UNDERSTANDING CLARIFICATION OF SWEET ORANGE JUICE BY MICROFILTRATION AND FOULING BEHAVIOUR
Sweet orange is a important citrus fruit grown throughout the world as it rich in phytonutrients properties and excellent source of vitamin C. The conventional clarification process involves more costs with personnel, equipment, and physical space. As an alternative, microfiltration (MF) has been applied in fruit juices for clarification. Clarification of sweet orange juice was carried out by microfiltration process using 0.2 µm size cellulose acetate MF membrane in a stirred cell. Flux decline was majorly due to deposits formed with soluble and suspended fraction of pectin, proteins and fibers, forming a low methoxy gel layer on membrane surface causing fouling during clarification. Long term flux decline was dictated by intermediate pore blocking in combination with growth of gel layer over the membrane surface. Reversible resistance was considered as domineering resistance and therefore, 90% of original permeate flux was recovered by following proper washing protocol to clean membranes. It was noticed that most of the total soluble solids (TSS), pH and vitamin C expressed as ascorbic acid of the feed were recovered in the permeate after filtration and there was no loss of the important properties pertaining to sweet orange juice.