PINEAPPLE JUICE CONCENTRATED BY OSMOTIC EVAPORATION

Pasteurized pineapple juice was concentrated by osmotic evaporation to produce a 51 °Brix concentrate that was reconstituted to single strength juice for evaluation. Headspace gas chromatography (HSGC) showed that the concentrate retained an average of 62% of the volatile components present in the initial juice. A sensory panel preferred initial juice over reconstituted concentrate, and noted a decrease in desirable flavor top notes as well as development of some processed flavor in the concentrate. Similar HSGC analysis of four other commercial juice samples showed a wide range of quantitative values for volatile components, with the initial juice being similar to the weakest of these commercial juices. Analysis of concentrated juice extracts permitted identification of additional less-volatile components not monitored directly by HSGC of the juice. Relatively low levels of these components were also present in the initial juice. Although this nonthermally produced concentrate retains more volatile components than when traditional thermal processing methods are used, addition of aqueous aroma to the concentrate may be required for satisfactory flavor. L'interet pour des methodes non thermiques de concentration de jus de fruit augmente depuis quelques annees. Dans cette etude, du jus d'ananas pasteurise est concentre par evaporation osmotique et le concentrat est reconstitue en un jus homogene pour l'evaluation de sa qualite. Des methodes analytiques sont utilisees pour determiner les teneurs en composes volatils pendant le procede de concentration et les profils de ces composes sont compares avec ceux de jus commerciaux prepares par concentration thermique.