Crossflow microfiltration for the cold stabilization of roselle ( Hibiscus sabdariffa L.) extract

Abstract

In this study, roselle extract was cold sterilized by crossflow microfiltration. At laboratory scale the optimal operating conditions at volumetric reduction ratio (VRR) 1 cannot be generalized when VRR is greater than 1. Indeed, at VRR 1 the optimal transmembrane pressure was 2.5 bar with a permeate flux of 185 L h −1 m −2, while at VRR 20 optimal pressure was 3.7 bar with a permeate flux of 95 L h −1 m −2. A simple model that allowed to represent the effect of VRR and transmembrane pressure on the permeate flux was adjusted with the experiments done at laboratory scale. This model used to predict the permeate flux using a semi-industrial pilot scale equipment gave a good match between the experimental and calculated performances. Permeate was collected aseptically and stored at 4, 20 and 37 °C for 90 days. A roselle extract storage at 4 and 20 °C was appropriate for consumption after a 3 month shelf life.