Quality of kiwifruit juice clarified by modified poly(ether ether ketone) hollow fiber membranes

Poly(ether ether ketone) with cardo group-based (PEEK-WC) membranes, in hollow fiber (HF) configuration, were prepared via the dry-wet spinning technique through the phase inversion process and used to clarify kiwifruit juice. The depectinised juice was processed according to a batch concentration configuration in selected operating conditions (transmembrane pressure, 1.6 bar; feed flowrate 70 L/h; temperature, 25±2 °C) up to a volume reduction factor (VRF) of 1.8. The quality of clarified juice was analysed in terms of total antioxidant activity (TAA), content of ascorbic, malic, succinic and citric acid, total polyphenols, suspended solids and total soluble solids (TSS). The prepared membranes allowed to remove suspended solids producing a clear juice with a content of organic acids, vitamin C and polyphenols comparable to that of the fresh juice. Accordingly, the TAA of the fresh juice was well preserved in the clarified juice.