Selective Retention of Phenolics From Pomegranate and Sour Cherry Juices Using Protein-Functionalized Electrospun Membranes

Fruit juices such as pomegranate (POM) and sour cherry (SC) are rich in phenolic compounds that contribute to antioxidant value but may also cause undesirable astringency and haze. This study introduces electrospun membranes functionalized with proteins for the selective retention of specific phenolics during juice filtration. Polyacrylonitrile (PAN) was blended with egg albumin (EA) or lactalbumin (LA), forming electrospun membranes (PAN/EA and PAN/LA, respectively) with tunable physicochemical properties. Feed solutions were characterized prior to electrospinning; protein addition increased electrical conductivity from 0.05 mS/cm to 0.6–0.7 mS/cm, slightly raised surface tension from 36.4 to 38.2 mN/m, and stabilized the dielectric constant across tested frequencies. These changes improved electrospinnability. Contact angle measurements confirmed enhanced surface hydrophilicity in protein-blended membranes (PAN/EA ~19.5°, PAN/LA ~28.5°, vs. PAN ~42°). When applied to POM and SC juices, the membranes showed selective phenolic removal. PAN/EA achieved nearly 100% removal of gallic acid from the SC juice via adsorption onto the membrane, while PAN/LA selectively removed ferulic acid from the juices. In contrast, the electrospun PAN membrane provided broad-spectrum phenolic adsorption, especially in POM juice. Filtration preserved pH but influenced °Brix, conductivity, and zeta potential depending on membrane composition. These findings demonstrate that tailoring membrane surface chemistry and feed formulation enables selective phenolic separation, improving juice clarity and sensory quality without compromising nutritional content. The study highlights the feasibility of protein-functionalized electrospun membranes as a non-thermal, scalable solution for fine-tuning juice quality.