## 3 Results
### GC-IMS Analysis
#### 3.1.3 Multivariate Statistical Analysis
Among the yellow horn seed oil, three ester compounds with OVAs \(\geq\) 1 were identified, including butyl acetate (ethereal, solvent, fruity, and banana), ethyl 2-methylbutyrate (fruity) and isoamyl acetate (sweet, fruity, banana, and solvent). Combined with olfactory analysis, it was determined that fruity aromas are distinctly detectable during their peak period. Pyrazines: With increasing roasting temperature, the content of pyrazine compounds in yellow horn seed oil VOCs significantly changed (\(p\) < 0.05), reaching a peak (4.76 mg/kg) in the sample roasted at 160 \({}^{\circ}\)C. The VOCs with OAVs \(\geq\) 1 contributed significantly to food aroma distribution. Seven Pyrazine compounds with OAVs \(\geq\) 1 were screened from the yellow horn seed oil, including 2,5-dimethylpyrazine (roasted, nutty, popcorn), 2-mthhyl-6-methylpyrazine (roasted, baked potato), 2,3,5-trimethylpyrazine (roasted, nutty), 3-ethyl-2,5-dimethylpyrazine (roasted, nutty), 2-ethyl-3,5-dimethylpyrazine (nutty, roasted, sweet), 2,6-diethylpyrazine (roasted, nutty, sweet), and 2,3-diethyl-5-methylpyrazine (raw peanut, potato). 2, 6-diethylpyrazine, an important product of the Maillard reaction [51], has been identified as a key aroma compound in sesame oil [11] and virgin rapeseed oil [52], providing nutty and toasty profiles. The results suggest that the presence of these aroma compounds contributes to the development of a nuanced roasted and nutty aroma in yellow horn seed oil. Ketones: Ketones are typically generated through amino acid decomposition and the thermal oxidative degradation of polyunsaturated fatty acids [14]. Ketones with carbon numbers below seven were VOCs derived from lipids, contribute to fatty, herbal, flowery, and sweet aromas in samples [53]. The contents of ketones were the highest in the 160 \({}^{\circ}\)C sample (1.0949 mg/kg) in the aroma assay of the yellow horn seed oil roasted at different temperatures. There were three aroma substances with OAVs \(\geq\) 1, including acetoin (sweet, buttery, and creamy), 4-hydroxy-2, 5-dimethyl-3 (2H) -furanone (sweet, soap, and bread), and 2-decanone (soap). Acetoin, as a short-chain ketone, could be derived from pyruvate conversion and citrate metabolism and/or conversion of diacetyl by diacetyl reductase enzyme [54]. Meanwhile, [PERSON] et al. [12] confirmed that acetoin was a key aroma compound, providing a buttery odor to camellia seed oil. 4-hydroxy-2, 5-dimethyl-3 (2H)-furanone was a product of the Maillard reaction [55], providing fruitiness and sweetness profiles to yellow horn seed oil. 2-decanone possesses a soap aroma in yellow horn seed oil, mainly formed from the degradation of linoleic acid [56]. Hydrocarbons: Hydrocarbons were mainly derived from the decomposition of fatty acids alkoxy groups [14]. The total hydrocarbon content was the highest in the 160 \({}^{\circ}\)C sample, with a content of 1.7149 mg/kg in yellow horn seed oil. The OAVs of the unsaturated and saturated hydrocarbons in yellow horn seed oil are mostly low due to their high odor threshold, which limits their contribution to food aroma. Only the OAV (3.64) of styrene (sweet, balsamic, floral, and plastic) exceeds 1 in the 120 \({}^{\circ}\)C sample, imparting an herbal and citrus aroma to the oil.