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Title: EVALUATION OF CONCENTRATED ORANGE AND PASSIONFRUIT JUICES PREPARED BY OSMOTIC EVAPORATION

Author
item Shaw, Philip - Phil
item LEBRUN, MARC - CIRAD-FLHOR, FRANCE
item DORNIER, M - CIRAD-FLHOR, FRANCE
item DUCAMP, M - CIRAD-FLHOR, FRANCE
item COUREL, M - CIRAD-FLHOR, FRANCE
item REYNES, M - ENSIA-SIARC, FRANCE

Submitted to: Lebensmittel Wissenschaft und Technologie
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2000
Publication Date: 4/4/2001
Citation: N/A

Interpretive Summary: Citrus and tropical fruit juices are heated during the process used to make concentrated juice products, and this heat processing changes the flavor of the concentrated juice. A milder process, called direct osmosis concentration, can produce concentrated juice without heating during the process. Such concentrated juices have more fresh juice flavor than heat- concentrated juice. We prepared concentrated orange and passionfruit juices by direct osmosis concentration and evaluated the concentrated juices by analysis and by taste tests to determine how much the juice had changed because of this mild concentration process. The concentrated juice retained about two-thirds of the flavoring materials present in the original juices. This is a much higher retention of flavor in the concentrated juice than when heat processing is used. Tasters were able to tell a difference between the original juice and juice made from the concentrated products in each case, but they had no preference for the flavor of either the initial juice or concentrated juice when the two were compared directly. This indicates only slight changes in flavor quality resulted from this process.

Technical Abstract: A pilot scale process involving microfiltration followed by osmotic evaporation 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 components showed a loss of about 32% of the volatile components in orange and about 39% in passionfruit juices. For both orange and passionfruit, sensory evaluations using triangle difference tests showed a significant difference between the initial juice and the reconstituted concentrate, while paired comparison preference tests showed no preference for either sample. In orange juice, a trained taste panel was used to evaluate six specific flavor characteristics in the two juices. The characteristics evaluated were green, fresh orange, fruity/floral, peel oil, cooked/processed and terpene. Although there were no significant differences found by the panel between the juices in any one characteristic, the average flavor score for each characteristic was slightly lower in juice from concentrate than in the initial juice. These results indicate that even though about a third of the flavor volatiles were lost during the process, the flavor of the initial juice was not preferred over the concentrated product. This study demonstrates the feasibility of using osmotic evaporation combined with microfiltration to prepare concentrated orange and passionfruit juices of intermediate concentration degree with high flavor quality.