i. Products from corn Nutritional value of corn Health benefits of corn Versatile products of corn ...
i.
Products from corn
Corn,
known in many countries as maize, is a domesticated grain. Amount of nutrients
in 100 gm of corn:
- Carbohydrates
- 9 gm
- Calcium
- 9 mg
- Dietary
fiber- 2.7 gm
- Fat-
1.2 gm
- Folate-
46 g
- Iron-
0.5 mg
- Magnesium-
37 mg
- Niacin-
1.7 mg
- Phosphorus-
120 mg
- Potassium-
270 mg
- Protein-
3.2 gm
- Sugars-
3.2 gm
- Vitamin
A- 10 g
- Vitamin
B- 15 mg
- Vitamin
C- 7 mg
- Energy-
90 kcal (360kJ)
- The
high amount of fiber present in corn helps lower cholesterol levels and
also reduces the risk of colon cancer.
- Corn,
if consumed in moderate quantities, has been seen to be beneficial for
those suffering from diabetes.
- Being
rich in folate, corn helps the generation of new cells, especially
important before and during pregnancy.
- Those
suffering from anemia have shown positive effects after consuming corn.
- The
pantothenic acid present in corn help the physiological functions of the
body.
- Owing
to the presence of thiamin, corn has been said to help in the metabolism
of carbohydrates.
- Corn
has been found to be helpful in treating kidney problems, including renal
dysfunction.
- Regular
consumption of corn, in moderate quantities, has been associated with
better cardiovascular health.
- The
beta-cryptoxanthin in corn makes it good for the health of the lungs
cryptoxanthin and may even help prevent lung cancer.
- The
insoluble fiber in corn makes it good for those suffering from common
digestive ailments, like constipation and hemorrhoids.
1.
Corn
starch
Corn is
one of the oldest cereal varieties. It originates from a region in present-
-day Mexico. The original corn varieties which only grew in regions of tropical
and subtropical climate evolved over the years by selective crossing and
finally produced high yields and obtained higher the ability to grow under
moderate climatic conditions.
Concerning
the utilization of corn two different possibilities are distinguished: silo
corn and grain corn. For silo corn production the whole plant is harvested when
still not fully ripe, chopped and stored in silos. Within these silos, which
are widely hermetic, lactic acid fermentation occurs. Chaff material is then
converted into durable silage which is primarily used for animal feeding in
winter.
Because
of the increased need for grain corn, special breeding programmes need focused
on corn-varieties suitable for the starch industry. These corn varieties
corn-varieties offer improved attributes such as increased starch content, easy
going processability and special qualities of the starch itself. Furthermore
special corn- itself. corn varieties were grown for specific technical
applications of starch. Among these are waxy corn and high-amylose corn.
Steps in
extraction of starch from corn
Supply /
Cleaning: First, supplied corn has to pass the incoming inspection.
If it meets with the specifications of the respective starch factory, it is
coarsely sieved to separate contaminations, e.g. stones, cobs, dust particles,
foreign grain material, and fine material. After cleaning, the corn kernels are
stored and then conveyed into steeping tanks.
Steeping: Well-conducted
steeping is an important prerequisite for high yield and conducted good starch
quality. At first the purified corn kernels are transferred into a tank
containing steep water. This step is conducted at 50° and lasts about 40 to 50
ning C hours. Steeping tanks are commonly series connected and operated by the
series-connected counter flow principle. For optimal steeping conditions steep
water is kept at pH 4 steep-water by addition of sulphuric acid or hydrochloric
acid and treated with sulphur acid dioxide. These conditions guarantee optimal
water absorption of the corn kernel, controlled fermentation by lactic acid
bacteria and loosening of the protein matrix. At the same time steep water
causes the softening of the kernels and the release of solubles. Growth of
lactic acid bacteria suppresses unwanted microorganisms such as yeasts, molds
and other bacteria. During steeping the size of kernels nearly doubles and the
water content increases from 15 % up to 45 %.
Coarse
grinding and degermination: After steeping one is able to
mash the corn kernels with a finger nail and remove the skin easily. After this
processing step it is also possible to take the germ out of the broken corn
kernel. This effect is utilized during the so-called degermination step. To
free the germs the kernels are coarsely ground in an attrition mill. The
grinding has to be conducted with care to avoid oil leakage out of the germs.
