A Comprehensive Study of Pomegranate Seed Oil Bioactive Content: Assessing the Impact of Drying on Its Quality...

This study focused on the characterization of the bioactive composition of pomegranate seed oil (PSO) and the evaluation of freeze, microwave, and convective drying (CD) on its chemical profile, oil yield, and antioxidant activity (AA). PSO characterization primarily included the determination of bioactive and fatty acid profiles using ultra high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QToF-MS) and gas chromatography-flame ionization detector (GC-FID), along with colorimetric assays for total phenolics, flavonoids, tannins, and antioxidant capacity. Freeze drying (FD) outperformed convective and microwave drying (MD) in the case of total phenolic content (TPC) (5.16 mg GAE/g), total flavonoid content (TFC) (1.96 mg CE/g), and AA (13.24 mg TE/g) and exhibited the highest concentration of polyunsaturated fatty acids (PUFAs) (93.41%). MD exhibited the lowest values for oil yield (11.93%), showed intermediate values for TPC, TFC, total tannin content (TTC), and AA and exhibited the lowest concentration of PUFAs (88.98%). CD resulted in the highest oil yield (15.84%) and TTC (9.43 total tannins/g) but in the lowest TPC (4.07 mg GAE/g), TFC (1.21 mg CE/g), and AA (3.89 mg TE/g). Overall, 32 bioactive compounds (BCs) were identified through UHPLC-QToF-MS analysis. Regarding the sum of BCs concentration, FD (56.07 mg BCs/g) and MD (52.79 mg BCs/g) outperformed convective (25.83 mg BCs/g) drying. Sixteen of these BCs were reported in PSO for the first time, including caffeoyl-glucose, tyrosol, and sakuranetin. GC-FID analysis confirmed the presence of 13 fatty acids in PSO, dominated by PUFAs. The findings confirm FD as the most effective method for maximizing oil yield, while preserving PSO's BCs, and highlight PSO's potential use as a high-value product for functional foods, nutraceuticals, and cosmetics. PRACTICAL APPLICATIONS: The increasing demand for functional food products necessitates the development of technologies that preserve their bioactivity. This research demonstrates that convective drying negatively affects the bioactive profile of pomegranate seed oil (PSO). For nutraceutical applications demanding maximum antioxidant activity and bioactive concentration of PSO, freeze, and microwave drying proved superior. These findings provide evidence for processors to shift toward these technologies to ensure final PSO products meet high bioactive specifications.