Supercritical CO2 and subcritical water technologies for the production of bioactive extracts from sardine (Sardina pilchardus) waste

The valorization of sardine (Sardina pilchardus) waste (SW) from a canning facility has been investigated within a biorefining approach. Sequential fractionation of SW into its constituents has been carried out using green solvents such as supercritical carbon dioxide (SCCO2) and subcritical water (sCW). The lipid fraction has been isolated through supercritical fluid extraction (SFE) with SCCO2 at 250 bar and 40 °C, yielding 20.3 ± 0.2 g oil/100 g SW with up to 17.2 %wt. omega-3 polyunsaturated fatty acids (PUFAs). Aiming at the protein fraction, sCW extraction/hydrolysis has been carried out at different temperatures (90, 140, 190 and 250 °C), using both SW and defatted sardine waste (DSW) from SFE experiments. Previous defatting increased protein recovery and purity. Bioactive properties of the fish protein hydrolysates (FPHs) obtained were affected by the extraction temperature. The highest antioxidant activity and in vitro antiproliferative effect were found in the extracts obtained at 250 °C.FCT/MCTES (UIDB/QUI/50006/2020), and Fundação para a Ciência e a Tecnologia through project PTDC/ASP-PES/28399/2017 and grants IF/01146/2015 and SFRH/BD/116002/201