Otherwise the oil is soaked up by the starch granules, which leads to reduced
starch quality. Separation of specifically lighter germs is conducted by means
of special hydro-cyclones. For complete degermination the grinding and
degermination steps are performed twice. Afterwards the germs are washed and
dried and finally sold to companies which utilize them for corn oil production.
Fine
grinding and extraction: The germ removal step is followed by fine grinding in
an impact mill to completely disrupt the cells of the endosperm and release the
starch granules. The resulting suspension is led over bend green cascades for
separation from fibre and other corn components. The starch milk, which
contains the protein fraction, the so-called gluten, passes through. The bend
screen cascades are connected in series. For complete washing out of the starch
and separation of the fibres they are operated by counter flow principle.
Additionally, washing water is added to the last process stage. The separated
residues are dehydrated and dried for use as an animal feed component referred
to as corn feed.
Gluten
separation: The crude starch milk still contains all the
dissolved proteins. This fraction is called gluten, and most of it is separated
off by means of two successive nozzle type continuous centrifugal separators.
The process utilizes density differences between starch and protein. The
protein fraction is dehydrated by means of a rotary drum filter, then dried and
used as a high protein feed additive. It is mostly given to chicken, since its
high xanthophylls shares positively affect egg yolk pigmentation.
Starch refining: The
starch milk, which still contains approximately 2 % of protein and fibres after
separation, is then refined in a multi-step cyclone plant. The last stage of
the multi-step cyclone plant is the one and only step of the wet milling
process where fresh water is added. By optimal construction and adjustment of
the plant it is possible to reduce the protein content in the starch below 0.3
% on dry matter. Hydro-cyclone plants have become accepted for starch refining
for their high performance, their low water consumption, and their low
maintenance efforts.
Dehydration
and drying: The refined starch milk, having a water
content of approximately 65%, is dehydrated in peeler centrifuges to a residual
water content of about 40 %. The inner layer of the filter cake is coloured
yellow and contains high amounts of protein. It is reintroduced into the
process. Pure starch is finally dried by means of a flash dryer. For optimal
shelf life residual moisture must not exceed 14 %.
List of
equipments required: Steeping tanks, mills, screen
bends, hydrocyclones, centrifugal machines and creen achines dryers
2.
Corn
oil
Corn oil
is oil extracted from the germ of corn. Its main use is in cooking, where its
high smoke point makes refined corn oil a valuable frying oil. It is also a key
ingredient in some margarines Corn oil is generally less margarines. expensive
than most other types of vegetable oils. One bushel of corn contains 1.55
pounds of corn oil (2.8% by weight). Corn agronomists have developed high-oil
varieties; however, these varieties tend to show lower field yields, so they
are not universally accepted by growers. Corn oil is also a feedstock used for
biodiesel. Other industrial uses for corn oil include soap, salve, paint, rust
proofing for metal surfaces, inks, textiles, nitroglycerin, and insecticides.
It is insecticides sometimes used as a carrier for drug molecules in
pharmaceutical preparations.
Constituents
of corn oil
Refined
corn oil is 99% triglyceride, with proportions of approximately 55%
polyunsaturated fatty acid, 30% monounsaturated fatty acid, an 15% saturated
fatty acid. and • • • Of the saturated fatty acids, 80% are palmitic acid
(lipid number of C16:0), 14% stearic acid (C18:0), and 3% arachidic acid
(C20:0). Over 99% of the monounsaturated fa fatty acids are oleic acid (C18:1
c) 98% of the polyunsaturated fatty acids are the omega-6 linoleic acid (C18:2
n 6 c,c) with the 2% remainder being the omega-3 n-6 alpha-linolenic acid
(C18:3 n-3 c,c,c) Steps in production • Raw material: The average bottle of
cooking oil contains vegetable oil, with no additives, preservatives, or
special flavorings. Atypically, corn oil is derived from the germ (embryo) of
the kernel. • Manufacturing process Corn oils, such are cold-pressed. This
method, process: pressed. which entails minimal processing, produces a light,
flavorful oil suitable for light, some cooking needs. These oils undergo many
steps beyond mere extraction to produce a bland, clear, and consistent oil.
