Concentration of passion fruit juice on an industrial pilot scale using osmotic evaporation

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°C. 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 h, 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.