Evaluation of concentrated orange and passionfruit juices prepared by osmotic evaporation

A pilot scale process involving microfiltration followed by osmotic evapora tion was used to prepare concentrated orange and passionfruit juices. Both juices were concentrated 3-fold to 33.5 and 43.5 degrees Brix, respectively . Quantitative headspace gas chromatographic analysis of 20-35 volatile com ponents showed a loss of about 32% of the volatile components in orange and about 39% in passionfruit juices. For both orange and passionfruit, sensor y evaluations using triangle difference tests showed a significant differen ce between the initial juice and the reconstituted concentrate. In orange j uice, a trained taste panel was used to evaluate six specific flavour chara cteristics in the two juices. The characteristics evaluated were green, fre sh orange, fruity/floral, peel oil, cooked/processed and terpene. There wer e no significant differences found by the panel between the juices in any o ne characteristic but the average flavour score for each characteristic was slightly lower in juice from concentrate that in the initial juice. This s tudy demonstrates the feasibility of using osmotic evaporation combined wit h microfiltration to prepare concentrated orange and passionfruit juices of intermediate concentration degree with high flavour quality.