Modeling and optimization of supercritical carbon dioxide extraction for isolation of valuable lipophilic constituents from elderberry (Sambucus nigra L.) pomace

•High pressure, ultrasound and traditional extractions tested for elderberry pomace.•Supercritical CO2 extraction parameters were optimised using SSC based RSM.•The yield of lipophilic substances at 53 °C /35 MPa / 45 min was 14.05%.•Extracted oil consisted mainly of linoleic (42%) and α-linolenic (34%) fatty acids.•Toxic sambunigrin content in extracts was very low, 0.5-0.7 ng/g. Supercritical carbon dioxide extraction (SFE-CO2) was employed and its parameters (pressure, temperature, time) were optimized in order to recover valuable non-polar constituents from elderberry juice processing by-products (pomace). Several other commonly applied hexane-utilizing fractionation techniques, namely pressurized liquid (PLE), ultrasound-assisted (UAE), Soxhlet and conventional solid-liquid (SLE, maceration) extractions, were used for comparison purposes. Under optimal SFE-CO2 conditions (53 °C, 35 MPa, 45 min), 14.05 g of the lipophilic fraction was recovered from 100 g of pomace, containing health beneficial polyunsaturated linoleic (42.0%) and α-linolenic (34.1%) fatty acids. In terms of extraction yields and time, the efficiency of SFE-CO2 was generally higher as compared to conventional Soxhlet and SLE, but lower than PLE and UAE. The cyanogenic glycoside sambunigrin content in elderberry pomace, all lipophilic extracts and extraction residues was very low (6.7–76.6 ng/100 g pomace) as compared to the EFSA’s acute reference dose for HCN (20 μg/kg BW). Generally, a small portion of antioxidants was recovered from elderberry pomace after lipophilic fractionation either with supercritical CO2 or hexane (TPC: 1.5–4.7 mg GAE/g, TEAC: 0.3–11.6 mg TE/g) and defatted elderberry pomace residues retained a considerable amount (>60%) of these bioactives.