Apple juice clarification using microfiltration and ultrafiltration polymeric membranes

The flux behavior of polyethersulfone (0.2 mu m), polyvinylidene fluoride ( 0.2 mu m), cellulose (0.2 mu m, 100 kDa, 30 kDa, 10 kDa), and polysulfone ( 0.2 mu m, 100 kDa, 30 kDa, 10 kDa) membranes was examined during dead-end f iltration of apple juice, Membranes with molecular weight cut-off of 30 and 100 kDa had superior pur performance to 0.2 mu m or 10 kDa membranes. A cr ossflow system equipped,with various tubular polymeric membranes was also u sed to clarify apple juice at a temperature of 50 degrees C, a crossflow ve locity of 3.3 m/s and a transmembrane pressure of 414 kPa. Steady state flu xes increased as the molecular weight cut-off increased from 9 to 200 kDa. When challenged with P. diminuta, log reduction values between 6 and 7 were obtained with the crossflow tubular polymeric system. Membranes between 20 and 200 kDa produced juices with similar initial characteristics drat unde rwent comparable changes during storage at 4, 25 and 35 degrees C over 4-16 wk. The impact of filtration through the 9 kDa membrane was however notice able on the physico-chemical properties since the apple juice had a green l int, lower soluble solids, lower flavanol content, and experienced minimal changes in browning and turbidity.