(399o) Ceramic Membrane Based Technology for the Clarification of Mosambi Znd Orrange Juice

Ultrafiltration (UF) and microfiltration (MF) of mosambi, orange, lemon, grape, apple, carrot, water melon, blood orange and pineapple juice were reported well. Amongst several beverage processing sectors, citrus fruits constituting orange, lemon, pineapple and mosambi are prominent due to their wider availability, low cost as well as high nutrition value to human health. Citrus fruits primarily constitute both lower molecular weight compounds (such as sugar, acid, salt, flavour, aroma compounds, etc.) as well as higher molecular weight polysaccharides (such as pectic material, cellulose, hemicellulose etc.) in addition to haze causing proteins and microorganisms. The presence of pectic material and protein in fruit juice is responsible for cloudiness and post bottling haze formation and their fermentation during long storage. The objective of clarification of fruit juice using membrane filtration is to eliminate the high molecular weight pectic material and its derivatives and retain low molecular weight solutes (valuable for human health) such as sucrose, acid, salt, aroma and flavour compounds in the clarified juice.

Recently, much work has been reported with respect to the clarification of citrus fruits using membrane technology. A critical insight into the literatures infers that mainly polymeric membranes have been studied for mosambi juice and other citrus juice clarification. This is due to the fact that polymeric membranes are inexpensive in comparison with the ceramic membrane and are very easy to use. However, the major drawback of polymeric membrane is their low corrosion resistance in acidic media and hence they possess lesser life cycle times for juice processing applications. For any industrial application, the lifespan of membrane is always a major issue. Many varieties of fruit juices are acidic in nature with pH in the range of 3 to 5. Henceforth, though experimental studies indicate the successful applicability of polymeric membranes for juice processing applications, industrialization of membrane technology for juice processing has not been promising so far. For these circumstances, the usage of ceramic membranes with high corrosion resistance in both acidic as well as basic media is rendered to be more beneficial, especially in the citrus juice sector. One of the striking limitations of ceramic membranes is their higher cost (1600 $/m²) in comparison with the polymeric membranes (50 to 200 $/m² (2010)). The higher cost of ceramic membranes is due to the utilization of expensive inorganic precursors such as alumina and zirconia and higher sintering temperature (more than 1100 ^oC) during membrane fabrication. Therefore, the development of low cost ceramic membranes is envisaged by utilizing low cost inorganic precursors and lower sintering temperatures.

Microfiltration (MF) of mosambi and orange juice using low cost ceramic membrane prepared from locally available inorganic precursors will be discussed. The average pore diameter, total porosity and hydraulic resistance of the prepared membrane were evaluated as 0.285 µm, 23.6 % and 9.26 × 10¹¹ m²/m³, respectively. Dead-end MF experiments were conducted for both centrifuged (CJ) and enzyme treated centrifuged (ETCJ) mosambi and orange juices. It was observed that after MF, important properties like TSS, pH, acidity and density of both CJ and ETCJ were almost unaffected. However, significant improvement in juice colour, clarity and AIS was observed. It was also noticed that the clarified juice can be stored in refrigerated condition for more than 30 days without significant change in juice quality. Different membrane pore blocking models were used to analyze the observed permeate flux decline.