Steps in
production
- Raw
material: The average bottle of
cooking oil contains vegetable oil, with no additives, preservatives, or
special flavorings. Atypically, corn oil is derived from the germ (embryo)
of the kernel.
- Manufacturing
process Corn oils, such are
cold-pressed. This method, process: pressed. which entails minimal
processing, produces a light, flavorful oil suitable for light, some
cooking needs. These oils undergo many steps beyond mere extraction to
produce a bland, clear, and consistent oil.
- Cleaning
and grinding Incoming
oil seeds are passed over magnets to grinding: remove any trace metal
before being dehulled or otherwise stripped of all dehulled extraneous
material. In the case of corn, the kernel must undergo milling to separate
the germ. The stripped seeds are then ground into coarse meal to provide
more surface area to be pressed. Mechanized grooved rollers or hammer
mills crush the material to proper consistency. The meal is then heated to
facilitate the extraction of the oil. While the procedure allows more oil
to be pressed out, more impurities are also pressed out with the oil, and
these must be removed before the oil can be deemed edible. before
- Pressing: The heated meal is then fed continuously into a
screw press, which increases the pressure progressively as the meal passes
through a slotted barrel. Pressure generally increases as the oil is
squeezed out from the slots in the barrel, where it can be recov
recovered.
- Extracting
additional oil with
solvents Seeds with more oil are pressed and solvents: solvent-treated.
After the initial oil has been recovered from the screw treated. press,
the oil cake remaining in the press is processed by solvent extraction to
attain the maximum yield. A volatile hydrocarbon (most maximum commonly
hexane) dissolves the oil out of the oil cake, which is then recovered by
distilling the light solvent out. In using a special machine, flakes of
meal are sent through wedge-shaped cells of a cylindrical vessel. The
solvent then passes through the matter to be collected at the bottom. The
solvent percolates through the matter which is periodically dumped and
replaced.
- Removing
solvent traces: Ninety
percent of the solvent remaining in the extracted oil simply evaporates,
and, as it does, it is collected for reuse. The rest is retrieved with the
use of a stripping column. The oil is boiled by steam, and the lighter
hexane floats upward. As it condenses, it, too, is collected.
- Refining
the oil: The oil is next refined
to remove color, odor, and bitterness. Refining consists of heating the
oil to between 107 and 188 degrees Fahrenheit (40 and 85 degrees Celsius)
and mixing an alkaline substance such as sodium hydroxide or sodium
carbonate with it. Soap forms from the undesired fatty acids and the
alkaline additive, and it is usually removed by centrifuge. The oil is
further washed to remove traces of soap and then dried. Oils are also
degummed at this time by treating them with water heated to between 188
and 206 degrees Fahrenheit (85 and 95 degrees Celsius), steam, or water
with acid. The gums, most of which are phosphatides, precipitate out, and
the dregs are removed by centrifuge. Oil that will be heated (for use in
cooking) is then bleached by filtering it through fuller's earth,
activated carbon, or activated clays that absorb certain pigmented
material from the oil. By contrast, oil that will undergo refrigeration
(because it is intended for salad dressing, for example) is
winterized—rapidly chilled and filtered to remove waxes. This procedure
ensures that the oil will not partially solidify in the refrigerator.
Finally, the oil is deodorized. In this process, steam is passed over hot
oil in a vacuum at between 440 and 485 degrees Fahrenheit (225 and 250
degrees Celsius), thus allowing the volatile taste and odor components to
distill from the oil. Typically, citric acid at. 01 percent is also added
to oil after deodorization to inactivate trace metals that might promote
oxidation within the oil and hence shorten its shelf-life.
- Packaging
the oil: The
completely processed oil is then measured and poured into clean
containers, usually plastic bottles for domestic oils to be sold in
supermarkets, glass bottles for exports or domestic oils to be sold in
specialty stores, or cans, plastic containers for food aid.
- By
products/waste: Since
corn oil is derived from a small portion of the entire kernel, it creates
corn meal and grits if it is dry milled, and corn starch and corn syrup if
it is wet milled.
- List
of equipments required Metallic
hoppers, Storage bin for germ, Dryer, Oil expeller and Oil filter
3.
