A process to concentrate coffee extract by the integration of falling film and block freeze-concentration

Abstract

A process to concentrate aqueous coffee extract by freeze concentration is proposed to achieve an industrially viable system. The techniques of falling film freeze concentration, fractionated thawing and block freeze concentration were studied. Batches of 40 kg of coffee extract with 5% initial solid concentration were freeze-concentrated in seven stages in a falling film multi-plate freeze concentrator. The ice from each stage was fractionally thawed to recover the coffee solids retained in the ice. The diluted fractions of the thawing stage were freeze-concentrated using the block technique. A concentrated extract with 32.6% solids and an effluent with 0.27% solids were obtained through the integration of these techniques. A concentration index of 6.5, a concentration efficiency of 99.2% and a solute yield of 95% were obtained. The integration of these simple techniques results in a concentration index and solute yield comparable to industrial standards in freeze-concentrated coffee extract production.