Extraction of aroma compounds of fruit juices by air stripping using a bubble column operating with antifoam and its effect on juice properties

The objective of this work was to evaluate the effect of air bubbling on the physicochemical properties and ascorbic acid concentration of fruit juices during the extraction of their volatile aroma compounds using a bubble column operated with antifoam. The ideal concentration of a commercial antifoam agent was also evaluated to ensure a non-foaming operation during air bubbling in the fruit juice for the range of gas superficial velocity between 1 and 2 cm/s. Besides, aroma extraction from a surrogate solution was evaluated, being the best extraction efficiency obtained for ethyl butyrate (97%), followed by hexanal (93%), ethyl acetate (81%) and linalool (32%). However, there was no significant variation of these efficiencies for the gas superficial velocities employed. Finally, after 4 h of air bubbling in fresh fruit juice, there were no changes of pH, total soluble solids, titratable total acidity and color of the juice and just a 15% reduction in the concentration of the ascorbic acid. Thus, the use of air stripping in a bubble column was proved to be an interesting alternative to extract aroma compounds from fruit juice without causing any appreciable change in its properties.