Supercritical CO2 extraction, chemical characterisation and antioxidant potential of Brassica oleracea var capitata against HO·, O2(·-) and ROO·.

In this work were extracted bioactive compounds from Brassica oleracea var capitata using supercritical CO2 and evaluated the antioxidant potential of the extracts. Five extractions were accomplished to investigate the influence of pressure (10-25 MPa) and temperature (20-60 °C) in the extraction yield, chemical composition and antioxidant potential towards peroxyl, superoxide and hydroxyl radicals. The highest extraction yield was obtained at 60 °C and 25 MPa, which was 0.47 wt% (run 2). In the characterisation of the extracts obtained was possible the identification of sulforaphane and iberin nitrile that present known biological properties. The extracts of all runs presented antioxidant activities towards the three radicals, but the highest activities for all radicals were using the extracts obtained in the run 2. The use of supercritical CO2 extraction to obtain bioactive compounds of B. oleracea var capitata showed to be a promising alternative to conventional extraction methods, since allowed the extraction of compounds with scientific and industrial interest.

Enzymatic synthesis of fructooligosaccharides by inulinases from Aspergillus niger and Kluyveromyces marxianus NRRL Y-7571 in aqueous-organic medium.

This work is focused on the synthesis of the fructooligosaccharides (FOS) from sucrose and inulin, using free, immobilized and pre-treated immobilized inulinase from Kluyveromyces marxianus NRRL Y 7571 and Aspergillus niger in an aqueous-organic system. Initially, the influence of pre-treatment using four different gases, propane, n-butane, CO(2) and liquefied petroleum gas (LPG), was investigated towards FOS production and best results were found when both enzymes were previously treated with LPG. The best reaction yields were obtained when the immobilized enzymes were treated with LPG. Considering FOS synthesis using the enzyme from A. niger, yields of 26.62% of GF2 (kestose), 30.62% of GF3 (nystose) and 8.47% of GF4 (fructosyl nystose) were achieved using sucrose as substrate. Using inulinases from K. marxianus NRRL Y 7571, 11.89% of GF2 and 20.83% of GF3 were obtained, using inulin as substrate. However, promising results were achieved using the free form of inulinase from A. niger (77.19% of GF2; 14.03% of GF3 and 0.07% of GF4) using inulin as substrate.