Clarification of red araçá (Psidium cattleianum Sabine) juice by membrane process: Analysis of permeate flux and loss of bioactive compounds

Abstract

Red araçá (Psidium cattleianum Sabine) juice was processed using porous membranes to obtain a clarified product with a high amount of phenolic compounds prior to its use as a juice or other beverage. The variations in the permeate flux and concentrations of phenolics were determined in a cross-flow system using a polyetherimide microfiltration membrane (0.44 µm) and polyethersulfone ultrafiltration membrane (50 kDa). Both membranes reduced the initial turbidity (445 ± 2) to almost zero, and resulted in a clear and transparent permeate with a yellow colour. The microfiltration membrane showed better performance with the lowest phenolic compound retention (23.6%) and the highest permeate flux (40.6 ± 2 kg/m2h) in batch mode operation. The permeate flux of the microfiltration system showed an initial sharp decrease followed by a gradual decrease, reaching almost 60% lower than the initial permeate flux. The permeate flux resistance was mainly due to the polarised layer (70.2%), and the predominant fouling mechanism was the partial pore blockage, thus indicating that the solids present in the raw juice had size of the same order as the membrane pores.