Starchy Staples Starchy Staples 4 Most plants store

Starchy Staples

Starchy Staples 4 Most plants store food reserves in the form of starch 4 Often these reserves are stored in underground organs 4 Some types of roots or modified stems

Starchy Staples 4 Potato, sweet potato and cassava among top ten crops 4 All are tropical in origin but grown extensively in temperate areas today

Starchy Staples 4 All propagated asexually 4 Highly productive > many tons per acre 4 Food insurance against some disasters such as fire, typhoons, or hail 4 High in carbohydrates, mostly starch, but low in protein and fat

Modified stems 4 Variety of functions. – some specialized for asexual reproduction – some specialized for food storage – some for both 4 Available for renewed growth upon the return of favorable weather conditions 4 Modified stems, like erect stems, have recognizable nodes and internodes.

Stolons or runners 4 Above ground horizontal stems that produce buds and roots at the nodes 4 These buds develop into new plantlets 4 Area can be quickly invaded through this method of vegetative reproduction

Rhizomes 4 Underground horizontal stems 4 Roots form all along the underside 4 Buds found at nodes can give rise to new plants 4 Rhizome may also be a food storage organ

Tubers 4 Enlarged storage tips of a rhizome 4 White potato is a tuber 4 "Eyes" of the potato are actually buds located at the nodes, and each bud can give rise to a new plant

Bulbs and corms 4 Modified stems found in monocots 4 Bulbs are erect underground stems with both fleshy and papery leaves - food is stored in the fleshy leaves -- onions 4 Bulbs themselves can multiply 4 Corms store food reserves in the stem --no fleshy leaves -- taro 4 Corms can multiply

Storage roots 4 Tuberous roots modified fibrous roots that become fleshy and enlarged with food reserves -- sweet potato – can also function in asexual reproduction 4 Tap roots are food storing organs for biennial plants such as carrots, rutabagas, and turnips

WHITE POTATO 4 Solanum tuberosum 4 Member of the family Solanaceae, Nightshade Family 4 Other members are tomato, eggplant, pepper, nightshade, and other poisonous plants

South American origins 4 Archeological evidence shows that 8000 years ago indigenous people living in the Andes Mts. collected wild potatoes (in what is now Peru) 4 At some point the potato became the staple food crop for the people in this area 4 When the Spanish conquered Peru in the 1530's, the potato was the staple of the Inca civilization spread over thousands of miles

Introduction to Europe 4 Potato introduced to Spain sometime during the middle to late 16 th century 4 Potato cultivation slowly spread throughout Europe - only accepted as a food for humans in the 18 th century 4 Lots of misinformation - Other members of the family known to be poisonous or hallucinogenic 4 Tuber is the only part safe to eat; all the above ground parts are poisonous

Potato in Ireland 4 Readily accepted in Ireland 4 Established crop as early as 1625 4 Dietary staple for the Irish peasant throughout the 18 th and the first half of the 19 th century 4 Climate and soil ideal for the potato 4 Even small plot could feed a family

Ireland 4 Potato was so successful that it led to population increase - from 1. 5 million to 8. 5 million between 1760 and 1840 4 The poor subsisted on potatoes, some milk, and only occasionally fish or meat 4 Estimates - average adult consumed between 8 to 12 pounds of potatoes each day

Phytophthora infestans 4 Fungus causes the disease late blight of potato 4 Fungus attacks and destroys the leaves and stem causing them to blacken and decay in a short time and stopping tuber growth 4 Tubers are also attacked and rot in the ground or even later in storage 4 In cool wet weather, the fungus can kill a plant within a week.

