Ceramic membrane filtration for isolating starch nanocrystals

Starch nanocrystals (SNC) present different sizes (microscale and nanoscale) limiting their yield, process parameters and properties. Therefore, hydrolysates from wheat starch were filtered using a microfiltration unit equipped with ceramic membranes to assess the cross-flow membrane filtration potential of SNC suspensions. Properties of feed, permeate and retentate were evaluated with dynamic light scattering, SEM, SEM-FEG and X-ray diffraction. Process parameters were also monitored. Achieved permeate flux was 306-510 dm(3) h(-1) m(-2) depending on membrane pore size and transmembrane pressure. Volume concentration ratio reached 13.7. Results show that microfiltration can be a promising solution to achieve separation of nanocrystals from non-fully hydrolyzed particles. No significant differences in final particles size were observed for all tested membranes. Analysis on permeate shows not only that collected nanoparticles are more crystalline than feed, but also that mostly B-type particles are produced during the first day of hydrolysis. These very promising results completely change the way of thinking with respect to SNC preparation. (C) 2011 Elsevier Ltd. All rights reserved.