The biochemical and antioxidant capacities comparative analysis of pre- and post-processing traditional Chinese garlic products by metabolomics

Fresh garlic (FG) is prized for its unique taste and rich bioactivity, which has led to the development of various traditional Chinese garlic products, including sweet garlic (SG), Laba garlic (LG), and black garlic (BG). This study compared the nutrient composition, allicin content, metabolomics, and antioxidant capacities of SG, LG, and BG with FG that employed the ultra-high performance liquid chromatography and quadrupole-time-of-flight mass spectrometry (UHPLC Q-TOF MS) and utilized high-throughput non-targeted metabolomics techniques. The results found that significant changes in nutritional components such as protein, fat, and total sugar occurred after the processing of garlic products. Principal component analysis (PCA) distinguished the metabolites of FG, SG, LG, and BG, indicating that processing methods significantly alter garlic compounds. There were also significant differences in sulfur-containing characteristic compounds such as gamma-L-Glutamyl-S-(2-carboxy-1-propyl)cysteinylglycine, N-γ-Glutamyl-S-allylcysteine, and S-Methyl-L-cysteine, as well as polyphenolic compounds like L-(−)-3-phenyllactic acid, naringenin chalcone, and kaempferol 3,7-diglucoside before and after garlic product processing. Notably, BG processing eliminated garlic's pungency and enhanced its antioxidant capacity. Random forest models and correlation analysis identified mulberrin, l-(−)-3-phenyllactic acid, and sn-glycerol 3-phosphate as key contributors to antioxidant activity. The study highlighted that traditional processing changed garlic's metabolism and physiological function, providing valuable data for the comprehensive utilization and development of the garlic industry chain. The enhanced antioxidant capacity of BG suggests potential applications in antioxidant therapy and the treatment of age-related diseases. It is recommended that further research should explore the potential health benefits of processed garlic products, especially BG.