Corn
syrup
Corn
syrup is a food syrup which is made from the starch of corn and composed mainly
of glucose. Corn syrup is used in foods to soften texture, add volume, prevent
crystallization of sugar, and enhance flavor. Corn syrup is distinct from
high-fructose corn syrup created when corn fructose syrup, syrup undergoes
enzymatic processing that produces a sweeter compound containing higher le
levels of fructose. The more general term glucose syrup is often used
synonymously with corn syrup, since glucose syrup is most commonly made from
corn starch starch.
Steps in
production
Glucose
or dextrose syrup is produced from number 2 yellow dent corn. When wet milled,
about 2.3 litres of corn are required to yield an average of 947g of , starch,
to produce 1 kg of glucose or dextrose syrup. A bushel (25 kg) of corn will
yield an average of 31.5 pounds (14.3 kg) of starch, which in turn will yield
about 33.3 pounds (15.1 kg) of syrup. Thus, it takes about 2,300 litres of corn
to produce a tonne of glucose syrup, or 60 bushels (1524 kg) of corn to produce
one short ton.
Formerly,
corn syrup was produced by combining corn starch with dilute produced
hydrochloric acid, and then heating the mixture under pressure. Currently, corn
, syrup is mainly produced by first adding the enzyme -amylase to a mixture of
corn starch and water. -amylase is secreted by various species of the bacterium
amylase Bacillus; the enzyme is isolated from the liquid in which the bacteria
are grown. ; The enzyme breaks the starch into oligosaccharides, which are then
broken into , glucose molecules by adding the enzyme glucoamylase, known also
as " - , amylase". Glucoamylase is secreted by various species of the
fungus Aspergillus; the enzyme is isolated from the liquid in which the fungus
is grown. The glucose the can then be transformed into fructose by passing the
glucose through a column that is loaded with the enzyme D-xylose isomerase, an
enzyme that is isolated , from the growth medium of any of several bacteria.
The
viscosity and sweetness of the syrup depends on the extent to which the
hydrolysis reaction has been carried out. To distinguish different grades of
syrup, they are rated according to their dextrose equivalen
4.
High
fructose corn syrup
High-fructose
corn syrup is produced by milling corn to fructose produce corn starch, then
processing that starch to yield , corn syrup, which is almost entirely glucose,
and then , adding enzymes that change some of the glucose into fructose. The
resulting syrup (after enzyme conversion) contains approximately 42% fructose
and is HFCS 42. The 42% fructose is then purified to 90% fruc fructose, HFCS90.
To make HFCS 55, the HFCS 90 is mixed with HFCS 42 in the appropriate ratios to
form the desired HFCS 55. The enzyme process that changes the 100% glucose corn
syrup into HFCS 42 is as follows:
- Cornstarch
is treated with alpha-amylase to produce shorter chains of sugars called
oligosaccharides.
- Glucoamylase
- which is produced by Aspergillus, a fungus in a fermentation vat breaks
the sugar chains down even further to yield the simple sugar glucose.
- Xylose
isomerase (aka glucose isomerase) converts glucose to a mixture of about
42% fructose and 50–52% glucose with some other sugars mixed in.
While
inexpensive alpha-amylase and glucoamylase are added directly to the slurry and
used only once, the more costly xylose-isomerase is packed into columns and the
sugar mixture is then passed over it, allowing it to be used repeatedly until
it loses its activity. This 42–43% fructose glucose mixture is then subjected
to a liquid chromatography step, where the fructose is enriched to about 90%.
The 90% fructose is then back-blended with 42% fructose to achieve a 55%
fructose final product. Most manufacturers use carbon adsorption for impurity
removal. Numerous filtration, ion-exchange and evaporation steps are also part
of the overall process.
The unit
of measurement for sucrose is degrees Brix (symbol ° Bx). Brix is a measurement
of the mass ratio of dissolved sucrose to water in a liquid. A 25 ° Bx solution
has 25 grams of sucrose per 100 grams of solution (25% w/w). Or, to put it
another way, there are 25 grams of sucrose and 75 grams of water in the 100
grams of solution. The Brix measurement was introduced by Antoine Brix.
