No abstract

Artichoke agro-industrial discards have proved an excellent source of polyphenolic compounds with high antioxidant capacity, which can be extracted at mild conditions. The aim of this study was to further separate these bioactive molecules from an ethanolic extract by using Colloidal Gas Aphrons (CGAs) generated from a cationic surfactant, Cetyl trimethylammonium bromide, CTAB (1 mM) and a nonionic one, Tween 20 (10 mM). Total proteins, total sugars, total phenolic content (TPC), antioxidant capacity (AOC) and polyphenolic profile were determined in the crude extracts and CGA fractions. Highest recovery was obtained with the nonionic Tween 20 at CGA to feed volumetric ratio 5 (RE%= 64) whereas the cationic CTAB proved more efficient (RE%= 58) at the highest ratio studied here (ratio 11). Antioxidant capacity followed the same trend as the recovery of polyphenols and highest enrichment in antioxidant activity for each of the 2 surfactants (1.5 for Tween 20 and 1.4 for CTAB) was obtained at those conditions that led to maximum recovery. Highest selectivity was obtained with CTAB. The interactions between the negatively charged polyphenols and the positively charged cationic surfactant drove the separation, whereas with Tween 20 hydrophobic interactions were predominant, and at the studied concentrations (10 mM) the separation of polyphenols within the micelles might also compete with the CGA separation. Polyphenolic profile of feed and CGAs fractions comprised mainly mono and dicaffeoylquinic acids and a small proportion of flavones. In most of the cases no enrichment of any particular polyphenol compound was observed from the initial extract to CGAs samples generated with Tween 20 and CTAB. However, at ratio 5 and with Tween, CGAs were enriched in dicaffeoylquinic acid. Future research should focus on studying further the activities and stability of these surfactant rich fractions in order to assess if the surfactant could offer any advantage to the formulation of these polyphenols.