Chemical constituents and taste
Spices provide of course only little contribution to the human nourishment. But they make food more tasty and enhances the appetite. The taste depends on certain chemical compounds mainly on essential oil content and composition. But not only the essential oil is responsible for the taste impression, also some of the other chemical components of caraway fruits are influencing the taste ().
Beside the mentioned chemical compounds, caraway contains tocopherol and tocotrienole, phenol-carbonic acids such as caffeic acid and gentisic acid, phenols and flavones (flavonole, quercetin etc.).
Description of the Taste
It is well known that the sense of taste can be realized as salty, bitter, sour and sweet with the tongue. Pungency is an impression of temperature and pain. Additionally we are smelling with the olfactory nerve such odours as aromatic, fruity, flowery, resinous, but also foul or burning ().
The taste and odour of caraway fruits is due to their essential oil content, which consists of two main components, the D(+)-carvone (45–60%) and the D(+)-limonene (35–55%). The latter one is not so important for the taste.
To describe a taste is very difficult. Therefore many different definitions can be found. Some of them are given below:
Warm biting but pleasant, slightly minty, medicinal (); tangy, tasty (); the smell is peculiar aromatic, the taste is spicy (); aromatic, spicy and somewhat burning, the smell is strongly aromatic ().
Herbs and spices are showing big differences concerning the ability to develop their aroma. But for the food industry it is very important to have standardized spices, which should not differ too much from one lot to the other. Seasonings are often composed from different spices. Triebe and Zobel () proposed a system with regard on the intensity of the three main taste components (Table Evaluation scale for the intensity of the three main taste components).
Corresponding to the intensity, the doses should be chosen (strong spices low amounts, weak spices high amounts). According to the authors, caraway should be on the average measured out from 0.7 to 1g per portion or one great pinch between three fingers.
Table Evaluation scale for the intensity of the three main taste components
|Taste intensity||Examples of spices for the taste|
|Weak||portulak||Tripmadam||lime tree blossom|
|Very weak||marsh mallow||lemongrass||blue lungwort|
The use of caraway fruits as spice
Caraway appears on the GRAS-list, a list of food additives which are generally recognized as safe by the FDA (Federal drug administration, USA) and is used as spice, seasoning, flavouring, oil and extract ().
Caraway is mainly commercialized as a dried, fallen apart mericarp, as a whole, broken or ground. Whole fruits are 3–7mm long, 1–2mm thick and slightly curved. The surface is dark brown with five main yellow rips. Although the quality standards of commerce are not very high, light coloured and uniform fruits in size and shape are of advantage. The darker the fruits are, the lower the price. Supposedly caraway from the Netherlands is somehow larger than from Eastern Europe () and is called “straw caraway” (). The essential oil content is not as important as far the whole fruits are commercialized and the typical taste is obvious. In general, annual caraway has lower essential oil contents than biennial.
Good quality product consist of not more than 2% foreign bodies (), whereas Siewek () pointed out, that good quality allows not more than only 0.2% foreign bodies.
Caraway powder has a yellowish-brownish colour and is not easy to distinguish from fennel powder. Under the microscope fragments of the endosperm there is often only the epidermal tissue to observe and the transverse cell layer is to realize whereas the secretory cavities are destroyed ().
Melchior and Kastner () are reporting some adulterations, especially with gout weed (Aegopodium podagraria L.). The mericarp of gout weed is smaller, round and dark brown. Siewek () but also Seidemann () pointed out, that in the past some cases of adulteration took place, but nowadays not. But it may happen that lower quality products of caraway are mixed with better ones.
Caraway is sometimes mixed up with cumin (Cuminum cyminum L.). Both species look very similar, but their taste is distinctly different.
Spices are sometimes heavily contaminated with different germs. Hartgen and Kahlau () have examined different spices in household packages for their contamination with Clostridium and assessed the colony number on plate count agar. They found that some spices were particularly heavily contaminated, especially pepper, curry, paprika, basil, allspice, coriander and chillies. Caraway was not among the contaminated spices.
To prevent contamination, it is necessary that caraway is harvested when the fruits are dry enough to be stored. If they are not, an artificial drying is necessary. A disinfection is not usual.
A joint group of FAO/IAEA/WHO investigated chemical, sensorial and toxicological effects on irradiated spices. They found that an irradiation of caraway seeds with 10kGy caused no toxicological problems, but the aroma was somehow altered ().
Spices, and as well as caraway fruits are normally packed in small glass bottles, coated paper bags or synthetic materials (PA/PE bags). The packing material should be impermeable for aroma compounds. Therefore the fruits have to be dry enough to prevent moulding (). Spices should be stored on a dry, cool, and dark place in order to keep the aroma as long as possible.
Use of the fatty oil for technical purposes
Petroselinic acid is an important raw material for oleochemical processes and can be easily cracked into lauric and adipinic-acid (). As fatty oil from caraway seeds is comparatively rich in petroselinic acid and some origins also in fatty oil content, the fatty oil of caraway fruits may be also used in the oleochemical industry.
The use of caraway roots as vegetable
Caraway roots can be cooked like carrots and have been used as a vegetable mostly in North European countries (). The saccharose content is comparable to that of carrots. In Nordic countries precocious shooting is not desirable, if the roots with young leafs are used as vegetable in early spring (). The frost resistant plant is rich in minerals and was in former days an early source of vitamin C. Nowadays still some, but very few people make caraway soup but it is not a common and even little known dish in Scandinavia. In Norway some efforts were made to reintroduce it as vegetable but up to now with little success ().
Use of the blooming plants as bee-pasture
Like most Apiaceae (Umbelliferae), caraway is visited by bees rather frequently, and is also described in the literature as a good bee-pasture (). However, no figures has been found about the real honey-yield capacity of caraway blossoms. As the acreage of caraway is normally not very large, it is not probably worthwhile for the beekeeper to produce “caraway honey” (despite the taste question).
Selections from the book: “Caraway. The Genus Carum”. Edited by Éva Németh. Series: “Medicinal and Aromatic Plants — Industrial Profiles”. 1998.