A more
universal measurement of sugars, including HFCS, is called dry solids. Dry
solids are defined as the mass ratio of dry sugars to the total weight of the
sugar solution. Since Brix is based on the refractive index of light against a
sucrose molecule it is not accurate when measuring other sugars such as
glucose, maltose, and fructose.
When an
infrared Brix sensor is used, it measures the vibrational frequency of the
sucrose molecules, giving a Brix degree measurement. This will not be the same
measurement as Brix degrees using a density or refractive index measurement,
because it will specifically measure dissolved sugar concentration instead of
all dissolved solids. When a refractometer is used, it is correct to report the
result as "refractometric dried substance" (RDS). One might speak of
a liquid as being 20 ° Brix RDS. This is a measure of percent by weight of
total dried solids and, although not technically the same as Brix degrees
determined through an infrared method, renders an accurate measurement of
sucrose content, since the majority of dried solids are in fact sucrose.
Recently,
an isotopic method for quantifying sweeteners derived from corn and sugar cane
was developed which permits measurement of corn syrup- and cane sugar-derived
sweeteners in humans, thus allowing dietary assessment of the intake of these
substances relative to total intake.
List of
equipment required
Thermostastic
control blower, agitator, extractor, boiler, utensils, blender and tanks
5.
Corn
flakes
Breakfast
cereal technology has advanced greatly since its origins in the late nineteenth
century. The latest innovation in the industry is the twin twin-screw cooking
extruder. The two rotating screws scrape each other clean as they rotate. This
allows the dough to move more smoothly than in an extruder with only one screw.
By using a twin-screw extruder, along with computers screw to precisely control
temperature and pressure, cereals that usually require about 24 hours to make
may be bout made in as little as 20 minutes.
a.
Steps in production
- Raw
Material: The most important raw
material in any breakfast cereal is grain. Most breakfast cereals contain
other ingredients, such as salt, yeast, sweeteners, flavoring agents,
coloring agents, vitamins, minerals, and preservatives. The sweeteners
used in breakfast cereals include malt (obtained from barley), white
sugar, brown sugar, and corn syrup. Some natural cereals are sweetened
with concentrated fruit juice. A wide variety of flavors may be added to
breakfast cereals, including chocolate, cinnamon and other spices, and
fruit flavors. Other ingredients added to improve flavor include nuts,
dried fruit, and marshmallows. Vitamins and minerals are often added to
breakfast cereals to replace those lost during cooking. The most important
of these is vitamin B-i, 90 % of important B which is destroyed by heat.
The antioxidants BHA and BHT are the preservatives most often added to
breakfast cereals to prevent them from becoming stale and rancid.
- Preparing
the grain: Grain is received at the
cereal factory, inspected, and eal cleaned. It may be used in the form of
whole grains or it may require further processing. Often the whole grain
is crushed between large metal rollers to remove the outer layer of bran.
It may then be ground more finely into flo flour. Whole grains or partial
grains (such as corn grits) are mixed with flavoring agents, vitamins,
minerals, sweeteners, salt, and water in a large rotating pressure cooker.
The time, temperature, and speed of rotation vary with the type of grain
being cooked. The cooked grain is moved to a conveyor belt, which passes
through a drying oven. Enough of the water remains in the cooked grain to
result in a soft, solid mass which can be shaped as needed.
- Making
flaked cereals: The
cooked grains are allowed to cool for several hours, stabilizing the
moisture content of each grain. This process is known as tempering. The tempered
grains are flattened between large metal rollers under tons of pressure.
The resulting flakes are conveyed to ovens where they are tossed in a
blast of very hot air to remove remaining moisture and to toast them to a
desirable color and flavor. Instead of cooked grains, flakes may also be
made from extruded pellets in a similar manner.
- Adding
coatings: After shaping, the cereal
may be coated with vitamins, minerals, sweeteners, flavors such as fruit
juices, food colors, or preservatives. Frosting is applied by spraying a
thick, hot syrup of sugar on the cereal in a rotating drum. As it cools
the syrup dries into a white layer of frosting.
List of
equipment required
Dehusker,
Flaker, Tanks, Dryer and Cooker
Source
: Science
Tech Entrepreneur Magazine, March
2011 issue
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