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Keywords:

  • Anthocyanin-rich extracts;
  • crossflow membrane filtration;
  • grape by-products;
  • haze removal;
  • polysulfone membranes

Summary

A comparative study on the clarification of anthocyanin-rich grape pomace extracts was carried out by tubular, hollow fibre and spiral wound industrial crossflow membrane units. Three polysulfone membranes were tested: a 500-kDa molecular mass cut-off (MMCO), and a 0.2- and 0.6-μm pore size cut-offs (PSCO). The 500- kDa MMCO and the 0.2-μm PSCO membranes produced particle-free extracts, while the 0.6-μm membrane showed deficient clarification. The 500-kDa MMCO membrane produced up to 3.7% loss of most of the individual anthocyanins, while the 0.6- and 0.2-μm PSCO membranes produced up to 2% only of some of the anthocyanins with higher molecular masses. Permeate steady fluxes of up to 53 L h−1 m−2 were obtained. Particles with sizes of 0.5–1.5 μm and the macromolecular anthocyanin–tannin complexes had a major impact on membrane performance. The obtained results are scalable to industrial installations.