Integrated membrane process for the production of highly nutritional kiwifruit juice

The aim of this study has been to design, on a laboratory scale, an integrated membrane process for the production of concentrated kiwi juice and its aroma recovery. Fresh depectinised kiwifruit juice was clarified by the ultrafiltration (UF) process. The clarified juice was concentrated by osmotic distillation (OD), as an alternative to the traditional vacuum evaporation, up to a total soluble solids (TSS) content higher than 60 °Brix at 25°C. Pervaporation (PV) runs were carried out before and after each membrane unit operation in order to identify the best configuration giving the minimal loss of aroma compounds. For the majority of the aroma compounds detected, the enrichment factor in the permeate of the fresh juice was higher than the clarified and concentrated juice. This result suggests the use of PV for the removal and enrichment of aroma compounds directly from the fresh juice, before any concentration process. The effect of UF and OD on the total antioxidant activity (TAA) and ascorbic acid content of the kiwifruit juice was also evaluated. On the basis of the obtained results, an integrated membrane process scheme for the production of highly nutritional kiwifruit juice has been proposed.