Drying of Fennel Plants: Oven, Freeze Drying, Effect of Freeze-Drying Time, and Use of Biopolymers

摘要

Fennel plants were oven and freeze dried. The influence of freeze-drying time on the concentration of the two main components, trans-anethole and isoanethole, of its essential oil was evaluated. Drying time up to 15 h led to 50% reduction of moisture content with minor increase in volatile losses, whereas drying time greater than 15 h resulted in a dried product with an aroma profile closer to the fresh one. Moreover, starch solutions and gelatin gels were tested as surface barriers. Both led to reduction of aroma compounds losses, but their concentration and state seemed to have no effect on this behavior.