Nettle seed oil

Nettle seed oil
Raw material plant (noun)	Big nettle ( Urtica dioica ) or pill nettle ( Urtica pilulifera )
colour	green-yellow to pure green
ingredients
Oleic acid	7-20%
Linoleic acid	66-86.5%
Linolenic acid	(0) 0.8-2%
Palmitic acid	4-7.5%
More fatty acids	Stearic acid (0) 4-7%
Other ingredients	Tocopherol approx. 400 mg / kg
properties
density	0.9266 kg / l
viscosity	${\displaystyle \eta }$= at 20 ° C: 48.89 mPa · s; at 35 ° C: 27.47 mPa · s; at 50 ° C: 17.46 mPa · s
Oxidation stability	5 h
Iodine number	138; 151.2 (Hanus)
Saponification number	170-187
Manufacturing and Consumption
use	Diet, fuel oil, medicine

The nettle seed with a seed coat

Nettle seeds: a - whole; b - in longitudinal section

Nettle seed oil is a vegetable oil obtained from the ripe seeds of the great nettle ( Urtica dioica ) or the pill nettle ( Urtica pilulifera ). The nettle seed oil is often also called nettle oil or nettle seed oil .

General chemical structure of vegetable oils, such as nettle seed oil. R ¹ , R ² and R ³ therein are long-chain alkyl radicals (≤ 10%) or alkenyl radicals (approx. 90%) with a mostly uneven number of carbon atoms. Like other vegetable oils, nettle seed oil is a mixture of triesters of glycerine , i.e. a triglyceride .

properties

The nettle seed oil is green in color and has a pleasant, fresh odor similar to carrot juice. The taste depends on the degree of refinement. Further key figures are:

Physical Properties

• Freezing point = −23 ° C
• Refractive index = 1.4770 at 20 ° C
• Dispersion = 44.33
• Crismer number = 106

Chemical properties

• Acid number = 6.1
• Ester number = 180.7
• Rhodian number = 85.5
• Hexabromide number = 2.59
• Acetyl number = 7.51
• Reichert-Meißl number = 0.31
• Poland's number = 0.20
• Hehner number = 95.51

composition

About 90% of the fatty acid residues in the triglycerides of nettle seed oil are unsaturated fatty acid residues and saturated fatty acid residues have a proportion of ≤ 10%.

Manufacturing

Growing the nettle exclusively for oil production is inefficient, as there are currently no cultivars with sufficient yields. However, when it is grown as a fiber crop on a large scale (such as during World War II) it produces enough seeds to make oil.

Semen extraction

The optimal harvest time is late September to mid-October, when the seeds are ripe. The plants are cut as in fiber production, but not placed in a crouch , but bundled and hung upside down. After sufficient drying, the seeds are shaken out into a cloth.

Since the seeds do not ripen at the same time, ripe seeds have to be separated from unripe ones, especially with the early harvest for fiber production in late summer it is necessary to separate the seeds, since there are more unripe seeds. The separation can be done by water because ripe seeds do not float in contrast to the immature ones and therefore collect at the bottom of the vessel.

Oil extraction

For research purposes, the pure oil is obtained by petroleum ether extraction. The extraction usually takes place in the following sub-steps:

• Crushing of the nettle seeds with a mortar , grinding etc. to enlarge the surface
• Add about 2.5 ml of petroleum ether (e.g. heptane ) to 1 g of nettle seeds
• Mix by shaking and stirring (e.g. with a magnetic stirrer )
• The mixture of substances is heated in a water bath
• From pipetting the fat phase (upper phase)
• Evaporation of the petroleum ether
• Bottling of nettle seed oil

Cold pressing or maceration is often used for conventional oil extraction , for example with sesame oil .

use

The nettle seed oil is a high-quality cooking oil with a slightly nutty herbal aroma. The use of just a few drops is recommended as it is very concentrated. With a good vegetable oil such as B. Olive oil , diluted in a ratio of 1: 3, it can be used for salads, sauces and in general for cold dishes. The oil can also be used to steam vegetables (e.g. onions).

