Jerusalem artichoke

Profile

Family

Asteraceae

Habit

perennial

Height

2.4 m

Spread

0.6 m

Growth

very fast

Lifespan

10 years

First yield

after 1 year

Hardiness

zone 4–9

Shade tolerance

light shade

Soil

Sand, Silt, Loam

Soil moisture

dry – very wet

pH

6 – 7.5

Synonyms

Topin Ambur, Jerusalem-Artischocke

Planned in gardens

3×

Flowering & harvest

Times apply to the northern hemisphere in a temperate climate and shift with altitude and cultivar.

Uses

Edible: Knollen – roh oder gekocht . Die Knolle entwickelt im Winter, insbesondere bei Frost, eine angenehm süße und ist dann einigermaßen verträglich. Ansonsten eignet sie sich am besten zum Kochen und kann wie Kartoffeln verwendet werden. Die Knollen sind reich an Inulin, einer Stärke, die der Körper nicht verdauen kann. Topinambur bietet daher eine reichhaltige Nahrungsquelle ohne viele Kalorien. Manche Menschen vertragen Inulin nicht gut, da es im Darm gärt und starke Blähungen verursachen kann. Die Knollen sind recht groß, bis zu 10 cm lang und 6 cm im Durchmesser. Da die Knollen leicht Druckstellen bekommen und schnell Feuchtigkeit verlieren, lässt man sie am besten im Boden liegen und erntet sie erst nach Bedarf. Das Inulin aus den Wurzeln kann in Fruktose umgewandelt werden, eine süße Substanz, die auch für Diabetiker unbedenklich ist. Die gerösteten Knollen dienen als Kaffeeersatz. Der Geschmack der Topinamburknollen ist süßlich, die Konsistenz wässrig und sie erinnert an Artischockenböden und Süßkartoffel. Die Knolle können sowohl roh in Salaten als auch in Salzwasser gekocht verzehrt werden. Auch frittiert wie Kartoffeln sind sie zum Essen geeignet. Ebenso kann ein Saft als Getränk zubereitet werden. Unter saurem Milieu kann dieser eingedickt werden und ergibt einen 90%igen Fructosesirup. Der goldgelbe bis braune Topinambursirup wird als alternatives Süßungsmittel verkauft. Besonders hervorzuheben ist der Inhaltsstoff Inulin, ein unverdauliches Polysaccharid. Als wasserlöslicher Ballaststoff ist Inulin ein wichtiges Präbiotikum. Der Gehalt an Inulin ist zum Zeitpunkt der Ernte am höchsten und sinkt bei der Lagerung ab. Der Gesamtgehalt (auf die Masse) an Zuckern bleibt dabei konstant.

Medicinal: Jerusalem artichoke is believed to have laxative, aphrodisiac, cholagogic, diuretic, spermatogenic, stomach-strengthening, and tonic effects, serving as a folk remedy for diabetes and rheumatism. The tubers, popular among diabetics, consist of 16% carbohydrates in the form of the polysaccharide inulin. Since 1922, Jerusalem artichoke has been included in diets as an adjunct to diabetes treatment. Inulin, a long-chain sugar compound, acts as a non-digestible fiber in the gut, fermenting in the colon and potentially causing flatulence. Regular inulin intake with food has been shown to lower blood lipid levels and promote the presence of Bifidobacteria. Trials conducted with weaning piglets as alternatives to growth promoters have encouraged the formation of lactoflora. In health food stores, Jerusalem artichoke is sold as chewable tablets or drinks to be taken before meals, mixed with water to swell in the stomach and slightly suppress appetite. The tuber contains betaine, choline, and saponins, believed to have anti-cancer properties. Additionally, Jerusalem artichoke contains polyphenols with potent antioxidant effects, protecting the plant from pests and harmful environmental factors. These compounds act similarly in the human body, making them highly beneficial for health. The tubers contain the phenolic acids salicylic acid (with antimicrobial and anti-inflammatory effects), chlorogenic acid (an antioxidant), and gentisic acid (bacteriostatic effects).

