Characterization of key aroma-active compounds in onion seasoning oil via sensory-directed flavor analysis and gas chromatography‑sulfur chemiluminescence detection

Onion seasoning oil produced by oil immersion is valued for its distinctive aroma and nutritional benefits, yet its key aroma compounds remain insufficiently characterized. Based on a strategy of combined molecular sensory science and gas chromatography‑sulfur chemiluminescence detection (GC-SCD) analysis, a total of 50 volatile aroma compounds were identified. Flavor dilution (FD) analysis highlighted 12 potent odorants, including dipropyl disulfide (FD up to 1024). Notably, 3-mercapto-2-methylpentan-1-ol, a potent odorant with a low mass spectrometry response, was identified and quantified via GC-SCD. Despite its trace concentration, it was the most significant contributor, exhibiting the highest odor activity value (OAV) of 677–989. Aroma omission tests confirmed the indispensable roles of both 3-mercapto-2-methylpentan-1-ol and dipropyl disulfide. The multi-instrument joint validation strategy provides an effective method for locating key aroma compounds in vegetable oil. These findings also provide a scientific foundation for optimizing production to enhance the quality of onion seasoning oil.