The feasibility of using hollow fiber ultrafi1tration
for clarification, stabilization and preservation of white
grape juice was evaluated. Flux and process parameters of
a hollow fiber membrane ultrafi1tration unit (Romicon pilot
scale, model FXS-MXII), were studied using white Riesling
grape juice. Optimum processing conditions were determined
for different nominal membrane molecular weight cut-off
values. The effect of cut-off value changes on viscosity,
pectin retention, pH, sugar content, titratable acidity,
haze reduction and color were evaluated.
Optimum conditions for processing were nominal membrane
molecular weight cut-off = 50,000, temperature = 50°C,
inlet pressure = 1.75 Kg/cm², outlet pressure = 1.40 Kg/cm²,
permeate flux = 72.57 L/M²-H. Concentration polarization and fouling of the membrane increased with feed juice viscosity
and were limiting factors in permeation rate. A
93% retention of pectins was achieved and haze reduction
was in the range of 91-93%. Sugar content, pH, titratable
acidity, and color were not affected for any of the nominal
membrane molecular weight cut-off values
