Concentration of kiwifruit juice by integrated ultrafiltration and osmotic distillation

The objective of this work was to develop and optimise an integrated ultrafiltration (UF) and osmotic distillation (OD) process for the production of concentrated kiwi juice with a high nutritional value. The UF process ws firstly used to clarify the unpasteurized fresh juice. In experimental tests performed according to the total recycle mode the effect of transmembrane pressure, axial flow-rate and temperature on permeate fluxes were studied. Experimental tests carried out according to the batch concentration mode, working in optimal operating and fluid dynamic conditions, were also performed. The clarified juice was concentrated up to about 65°Brix by osmotic distillation (OD). The effects of UF and OD processes on the total antioxidant activity (TAA) and other physico-chemical compounds of the kiwifruit juice were also evaluated. On the basis of the resuls obtained on laboratory scale an integrtaed membrane process scheme for the production of concentrated kiwifruit juice with high quality is proposed.