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

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 byproducts (pomace). Several other commonly applied hexane-utilizing fractionation techniques, namely pres-surized liquid (PLE), ultrasound-assisted (UAE), Soxhlet and conventional solid-liquid (SLE, maceration) extractions, were used for comparison purposes. Under optimal SFE-CO2 conditions (53 degrees 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 alpha-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 mu g/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.