Carbohydrate Metabolites

4.4.1 Human Uses of Starch from Plant Storage Organs

Starch is a primary energy source for humans. We obtain it in abundance from cereal grains such as wheat (Triticum aestivum), rice (Oryza sativa), barley (Hordeum vulgare), oats (Avena sativa), rye (Secale cereale), and maize (Zea mays). It also occurs in abundance in tubers of potato (Solanum tuberosum), oxalis (Oxalis spp.) and tuberous roots of yam (Dioscorea spp.), yautia (Xan-thosoma brasiliense), sweet potato (Ipomoea batatus) (Figure 4.8), cassava (Manihot esculenta), hog peanut (Apios americana), and Indian turnip (Psoralea esculenta). Jerusalem artichoke (Helianthus tuberosus) tubers (Figure 4.9) do not contain starch, but rather, fructan as the primary storage carbohydrate (see Chapter 2). Starch is used to make breads, tortillas, enchiladas, cakes, pies, pancakes, waffles, and crackers.

FIGURE 4.8 Tuberous roots of the sweet potato, Ipomoea batatus. (Photo by Peter Kaufman.)

Regarding the potato (Figure 4.10), it has been in cultivation since 500 B.< In the 17th and 18th centuries, potatoes formed a major staple item in the diets of people from Ireland (an intake of almost 2.5 kg/d per person). However, during the mid-1840s, the late blight of potato fungal pathogen (Phytophthora infestans) destroyed more than 80% of the crop 2 years in a row. This resulted in the starvation of more than 3 million Irish people and the mass emigration of Irish citizens to New England in the U.S.1518

The following is an essay on starch from the tuberous roots of Indian breadroot (Psoralea esculenta, in the legume family, Fabaceae) (Figure 4.11A and B) prepared by University of Michigan SROP (Summer Research Opportunity Program) student Lynn Pennacchini (Figure 4.12A), based on her own personal experiences with the uses of this plant by Amerinds in South Dakota.*

* Resource information for this essay on Indian breadroot was obtained from the following sources: (l) Ansel Woodenknife, Interior, SD 57750; (2) Plants For a Future, a Resource and Information Centre for Edible and Other Useful Plants: Species Database (Homepage: http://www.npsc.nbs.gov);

(3) Northern Prairie Science Center, Northern Prairie Resources (Homepage: http://www.npsc.gov);

(4) Daniel Moerman's two volume paperback text, Medicinal Plants of Native America, University of Michigan Museum of Anthropology Publication, Ann Arbor, Michigan, 1986; (5) Heart of the Earth Market, WoodenKnife Indian Fry Bread Mix (Homepage: http://www.black-hills.com/~hrtearth/); and (6) Soule, J.P. and Piper, J.K., Farming in Nature's Image, Island Press, Washington, D.C. and Covelo, CA, 1990.

Special thanks go to Dan Marcus, who provided transportation to Lynn Pennacchini for this study in South Dakota, and to the Summer Research Opportunity Program at the University of Michigan for their financial support.

FIGURE 4.9 Tubers of the Jerusalem artichoke, Helianthus tuberosus. (Photo by Peter Kaufman.)

Research Essay

P. esculenta (Indian breadroot) has historically been found in Zone 4 hardiness regions of North America, south to Texas and north to Canada. It is most prevalent in the Great Plains of the U.S. and Canada. Indian breadroot is an indicator of a healthy prairie and is now most commonly found in the prairies of North and South Dakota. Human development has caused the plant's disappearance in many regions, mainly because it is very intolerant of root disturbance. Cultivation has not been successful because modern farming practices impose undue stress on the plant. Therefore, it would be most beneficial to cultivate the plant in a natural prairie setting, using alternative farming techniques, such as prescribed burns to prevent succession to a shrub/woodland ecosystem.

Indian breadroot is very hardy in that it tolerates very warm summer and very cold winter temperatures and can withstand drought. It will grow in a variety of soils, but prefers gravely soils, particularly those that have their origin from limestone. In such locations, it usually grows in patches of four or more plants. The plants are most prevalent on the southeast sides of hills, growing in association with grama (Bouteloua spp.) grass. They are characterized by having purple flowers and masses of silvery hairs on the stems and leaves. Like many other herbaceous

FIGURE 4.10 Elementary school children and teacher collecting tubers of the potato plant, Solanum tuberosum. (Photo by Peter Kaufman.)

legumes (e.g., peas, beans, clovers, alfalfa), it has nitrogen-fixing bacteria in association with root nodules. This provides considerable benefit to neighboring plants.

Indian breadroot was probably the most important food plant gathered by the Indians who lived on the prairies of the U.S. and Canada. It was so important and sacred to these people that it influenced the selection of their animal hunting grounds. It is known to the Lakota Indians as Tinpsila. Tinpsila has been a source of food and commerce in the Great Plains for centuries. In the Lakota language, the month of June is called "tinpsila i Kwaca wi", meaning the moon when the breadroot is ripe. This is the time when the flowers die down and the tuberous roots are ready to harvest. The tops of the plant are left in place to dry so that they can be blown across the prairie by wind to re-seed itself.

