Biorefining of blackcurrant (Ribes nigrum L.) buds into high value aroma and antioxidant fractions by supercritical carbon dioxide and pressurized liquid extraction

• SFE–CO2 parameters were optimized for blackcurrant buds by CCD–RSM.
• The predicted values of extraction closely matched measured experimental values.
• The maximal predicted and experimental extract yields were >8%.
• SFE and distillation residues were biorefined by pressurized liquid extraction.
• The fractions were analysed by GC and evaluated by antioxidant capacity assays.

Berries are the main commercial product of blackcurrant (Ribes nigrum), while other plant anatomical parts such as leaves and buds are used as a source of high value aromas, which are commercially isolated with organic solvents. In this study supercritical fluid extraction with CO2 (SFE–CO2) and pressurized liquid extraction (PLE) of blackcurrant buds is reported for the first time. SFE–CO2 parameters were optimized by using central composite design (CCD) and response surface methodology (RSM) for obtaining high yields of extracts. The maximum yield was obtained at 24.9 MPa, 60 °C and 68 min extraction time. The highest estimated SFE–CO2 yield (8.38 %) was similar to the experimentally obtained and it was higher than Soxhlet extraction (6.04 %) and hydrodistillation (up to 2.26 %) yields. Hydrodistillation and SFE–CO2 residues were further extracted by PLE with methanol, resulting 7.49 and 20.77% of extracts, respectively. Blackcurrant bud extracts possessed strong antioxidant capacity; the main volatile constituents were sabinene and δ-3-carene both in SFE–CO2 and hydrodistilled oils.

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