장혜미 (한국기초과학지원연구원)

장경순 (한국기초과학지원연구원)

장혜미 (한국기초과학지원연구원)

장경순 (한국기초과학지원연구원)

Onions (Allium cepa) are widely cultivated in South Korea, yet comprehensive region-specific chemical characterization remains limited. This study employed untargeted metabolomic profiling using UPLC-TIMS-QTOF MS to analyze ethanol extracts from onions collected across 56 locations nationwide. A total of 2,339 (positive mode) and 1,350 (negative mode) molecular features were detected, with only 242 compounds annotated through spectral matching. To improve coverage, accurate mass-based molecular formula prediction yielded 1,992 unique formulas, enabling molecular index analysis. Unsupervised K-means clustering of annotated compounds and molecular formulas consistently separated samples into two chemotypic groups: Central-Southwestern (CSW) and Southeastern (SE).

SE onions exhibited elevated H/C ratios and were enriched in lipid-like molecules, especially linoleic acid derivatives, likely reflecting adaptive responses to high humidity, solar irradiance, and mineral-rich volcanic soils. In contrast, CSW onions had higher modified aromaticity index (AI_mod) and double bond equivalent (DBE) values and contained abundant indole derivatives and other organoheterocyclic compounds, shaped by stable inland climates and nutrient-rich loamy soils. The functional network analysis confirmed the region-specific enrichment of antioxidant, anti-inflammatory, and cardioprotective metabolites. Despite regional divergence, CSW and SE onions both shared abundant phenolics, notably quercetin and kaempferol glycosides, indicating strong nutraceutical potential.

These findings highlight agro-environmental influences on onion metabolomes and support metabolomic fingerprinting for origin authentication and cultivar development. Future studies combining transcriptomics, soil analysis, and broader extraction methods will clarify regional phytochemical variation.