## 4 Conclusions  
CCD-RSM was employed to optimize the P, T and \(\tau\) in order to produce single variety _Ella_ hop SFE-CO\({}_{2}\) extracts with high yield (RFI) and strong ORAC (RFII). Statistically significant and reproducible models were obtained for both RFs, while \(\tau\), P and P\({}^{2}\) together contributed to the \(>\)70% of the observed changes in extract yield and TEACORAC values. Under the optimal extraction conditions (37 MPa, 43 \({}^{\circ}\)C, 80 min), SFE-CO\({}_{2}\) amounted to 26.3 g/100 g of the greenish-brown lipophilic fraction with 867.9 mg/g E total bitter acid content, 1.5/1 \(\alpha\)- to \(\beta\)-bitter acid ratio and 1481 mg TE/g E ORAC. Optimized SFE-CO\({}_{2}\) also offered up to \(\sim\)3-fold higher extraction yield and antioxidant recovery and also substantially shortened exhaustive extraction of bitter acids from hop pellets in comparison to the classical commercial one-stage SFE-CO\({}_{2}\) at 10-15 MPa and 40\({}^{\circ}\)C. The cumulative amount of lipophilic pigments (carotenoids and chlorophylls) was negligible as compared to the bitter acid content (\(<\) 0.04% of the total extract mass). The major identified volatile compounds were monoterrene hydrocarbons \(\beta\)-pinene (up to 7.0%) and \(\beta\)-myrcene (up to 6.2%), sesquiterpene hydrocarbons \(\beta\)-humulene (up to 7.0%), \(\alpha\)-humulene (up to 9.9%) and \(\alpha\)-selinene (up to 14.9%), also unsaturated ester methyl-4-decenoate (up to 11.1%), providing fruity, herbal, spicy and woody odor to the _Ella_ hop SFE-CO\({}_{2}\) extracts. The variations in the headspace aroma profile under the different experimental conditions outlined the tunability of supercritical CO\({}_{2}\) to produce extracts with different organoleptic properties utilizing the same hop variety. To the best of our knowledge, the recovery of bitter acid and antioxidant-rich fractions from dual-purpose _Ella_ hops via SFE-CO\({}_{2}\) has been reported for the first time. Due to the high concentration of valuable bioactive constituents and particular aroma characteristics, such single variety hop SFE-CO\({}_{2}\) extracts could find multipurpose applications not only in brewing, but also in pharmaceutical, nutraceuticaltial and cosmetics industries. **Supplementary Materials:** The following are available online at [[https://www.mdpi.com/article/10.3390/antiox10060918/s1](https://www.mdpi.com/article/10.3390/antiox10060918/s1)]([https://www.mdpi.com/article/10.3390/antiox10060918/s1](https://www.mdpi.com/article/10.3390/antiox10060918/s1)), Table S1: Fit statistics parameters for the quadratic models of _Ella_ hop SFE-CO\({}_{2}\) extract yield (RFI) and TEACORAC (RFII); Table S2: Confirmation parameters for the quadratic models of _Ella_ hop SFE-CO\({}_{2}\) extract yield (RFI) and TEACORAC (RFII) at the optimal conditions of the process (37 MPa, 43 \({}^{\circ}\)C, 80 min); Table S3: Analysis of correlation between TEACORAC and phytochemical composition of _Ella_ hop SFE-CO\({}_{2}\) extracts obtained under the different experimental conditions; Table S4: Volatile compound composition (GC peak area arbitrary units \(\times\) 10\({}^{7}\)) of _Ella_ hop SFE-CO\({}_{2}\) extracts obtained under different experimental conditions; Figure S1: Response surface 3D and 2D plots showing the effects of independent variables pressure (P), temperature (T) and time (\(\tau\)) on the _Ella_ hop SFE-CO\({}_{2}\) extract yield (g/100 g HP); Figure S2: Response surface 3D and 2D plots showing the effects of independent variables pressure (P), temperature (T) and time (\(\tau\)) on the _Ella_ hop SFE-CO\({}_{2}\) extract TEACORAC (mg TE/g HP). **Author Contributions:** Conceptualization, V.K. ; methodology, V.K., M.S. and A.P. ; validation, N.E.N., M.S. and V.K. ; formal analysis, N.E.N., M.S. and V.K. ; investigation, N.E.N., V.V., L.T. and A.P. ; resources, P.R.V. and V.K. ; data curation, N.E.N., M.S. and V.K. ; writing--original draft preparation, N.E.N. and V.K. ; writing--review and editing, M.S., P.R.V. and V.K. ; supervision, V.K.