The aim of this study was to examine the effectiveness of cryomilling (CM) pretreatment on the isolation of fennel seeds essential oil (EO). Therefore, the study included (i) the process optimization and comparison of the efficiencies of hydrodistillation (HD) and steam distillation (SD); (ii) the evaluation of the effect of the CM application prior to the distillation method (selected based on the results obtained in the first part) on the EO yield; (iii) the evaluation of possible quality differences of the EOs obtained with the performed isolation methods. The obtained results showed that HD (at a solid to liquid ratio 1:10 and a distillation time of 120 min) was more efficient in terms of the EO yield compared to SD (at a pressure of 0.83 bar and distillation time of 117 min as optimal conditions). Moreover, an increased EO yield or even reduced distillation time was observed when HD was combined with a 3 min or 5 min CM pretreatment. GC-MS analysis showed no qualitative differences in chemical composition upon any of the applied isolation procedures, although higher amounts of volatiles were found in the cryomilled samples. The results of this study could be of interest to academia and the EO industry, as CM showed a positive aspect in EO isolation that could provide economic benefits in terms of higher yields or energy savings.

In this study, fennel essential oil (EO) was spray-dried, varying the wall material type (two-component blends of maltodextrin (MD), β-cyclodextrin (β-CD) and gum arabic (GA)), the wall material ratio (1:1, 1:3 and 3:1) and the drying temperature (120, 160 and 200 °C). A total of 27 powders were analyzed for their moisture content, solubility, hygroscopicity, bulk density and particle size, while powder recovery and oil retention were determined in terms of encapsulation efficiency. The morphology and chemical composition of the powder obtained under optimal conditions were additionally analyzed by scanning electron microscopy and gas chromatography-mass spectrometry. The results showed that all of the powders had generally good properties, exhibiting a low moisture content, high powder recovery and high oil retention. A 1:3 MD:GA mixture and a drying temperature of 200 °C were found to be optimal for the spray-drying of fennel EO, producing a powder with a low moisture content (3.25%) and high solubility (56.10%), while achieving a high powder recovery (72.66%) and oil retention (72.11%). The chemical profiles of the initial and encapsulated fennel EO showed quantitative differences without qualitative changes, with an average 24.2% decrease in the volatiles in the encapsulated EO. Finally, spray-drying proved to be a successful tool for the stabilization of fennel EO, at the same time expanding the possibilities for its further use.

This study aimed to determine the optimal pressure and temperature for the maximum extraction yield and recovery of lipophilic bioactive compounds (BACs) during the supercritical carbon dioxide extraction (SCO₂) of fennel seeds. For this purpose, the SCO₂ pressure (78.6–361.4 bar) and temperature (35.9–64.1 °C) were varied and optimized, and all of the extracts obtained were analyzed for the volatiles, fatty acids, sterols, tocochromanols and carotenoids. The results showed that the maximum extract yield and content of all of the compounds analyzed favored a higher pressure (320 bar) and lower temperature (40 °C), except for the volatiles, which were the highest at 120 bar and 42 °C. However, the optimal SCO₂ conditions for obtaining the highest overall total lipophilic fraction were 320 bar and 40 °C, respectively. The fennel SCO₂ extract obtained under these conditions contained 18 volatiles (trans-anethole as the major component), 12 fatty acids (oleic and petroselinic as the major compounds), 12 sterols (β-sitosterol and stigmasterol as the major compounds), two pentacyclic triterpenoids (α-, β-amyrin), one tocopherol (α-tocopherol), two tocotrienols (γ-, δ-tocotrienol) as well as two carotenoids (lutein and β-carotene). The SCO₂ proved to be very efficient for the isolation of various lipophilic BACs from fennel, and the results of this study may be of interest to academia and industry.