Tangential microfiltration of orange juice in bench pilot

The aim of this study was to introduce the tangential microfiltration (TMF) technique on the production of orange juice (TMFJ), and compare it with pasteurised juice (control) as regards chemical composition and sensorial characteristics. We used a TMF pilot equipped with four monotubular ceramic membranes (0.1, 0.2, 0.8 and 1.4[mu]m) arranged in series with a filtering area of 0.005 m2 each. Commercial flash-pasteurised orange juice was used as the initial product. Experiments were divided Into three parts: a) the characterisation of the TMF pilot; b) optimisation of operational conditions; c) production of the TMFJ. In the second part, membrane with 0.8-[mu]n pores presented best flux followed by those with 1.4-, 0.1-, and 0.2-[mu]m pores. However, to guarantee permeate sterility, we chose the membrane with 0.1-[mu]m pores for TMFJ production. Initially, the orange juice was sieved in order to separate part of the pulp, being subsequently submitted to TMF. A mixture of retentate and pulp was made, and was subsequently pasteurised. We obtained the TMFJ by adding the permeate to the mixture. TMFJ presented soluble solids content (°Brix), pulp, pH, and titrable acidity similar to the initial pasteurised juice (control). Nevertheless, 28% of vitamin C was lost during the TMFJ production. According to the juice taster panel, the control juice presented best sensorial characteristics (greater aroma Intensity and fruity flavour) when compared with the TMJF. (Resume d'auteur)