Tailoring composition and nanostructures in supramolecular solvents: Impact on the extraction efficiency of polyphenols from vegetal biomass

Abstract

Polyphenols are one of the most appreciated antioxidants nowadays. Industry has an enormous interest in their efficient extraction from vegetal biomass, but most of current methods are neither eco-friendly nor cost-effective. Supramolecular solvents (SUPRAS), made up of self-assembled amphiphilic aggregates, have shown a great potential for the extraction of bioactives from biomass as well as for the compliance with many green chemistry criteria. Comparative studies on the extraction capability of different types of SUPRAS are essential for their application-oriented tailoring. In this study, seven SUPRAS made up of reverse hexagonal aggregates and sponge-like structures were synthesized in a variety of hydro-organic mixtures from 1-octanol and 1,2-octanediol, respectively, and their capability for the extraction of polyphenols from raspberries was evaluated. SUPRAS were characterized in terms of formation phase diagrams, composition and structure. Sponge-like SUPRAS of 1,2-octanediol, which had abundant aqueous interconnected channels (35.5–39% w/w), showed excellent solubilisation properties for both the highly polar polyphenol glycoside conjugates and the less polar polyphenols. Optimal values were obtained with SUPRAS of 1,2-octanediol and 1,3-propanediol that provided a total polyphenolic content of 9.57 ± 0.19 mg GAE/g FW sample. This value was up to three times higher than that obtained with ethanolic extracts. Polyphenol glycosides (from quercetin, naringenin, kaempferol, coumaric acid and catechin) were the predominant identified metabolites.