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Abstract
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.
Notes
*Mean value of three runs ± std.
*Mean value of three runs ± std.
a Relative retention indices to C8-C24 n-alkanes on the DB-WAX and CP-SIL 8.
b The percentage composition was calculated from the chromatograms obtained on the CP-Sil 8 column. Normalized peak area %, tr: <0.1%, nd: not detected.
c A: MS data and retention index in agreement with those of authentic compound; B: MS data and retention index in agreement with those in literature; C: MS data in agreement with those in NIST and Wiley libraries.
d % v/w: Volume of oil to weight of leaves (in g). All data represent the mean values of three independent replicates.
*Mean value of three runs ± std.
*Mean value of three runs ± std.
*Mean value of three runs ± std.