Qualitative Analysis of Chemical Composition Changes Before and After Lactobacillus Fermented Ziziphi Spinosae Semen by LC‐MS and Prediction of Fermentation Mechanism

This study aimed to screen dominant Lactobacillus strains for fermenting Ziziphi Spinosae Semen (ZSS), analyze chemical composition changes before and after fermentation, and speculate on the fermentation mechanism. Liquid fermentation of ZSS was conducted using Lactobacillus plantarum, Lactobacillus paracasei, Lactobacillus acidophilus, and Lactobacillus rhamnosus. HPLC was employed to determine the content of spinosin, 6'''-feruloylspinosin, jujuboside A, and jujuboside B. Total phenolic content (TPC), total flavonoid content (TFC), and antioxidant capacity were measured using UV spectrophotometry. Principal component analysis (PCA) was employed to identify the optimal fermentation strain, and UPLC-Q-Exactive Orbitrap-MS technology was used for qualitative analysis of chemical components before and after fermentation. Results indicated L. plantarum as the optimal fermentation strain. UPLC-Q-Exactive Orbitrap-MS analysis revealed 41 chemical components in the unfermented sample, reduced to 30 post-fermentation. L. plantarum was hypothesized to catalyze enzymatic hydrolysis breaking C─O bonds, N─C bonds, acyl groups, and glucosyl groups, facilitating interconversion among compounds.