Development of Progressive Freeze Concentration and Its Application: a Review

Progressive freeze concentration (PFC) forms a single ice crystal in the system; therefore, the system is much simpler as compared with the conventional method of equilibrium suspension crystallization (ESC) for freeze concentration, in which many small ice crystals are formed. The concentrate by PFC, as well as ESC, retains the original profile of components after the concentration, which is much different from other methods of concentration like evaporation and reverse osmosis. PFC was successfully applied to concentrate coffee and tea extract. PFC was also applied to concentrate natural flavors, which was recovered from the condensate in the evaporation process of fruit juices. PFC was applied to concentrate various fruit juices, and the concentrates could be fermented to produce new-type fruit wines without chaptalization. Among fruit juices, melon and watermelon were included. These were known to be difficult in concentration for their high thermal sensitivity and viscosity. PFC was also applied to concentrate fermented alcoholic drinks like Japanese sake. In this case, the concentrate retains the similar flavor profile with the original fermented product. This provides an entirely new method for the concentration of alcoholic drink as compared with the conventional distillation, in which flavor profile completely changes from the original fermentate. Some of the applications described above are presently not available in the market and became possible only by PFC, due to its high flexibility in the operation mode and the production scale as compared with ESC, which is applicable only to large-scale continuous operation.