Late blight disease in Europe 4 First appeared in Europe in 1844 4 Accidentally carried with new varieties of potato from Central or South America 4 First appeared in Ireland in August of 1845

Irish potato famine 4 Disease struck several times during the period of 1845 to 1849 4 Widespread destruction of the potato crop led to devastating famines among the Irish 4 Over one million died from starvation or from diseases that followed the famine 4 1. 5 million Irish emigrated to other areaespecially the United States, resulting in a 25 -30% decline of the population

Potato in rest of Europe 4 Widely grown in Europe because it was encouraged by the aristocracy as a cheap food for the peasants 4 By the end of 18 th century potato gained widespread acceptance throughout Europe 4 Potato blight devastated the crops in Europe but effects were not as severe as the Irish famine since the potato was not the sole dietary staple

Potato in the United States 4 Potato made its appearance in North America through the European colonies 4 There is some doubt as to the exact date of introduction 1621? or 1719? 4 Confusion in historical records between the white potato and the sweet potato 4 Word potato stems from the Arawak Indian word batata which actually referred to the sweet potato

United States today 4 U. S. production about 5% of the world total 4 Potatoes grown in virtually every state 4 Top producing states are Idaho, Washington, and Maine 4 One-third of U. S. harvest consumed fresh 4 One-half is processed to make frozen French fries, potato chips, dehydrated flakes, and other products including potato starch.

Processed potatoes 4 Nothing new - Peruvian people from high in Andes Mts have made chuno, a freeze-dried dehydrated potato, for about 2000 years 4 Tubers are spread on the ground when a heavy frost is expected 4 Following freezing, the potatoes thaw during the day and are trampled to get rid of water repeated until completely dried 4 Chuno can be stored for several years without spoiling

Solanum tuberosum 4 Solanum, a large genus with over 2000 species 4 Member of the Solanaceae or nightshade family 4 Almost 6000 cultivars but most commercial growers plant a limited number of varieties 4 In the U. S, 12 account for 85% of the potato harvest

The potato plant 4 Bushy herbaceous annual with an alternate arrangement of large pinnately compound leaves - does best in cool climates 4 Two types of stems are produced – ordinary stems with leaves – underground rhizomes which end in tubers 4 Anatomically, the tuber is a modified version of a dicot stem

Potato cultivation 4 Propagated by "seed potatoes" - small pieces with at least one eye 4 Produces plants genetically identical to the parent and maintains the desired traits within a cultivar 4 Seed potatoes produced by farmers who specialize in growing only seed potatoes

Asexual reproduction 4 Advantages - faster and produces plants with desired qualities 4 Disadvantages - genetically identical plants share the same susceptibility to adverse environmental conditions and diseases – Most of the potatoes in Ireland were genetically identical - derived from one or two plants introduced into the country – A monoculture is always risky

Four familiar cultivars 4 Round white is an all purpose potato good for boiling, baking, or processing into chips, fries, or flakes 4 Russets (Idahos) elongate cylindrical tubers have a corky russet-colored skin and mealy texture - excellent baking potatoes and ideal for French fries 4 Round reds and long whites usually sold as new potatoes - harvested earlier in the growing season and have a very thin skin

Nutrients in potatoes 4 Rich in carbohydrates (about 25% of the fresh weight); parenchyma cells within the pith are filled with starch grains. 4 Low in proteins (only 2. 5%) but good protein quality 4 Fat free - no cholesterol 4 Good source of vitamins, minerals, and fiber (which occur in the periderm)

Return of Late Blight 4 Late blight of potato has remained a major pathogen for both potato and tomato 4 Various fungicides developed to control the fungus 4 New strains of fungus have recently evolved that are resistant to the effective fungicides 4 Late blight once again poses a major threat for cultivation of potatoes

Sweet potato - Ipomoea batatas 4 Storage root 4 Vine in the morning glory family 4 Propagated vegetatively from “slips” 4 Requires a long, warm, growing season 4 Susceptible to chilling injury

Discovered by Columbus 4 Discovered on first voyage - 1492 4 Introduced to Spain on his return, 4 About 50 years earlier than the introduction of the white potato 4 Arawak peoples in Caribbean called it batata corrupted into the word potato 4 Originally “potato” was Ipomoea batatas but Solanum tuberosum later called that

Sweet potato 4 Following the introduction Widely grown in Spain and other Mediterranean countries 4 Considered a delicacy in Europe 4 Rumored to be an aphrodisiac, a claim that was later transferred to the white potato along with the name

