Recovery of trypsin inhibitor by soy milk ultrafiltration using a rotating disk system

Defatted soy milk was ultrafiltered at 50 kDa using a shear-enhanced rotating disk filtration system developed at the Technological University of Compiegne. The objectives were to concentrate soy milk proteins while removing in the permeate soy trypsin inhibitor (STI) which is an anti-nutritional factor, but can be used for medical applications. Maximum permeate flux at a rotation speed of 2500 rpm, a TMP of 140 kPa and initial concentration, was 37 L h−1m−2 when a smooth disk was used and rose to 95 L h−1m−2 when the disk was equipped with 6 mm high vanes. In concentration tests without permeate recycling, the permeate flux decayed logarithmically with increasing volume reduction ratio (VRR).The maximum theoretical VRR extrapolated to zero flux was found to be 5 for both disks.