278 Handbook of herbs and spices
the odour and flavour are attributed. The essential oil concentration of seeds was in
the range 2.9–5.1% (v/w). The carvone and limonene contents of the essential oils
were in the range 59–77% and 26–41%, respectively from C. carvi (cv. Sylvia) in
Norway (Dragland and Aslaksen,1996).
The chemical constituents of caraway can be classified as primary and secondary
metabolites. The first group comprises substances playing a vital role and necessary
in normal cell life processes, the second is usually of broader interest due to the
presence of bioactive substances contributing to flavour, fragrance and medicinal
value. Our major concern is with secondary metabolites as they yield bioactive
substances specific to a crop species. Thus, the growing interest nowadays is for
secondary metabolites, viz., terpenes, flavonoids, coumarins and phenolic constituents
of Carum carvi due to their antioxidative properties. The main primary metabolites
identified and characterized for caraway samples by various workers are saccharides
(monosaccharides – glucose, fructose, disaccharides-sucrose; trisaccharides –
umbelliferore (Hopf and Kandler 1976), lipids (triglycerides, 66%; free fatty acids,
5.1%, steroids, 0.4%, hydrocarbons, 0.2%; chlorophyll, 0.2%; waxes,0.1%; free alcohol
0.1% (Stepanenko, et al.,1980), amino acids such as alanine, phexylalanine, methionine,
glutamic acid, serine and valine (Perseca et al., 1981), endogenous abscisic acid
(ABA) 120 mg/kg of d.wt (Mendez, 1978) and other minor miscellaneous constituents,
caraway choline, 0.03–0.15% (Matsuzawa and Kawa, 1996). A linear relationship
between ABA content and dormancy degree in caraway seed has been noticed (Hradlik
and Fiserova, 1980). The constituents carvacrol, cumin alcohol and cumin aldehyde
found in volatile parts of caraway essential oil are phenolic substances.
Research on the constituents responsible for the antioxidant properties of Carum
has led, among others, to carvacrol (Lagouri and Boskau, 1995) and dihydro-derivatives
of main terpenes-dihydrocarbon and dihydrocarvecol are the important mixtures of
stereoisomer. The contents of other minor and trace substances in the oil may vary
within broad limits as shown in Table 15.1., which presents an analysis of seed
samples from Egyptian origin and mid-European countries. Upon hydro-distillation,
the seeds gave 3.5% oil on dry weight basis and upon GC-MS examination, the oil
was found to contain carvone as a major constituent (81.5%) Chowdhury (2002). The
other constituents identified were citronellyl acetate, dihydrocarvone, eugenol,
isolimonene and limonene oxide, d 3-carene, camphene, caryophyllene, carveol, r-
cymene, dihydrocarveol, linalool, r-mentha-2,8-dien-1-ol, myrecene, a-pinene, b-
pinene, phellandrene, sabinene, a-terpinene and terpinelene and were isolated in
trace amounts.
In field tests carried out over several years in Vienna, Austria, essential oil content
was 2.8–3.3% in annual and 3.9–5% in biennial caraway cultivars. In caraway, cis-
and trans-dihydrocarvone and some isomers of carveol and dihydrocarveol were
present in the range 0.5–1% each. Solvent extraction of the crushed seeds with
hexane, a method using triple extraction and ultrasonic treatment, led to nearly identical
results as hydro-distillation with dill, but to carvone values 16% lower with caraway
(Bailer et al., 2001). The four varieties (Gintaras, Rekord, Chmelnickij and Prochana)
were studied by Venskutonis et al., (1999) under different nitrogen fertilizer regimes
(0–120 kg ha–1) and found that total content of essential oils in fruits varied from 1.9
to 4.3 ml 100 g–1. Percentage concentrations of the main caraway compounds limonene
and carvone were in the range 38.2–52.3% and 45.7–59.7%, respectively. These
compounds accounted for more than 96% of the total essential oil of all analyzed
samples.