Sweet potato 4 Native to tropical South America 4 Cultivation several thousand years in Peru 4 Widely grown as a staple crop in Central America and tropical South America 4 During this same period also cultivated in several Pacific Islands and New Zealand 4 An earlier introduction by early seafaring natives? or natural dispersal of seeds? 4 Thor Heyerdahl's traveled from Peru to Polynesia in the reed raft Kon Tiki in 1947

Sweet potato today 4 Significant crop throughout the tropics and expanded to warm temperate regions 4 Used as livestock feed as well as an important food staple 4 China dominates the world's production 4 Important in several African countries 4 In the United States primarily grown in the South often called “yams”

Nutrition 4 Rich in carbohydrates and certain vitamins and minerals 4 Especially good sources Vitamin A and C 4 Some of the carbohydrates are present in the form of sugar 4 About 50% more calories than white potatoes but slightly less protein

Cassava - Manihot esculenta 4 Tuberous root - member of the spurge family (Euphorbiaceae) 4 Many names: manioc, tapioca, yuca 4 Vital food for millions in the tropics 4 Ranks fourth as a source of calories for humans in tropical countries 4 Tapioca pudding only familar cassava product in US.

Origin and spread of cassava 4 Origins in South America, probably Brazil; 4 May have been independently domesticated in Central America 4 Well established crop in the New World tropics long before the arrival of the Europeans

Cultivation today 4 Brazil leading producer in South America 4 Portuguese introduced cassava into West Africa in the 16 th century 4 Extensively cultivated in Africa today 4 Asia, especially Thailand Indonesia, closely follows Africa in annual production with South America a distant third

Botany 4 Tall shrub with numerous tuberous roots that are similar in appearance to sweet potatoes but usually much larger

Propagation 4 Propagated by stem cuttings - none of the root is used 4 Growth is fairly rapid and little care is needed following planting 4 Can also be cultivated from seed which can be a source of new genetic varieties 4 Roots harvested from 8 mos to 2 years

Environmental tolerance 4 Tolerant to a wide range of moisture and soil conditions 4 From hot lowerlands to cool highlands 4 Requires well drained soils to prevent root rot. 4 Tolerate extended dry periods ( up to 6 mos) 4 Resistant to many insects and fungal pathogens

Processing 4 Once harvested, roots subject to rapid decay and must be dried or processed by 24 hrs 4 Sweet or bitter varieties based on the concentration of poisonous hydrocyanic acid (HCN) 4 If not removed, this toxin cause death by cyanide poisoning

Cyanogenic glycosides 4 The HCN is liberated by the action of enzymes upon cyanogenic glycosides present in cassava 4 Distinction between the sweet and bitter varieties is the concentration of the toxins 4 Environmental conditions are known to influence the production of cyanogenic glycosides

Removing the toxins 4 Sweet varieties with low HCN levels can be eaten with little preparation; peeling followed by boiling, steaming, or frying 4 Bitter varieties must undergo extensive preparation to detoxify before eating 4 Traditional methods of treating the peeled bitter roots vary and include drying, soaking, boiling, grating, draining, and fermenting, or combinations

Traditional preparation 4 In South America, the traditional preparation produces a meal called farinha 4 Peeled roots are grated and squeezed through a long cylindrical woven basket known as a tipiti 4 One end of the tipiti is tied to a tree while the other end is tied to a pole which is used to stretch the tipiti, thereby expressing juice from the grated pulp

Cassava Bread 4 Grated cassava meal is used to prepare a flat bread

Nutrients 4 Starch is the main nutrient approximately 30% of the fresh weight 4 Very low in protein (1% or less) and 4 Can result in kwashiorkor - among peoples who rely on cassava exclusively

Other uses of cassava 4 Asia and the Americas also used for animal feed and for commercial starch production 4 Cassava starch has many applications in the food, textile, paper, and pharmaceuticals 4 Tapioca pudding made by cooking tapioca pearls with milk, eggs, sugar, and vanilla 4 The pearls are partly gelatinized cassava starch made by heating moist cassava flour in shallow pans

Yams - Dioscorea spp. 4 True yams - Tuber crop 4 Important staples in many areas: – West Africa, southeast Asia, Pacific Islands, and Caribbean Islands 4 Genus has several hundred species of which ten are major food sources 4 Yams have been cultivated for over 5000 years in tropical Africa.

