4. Conclusion
Nylon-6 nanofibrous membranes, with fibers of diameter around 95 nm, display structural, mechanical and transport features that make them ideal devices for filtering purposes, namely, interconnected and pseudo-porous structure, very high porosity (94%), remarkable resistance to transversal stress and good permeability to water. NFM with thickness around 124 μm, operating at a transmembrane pressure of 345 kPa (50 psi), produced apple juice with optical characteristics similar or superior to that of commercial clarified juices. NFM showed a higher adsorption capacity towards undissociated polyphenols rather than to lighter phenolics like caffeic acid, which results in the selective removal of bitter polyphenols at the pH of apple juice (3.5). NFM enable the combination of the conventional sieving mechanisms, typical of microporous filters, with the ability of affinity membranes to remove specific compounds.