Jerusalem artichoke or Sunchoke

Taxonomy of the Jerusalem artichoke or Sunchoke
Superdominium/Superdomain: Biota
Domain/SuperKingdom: Eucarya
Kingdom: Plantae (Plants/Piante)
SubKingdom: Tracheobionta (Vascular plants/Piante vascolari)
Superdivisio/Superdivision: Spermatophyta (Seed plants/Piante con semi)
Divisio/Division: Magnoliophyta Takht. & Zimmerm. ex Reveal, 1996 (Flowering plants/Piante con fiori)
Subdivisio/Subdivision: Magnoliophytina Frohne & U. Jensen ex Reveal, 1996
Classis/Class: Rosopsida Batsch, 1788
Subclass/subclass: Asteridae Takht., 1967
SuperOrdo/Superorder: Asteranae Takht., 1967
Ordo/Order: Asterales Lindl., 1833
Familia/Family: Asteraceae Martynov, 1820
Subfamilia/Subfamily: Helianthoideae (Cass.) Lindl. in Loud., 1829
Tribus/Tribe: Heliantheae Cass., 1819
Subtribus/Subtribe: Helianthinae (Cass.) Dumort., 1827
Genus: Helianthus L. (1753)
Species: Helianthus tuberosus L. (1753)

The synonyms of Helianthus tuberosus are the following:
The common names in the world of the Jerusalem artichoke are:
The Jerusalem artichoke, also called the sunroot, sunchoke, earth apple or topinambour.
Jerusalem artichokes are native to North America. The French explorer Samuel de Champlain brought them to Europe after coming across them at Cape Cod in 1605. He described them as tasting like artichokes, and is likely to be responsible for this part of their name. The Jerusalem part is thought to be derived from girasole, the Italian for sunflower to which they are related. Another theory suggests the name is a corruption of Terneuzen, the Dutch city from where the root was introduced to England in 1616.
Topinambur is the transcription of a Brazilian word, this has induced some to consider the species of South American origin. The Canada potato name would seem to indicate North American origin as they would want the more recent guidelines. In fact it would have been found again for the first time in Canada in 1603 from the french Samuel Champlain who, imported it in France to 1604 . Already in the 1616 the naturalist and botanist Fabio Colonna, in the second edition of its work " Ecpharais" , it writes of this plant indicating it such as Flos solis farnesianus. In fact, this plant cultivated in the " Farnese" garden to Rome, it was known with the gross name of “sunflower articocco”.
Jerusalem artichokes were first cultivated by the Native Americans long before the arrival of the Europeans; this extensive cultivation obscures the exact native range of the species. The French explorer Samuel de Champlain found domestically grown plants at Cape Cod in 1605. The Jerusalem artichoke was titled “best soup vegetable” in the 2002 Nice festival for the heritage of the French cuisine.
Despite its name, the Jerusalem artichoke has no relation to Jerusalem, and it is not a type of artichoke, even though both are members of the daisy family.
The origin of the name is uncertain. Italian settlers in the USA called the plant “girasole”, the Italian word for sunflower because of its resemblance to the garden sunflower (both the sunflower and the sunchoke are part of the same genus: Helianthus). Over time the name “girasole” may have been changed to Jerusalem. To avoid confusion, some people have recently started to refer to it as sunchoke or sunroot.
The artichoke part of the Jerusalem artichoke's name comes from the taste of its edible tuber. Samuel de Champlain, the French explorer, sent the first samples of the plant to France, noting that its taste was similar to an artichoke.

Botanical characteristics, biology and physiology
It is a herbaceous perennial plant growing to 1.5–3 m tall with opposite leaves on the lower part of the stem becoming alternate higher up (Figure 1). The roots are branched (Figure 2) from which start the growth of the tubers. The tubers are elongated and uneven, typically 7.5–10 cm long and 3–5 cm thick (figure 5), and vaguely resembling ginger root, with a crisp texture when raw. They vary in colour from pale brown to white, red or purple (Figure 3). The leaves have a rough, hairy texture and the larger leaves on the lower stem are broad ovoid-acute and can be up to 30 cm long and the higher leaves smaller and narrower (Figure 4).
The flowers are yellow, produced in capitate flowerheads which are 5–10 cm in diameter, with 10–20 ray florets (Figure 5).
Pappi of 2 aristate scales 1.9-3 mm plus 0-1 deltate scales 0.5-0.8 mm. From this derive the fruits (Figure 6). About chromosomes 2n = 102. Helianthus tuberosus is variable, probably in part stemming from hybridization with other polyploids , including Helianthus pauciflorus, Helianthus resinosus, and Helianthus strumosus. Helianthus tuberosus is so widely spread as a weedy species that its original distribution is difficult to discern. It has been used as a food plant for its tubers by native Americans (although not necessarily domesticated or even cultivated) ; it has been developed as a crop primarily in Europe, where it has become widely naturalized. The common name Jerusalem artichoke is a misnomer.