Other uses: The plants are a good source of biomass. The tubers are used industrially for producing alcohol, among other things. Alcohol fermented from the tubers is said to be of higher quality than that from sugar beets. Topinambur is a fast-growing plant that can be cultivated as temporary summer cover. It is short-lived, reaching a suitable height only in July before dying off in October. Topinambur has been used for distillation since the late 19th century. In Baden, the tubers are processed into a digestive schnapps known by various names such as "Topinambur brandy," "Topinambur," "Topi," "Erdäpfler," "Erdgold," "Rossler" (derived from Ross potato), or "Borbel." Topinambur brandy has a fruity aroma and a slightly nutty-sweet flavor. It is characterized by an intense yet pleasant earthy taste, reminiscent of gentian. Before distillation, the Topinambur tubers must be thoroughly washed to remove all traces of soil. Inadequate cleaning can result in an unpleasant taste, and in the worst case, lead to fermentation issues. Topinambur brandy is sometimes refined into "Red Rossler." This involves infusing it with bloodroot roots, extracting plant compounds that give "Red Rossler" a slightly bitter and astringent taste, as well as its red color. "Red Rossler" is used as a home remedy for stomach upsets, diarrhea, or abdominal pain, but is also enjoyed without physical discomfort, such as to aid digestion after a hearty meal. Besides bloodroot, other ingredients like currants are used in making "Red Rossler." "Red Rossler" is sold with an alcohol content of 40–45% by volume. Currently, over 90% of the harvested Topinambur tubers in Germany are processed into spirits in fruit distilleries. The length of the non-fermentable inulin molecules has little significance during fermentation and subsequent distillation into spirits. According to the Spirits Monopoly Act, Topinambur is classified as a fruit substance. To a lesser extent, Topinambur was also used as a raw material for fructose production. Fructose is interesting because it is sweeter than sugar (sucrose) or glucose. However, sugar extraction from Topinambur was challenging and costly and was no longer pursued around the Second World War. Today, there are techniques that make it easier to produce fructose from Topinambur by utilizing the fact that fructose is already present in high concentrations in the tuber after the hydrolysis of the polysaccharide inulin. In the past, Topinambur was also fed to domestic animals (cattle, horses, pigs). The closely related species Helianthus maximiliani is still used as animal feed in the USA. Today, products are available as supplementary feed for horses, dogs, and small animals. It is considered excellent feed for sheep and pigs. Topinambur is also grown as a wildlife food plot and feed. Rabbits, red and roe deer dig up the tubers, while the stems provide good cover for birds and small animals. Wildlife mainly consumes the young shoots for grazing. Adult plants are rarely eaten by wildlife, as the leaves are apparently too rough. Especially in midwinter, the tubers are exposed by animals. The Topinambur wildlife plot helps minimize browsing and damage to the adjacent forest. In addition to wild boars, muskrats, rats, voles, and wild rabbits also feed on the tubers. Since Topinambur is a neophyte and partly invasive, planting should not be done near flowing waters. This can lead to significant damage to the bank protection due to the burrowing activities. The burrowing activities of rodents also contribute to the spread of the plants. Tubers and tuber fragments exposed by rodents are often washed away by flowing waters and then colonize new habitats. Although Topinambur can now be considered an invasive plant, cultivation under regulated conditions is very feasible and beneficial. Due to its good cultivation properties and high biomass production, Topinambur can also be used as an energy crop and plays a potential role as a renewable resource. Both the vegetative parts and the tubers can be fermented into biogas and bioethanol or dried and processed into fuel. Before ethanol production, the tubers should have experienced frost to activate inulinase, which converts the inulin present in the tuber into fermentable sugars. A multi-year culture is possible for biogas utilization. The dry matter yield (foliage and tubers) can reach up to 30 tons per hectare. Approximately 8140 cubic meters of biogas per hectare can be obtained from the foliage, about 10% less than from silage maize cultivation. If the tubers are also harvested, an additional yield of about 2150 cubic meters of biogas per hectare is possible. However, there have been only a few years of cultivation experience with Topinambur for energy use. In ethanol refining, the inulin yield and the form of inulin molecules have little influence. Topinambur is now only surpassed by sugar beet in bioethanol production. Topinambur can also be dried and used as fuel in pellet form. They can be used in wood chip or pellet heaters without modifications. On average, 3.1 kg of Topinambur foliage pellets correspond to the heating power of 1 kg of heating oil.

Growing

The plant is easy to grow, thriving best in loose, neutral loam but also doing well in sunny locations on most soils and under various conditions. It prefers nutrient-rich soil for higher yields, with lighter, well-drained sandy loams being more suitable to avoid damaging tubers during harvest. It dislikes shade and benefits from some lime in the soil. Topinambur can withstand annual rainfall ranging from 31 to 282 cm, average temperatures between 6.3 to 26.6°C, and a pH range of 4.5 to 8.2. Originally cultivated by Native Americans as a food crop, Topinambur is now grown in temperate zones for its edible tubers, with specific named varieties available. It is adaptable to all soil types and climates where maize grows, surviving in poor soils and cold regions like Alaska, tolerating both heat and frost. While the first frost kills stems and leaves, the tubers can endure months of frost. Particularly suitable for dry regions and poor soils, Topinambur yields more than potatoes. Tuber production responds to decreasing daylight in late summer, averaging between 1 and 2 kg per square meter. Highly cold-resistant tubers can be left in the ground over winter but may attract snails. In areas prone to snail infestation, it is advisable to harvest the tubers in late autumn for winter storage. Due to vigorous spring growth, not all tubers can be harvested at once. In Northern Europe, the plants do not flower, being sensitive to daylight length, requiring longer light periods for growth and shorter ones for tuber formation, not thriving in areas with short days. An effective weed suppressor, Topinambur provides dense shade outcompeting other plants. Its young shoots are highly attractive to snails, posing a threat to the plants. Species of this genus are rarely if ever bothered by browsing deer or rabbits. In the specified zones, Topinambur is heat-resistant. It blooms in the UK only after a long, hot summer, rarely producing seeds. It grows well alongside maize and can be invasive. The plant spreads through rhizomes or runners, with a root system consisting of swollen, potato-like roots.

Propagation

Seed: Sow in a cold frame in spring. Once seedlings are large enough, transplant them into individual pots and keep them in the greenhouse throughout the first winter. Plant them in late spring or early summer, after the last expected frosts, in their final position. Divide in spring or autumn. Harvest tubers in late autumn or winter, either replant immediately or store in a cool, frost-free place and plant in early spring. Jerusalem artichoke propagates through tubers, best planted as early as possible in spring when the soil can be worked well. Late planting generally reduces tuber yield and size significantly. Whole tubers or pieces of about 50 g (2 oz.) should be planted like potatoes, covered to a depth of 10 cm. Pieces over 50 g do not increase yield, but smaller ones decrease it. Planting deeper can delay emergence, weaken shoots, and cause tubers to develop deeper, complicating harvest. Basal cuttings in spring. Harvest shoots when they are about 10–15 cm long with a sufficiently large underground stem. Pot them individually and place in a cold frame or greenhouse in partial shade until well-rooted. Plant them out in summer.

Origin & habitat

Eastern North America - From Nova Scotia to Minnesota and Kansas. Sometimes found growing wild in the wild.

Shallow water and moist soil, steering clear of highly impoverished soils and extremely acidic environments.

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