Cereal Grains, Legumes & Oilseeds
Ag Processing
Cereal Grains
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Many types
Markets have expanded their range of uses
General Structure and Composition
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Outer bran coat
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5% of the kernel
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Cellulose
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Minerals and some vitamins
Aleurone layer
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8% of the kernel
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Lies just under the bran coat
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Rich in protiens, phosphorus and thiamine
Endosperm
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82% of the kernel
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Large, central portion of the kernal
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Contains the most starch
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Also contains most of the protien but has very little mineral or fiber
Germ
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Small
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Rich in fat, protein, minerals also contains most of the riboflavin
Cereals
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Processed grains that are generally 75-80% carbohydrates
Fiber is also an important attribute
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Bran cereals may contain 10-26 grams of fiber per cup
Contain both soluable and insoluable fiber
Insoluable fiber is good for the digestive tract and helps reduce
the risk of certain cancers
Soluable fiber- lowers blood cholesterol, originates in the
endosperm and is found in oats, legumes, fruits and vegetables
Starch
Starch
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Storage form of carbohydrate deposited as granules or
aggregate of granules in the cells of plants
Size and shape of the granules differ from various sources
Parts of the plant that serve most prominently in the
storage of starch are:
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Seeds—cereals and legumes
Roots and tubers—parasnips, potatoes, sweet potatoes
Cassava root—Tapioca
Pith of the Tropical palm--Sago
Starch Make-up
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Granules are made up of many starch molecules arranged
in an organized matter
Two types
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Amylose
Amylopectin
Amylose
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Polysaccharide of glucose
Contributes gelling characteristics to cooked and cooled
starch mixtures
Amylopectin
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Highly branched polysaccharide of glucose
Provides thickening properties but does not usually
contribute to gel formation
Most starches are a mixture of the two
Milling of Grains
History of Milling
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Stones, wood were used by primitive people
Led to water driven mills with large mill stones
Modern milling replaced the mill stone with rollers
Flour Milling
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Bran covering, germ and endosperm are seperated to a
desired extent
Endosperm is pulverized
Middlings (inner portion of the kernel) is fed through a
series of smooth rollers after being seperated from the
bran to further reduce the size of the particles and
produce a finer flour
6-8 streams of flour are produced from the rolling and
sifting of the purified middlings, this results in various
grades and types of flours. They vary in bran, germ and
gluten content
White Flour
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Final production step is often bleaching and/or maturing
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Freshly milled unbleached flour is yellowish in color when used
for baking produces a fairly course textured loaf
If the flour is stored for several months the color lighten and
the baking qualities improve
FDA approves the use of nitrogen trichloride and
nitrogen tetroxide, chlorine dioxide, benzyl peroxide,
acetone peroxides, & azodicarbonate to bleach and
mature flour
The flour then must be bleached
Flour Composition Depends On
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Class of wheat used
Conditions under which the wheat is grown
Degree of fractionation
Classes of Wheat
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Hard, Soft, Durum
Durum is used almost exclusively for producing semolinagranular flour of high gluten content and is in the
manufacturing of macaroni products
Hard Red Spring
Durum
Hard Red Winter
Geographical Production Areas
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Hard Spring Wheats
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Hard Winter Wheats
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South Central and Middle Central States
Soft Winter Wheats
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North Central US, Western Canada
East of the Mississippi River and Pacific Northwest
Climatic and soil conditions affect the composition of
wheat, wide varations may occur within the classes
http://www.smallgrains.org/WHFACTS/growreg.htm
Grades of Flour
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Based on the four streams used to make them
Straight grade should contain all of the four streams resulting
from the milling process
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However 2-3% of the poorest streams is withheld and very little
flour on the market is straight grade
Patent flours come from the more refined portions of the
endosperm & may be made from any class of wheat and are
divided as followed in order of quality
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First Patent
Second Patent
First Clear
Second Clear
Red Dog
Types of White Flour
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Bread Flour
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All-Purpose Flour
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Less strong and elastic gluten than bread flour
May be a blend of hard and soft wheat or entirely hard or soft winter wheats
Pastry Flour
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Slightly higher percentage of gluten and a much stronger and more elastic gluten
than other types of flour
Made chiefly from hard wheat
Made from soft winter wheat
Contains a weaker quality of gluten and a slightly lower percentage of gluten
than bread and all purpose flours
Cake Flour
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Specially prepared to reduce the gluten content about 7%
Best made from soft wheat
Finely ground
Highly bleached with chlorine
Enriched Flour
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White flour to which specified B vitamins and iron have
been added
Calcium and vitamin D may also be added
