Clarification of Satsuma Mandarin Juice by Ultrafiltration

Abstract

The clarification of Satsuma mandarin (Citrus unshiu Marc.) juice by ultrafiltration was investigated by the use of DDS plate-and-flame module with three kinds of membranes, GR 51 PP, GR 61 PP and GR 81 PP (molecular weight cut-off of 50000, 20000 and 6000, respectively). (1) The effects of process parameters on the permeation flux were studied. The permeation flux increased with an increase in flow rate or temperature. The higher operating pressure gave a higher permeation flux in GR 81 PP, however, the increase of pressure gave the decrease of permeation flux in GR 51 PP and GR 61 PP. (2) Permeation flux of the membranes was mostly restored by cleaning with warm alkaline detergent solution after treatment. (3) In ultrafiltration of 10° Bx, 20° Bx and 30° Bx juices by a batch operation, the amount of soluble solid permeated through the membranes was larger in 30° Bx juice than that in 10° Bx or 20° Bx juices. The permeation of juice components such as soluble solid, acid, amino-nitrogen and vitamin C were partially rejected. Pectin was scarcely detected in permeates. (4) A higher permeation flux was observed in Satsuma mandrin juice treated with suitable concentration of a pectic enzyme before ultrafiltration. (5) The compositions of Satsuma mandarin juice and lemon juice clarified by ultrafiltration was almost the same as those by conventional enzymatic treatment and celite filtration, but the colour and flavour was a little better in ultrafiltrated juice.