The starchy tuberous root (Figures 4.11A and B and 4.12B) has traditionally been the food source of the plant (see Table 4.1 on the amounts of phytochemicals found in P. esculenta roots). Women and children used to gather the tuberous roots to eat raw, to put in stews, or to grind up into a powder for different cooking uses. Today, Ansel Woodenknife, a Lakota Indian of South Dakota, carries on traditional uses of tinpsila by marketing Woodenknife Indian Fry Bread Mix, which uses tinpsila powder as an ingredient. Other ingredients include: wheat flour, sugar (sucrose), corn starch, bicarbonate of soda (NaHCO3), sodium aluminum sulfate, and acid phosphate of calcium.

Indian breadroot has also been used by Great Plains Indians for its medicinal properties. The Cheyenne Indians used it as a burn dressing and as a diuretic. The Blackfeet Indians brewed a tea from Indian breadroot to treat sore throats, chest problems, gastroenteritis, and to treat earaches. The chewed root was applied to sprains and fractures and would be sprayed into a baby's rectum to treat gas pains. The Arapaho Indians used it as a moisturizer, a tea for headaches, and to clear a throat.

FIGURE 4.11A Xerox image of plant of Indian breadroot, Psoralea esculenta, vegetative plant obtained from a prairie ecosystem in South Dakota. (Courtesy of Lynn Pen-nacchini.)

Currently, there is a very small market for this plant. An increase in demand for the root, due to current evidence of its medicinal value, may have health benefits, but could potentially have damaging ecological and cultural effects. The plant requires several years to flower and seed itself. Therefore, it is important to wait until the plant is fully mature before harvesting it. Because of the current socioeconomic issues of Native Americans, an increase in demand may trigger over-harvesting of the plant in its natural prairie habitat and lead to its decline in the wild. In addition, financial rewards due to an increased market may attract outsiders to begin harvesting the plant as well.

To successfully harvest Indian breadroot in the wild, people must be respectful, knowledgeable, and sensitive to the plant and its needs! Cultivation may be the answer. Modern farming techniques to date have been unsuccessful. Alternative farming techniques which rely on the natural dynamics of a prairie are being investigated at the Land Institute in Kansas. Using such alternative approaches to farming, Indian breadroot has the potential to be high-yielding and successful in commercial cultivation if it is domesticated and grown in a natural prairie setting.

FIGURE 4.11B Xerox image of an older plant of P. esculenta at a later, flowering stage of development. (Courtesy of Lynn Pennacchini.)

4.4.2 Secondary Fermentation from Modified Barley Substrate (Starch)

Here, we return to the grains of barley (Hordeum vulgare), the rich source of starch as a carbohydrate food source we mentioned in Section 4.4.1. This same starch is used for alcoholic fermentation in the brewing of beer. First, the starch must be hydrolyzed by a- and P-amlyases, ultimately yielding the sugar, D-glucose. This happens during seed germination during which time the plant hormone, gibberellic acid (produced in the embryo or germ and the scutellum tissue of the grain and secreted to the aleurone layer), stimulates the de novo synthesis of a-amylase by transcriptional up-regulation in the aleurone layer of the grain. Under anaerobic conditions (in the absence of oxygen), beer yeasts (Saccharomyces cerevisiae), convert the sugar released from the hydrolysis of

FIGURE 4.12A Author of Indian breadroot essay, Lynn Pennacchini, standing in South Dakota prairie where this plant is native, with Ansel Woodenknife, a Lakota Indian of South Dakota. (Photo courtesy of Lynn Pennacchini.)

.iflM"

FIGURE 4.12B A plant of Indian breadroot showing the tuberous root; top of plant, the shoot, is shown at the bottom of the photo. About one fourth the actual size. (Photo courtesy of Lynn Pennacchini.)

TABLE 4.1

Amounts of Phytochemicals Found in Roots of Psoraea esculenta, Indian Breadroot

Amoun

Chemical t (ppm)

Alanine Arginine Ascorbic Acid Aspartic Acid ß-Carotene Calcium Cystine-(Half) Fat Fiber Glutamic Acid Glycine Histidine Iron

Isoleucine Leucine Lysine Magnesium Methionine Phenylalanin e

Phosphorus

Potassium

Proline

Protein

Serine

Starch

Sugars

Threonine

Tryptophan

Tyrosine

Valine

Water

1,139 7,976

8,989

5,100 802

36,800 160,300 12,319

500 2,800 1,266

1,857 698,400 56,000 1,477 633 1,899 1,730 569,800

High (ppm)

70,000 422,000

From Internet, Hot-Bot Program, Phytochemical Data Base.

starch to carbon dioxide and ethyl alcohol (« 4% ethanol). Some of the flavor of beer comes from hops (Humulus lupulus) (Figure 4.13) which produces the primary flavoring constituent, lupulin, in glandular hairs located on bracts of the flowers.

FIGURE 4.13 A hops plant vine (Humulus lupulus). (Photo courtesy of Peter Kaufman.)

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