Figure 1 – Plant of the Jerusalem artichoke. Figure 2 - Roots and tubers of the sunchoke.
Figure 3 – Tubers of sunchoke. Figure 4 – Leaves and inflorescences.

Figure 5 – Flowers of Jerusalem artichoke. Figure 6 - Fruits of the sunchoke obtained by a pappus.

The biological form of sunchoke is G bulb (perennial herbaceous plant, with subterranean bulbs).
The flowering is VIII-X.
The chorological kind is Avv (adventitious or naturalized species that spontaneously sprayed in nature on several territories different to native area.
The growth can occur at altitude (min/max) of 0/800 m.

Unlike most tubers, but in common with other members of the Asteraceae, the tubers store the carbohydrate inulin instead of starch. For this reason, Jerusalem artichoke tubers are an important source of fructose for industry.
The crop yields are high, typically 16-20 t/ha for tubers, and 18-28 t/ha green weight for foliage. Jerusalem artichoke also has a great deal of unused potential as a producer of ethanol fuel, using inulin-adapted strains of yeast for fermentation.
Jerusalem artichokes are easy to cultivate, which tempts gardeners to simply leave them completely alone to grow. However, the quality of the edible tubers degrades unless the plants are dug up and replanted in fertile soil. This can be a chore, as even a small piece of tuber will grow if left in the ground, making the hardy plant a potential weed.
The tubers are sometimes used as a substitute for potatoes: they have a similar consistency, and in their raw form have a similar texture, but a sweeter, nuttier flavor; raw and sliced thinly, they are fit for a salad. The carbohydrates give the tubers a tendency to become soft and mushy if boiled, but they retain their texture better when steamed (figure 7).

Figure 7 – Tuber yield of Jerusalem artichoke.

The inulin cannot be broken down by the human digestive system, which can cause flatulence and, in some cases, gastric pain.
Sunchokes have 650 mg potassium per 1 cup (150 g) serving. They are also high in iron, and contain 10-12% of the US RDA of fiber, niacin, thiamine, phosphorus and copper.
Jerusalem artichokes also can be used as an animal feed, while they must be washed for most animals, pigs can harvest them through their own volition. The stalks and leaves can be harvested and used for silage, though cutting the tops greatly reduces the harvest of the roots.
You will find Jerusalem artichokes in most textbooks but in few gardens. The knobbly tubers are used as an alternative to potatoes, fine for slimmers but not to everyone’s taste. To buy some and try them before planting a row. These grow anywhere hardy plants will tower up to 3 m or more, an excellent screen or windbreak but a line of them will form a light-robbing shield for lowly vegetables planted below. The name indicates a close relationship to the sunflower and not the Middle East. The name comes from the Italian word “girasole” (sun follower).

Plant facts
Tubers bought from the greengrocer or supermarket can be used for planting. Choose roots which are the size of a small hen’s egg.
The time between planting and sprouting is 2-4 weeks;
Expected yield per plant: 1.5-2.5 kg; Approximate time between planting and lifting: 40-50 weeks; Ease of cultivation: Easy, but staking will be necessary.

Soil facts
Plant in rows 45 cm apart, with a distance of 90 cm between rows. Plant 15 cm deep, and replace earth carefully. Make a low ridge with a rake.

Looking after the crop
There are few distinct varieties known. The literature mentions “Mommoth French White” and/or “French White Improved” as varieties, but it is believed that in most cases existing stocks are mixed to such a degree that strains, rather than true varieties, exist. A few varieties are listed and available from seed companies.
Interested growers should plant local stock which is known to be adapted to the area and produce acceptable yields. Since limited information about how well the varieties grow under Italy growing conditions, only small plantings should be considered to determine the most adapted variety before making large plantings.
If local plant stock cannot be found, the following table lists some possible seed sources:
use in the kitchen of Jerusalem artichoke
As Jerusalem artichokes have a tendency to collapse when cooked, they are commonly used in soup. Palestine soup made with Jerusalem artichokes and enriched with cream is a classic English dish. They can be used almost anywhere you would use potatoes: mashed, sautéed with butter and herbs, baked au gratin, or stewed in stock, and they make great chips.
The sweet, nutty flavour means they work well with salty foods such as ham and smoked fish. Chicken and game birds are other good partners. Jerusalem artichokes can be used raw and grated in salads, providing they are coated with lemon juice to prevent discolouration.
Here are some representations of Jerusalem artichokes prepared in the kitchen, in the pan (Figure 8) and sautéed (Figure 9).

Figure 8 - Topinambur in pan.

Figure 9 - Sautéed topinambur.

Handling and Storage
The skin of Jerusalem artichokes is very thin. Care should be taken in handling to avoid skinning, cuts and bruises. The skin is also susceptible to rapid moisture loss so the crop should be put in storage immediately after harvest. Cold storage facilities should have high humidity (85 to 95% relative humidity) and a temperature near15 °C. Under these conditions, tubers can be kept for several months. If the tubers are to be washed, fresh water sanitized with bleach should be used.

Quality Characteristics and Criteria: tuber size and shape are critical quality attributes and are strongly modulated by cultivar and production conditions. Many clones have an irregular tuber surface topography due to branching, an undesirable trait.