Enrichment of bakers white bread and rolls was made
compulsory by the federal government in 1941 as a war
measure to improve the nutritional status of people
After the war, enrichment became voluntary
Gluten
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85% of the protiens of white flour are insoluable
Separate into two fractions
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Gliadin—syrupy substance that may bind the mass together
Gutenin—exhibits toughness and ruberiness that contribute to
strength
Together they form gluten
Other Flours
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Cornmeal
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Corn flour
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Used for making extruded cereals, cakes, cake donuts, cookies and
crackers
Oat flour
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Used to make commercial pancake mixes
Barley flour
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Used to make quick breads
Not common
Cakes, cookies, crackers
Rice flour
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Used in many products as a substitute for those who have an allergy to
wheat
Cannot be used in products that require gluten
Basically rice starch
Corn Refining
Corn Refining
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Leading example of value added agriculture
1.2 million bushels of corn are used to produce for the
world market
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Refiners separate shell corn into its components
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Food
Industrial and feed products
Starch
Oil
Protein
Fiber
Convert them into higher value products
Inspection and Cleaning
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Upon arrival the corn is inspected and cleaned twice to
remove cob, dust, chaff and foreign materials
Corn Refining
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See handout
Steeping
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Corn is soaked for 30-40 hours in 50 degree F water
Moisture level of the corn is increased from 15 to 45%
More than doubles in size
Mild acidity of the steep water begins to loosen the
gluten bonds and release starch
Corn is coursely ground after steeping to break the germ
loose
Steepwater is condensed to capture nutrients for use in
animal feed and for use in later fermentation processes
Ground corn in a water slurry goes to the germ
seperators
Germ Separation
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Cyclone separators spin the corn germ out of the slurry
Germs are pumped onto screens and washed repeatedly
to remove starch
Mechanical and solvent processes are used to extract the
oil from the germ
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85% of the oil in the corn is found in the germ
Oil is then refined and filtered into finished corn oil
Germ residue is saved as another component of animal
feed
Fine Grinding and Screening
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Corn and water slurry are ground a second time in an impact
or attrition impact mill after leaving the germ seperator
This releases the starch and gluten
Suspension of starch, gluten and fiber flows over concave
screens that catch fiber but allow starch and gluten to pass
through
Fiber is collected, slurried and screened a second time to
reclaim residual starch or protien then sent to the feed house
where it is used as a major ingredient in animal feeds
Starch-gluten suspension called mill starch is piped to the
starch seperators
Starch Separation
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Mill starch is passed through a centrifuge where the
gluten is spun out for use in animal feeds
Starch is diluted, washed 8-14 times, rediluted and washed
again to remove protiens to produce high quality starch
that is more than 99.5% pure
Starch is dried and marketed in one of the following
forms
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Unmodified corn starch
Modified speciality starch
Corn syrup and dextrose (most)
Syrup Conversion
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Starch suspended in water is liquified in the presence of acid
and/or enzymes that convert the starch to a low dextrose
solution
Treatment with another enzyme continues the conversion
process
Throughout the process refiners can halt acid or enzyme
actions at key points to produce the right mix of sugars like
dextrose and maltose for syrups that meet different needs
For example:
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To produce low to medium sweetness syrups starch to sugar
conversion is halted at an early stage
In others the conversion is allowed to continue until the syrup is
nearly all dextrose. The syrup is then refined in filters, centrifuges and
ion-exchange columns and excess water is evaporated.
Syrups are then sold directly, crystallized into pure dextrose or
further processed to create high fructose corn syrup
Fermentation
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Dextrose is one of the most fermentable sugars
Following the conversion of starch to dextrose many
corn refiners pipe dextrose to fermentation facilities
where the dextrose is turned into alcohol
After fermentation the resulting broth is distilled to
recover alcohol or concentrated through membrane
separation to produce other bio-products.
Carbon dioxide from fermentation is recaptured for sale
and nutrients remaining after fermentation are used as
componenets of animal feed ingredients.
Bioproducts
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Ethanol
Organic acids
Amino acids-used in animal nutrition
Vitamins
Food gums
Citric and lactic acids
Plastics
Eco-foam packing peanuts
Legumes
Legumes
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Provide protien and energy to much of the world’s
population
Found almost everywhere in the world
Common Legumes
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Alfalfa
Beans
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Kidney, Navy, Pinto, Snap
Cowpea
Chickpea
Field pea
Garden Pea
Lentil
Lima Bean
Peanut
Soybean
Nutritional Composition
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Good sources of
Carbohydrates
Fats
Proteins
Minerals
Vitamins
Mixtures of legumes and grains have a protein quality that
comes close to that of animal protein
Legume Products
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Fermented Foods
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Flours
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Soybean flour (used to make soy milk and low-gluten baked
foods)
Imitation meat
Infant formulas
Oil
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Soysauce, tempeh, tofu
Soybean and peanut
Sprouts
Assignment
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Design a poster showing all the products that can be
made from soybeans. Show pictures of these products
and give a description of them.