Download starchy staples - muhammad1988adeel

STARCHY STAPLES
• Potato, Sweet potato, Cassava
• Most of staples popular in Pakistan
• Starch food reserves in underground organs
(roots or modified stem)
• Starch-polymer of glucose molecule
• Tropical origin
• High in carbohydrates, low in proteins
STARCH MOLECULE
• Amylose poly-(1-4) glucose,
a straight chain
• Tends to coil up into a helix
Amylopectin is poly(1-4)
glucose with branches
• Open molecular structure
than amylose
• Because it has more ends
broken more quickly than
amylose by amylase enzymes
•
Modified Organs
• Rhizome underground horizontal stem
• Food storage organ
• Leaves reduced in form of scales on
surface of rhizome
• Roots adventitious
• Buds on nodes give rise to new plants
•
•
•
•
Tubers enlarged storage tip of rhizome
White potato
Eyes are buds that form new plant
Bulbs modified storage organs mostly in
monocots
• Underground stems with fleshy leaves
• Onions, Tulips
• New bulbs can develop in the leaves axils
White Potatoes
•
•
•
•
•
•
Solanum tuberosum associated with Ireland
Established in 1965
Dietry staple food for Irish people
Ideal climate and soil for potato
Small plots of land sufficient to feed a family
Historian link population explosion to
presence of reliable food
• Average adult consumption of potato 4 to
6kg each day
• Reliance on potatoes set the disaster: Irish
potato famine of 1845-1849
• Pathogen Phytophthora infestans cause of
late blight of potato
• Fungus attacks leaves, blacken them stopping
tuber growth
• In cool wet weather, fungus kills plant within
a week
•
•
•
•
Disease appeared in 1845 in Ireland
Widespread destruction of potato crop
1million people died from starvation
Resulted 20-30% decline of population in
Ireland in Ireland in less than a decade
• Conflicts between English rulers and Irish
people another reason
• In history, Ireland a colony of English people
and Irish were shamelessly exploited
Solanum tuberosum
•
•
•
•
•
Genus Solanum- cultivated potato
2,000 species in Solanaceae
S. tuberosum 6,000 cultivars
Europe produce 70% of world crop
China second leading producer and next
Brazil
• Stem of two types
• Ordinary foliage bearing stems
• Underground rhizome that ends in tubers
• Anatomically, tuber modified version of dicot
stem
• Enlarged pith, a ring of vascular bundle, and
narrow cortex
• Vascular tissue appear black in potato chips
with narrow cortex on outside and large pith
within ring
• Cool season crop with maximum tuber
production ranging under 15to 18C
• Higher temperature inhibit tuber production
(29C)
• Potato cultivation through propagation by
seed potatoes, small tubers or cut pieces
containing at least one eye
• Seed potatoes cultivation- asexual
reproduction producing plants genetically
identical to their parents and maintaining
desired traits within a cultivar
• Seed potatoes checked for diseases
• Fast method
• Disadvantage- Share same susceptibility
to adverse environmental conditions
• Susceptible to Phytophthora infestans
and Colorado potato beetle
• Potato beetles became resistant to
chemical insecticides used for control
Red
Russet
Potatoes Varieties
white
• Round white used for baking, chips, fires
• Russets elongate, cylindrical tubers, excellent
for baking purposes, common in Pakistan
• Russets potatoes high in starch
• Round red and long white relatively new
• Good for boiling steaming, roasting
• Potatoes rich in carbohydrates (25% of
fresh weight)
• Parenchyma cells within pith filled with
starch grains
• Vitamin, minerals and fibers in cortex
and periderm
• Nutritional value enhanced when
consumed with skin
Sweet Potatoes
•
•
•
•
•
•
Ipomoea batatus
Storage root in family Convolvulaceae
Habitat vine
Columbus discovered sweet potatoes
Native to South America
China dominating country in production
• Drier, starchier variety in Northern
States
• Sweeter, moist, deep orange (Yams)
common in South
• Rich in carbohydrates, vitamins and
minerals
• 50% more calories than white potatoes
• Root source of carotene, vitamin A, C
• Thanksgiving diet
Bananas
• Important dietary staple in in tropical
countries
• Popular dessert, source of starch and
potassium
• Sweet banana
• Tree habitat
• Herbaceous with height of 6meters or
20 feet
•
•
•
•
Bananas native to Southeast Asia
Cultivated 2500 years
Genus Musa in Musaceae
Require tropical climate with constant
moisture
• Cultivated for food, fibre, foliage
(natural waxed paper)
Banana Tree
Plantains
•
•
•
•
•
•
•
Important food in poor countries
Planta-sole of foot
Genus Plantago
P. ovata P. afra (Grown in India)
Twice the size of banana
Sour or sweet in taste
Ripe black plantain more sweet than banana
Plantains
• Ten times more B-carotene than banana
• Source of vitamin A, C, B6, potassium, iron
and magnesium
• Helpful in treating ulcers
• Green, unripe varieties have enzymes for
healing
CASSAVA
•
•
•
•
Manihot esculenta
Family Euphorbiaceae
Known as Manioc, Yuca, Mandioca
Ranks fourth behind rice, sugar and corn as
source of calories in tropical countries
• Tall shrub with palmately compound leaves
• Can tolerate dry period upto 6 moths
CASSAVA
Cassava plant
Roots
• Varieties may be sweet or bitter
• Hydrocyanic acid (HCN)
• If not removed, toxin may cause death by
cyanide poisoning
• HCN liberate through enzymatic actions
cyanogenic glycosides
• Sweet and bitter varieties differ only on
cyanide content
• Environmental conditions influence cyanide
production
• Sweet variety can be bitter under different
condition
• Traditional methods for treating bitter ones
varies
• May include drying, soaking, boiling, draining
• Processed to make flour
• In Indonesia, peeled roots sliced, dried in
sun, allows HCN to diffuse
• Resulting chips called gaplek
• Stored for long period of time or ground
into flour
• Breads, cakes, cookies, noodles
• Starch rich (30% of fresh weight)
• Protein content is being improved
through cassava breeding programmes
• Roots also contain calcium, vitamin B
and C
• Being used for Bioethanol
Recommended Links
• http://www.all-about-potatoes.com/types-ofpotatoes.html
• www.botany.org
• http://www.geneconserve.pro.br/bio_rogers.
htm
• http://www.mrothery.co.uk/biochm/biochmn
otes.htm