Supercritical Fluid Extraction of Lipids from Rowanberry Pomace with Pure CO2 and Its Mixtures with Ethanol Followed by the On-Line Separation of Fractions

Abstract

Fruit processing by-products contain various classes of bioactive constituents, which may find applications as ingredients for foods, nutraceuticals or cosmeceuticals. This study explored the fractionation of lipophilic rowanberry pomace extracts isolated with pure supercritical CO2 and its mixtures with a co-solvent ethanol by their on-line separation at subcritical conditions. Rowanberry pomace lipids were extracted with supercritical CO2 (42.4 MPa, 53 °C) using 0–7% of ethanol, and then fractionated by reducing the first separator’s (S1) pressure to 7 MPa and cooling it to 0, −10 and −20 °C to precipitate the ‘heavier’ fraction (HF). The second separator (S2) was depressurized at ambient temperatures to collect the ‘lighter’ fraction (LF). The yield of the LF increased by decreasing the S1 temperature and increasing the amount of the co-solvent. The concentration of β-carotene was increased in the LF by decreasing the S1 temperature and increasing the co-solvent concentration; at −20 °C it was 66.7% higher than in the non-fractionated extract. The concentrations of tocopherols and phytosterols were also remarkably higher in the LF. In total, 62 compounds were identified in the headspace volatile fraction of the LF, benzaldehyde and benzyl alcohol being the most abundant constituents. In conclusion, fractionation enabled us to obtain fractions with higher concentrations of the selected classes of lipophilic rowanberry constituents.