Abstract

Osmotic evaporation to concentrate clarified passion fruit juice was tried out on an industrial scale. A pilot plant that was equipped with a module containing 10.2 m(2) of polypropylene hollow fibres was used to concentrate passion fruit juice up to a total soluble solids (TSS) content higher than 60 g/100 g at 30 degreesC. Tangential velocity, temperature and concentration of solutions significantly influenced evaporation flux. An average evaporation flux of almost 0.75 kg h(-1) m(-2) was obtained with water, 0.65 kg h(-1) m(-2) when juice was concentrated to 40 g TSS/100 g and 0.50 kg h(-1) m(-2) when it reached 60 g TSS/100 g. A long-term trial, lasting 28 m(-2), was successfully carried out without membrane fouling. Osmotic evaporation can be also conducted as a multistage procedure, giving a constant evaporation flux of around 0.62 kg h(-1) m(-2) when juice was concentrated from 14 to 60 g TSS/100 g. Sensory quality and vitamin C content were well preserved in the concentrated juice. (C) 2000 Elsevier Science Ltd. All rights reserved.