280 Handbook of herbs and spices
columns were used to obtain enantiomeric separation of both aroma compounds and
two varieties of caraway were used for investigation. In Plewicki, the concentrations
of limonene and carvone were 31.41 and 36.24 mg/g, respectively, and in Konczewicki
they were 17.60 and 22.46 mg/g, respectively. The enantiomeric ratio was stable for
both compounds in the analyzed samples. The purity, expressed as a percentage of +
optical form to total, was high for R(+)-limonene (99.1–99.5%) and S(+)-carvone
(99.4–99.8%) in caraway seed oils (Zawirska, 2000). Microsomal preparations from
fruits of annual (cv. Karzo) and biennial (cv. Bleija) forms of C. carvi catalyse the C-
6 hydroxylation of (+)-limonene to (+)-trans-carveol, the key intermediate in the
biosynthesis of carvone ((+)-limonene-6-hydroxylase activity) as reported by
Bouwmeester et al., (1998, 1999).
The biosynthesis of the monoterpenes limonene and carvone in the fruits of caraway
(Carum carvi) proceeds from geranyl diphosphate via a three-step pathway. First,
geranyl diphosphate is cyclized to (+)-limonene by a monoterpene synthase. Second,
this intermediate is stored in the essential oil ducts without further metabolism or is
converted by limonene-6-hydroxylase to (+)-trans-carveol. Third, (+)-trans-carveol
is oxidized by a dehydrogenase to (+)-carvone. The presence of antiproliferative
polyacetylenes was suggested in Carum carvi (fruit and root) and were successfully
isolated by Nakano et al., (1998).
The coumarins in caraway seed were identified as umfelliferone, coumarin and
scopoletin, (Nielsen,1970) whereas the furocoumarins reported are 8-methoxypsoralen
(8-MOP). Five methoxypsoralen (5-MOP) were detected of bioassay of caraway
seeds of low quality of 0.005 mg/g of dry weight (Ceska et al.,1987). The coumarins
and furocoumarins are known to have antibacterial, potent photosensitizers when
activated by near UV light and thus they are phototoxic, mutagenic and photo-
carcinogenic and also exhibit strong seed germination inhibiting action. Due to such
properties as described by Ruszkowska (1998) coumarins have been identified for
utilization in psoriasis treatment and in sunscreen lotions preparation.
The presence of a high content of phenolic substances is attributed significantly as
a stabilizing effect of some spices on food especially on meat products. The phenolic
functional group is known to have antimicrobial or antioxidant properties of active
substances. The phenolic compounds identified in Carum seed are flavonoids,
glycosides, derivatives of quinic acid, proteids and tannins. The isolation of a flavone
from the methanolic extract of the seeds of Carum carvi was characterized by Rahman
and Hossain (2003) as 4¢,5,7-trihdyroxy-2¢-methoxyflavone.
The major constituents of essential oil of caraway are carvone and limonene,
which are known to possess insecticidal or insect-repellent effects (Zuelsdorff and
Burkholder, 1978, Su, 1987), antibacterial and antifungal effects (Janssen, et al.,
1988), inhibition of seed germination (Asplund, 1968) and sprouting in potatoes
(Beveridge, et al., 1981). The chemical structures of carvone and limonene, the
major compounds of caraway essential oil, are illustrated, in Fig. 15.1.
15.4 Main uses in food processing........................................................
Caraway is widely used as a spice for culinary purpose and for flavouring various
food products. The main caraway products are fruit (generally known as seed), herb
and seed oils. It was popular from ancient times for its use in folk medicines and the
entire plant of caraway has its herbal value but commercially it is valued for fruit.