A comparative study on composition and antioxidant activities of supercritical carbon dioxide, hexane and ethanol extracts from blackberry (Rubus fruticosus) growing in Poland

BACKGROUND: Large quantities of blackberry seeds are produced as a pomace during the processing of juice and jam production; thisby-product is a very interesting rawmaterial both foroil manufacturingandas a source of bioactive compounds. In thiswork the composition, yield and antioxidant activity of three types of Rubus fructicosus pomace extracts isolated by liquid extraction using solvents of different polarity, as well with supercritical CO2 fluid extraction have been compared. RESULTS: The highest extract yield was reported for Soxhlet extraction using ethanol as a solvent (14.2%). Supercritical carbon dioxide and hexane extracts were characterised by the highest content of phytosterols (1445 and 1583mg 100 g(-1) of extract, respectively) among which beta-sitosterol was the main one, while the concentration of tocopherols, with predominant gamma- isomer, was the highest for both hexane and ethanol extracts, being 2364 and 2334mg 100 g(-1), respectively. Using a GC-MS method 95 volatiles, in which non-saturated aldehydes were predominant, were identified in the essential oil of seed pomace and in the volatile oil isolated from supercritical extract. The ethanolic extract which is characterised by the highest phenolic content (9443mg GAE 100 g(-1)) exhibited the highest antioxidant activity (according to the ABTS(.+) and DPPH. assays). CONCLUSION: Allpomace extracts examinedwere of high quality, rich in essentialomegafatty acids andwith a veryhigh content of bioactive compounds, such as phytosterols and tocopherols. The high nutritional value of extracts from berry seed pomace could justify the commercialisation of specific extracts not only as food additives but also as cosmetic components. (C) 2017 Society of Chemical Industry