Transcript Cereal Crops

Cereal Crops
Major, minor, wild and Pseudo-
Wheat
• Triticum- more than 10-20 species distributed
through Eastern Mediterranean to Iran.
• Temperate crop
• Complex ancestry and were first domesticated in
the Near east some time before 7000BC.
• Evolution through polyploidy
– Diploid – T.monococcum(einkorn)
– Tetraploid – T.dicoccon (emmer)
– Hexaploid – T.aestivum (common bread wheat
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T.durum (durum, flint, hard or macaroni)
Wheat
• Most important are bread and durum
wheat
• Prehistoric cultivars are being revived
• Emmer and einkorn – high amylose and
not suitable for leavened bread
• Two main proteins- glutenin and gliadin
which makes the dough elastic when
mixed with water.
Chemistry
• 82-94% of the grain is endosperm
– Starch 90% and proteins 6-9%
• 6% - embryo rich in proteins and yield fatty oil.
• Chief proteins are glutelins and gliadins which
contain all essential amino acids except lysine
and threonine.
• Whole wheat – bran (pericarp and integumants)
11-15% proteins, vitB and minerals
Cooking
• Dough mixed with water and yeast.
• Forms gluten complex produces loaves
• Yeast carry out fermentation and produces
CO2 and dough rises.
• Baking sets the dough by
– drying the starch
– denaturing proteins and
– Killing the yeast
Wheat
• Two major events impacted wheat production
– Growing rust (Puccinia garminis) resistant varieties
and
– Modern industrial flour mills.
• Flours
– Whole or graham flour: 100% grain, nothing added or
removed
– Brown flour: 85% grain
– White flour: 75-78% grain with bran and germ
removed.
• White flour has longer shelf life than brown due
to oils
Rice
• Oryza – 20 species distributed in tropical and
subtropical areas, growing in humid forests and
open swamps
• Oryza sativa; O.glaberima; and O.barthii
• Irrigation began in china; 9000 – 12000 years
• Second most important crop in terms of global
population.
• Usually associated with low income and poverty
but considered a symbol of fertility
• 1.7 billion people use it
Rice
• Needs hot, moist climate and large
quantities of water to grow well
• Two types
– Upland rice – no need of standing water
– Paddy rice – grows in standing water
• Unhusked grain – known as paddy
Rice
• While cooking gelatinzes and cell wall ruptures.
• Two to three races
– indica type – long-grain; dry and separate
– Japonica or sativa – short grain soft and slightly gleuy
– Javanica – indochina; equatorial plane, gleuy
• Gelatinous temperature and amylose content.
– High amylose – dry and flaky
– Low amylose – sticky and moist
• Mainly contains starch, 12% proteins
– Glutelins, albumins, prolines
• Lack lysine and theornine
• Removing bran and germ removes thiamine - beriberi
Maize
• Zea mays
• Domesticated in Central America; only cereal
used as vegetable; largest cereal
• Ancestor – mexican teosinte
• Flowers unisexual
• 70% endosperm and 11% embryo
• 11% protein in the aleuron layer
– Germ yields glutelin while aleuron layer has zein
– Zein – rich in leucine but lack lysine and tryptophan
– Excess leucine prevent conversion of tryptophan to
niacin - pellagra
Maize
• Maize has hard vitreous and soft floury
endosperm
• Types
– Flint – mostly hard endosperm – round when
dry
– Dent –high floury center – shrinks when dry
– Soft – mostly soft endosperm
– waxy corn
Barley
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Hordeum vulgare
A temperate plant; domesticated plant
A major animal feed and brewing
Has low gluten and cannot be leavened
Has beta glucan – lower blood cholesterol
Reduces colon cancer
Sorghum
• Sorghum bicolor – tropical Africa.
• Major food in India, and Africa where
leavened bread is not important
• Very versatile crop
• Black and brown sorghum has polyphenol
such as condensed
Oats
• Avena sativa
• Has elongated caryopsis
– Two aleurone layers
– 12-13% proteins; 4-5% oils; 66-77% CHO and 1215% crude fiber (reduce blood sugar by reducing
absorption)
• Oats used more for medicinal value
• Has all essential amino acids
• They are heat processed to denature enzyme
Millets
• General term for several small seeded
grain
• Pearl millets: Pennisetum glaucum
• Most drought resistant
• High proteins and ash content
Rye
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Secale cereale
Feed cereal
Alcoholic drinks
Infections – ergot
Has pentosans not starch – does not
disintegrates and gelatinization – soft
crumbs
• Usually mixed with wheat flour
Triticale
• Intergeneric hybrid
– Triticum and Secale
Pseudocerals
• Herbaceous dictolydons
• Amaranthus – new world; mexico –Incas and Aztecs;
puffed or milled, 30% proteins; squalene – precursor of
steroids triterpenoids
• Chenopodium – grains of chenopods. New and old
world; essential amino acid lysine; need cortication
• Fagopyrum: Buckwheat; China; high protein; dermatitis if
not decorticated
• Have salt soluble proteins and water soluble albumins
• No gluten
Sources of Sugar
• Sucrose is the major source of sweetening
principle
• Artificial sweetener are introduced due to health
problems, such as diabetes, obesity..
• Carbohydrates
– Simple sweet; out of more the 60 monosaccharides,
fructose is most sweet; sugar alcohols, amines and
acids are sweet.
– Complex-polymer not so sweet
Sugarcane
• Saccharum officinarum L.(Poaceae)
– 12-15% sucrose, glucose and fructose
– 12-20% fiber
– .3-.4% nitrogenous compounds
– Fats, waxes, acids and pectins
• Sugarcane juice: acotinic acid, citric and
malic acids; vit B, D and enzymes like
invertase and oxidases
Sugar beet
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Beta vulgaris var. rapa
Roots have upto20% sugar
Betaine is commercially extracted
Waste has galacturonic acid – used to
synthesize vit c
Maple
• Acer sacchrum and A.nigrum.
• The sap is tapped by cutting incisions on
the sapwood.
• The extract is boiled and poured into
molds
Palm sugar
• Coconut – Cocos nucifera
• Wild date palm – Phoenix sylvestris
Sweetening principles from plants
Terpenes
• Licorice – Glycrrhiza glabra (Fabaceae)
• Tripterpenoids – glycyrrhizin is a saponin.
50 times sweeter than sugar
• Looses sweetness after hydrolysis
• Expectorant, laxative and antiinflammatory
Terpenes
• Stevia
Proteins
• Discoreophyllum cumminsii Diels –
Menispermaceae
• Perennial dioecious twiner; produces small red
berries.
• Mucilage inside the berries are extremely sweet
• Monellin -9,000 times sweeter than sucrose
• A peptide with 91 amino acids
• Not heat tolerant
• Tropical W. Africa
Proteins
• Thaumatococcus danielli Benth.
(Marantaceae)
• Rhizomatous herb –tropical Nigeria
• Rarely fruits – seeds are very sweet
• Taste modifier
• Thaumatin - protein
Glycoprotein
• Synsepalum dulcifolium (Sapotaceae) –
taste modifier