Chapter 9 - Production of citrus juice concentrates

Abstract

The main objectives of concentration of citrus juices are: reduction of mass and volume, resulting in reduction of the cost of packaging, storage and transportation and better stability of the concentrate due to the reduction of water activity. Several physically different methods are available for water removal. These include evaporation, freeze concentration, reverse osmosis, osmotic water transfer, and chemical complexation. Evaporation is the leading method of water removal in the citrus industry. Evaporation of citrus juices poses a number of specific problems such as thermal damage to quality, loss of volatile aroma, and increase in viscosity. Thermal damage is minimized by evaporating under vacuum. Aroma loss is compensated by cutting back with fresh juice or with essence recovered from vapors. Energy expenditure is reduced by multieffect evaporation and vapor recompression. Short residence boiling film evaporators are preferred. The different types belonging to that class are described. Most evaporator suppliers also offer essence recovery systems. The methods of concentration by reverse osmosis and freeze concentration are described. Concentrates for retail trade are frozen. Concentrates for reprocessing are pasteurized, aseptically filled into containers of different sized and stored or transported under refrigeration.