Yams 4 Tubers vary from size of potatoes to massive ones often weighing over 80 lbs 4 Prepared in ways similar to potatoes 4 20% starch with about 2% protein 4 Medically the tubers were an important source of sapogenins, a type of steroid used to make human sex hormones and cortisone

Taro - Colocasia esculenta 4 Corm (underground storage stem) 4 Member of the Araceae or arum family 4 Related to and resembles elephant's ears 4 Poi - the traditional dish of the native Hawaiians prepared from taro 4 Foods are also wrapped and cooked in the leaves during a Hawaiian feast or luau

Preparation 4 Corms are steamed, mashed, made into a dough, and allowed to ferment to prepare poi 4 Taro may also be cooked in ways similar to potatoes or processed into flour, chips, and breakfast foods 4 Nutritionally - around 25% carbohydrate, 2% protein and very little fat

Bananas 4 Good source of energy since it’s rich in starch 4 Some converted to sugar as the fruit ripens 4 Good source of potassium

Bananas: the starchy fruit 4 Important dietary staple for millions in tropical countries 4 Bananas are true fruits 4 Starchy plantains are traditionally cooked and eaten as a vegetable 4 Africa leader in plaintain production 4 Cultivation of sweet banana greatest in Central America

Origin and early domestication 4 Native to southeast Asia 4 Among the first cultivated plants in area 4 Polynesians spread the banana throughout the Pacific islands 4 Cultivated in India for at least 2500 years

Spread of banana 4 Arabian traders introduced bananas into parts of Africa about 2000 yrs ago 4 Word "banana" comes from West Africa 4 Portuguese and Spanish colonizers spread bananas throughout tropical regions 4 Early in the 16 th century they were introduced to the New World 4 Became established very early

Early 20 th century 4 United Fruit Company (and other companies) developed extensive banana plantations in Central America along with corporate-run railroads and steamships 4 For 50 yrs United Fruit exerted control over the economies and governments of several countries - "banana republics" 4 Rise of nationalism starting in the 1950 s led to the decline of United Fruit

Botany of banana 4 Produced by various species in the genus Musa in the Musaceae, the banana family. 4 Most cultivars are sterile triploids 4 Need tropical climate and constant moisture 4 Cultivated for the fruit, the fiber or even the foliage which is often used to wrap foods

Banana plant 4 Often called a tree but large herbaceous monocot 4 May be 20 ft or more in height 4 "Trunk" not woody but is actually a rosette of overlapping, tightly packed leaf bases which arise from an underground corm. 4 Large leaves

Fruit production 4 Apical meristem converts from vegetative growth to flowering 4 Single monoeocious inflorescence develops 4 Flowering stalk contains 5 to 13 groups of flowers (often called hands or bunches) 4 Most groups contain female flowers that develop parthenocarpic fruit 4 Male flowers confined to the end of the inflorescence

Fruit Production

Propagation 4 Fruit production ends the life of a plant 4 New suckers develop from the corm 4 Since the fruits are seedless these suckers are used in vegetative propagation 4 Suckers reach maturity in 9 to 12 months

Starchy Staples 4 Starchy staples are an important source of food for people in every area of the world 4 These starchy staples as well as many of the starchy grains are also grown for many nonfood uses as well

Other uses for starch 4 Adhesives – cardboard, paper bags, gums for envelopes and stamps 4 Sizings (fillers or coatings) – manufacture of paper, cloth, thread, and yarn – strengthen the material, impart a smooth finish, or prepare the surface for dyes 4 Pharmaceutical industry as a binding and coating 4 Laundry starch 4 Production of sugar-based sweeteners 4 The fermentation by yeast produces alcohol

Summary 4 Modified stems and storage root function as food reserves, for asexual reproduction, and storage 4 Starchy staples include some of the world's foremost crops and play major roles in the human diet 4 Potato pivotal to developing societies from the ancient Incas in South America to the preindustrial countries of Europe, especially 19 th century Ireland