Efficiency study on vertical-finned crystalliser for concentration of carrot juice

Abstract

Vertical-Finned Crystalliser (VFC) is a new innovation of the progressive freeze concentration method which is applied in concentration of carrot juice. The aim of this research is to observe the efficiency of this newly designed crystalliser in preserving the beta carotene content in the carrot juice concentrate. The crystalliser is equipped with a cooling jacket and extended surface of heat transfer area which makes it possible to obtain high efficiency operation, highly concentrated carrot juice and pure ice layer in the process. The process started with feeding the carrot juice into the crystalliser and the ethylene glycol coolant was pumped into the cooling jacket. Both carrot juice and coolant were circulated in the crystalliser and cooling jacket using two different pumps, until a layer of ice was formed on the inner wall of the crystalliser, including the extended surface/fins. The range of coolant temperature investigated was -6 °C to -12 °C and circulation flowrate of 1,600 mL/min to 2,800 mL/min at constant operation time of 50 min. The efficiency of the process was observed based on the average concentration efficiency value, η (%) and effective partition constant, K using concentration value from the sample absorbance analysis result of UV-Vis spectrophotometer. It was found that the increase in freezing rate (-8 °C) brought about the increase in average concentration efficiency value, η and lower K-value. Meanwhile, the best circulation flow rate was 2,800 mL/min giving higher value of efficiency and lower K-value. The present concentration method using PFC with VFC will be applicable in the industry especially to produce a variety of concentrated liquid food. , N., Azlan, N., Amran, N.A., Zakaria, Z.Y., Ngadi, N., Hashim, R., Jusoh, M.