Starchy Staples

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Starchy Staples
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Starchy Staples

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

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Starchy Staples

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

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Starchy Staples

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

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Modified stems

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

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Stolons or runners

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

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Rhizomes

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

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Tubers

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

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Bulbs and corms

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

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Storage roots

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

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WHITE POTATO

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

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South American origins

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

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Introduction to Europe

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

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Potato in Ireland

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

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Ireland

• Potato was so successful that it led to
  population increase - from 1.5 million to 8.5
  million between 1760 and 1840
• The poor subsisted on potatoes, some milk, and
  only occasionally fish or meat
• Estimates - average adult consumed between 8 to
  12 pounds of potatoes each day

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Phytophthora infestans

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

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Late blight disease in Europe

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

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Irish potato famine

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

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Potato in rest of Europe

• Widely grown in Europe because it was encouraged
  by the aristocracy as a cheap food for the
  peasants
• By the end of 18th century potato gained
  widespread acceptance throughout Europe
• 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

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Potato in the United States

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

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United States today

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

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Processed potatoes

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

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Solanum tuberosum

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

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The potato plant

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

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Potato cultivation

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

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Asexual reproduction

• Advantages - faster and produces plants with
  desired qualities
• 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

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Four familiar cultivars

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

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Nutrients in potatoes

• Rich in carbohydrates (about 25 of the fresh
  weight) parenchyma cells within the pith are
  filled with starch grains.
• Low in proteins (only 2.5) but good protein
  quality
• Fat free - no cholesterol
• Good source of vitamins, minerals, and fiber
  (which occur in the periderm)

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Return of Late Blight

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

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Sweet potato - Ipomoea batatas

• Storage root
• Vine in the morning glory family
• Propagated vegetatively from slips
• Requires a long, warm, growing season
• Susceptible to chilling injury

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Discovered by Columbus

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

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Sweet potato

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

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Sweet potato

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

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Sweet potato today

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

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Nutrition

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

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Cassava - Manihot esculenta

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

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Origin and spread of cassava

• Origins in South America, probably Brazil
• May have been independently domesticated in
  Central America
• Well established crop in the New World tropics
  long before the arrival of the Europeans

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Cultivation today

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

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Botany

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

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Propagation

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

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Environmental tolerance

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

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Processing

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

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Cyanogenic glycosides

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

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Removing the toxins

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

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Traditional preparation

• In South America, the traditional preparation
  produces a meal called farinha
• Peeled roots are grated and squeezed through a
  long cylindrical woven basket known as a tipiti
• 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

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Cassava Bread

• Grated cassava meal is used to prepare a flat
  bread

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Nutrients

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

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Other uses of cassava

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

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Yams - Dioscorea spp.

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

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Yams

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

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Taro - Colocasia esculenta

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

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Preparation

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

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Bananas

• Good source of energy since its rich in starch
• Some converted to sugar as the fruit ripens
• Good source of potassium

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Bananas the starchy fruit

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

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Origin and early domestication

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

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Spread of banana

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

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Early 20th century

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

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Botany of banana

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

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Banana plant

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

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Fruit production

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

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Fruit Production
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Propagation

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

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Starchy Staples

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

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Other uses for starch

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

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Summary

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