Filtration of apple juice by nylon nanofibrous membranes

• Nanofibrous membranes have excellent mechanical feature to be used as filters.
• Nanofibrous membranes have high permeability to water flow.
• At high pressure, nanofibrous membranes have low polarization resistance.
• Nanofibrous membranes remove more color and turbidity than commercial membranes.
• Nanofibrous membranes selectively adsorb hydrophobic phenols, like bitter polyphenols.

Nylon-6 nanofibrous membranes (NFM) produced by electrospinning were applied as filter medium to clarify apple juices. The NFM exhibited good mechanical properties, lower density and higher porosity compared to commercial polyamide membranes. The filtration mechanism (initial filter, polarization and cake resistances) and the physicochemical characteristics of the filtrate (color, turbidity, acidity, antioxidant capacity, phenols, organic acids and sugars) were studied at pressures of 207, 276 and 345 kPa and with NFM of thickness ranging from 16 to 124 μm. NFM showed superior performance than commercial membranes regarding removal of turbidity, color and bitter phenolic compounds, yet maintaining the antioxidant capacity of the juice. Furthermore, NFM were able to selectively adsorb undissociated polyphenols, like tannins. Adsorption increased at higher pressures. This work demonstrates the potential of NFM as filters for the production of clarified juices and other industrially relevant beverages.