JERUSALEM Artichoke an Inulin Source

The Jerusalem artichoke (Helianthus tuberosus L.) grows as a native plant over a large part of the United States, being most abundant in the Corn Belt. It is usually found in the most fertile soils, especially in the alluvial soils bordering streams, and occurs from Alabama to Ontario and from the Atlantic coast to Kansas and Nebraska. It was introduced into Europe, probably by the French, in the early part of the seventeenth century. It was erroneously credited to Brazil, and this mistake was not, corrected by botanists until the decade between 1880 and 1890.  As a crop plant it is new, having had little improvement at human hands. The present varieties in the United States have all been wildlings. It thus forms an interesting study in the origin of cultivated crops.

FIG. 128.—Jerusalem artichoke varieties. Left to right, from San Francisco, Calif., Toronto, Canada, and Norfolk, Va.

The Jerusalem artichoke has a varied usefulness. It is peculiar among our cultivated field crops in that it stores its carbohydrates as inulin rather than as starch. This character is connected with much of its interest and usefulness.

At present it is most extensively grown in France, where about 300,000 acres are planted annually. The tubers there are largely used for feeding cattle and sheep, though part of the crop is fed to swine and horses. It is very widely grown in both the Northern and Southern Hemispheres, being quoted by seedsmen from Sweden to New Zealand. Outside of France, however, it is nowhere an important crop. In the United States, where it is native, it is known to many people but is not extensively planted.

This plant is very productive and its culture is not expensive. But there are difficulties in storing the tubers, on account of shriveling and decay, and the plant has a considerable reputation as a weed.

As a human food it gives a pleasant variation to potatoes and garden roots. Probably its widest use at present is in the form of homemade-pickles. When boiled it is much more watery than potatoes or the ordinary roots. It has a decidedly sweet flavor in all types of cooking. Probably the best mode of preparation is as chips, made by frying thin slices in deep fat. These are very crisp and are much sweeter than potato chips. They may also be prepared by baking in a slow oven, thus becoming less watery.

Recent experiments have shown that the Jerusalem artichoke may be used by diabetic persons to a much greater extent than any foods containing starch. This fact has given it great interest to a large and apparently increasing group of people who are subject to this disease. Thus it appears to be on the way to wider use as a human food generally, since if used extensively as a food for diabetic patients its use will doubtless spread to other people.

Its greatest usefulness in the past has been as a stock feed. The tubers have been fed to all kinds of livestock. In France, as above stated, they are mostly used for sheep and cattle, and in this country they are most frequently grown for hogs. They have been highly recommended for this purpose, but have never superseded corn. The leaves and branches are also good stock feed and are extensively used abroad. The stalks may be cured in the same way as corn stover, or they may be made into silage. Judging by the past, it is not probable that the Jerusalem artichoke will make much headway against corn for fattening livestock or for forage or silage. In France it is grown outside of the limited maize-growing region, and in the United States it is most extensively grown in the South and in"the Pacific Northwest where corn is not a very certain crop.

It has been. investigated in Europe as a source of industrial alcohol and is apparently about as useful for that purpose as the beet. Some of the French crop of tubers is worked into alcohol.

At present it has promise as a source of levulose or fruit sugar, which is obtained from the inulin contained in its tubers. Levulose has a sweetening power much greater than that of sucrose or cane sugar, which is the sugar most widely known. Levulose bears the same relation to inulin that dextrose (corn sugar) does to starch.  Inulin is fairly widely distributed in the plant kingdom. The most promising producers are all members of the composite family, to which the sunflowers belong and which includes the Jerusalem artichoke, the dahlia, and chicory. Of the three, Jerusalem artichoke seems to offer the greatest promise as a source of levulose.

The tubers of different varieties tested at the Arlington Experiment Farm at Rosslyn, Va., vary in levulose-producing ability from 10 to 16 per cent, moist weight. They also vary greatly in productiveness and in adaptability to harvesting with machinery. Some 50 or more distinct types have been studied to some extent at the Arlington farm. There are probably many hundreds of varieties to be found in various parts of the United States east of the Rocky Mountains. Canada can also furnish many types. If the Jerusalem artichoke is to become important as a source of inulin it is important that as wide search as possible be made for the best producers, also that seedlings be grown and that crosses be made. The important characters on which to base selection are (1) short runners, so that the crop may be harvested by machinery; (2) productiveness; (3) high inulin content, and (4) earliness of maturity.

The subject may be summarized as follows:
   The Jerusalem artichoke is the first plant native to what is now the United States to obtain a status as a field crop.  It is most extensively grown at present in France, where the 1925 crop was grown on about 300,000 acres.
   It stores its carbohydrates as inulin instead of starch.
   As a human food it offers a variation from potatoes and has promise of increase in usefulness through its suitability for the diet of persons affected with diabetes.
   As a forage crop, as either tubers or plants, it must compete with maize and will probably find its expansion outside the maize region.
   As a source of levulose it has no competitors any better developed than itself, and it is here that its greatest present interest lies.
   Its varieties are very numerous and are scattered over the United States and Canada, east of the Rocky Mountains and north of Georgia. Wide search is needed to find the varieties best adapted for inulin production.