Nettle seed oil was also used as fuel and lamp oil in the past.

Furthermore, nettle seed oil is said to help with hair loss, rheumatism , cell renewal , blood cleansing, skin rashes and the shrinkage of a myoma through internal or external use.

Breeding and crossing experiments

So far, there have only been a few breeding attempts to achieve increases in yield. Cross-breeding experiments were carried out between the great nettle and the pill nettle. The aim was to combine the abundance of Urtica dioica seeds (up to 20,000 seeds per plant) with the very large oil-containing seeds of Urtica pilulifera ( TKM of 2.63 g) in order to increase the oil yield. The aim was to make the oil commercially usable as a valuable by-product in addition to the fibers obtained. All attempts at crossing failed. In the future, the oil content, which is 32.65%, as well as the number of seeds and the TKM could be increased through breeding.

Possible confusion with other oils

Two types of oil are sold under the names nettle oil, nettle seed oil and nettle seed oil. The name nettle oil is usually only understood as an extract from unspecified parts of the nettle plant such as leaves or roots with a vegetable oil such as B. sunflower or rapeseed oil and not the oil obtained from the seeds. Nettle seed oil, on the other hand, is the oil pressed from nettle seeds, but depending on the type of extraction it may contain other oils such as sesame oil .

literature

• R. Prögler: The nettle seed oil . In: Fats and Soaps. Volume 48, Issue 9, September 1941, online (PDF; 19.67 MB), Chemisches Zentralblatt. No. 7, 1942, p. 946, on delibra.bg.polsl.pl, accessed on May 15, 2017.
• Klaus Becker and Stefan John: Color atlas of useful plants in Central Europe. Ulmer, Stuttgart (Hohenheim) 2000, ISBN 978-3-8001-4134-0 .
• Joachim Hackbarth : The oil plants of Central Europe. Scientific publishing company, Stuttgart 1944.
• Gustav Bredemann : The great stinging nettle - research on its cultivation for fiber production. Akademie-Verlag, Berlin 1959.

Web links

• Feed additive "nettle seeds"
• Kew Gardens , Seed Information Database: Search: Genus: Urtica (Eng.)

Individual evidence

1. ↑ ^{a b c d e f g} Vandna Sharma: Analysis of the oils from unconventional oil bearing seeds from plants in Himachal pradesh. Himachal Pradesh University, 1995, Chapters 6-2, online (PDF; 713 kB), archived at Shodhganga , accessed on May 15, 2017.
2. ↑ ^{a b c d e f g h i j k} R. Prögler: The nettle seed oil . In: Fats and Soaps. Volume 48, Issue 9, September 1941.
3. ↑ ^{a b c d e f g} Sibel Uluata, Nurhayat Özdemir: Antioxidant Activities and Oxidative Stabilities of Some Unconventional Oilseeds. In: J. Am. Oil Chem. Soc. 89 (4), 2012, pp. 551-559, doi : 10.1007 / s11746-011-1955-0 .
4. ↑ Lilian Meier: Grosse nettle - Urtica dioica , 2008 (PDF; 251 kB), on kon-text.ch, accessed on May 15, 2017.
5. ↑ Andreas Paul: Discovering Biology Today SII. Bildungshaus Schulbuchverlage, Braunschweig 2004, ISBN 978-3-507-10560-7 , p. 475.
6. ↑ Klaus Becker and Stefan John: Color atlas useful plants in Central Europe. Ulmer, Stuttgart (Hohenheim) 2000.
7. ↑ SPECIES: Urtica dioica: Botanical and Ecological Characteristics. US Forest Service.
8. ↑ G. Bredemann: The Great Stinging Nettle - Research on its cultivation for fiber production Akademie-Verlag, Berlin 1959.
9. ↑ Heidelore Kluge: Stinging nettle: medicinal plant and more. Haug, Heidelberg 1999, ISBN 978-3-7760-1751-9 .