"quality is not damaged appreciably by the short time exposure to heat. Single pass evaporatorsinclude the tubular rising film (Figure 14), falling film, combination of these (Saravacos, Moyer& Wooster, 1970).To retain the naturalflavor of fresh apple juice, it is necessary to concentratethe juice by evaporation at temperature sufficiently low to minimize chemical changes(Reineccius, 1998).Figure 14: Rising film evaporator The apple juice concentrate from evaporation also has certain drawbacks, e.g. heat degradationof aroma compounds, important losses of volatile aroma compounds and high energyconsumption. In order to avoid such problem new methods developed are (i)Clarification of raw apple juice using an EMR.(ii)Apple juice preconcentration by RO. ( Alvarez et al.,2000).b) Freezing:Concentration of OJ is used to store juice for blending and also for transport.OJ is passedthrough a multiple effect evaporator (Figure 15) under vacuum which lead to the concentrationof the orange juice. Concentrate is stored chilled or frozen to reduce the non- enzymatic[21] browning reactions and attack from Saccharomyces rouxii (Ashurst, 1996).Concentration byfreezing is adopted for juices with sensitive aroma constituents such as OJ (Sivasankar, 2002).Concentration by freezing is the system that comes closest to the ideal objective of separatingwater from the food product without affecting the other components. The greatest advantagesoffered by the use of cryoconcentration rather than other technologies are the low temperaturesreached in the process and there is no loss of volatiles (Sánchez et al., 2010). Figure 15: Multiple effect evaporatorGel formation is a drawback in the case of the OJ concentrate. It is due to the action of pectinesterase (PE) on insoluble pectin. The action of PE on insoluble pectin has been correlated to thedegree of clarification(Panesar, Marwaha& Kumar, 2010).Deaeration:Deaeration is a processing step applied immediately before pasteurization to remove air, inparticular oxygen, incorporated into OJ during extraction. Vitamin C is believed to be the[22] compound the most affected by dissolved DO in orange juice (García -Torres et al., 2009). Juicesare deareated by spraying them in a vacuum deareated (Brown, 2014).Pasteurization:The pasteurization is aimed at inactivating the spoilage organisms (Hui, 2008).The differentmethods are as follows: Thermal methods:Heating is employed to destroy spoilage and pathogenic micro-organism as well as to stabilizethe juice cloud by deactivating the pectinase enzymes natural to the juice. Conventional thermalprocessing for juice pasteurization is categorized as HTST (65-86 °C) & SP (90-99 °C)(Hemming, 2011).HTST pasteurization:HTST is normally carried out in a plate heat exchanger which represents the advantage of havingthe stages of preheating, heating, holding and cooling in a single passage (Ortega-Rivas, 2009).In this pasteurization temperature is 86°C for 1.4 s for orange juice. A high quality orange juiceis obtained at a temperature of 91 °C. This temperature is required to deactivate the enzymepectinase. No growth of micro-oranism has been detected in the orange juice heated attemperature exceeding 62 °C for 12 s ( Hemming,2011).[23] Figure 16: HTST SystemUHT:It involve the production of a sterile product by rapid heating to a high temperature followed byshort holding time and ending with a rapid cooling (Ortega-Rivas,2009).In UHT treatment theOJ is heated to 115 °C, for few seconds and then cool down to 4 °C (Yang,2002).Drawback:Citrus juices are sensitive to heat. Their vitamin content and aroma and flavor may be lost ordamaged by undue exposure to heat (Hui, 2008).Non Thermal preservation method:Nonthermal pasteurization methods such as high hydrostatic pressure, pulsed electric field, andultrasound and irradiations have also been employed in fruit juices to overcome the negativeeffects of thermal pasteurization (Anejaet al., 2014). The flavor and nutritional quality of OJ is[24] usually unaffected by these technologies, although microorganisms and enzymes may beinactivated (Sánchez-Moreno et al., 2005).HPP when carried out around roomtemperatureinactivates bacterial cells, yeasts and molds without the use of heat. HPP typicallyuses pressures of 300–700 MPa for periods of 30 s (Timmermans et al.,2011) to inactivatepathogen such as Salmonella in orange juice ( Hemming,2011) and E.coli in case of apple juice(Demirci& Ngadi,2012).In case of apple juice Ultraviolet irradiation is used for pasteurization.The UV range around 200-280 nm is germicidal and can effectively inactivate bacteria in case ofapple juice. This range is effective in inactivating enzyme including peroxidase and polyphenolin apple juice (Rai&Bai, 2014).Removal of Bitterness:The bitter taste in the citrus fruit juices is mainly because of naringin and limonin.In the orangejuice basically limonin is present. The factors that influence the bitterness of the orange juice areas follows:a. Type of the orange used for the production.b. Climatic factors.c. How the squeezing is done (Dugo and Giacomo, 2003). Bitterness in the case of the OJ is mainly because of the conversion of the limonite A- ringlactone to limonin which is aided by the pasteurization .Bitterness associated with limonin islikely to be detected at pH 3.8 (Woodroof and Luh, 1986) Fruit processing industry uses twotypes of the absorbing substances i.e. activated carbon and non-ionic resins (Dugo and Giacomo,[25] "