Products from corn

Nutritional value of 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)

Health benefits of corn

• 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.

Versatile products of corn

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

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

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

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:

1. Cornstarch is treated with alpha-amylase to produce shorter chains of sugars called oligosaccharides.
2. 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.
3. 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

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.

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