Comparative Evaluation of Clarification and Concentration Technique for Kinnow Fruit Juice

The effect of centrifugation (CF) and ultrafiltration (UP) on the concentration of kinnow fruit juice by reverse osmosis (RO) as well as vacuum thermal evaporation (VTE) is reported. The extracted juice was filtered and concentrated by RO with and without UP or CF. Another batch was concentrated by VTE without any pretreatment. UP was done by using a labscale membrane processing unit with polysulfone membranes while thin film composites were used for RO. The average permeate flux during RO of the juice without any pretreatment was less (14.11 l/m^2/h ) as compared to the average permeate flux of centrifuged juice (15.45 l/m^2/h). Highest permeate. flux .of 18.75 l/m^2/h was observed for the RO of ultrafiltered juice. The clarity (% T at 650 nm) of the concentrates was less as compared to the original juice except for the UF concentrate where it was very high. The acidity, ascorbic acid and carotenoids of RO concentrate with UF were significantly different from the RO concentrate of centrifuged juice as well as thermally evaporated one. Most of the quality parameters of UP and RO concentrate, as well as CF and RO concentrates were significantly different from RO concentrate without any pretreatment. Comparative evaluation of sensory characteristics of the concentrates showed that the difference among them was not significant.