists (AOAC) validation guidelines. The 20 metabolites were simultaneously extracted from kimchi with different degrees of fermentation and quantitatively analyzed using LC-Q-Orbitrap MS. These results were analyzed using linear discriminant analysis and heat mapping, and the metabolites were grouped into early, middle, and late stages of fermentation. Malic acid (6.518-7.701 mMol) was only present in the initial stage of fermentation, and l-phenylalanine rapidly increased from the middle stage (2.180 mMol) to late stage (4.770 mMol). Lactic acid, which is representative of the sour taste of kimchi, was detected in the middle stage and increased rapidly up to 74.452 mMol in the late stage. In summary, in this study, 20 major kimchi metabolites were accurately analyzed within 10 min and grouped based on the degree of fermentation. Therefore, the method established in this study accurately and rapidly provides information on kimchi consumption and fermentation that could be highly valuable to the kimchi industry and kimchi consumers.
泡菜是一种传统的韩国腌制食品，由各种蔬菜经自然乳酸菌发酵制成。有机酸、游离糖和氨基酸是乳酸菌发酵过程中产生的关键代谢产物，它们决定了泡菜的味道和品质。然而，每种代谢产物通常使用独立的分析方法进行分析，这既耗时又昂贵。因此，在本研究中，我们开发了一种基于液相色谱-四极杆-轨道阱质谱联用仪（LC-Q-Orbitrap MS）的方法，利用该方法可以在10分钟内同时分析20种具有代表性的发酵泡菜代谢产物。对所建立的方法进行了验证，发现其检测限、定量限、线性、精密度和准确度均符合美国官方农业化学家协会（AOAC）的验证指南。从不同发酵程度的泡菜中同时提取这20种代谢产物，并使用LC-Q-Orbitrap MS进行定量分析。利用线性判别分析和热图对这些结果进行分析，将代谢产物分为发酵早期、中期和后期。苹果酸（6.518 - 7.701毫摩尔）仅存在于发酵初期，L-苯丙氨酸从中期（2.180毫摩尔）到后期（4.770毫摩尔）迅速增加。代表泡菜酸味的乳酸在中期被检测到，并在后期迅速增加至74.452毫摩尔。总之，在本研究中，20种主要的泡菜代谢产物在10分钟内被准确分析，并根据发酵程度进行了分组。因此，本研究建立的方法准确、快速地提供了有关泡菜消费和发酵的信息，这对泡菜产业和泡菜消费者可能具有很高的价值。
