Low-energy membrane-based processes to concentrate and encapsulate polyphenols from carob pulp

Abstract

Forward osmosis (FO) and emulsification with dynamic membranes of tunable pore size (DMTS) were assessed to concentrate and encapsulate polyphenol extracts from carob pulp. In the FO step, a feed solution temperature of 40 °C resulted in the fastest concentration and the highest polyphenol yield. Moreover, FO at 35 °C enabled to concentrate up to about 20 times in 3 h using a pilot scale unit of 0.5 m2 of membrane area. Phenolic compounds were subsequently encapsulated in the inner water phase (W1) of water-in-oil-in-water (W1/O/W2) emulsions produced with DMTS, which enabled to obtain emulsions with a monomodal droplet size distribution (span<1, d3,2 ≤20 μm), and polyphenol encapsulation efficiencies ranging between 87.0 ± 0.2% and 77.4 ± 0.4%. To extend the shelf-life of the encapsulated polyphenols, solid microcapsules were produced by spray drying. After rehydrating the solid microcapsules, the structure of the W1/O/W2 emulsion was partially recovered.