276 Handbook of herbs and spices
sheaves for a period of 7–10 days before they are threshed. This short period from
cutting to threshing is very essential, since then the fruits become finally formed and
coloured. Warm weather favours this process, however, too intensive insolation is
unwanted, when threshers are also used. However, transport of dry plants from the
field usually increases yield losses (Hecht et al., 1992). In a study by Wander (1997)
thresher drum speed had exhibited no adverse effect on seed or carvone yield while
threshing caraway. After threshing and mechanical cleaning, the fruits should be re-
dried down to 10–12% moisture content. Then for some time, the fruits should be
kept loose in a thin layer, being frequently mixed, within a dry and aerated storeroom
to finally establish their moisture content. Such prepared raw material is packed into
sacks and if inadequately stored, can go musty and mouldy, thus becoming useless as
raw material (Weglarz, 1998). Spices should be stored on a dry, cool and dark place
in order to keep the aroma as long as possible. The shade-dried seed contains more
oil content than the sun-dried seed. The seed can be cleaned easily with a screening
mill followed by a gravity separator. The fresh seed should be taken to the oil
extraction unit for more recovery of essential oil content (Malhotra, 2006a,b).
15.2.8 Cultivars
There are annual and biennial forms of Carum carvi, existing with slight uncertain
differences in morphological and anatomical characteristics between these two
morphotypes of caraway (Hornok, 1986). Concerning essential oil content, there is a
clear distinction between these two with about 3% for annual and 4% for biennial
caraway (Bouwmeester et al., 1995)
Different cultivars have been recommended for cultivation in different provinces.
The popular biennial type landraces and varieties of caraway are Noord-Hollandsche,
Mansholts and Volhouden. In 1972, a non-shattering variety ‘Bleija’ was developed
through Volhouden and Mansholts. Two spring type annual caraway varieties ‘Karzo’
and ‘Springcar’, were both registered in the years 1993 and 1995, respectively. In the
Mediterranean region, varieties mostly originated from local wild populations and
they are known as ‘Balady’ in Arabic. In order to get the highest seed, essential oil
and carvone yields, the identified varieties/landraces popular in a province should be
used for cultivation. There is one report of transgenic caraway from the Netherland
(Krens, et al., 1997). A population of annual caraway was evaluated over nine years
for quality parameters in comparison to biennial caraway in the Central German area.
Annual caraway has the potential to reach yield and quality levels of biennial varieties.
Plant height, 1000-seed weight, carvone content and taste were satisfactory, but
earliness, homogeneity, yields, contents of essential oils and colour need improvement.
Also, the causes of low seed germination (40%) have to be investigated (Pank and
Quilitzsch, 1996).
Clear agro-botanical differences were observed between wild and cultivated
populations. Cultivated populations were characterized by a longer growing period,
differences in rosette growth habit, larger and heavier seeds, and a higher and more
constant seed germination capacity. The essential oil content of all seeds was
variable (2.3–7.6%); the average oil contents of wild and cultivated forms were 5.0
and 5.1%, respectively. The highest oil contents were found in a cultivated Swiss and
a wild Finnish population (7.6 and 7.5%, respectively). The average oil content of
wild Finnish populations was significantly higher (5.3%) than that of cultivated
Finnish forms (4.8%). The main constituents of most of essential oil