Carboxyl-containing components delineation via feature-based molecular networking: A key to processing conditions of...

Carboxyl-containing components (CCCs) was the key chemical markers for fermented soybean, whose composition and content would be dramatically changed during the fermentation processes. To select the optimal fermented conditions, a rapid and sensitive 5-(diisopropylamino)amylamine derivatization, ultra-high performance liquid chromatography-quadrupole-time-of-flight/mass spectrometry and feature-based molecular networking method was established for determination CCCs and the developed method was successfully applied to compare the dynamic changes of CCCs under different processing conditions. A total of 120 components were identified, the optimum fermentation conditions were the temperature at 30 °C, 50% humidity, with a 2-hour steaming time. Sixteen chemical markers with significant differences were screened. Furthermore, molecular docking technology was used to verify the antiperoxidative effect of these chemical markers. Accordingly, we focused on the high-content, little-studied active CCCs rather than the low-content and well-studied flavonoids. This study was helpful for the nutraceutical development and contributed scientific basis to further exploring quality evaluation of fermented food.