Comparison of extraction and refinement techniques for volatile compound analysis in camellia oil

The processing techniques of camellia oil, containing freshly squeezed (FSCO), refined (DFCO), cold-pressed (OFCO), and hot-pressed (RFCO), significantly influence flavor compounds and organoleptic properties. In this study, the preference for FSCO and RFCO was revealed by sensory evaluation due to the "fruity" and "roasted" flavors, respectively. Flavor differences among oils were accurately distinguished by the E-nose. A total of 77 and 116 odorants were identified by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and gas chromatography-mass spectrometry (GC-MS), respectively. The gas chromatography-olfactometry (GC-O) and detection frequency analysis identified 34 active-aroma compounds with DF ≥ 2. Aroma recombination and omission experiments further confirmed that (E)-2-nonenal and nonanal, derived from the degradation of unsaturated fatty acids, significantly contributed to "green" and "fruity" aromas. Notably, these concentrations positively correlated with sensory preference. This study provides valuable insights into the flavor identification of camellia oil and the improvement of processing techniques.