## 3 Results and Discussion
### Comparison of Volatile Compounds  
The volatile compounds, a key sensory characteristic that varies across different types of camellia oil, were detected and identified. The analysis results revealed the presence of 157 volatile compounds in various types of camellia oil, including C.O, C.S, C.G, C-C.O, C-C.O-DAG (40%), and C-C-O-DAG (80%) (Table S1). Among these, C.O primarily contained six volatile compounds, namely octane (1.85 mg/kg), nonanal (1.77 mg/kg), benzene acetaldehyde (1.23 mg/kg), 1-butanol (1.17 mg/kg), hexanal (1.11 mg/kg), and ethyl tiglate (1.06 mg/kg). Conversely, C.S was characterized by acetic acid (4.48 mg/kg), 2,3-butanediol (1.16 mg/kg), and hexanal (1.07 mg/kg) as its main components. Furthermore, ethanol (6.59 mg/kg), acetic acid (2.52 mg/kg), heptanal (1.41 mg/kg), 1-butanol (1.36 mg/kg), butanoic acid (1.29 mg/kg), D-limonene (1.11 mg/kg), and ethyl acetate (1.03 mg/kg) were identified as the major volatile compounds in C.G. In addition, different volatile composition profiles were observed between refined camellia oil (C-C.O) and cold-pressed camellia oils (C.O, C.S, and C.G), indicating that refining processes, such as degumming, neutralization, bleaching, and deodorization, substantially alter the odor profile of camellia oils [16]. Volatile compounds formed during refining are typically the result of thermal degradation and oxidation. For instance, alcohols, aldehydes, ketones, and other oxidation products are generated due to the exposure of camellia oil to high temperatures and the removal of natural antioxidants [53]. Specifically, volatile compounds, such as 1-penten-3-ol (0.04 mg/kg), 4-hydroxy-3-hexanone (0.02 mg/kg), 1,2-ethanediol (0.02 mg/kg), 1,4-butanediol (0.01 mg/kg), 3-heptanone (0.35 mg/kg), 1-pentanone (0.05 mg/kg), and 1-hydroxy-2-butanone (0.03 mg/kg), were found in refined camellia oil (C-C.O) but were not detected in cold-pressed camellia oils  
Figure 5: Cluster heat map of bioactive components of different types of camellia oils. C.O, _C. oleifera_; C.S, _C. semiserata_); C.G, _C. gauchounensis_; C-C.O, commercial _C. oleifera_; C-C.O-DAG (40%), commercial _C. oleifera_ diacylglycerol oil (40%); and C-C.O-DAG (80%), commercial _C. oleifera_ diacylglycerol oil (80%). (C.O, C.S, and C.G) (Table S1). The refining process, particularly the deodorization step, can remove both useful and undesirable volatiles, resulting in a more neutral sensory profile compared to cold-pressed oils [16; 53]. Notably, DAG-enriched camellia oils exhibited distinct volatile compound profiles, showcasing higher levels of ethanol (0.87-1.16 mg/kg) and octane (0.57-0.65 mg/kg), while having lower levels of 3-heptanone (not detected) and toluene (0.04-0.05 mg/kg) compared to C-C.O, which had levels of 0.11 mg/kg, 0.02 mg/kg, 0.35 mg/kg, and 0.37 mg/kg, respectively. These differences suggested that both the varieties of camellia oils and the technique of the DAG-enriched process significantly impact the volatile compounds of camellia oil [16; 31]. The volatile compounds present in different types of camellia oils, encompassing a range of organic compounds, including alcohols (25), acids (12), esters (16), aldehydes (16), ketones (14), aromatic (4), hydrocarbons (20), and other categories (5), are illustrated in Figure 6. Significant disparities in the volatile compound composition were observed among the different camellia oil samples. Notably, C.G exhibited markedly higher levels of alcohols (9.99 mg/kg) compared to C.O (3.20 mg/kg) and C.S (3.30 mg/kg), while C.S showcased elevated concentrations of acids (5.60 mg/kg), likely attributable to genetic variations and the growth environments among camellia oil varieties [54]. Furthermore, esters were found to have relatively low concentrations across most samples, with C.G displaying slightly higher levels. The presence of aromatics remained relatively consistent across C.O, C.S, and C.G, with minimal variation noted.