Horticultural Maturity Indices: the tubers are harvested in the late Fall, generally after the first frost. In production areas where harvest can be accomplished throughout Winter (see below), the crop can be field-stored and harvested as needed. Elsewhere, harvest is followed by cold storage.

Grades, Sizes, and Packaging: there are no existing standard grades. Generally larger tubers with smooth surfaces are preferred. Polyethylene bags are the typical package, though precise recommendations are not established. Package physical parameters vary with storage temperature, product volume, and other factors.

Pre-cooling Conditions: Generally pre-cooling is not required, though placing the tubers under favorable low temperature conditions as soon as possible after harvest is recommended.

Storage Options: the three primary storage options are refrigerated storage, common storage in root cellars, and in situ field storage. In common storage in root cellars, champs or pits, cooling is obtained from the natural low temperatures of the outdoor air and/or soil (Shoemaker, 1927). In the first two options (refrigerated and common storage), tubers are harvested in the Fall and placed in storage. With field storage, however, tubers are left in the ground and harvested as needed. Cold storage is highly effective, but costly. Regardless, refrigerated storage is routinely used for seed and fresh market tubers, especially in situations where field storage is not a viable alternative. Root cellars, champs, and pits are used when the tubers must be harvested in the Fall, prior to the ground freezing or other adverse conditions occurring, and refrigeration is not available or prohibitively expense.
The selection of in situ field storage is dependant upon several factors. Location is the primary determinant in the potential success of in situ field storage. Field storage is a viable option in northern hemisphere production areas where cold soil temperatures prevail throughout the Winter, but freezing of the soil surface is uncommon. Sandy, well-drained soils are preferred because they allow harvest throughout the Winter. Locations that do not meet these criteria generally require the use of refrigerated or some form of common storage.

Controlled Atmosphere (CA) considerations: the benefit of CA storage has not been adequately assessed. Storage of tubers in 22.5% CO2 + 20% O2, significantly retarded the rate of inulin degradation, apparently through an effect on enzyme activity .

Retail Outlet Display considerations: water loss accounts for the majority of postharvest losses during retail sales. Product should be displayed in refrigerated display cases and when not packaged, under high RH conditions such as that afforded by mist systems.

Chilling Sensitivity: tubers can withstand low temperatures without damage, but freeze at - 2.2 °C. Freezing at - 10 °C, whether in the field or storage, causes rapid deterioration, but nonlethal freezing at - 5 °C causes little damage. As with most fleshy plant products, temperature at which freezing damage occurs and extent of damage varies with cultivar, season, preconditioning, rate of freezing, and other factors.

Ethylene Production and Sensitivity: tubers are not sensitive to ethylene. To get mL/kg/h, divide the mg/kg/h rate by 2.0 at 0 °C , 1.9 at 10 °C, and 1.8 at 20 °C. To calculate heat production, multiply mg/kg/h by 220 to get BTU/ton/day or by 61 to get kcal/metric/ton/day.

Physiological Disorders
Storage losses are due primarily to desiccation, rotting, sprouting, freezing, and inulin degradation. Desiccation remains a significant storage problem even though losses can be fairly easily circumvented with proper storage conditions. Storage at high RH is essential because tubers lack of a corky surface layer similar to that found on potatoes to reduce water loss, and have a thin, easily damaged surface that permits rapid water loss. While beneficial for some produce, γ-irradiation greatly accelerates inulin degradation and is of little storage value.

Postharvest Diseases
Storage rots are a serious problem; higher storage temperatures result in greater loss. Approximately 20 organisms causing storage rots have been isolated from Jerusalem artichoke tubers.
The organisms most frequently isolated were: The indicated pathogens are the most serious organisms causing rots at low storage temperatures. Sclerotium rolfsii Sacc. and Erwinia carotovora spp. carotovora (Jones) Bergey et al., in contrast, are not significant pathogens at temperatures below 20 °C . Storage rots are controlled by storage at 0 to 2 °C, removal of diseased tubers, minimizing mechanical damage, and proper RH control.

Special Considerations
During storage, tubers undergo significant alterations in carbohydrate chemistry which, depending upon the intended use, can have a pronounced effect on quality. Inulin is not one compound, but a series of molecules of varying chain length that begin to depolymerize during storage, whether harvested or left in situ. The degree of polymerization is critical for uses such as fat replacement or high fructose syrups. With the former, as the chain length decreases, the ability of inulin to mimic a lipid diminishes. Likewise, with progressive depolymerization, the ratio of fructose:glucose decreases and upon hydrolysis yields a progressively less pure fructose syrup. For example, during Winter storage the fructose:glucose ratio decreases from 11 to 3. Thus, syrups derived from stored tubers contain a lot more glucose.

The Jerusalem artichoke is a very strong growing perennial and can become a weed problem. Since it is nearly impossible to harvest all the tubers in a field or garden, there will be a large number of volunteer plants the following spring. It is important to destroy all these volunteer plants before they can set tubers in August.


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