Corn, known in many countries as maize, is a domesticated grain. Amount of nutrients in 100 gm of corn:
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 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
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 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:
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
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.
List of equipment required
Dehusker, Flaker, Tanks, Dryer and Cooker
Source : Science Tech Entrepreneur Magazine, March 2011 issue