Effect of hot air and freeze drying on the volatile compounds of dill (Anethum graveolens L.) herb

Volatile compounds of fresh, hot air dried and freeze dried dill (Anethum graveolens L.) herb were studied by gas chromatography-mass spectrometry. Of the 25 volatile components identified, 16 the most abundant compounds were analysed quantitatively. The major primary aroma compounds were α-phellandrene, 3,6-dimethyl-2,3,3a,4,5,7a-hexahydrobenzofuran,β-phellandrene, limonene, α-pinene, p-cymene and myristicin. Severe loss of these components occured during the drying of dill. E.g. the retention of the benzofuranoid, the most important aroma component of the dill herb, was from trace to 1.3 % in hot air dried samples and 3.5—20 % in freeze dried samples. During the drying secondary aroma compounds are formed consisting over 50 % of the total volatiles. Among these phytadienes, especially neophytadiene, were the major components. The best result was obtained by freeze drying, but the product contained only one quarter of the total aroma compounds of the fresh dill herb.