HASTINGS COLLEGE FACULTY LECTURES:
“THE PRODUCTS OF CORN”
VERNON B. FLEHARTY
Corn is the aristocrat of cereals. It is and always has been a crop of the Western hemisphere. In 1492, when Columbus returned from his adventure across the western ocean, he not only brought news of a New World, but also grains of maize, or Indian corn, until then unknown in Europe. Although this was near the end of the fifteenth century, already corn occupied an important place in the civilization of the Western World. Columbus’ descriptions in his letters to King Ferdinand of fields of corn eighteen miles long would indicate that it was a staple crop in the Western Indies. In order to have reached this stage it must have been intensively cultivated a long time before Columbus arrived.
For most of our common plants there is a corresponding wild plant which, when cultivated resembles its uncultivated relative. For instance, the original wild plant which has developed into the potato was a native of Chile, Peru, and Mexico. Melons grew wild in India and Africa. But, so far, no wild plant has ever been found which resembles our corn plant. Its origin is somewhat of a mystery.
However, we do know that it has been cultivated in the Western World since prehistoric times. It has been found in the ancient tombs of Peru, the prehistoric mounds of Ohio, and in the cliff dwellings of the Southwest. It figured in ancient men’s religious ceremonies. In the holiest temples, the Incas offered maize and Montezuma’s festal bread was made of cornmeal. Each tribe has its own story of how corn came to earth.
Regardless of its origin, it was the means of subsistence of all the Indians of all three of the Americas. It not only served them as food, but the cobs were used as fuel and the husks were dried and shredded to make rough beds or mats.
It has been said: “Greece gave us art; Rome gave us government; and the Indians gave us the great and enduring gift of corn.” Corn is our special inheritance from them. When Jacques Cartier, the French navigator, ascended the St. Lawrence River, the land where Montreal now stands was covered with corn. In Virginia, the English found it growing in the open spaces in the forests. The Pilgrims were probably saved from starvation their first winter in America by the discovery of an abandoned store of Indian corn. The methods of growing corn used by the Indians were passed on to the white man. They taught him how to cultivate, harvest, and store it. Also from the Indians, he learned how to make hominy, mush, and succotash, as well as how to service various household uses of other parts of the plant.
By 1611 there were thirty acres of corn surrounding the James River settlement. Today there are more than 100,000,000 acres grown each year. Corn is the most important single crop in America.
In 1753, when Carolus Linnaeus, the Swedish botanist, published his plans for the systematic naming of all plants, he gave corn the name “Zea Mays.” “Zea” is the Greek word meaning cereal or grain, which in turn, comes from the Greek verb “to live.” In addition to its technical botanical names, corn has two common names: “corn” and “maize.” “Corn” is the general name which, from earliest times, has been applied to any cereal that could be ground into flour to make bread; and since corn was the bread cereal of the Indians, the first settlers called it “Indian corn.”
A grain of corn is rather small, yet this insignificant looking seed is potentially the large corn plant, which under the right conditions is capable of growing to a height of sixteen feet. From the botanical standpoint this small grain consists of three parts: the embryo, the endosperm, and the pericarp. The embryo, or germ, is really a tiny plant ready to start growing whenever suitable conditions are supplied. The endosperm, the largest part of the grain, is the reserve supply of food, consisting mainly of starch, sugar, protein, fat, mineral salts, and vitamins enough to feed the tiny plant until it can form leaves and roots to draw its own food from the air and soil. The pericarp or “hull” is a tough dry membrane covering the embryo and endosperm between the times of harvest and planting.
From the standpoint of man, this grain of corn has another story to tell. These insignificant grains of corn are of far greater importance to the welfare of the people of America than are her armies and navies. Corn is one of the most important sources of food for both men and animals. It contains all the ingredients necessary for the production of beef, pork, poultry, milo, eggs, butter, and cheese. It sees service at the table as bread, the oil in salad dressing, the cornstarch in puddings and pies, as cereal, and as syrup or sugar in jams, jellies, preserves, and pickles.
The embryo, or germ, consisting of about one tenth of the whole grain, is approximately one-third oil, one-third carbohydrate, one-fifth protein, one-tenth ash, three percent fiber, and, at times, traces of vitamins B and E. From the standpoint of food, the oil, ash, and vitamins are the most important. Corn is rich in fat, containing about twice as much fat or oil as wheat, three times as much as rye, and twice as much as barley, but only two-thirds as much as hulled oats. The endosperm or body of the seed, which amounts to over four-fifths of the entire grain, consists chiefly of starch and a little ash and fiber. The hull or pericarp, occupying about one-twentieth of the whole grain, consists mainly of pentosans and a little fiber and ash.
If we consider the kernel as a whole, we find it contains protein, carbohydrates, fiber, cellulose (or roughage), fat, and ash. Because the Indians and early settlers used the whole grain, these are the important elements they received when eating hot cakes, corn pones, ash cakes, Johnny cakes, hasty puddings, and other corn dishes. It is what we get when we eat corn on the cob, canned corn, popcorn, cereal, and breads manufactured from the whole grain. But today, much of our corn comes to us as corn meal, which contains only the endosperm or starchy part of the grain. The miller removes the embryo because he makes the meal in large quantities and if the embryo is kept any length of time, the oil becomes rancid, spoiling the corn meal. There is some objection to hulls, so they are removed by boiling. Consequently, the corn meal as it comes from the miller today, has lost most of its fat, and over half of its cellulose, protein, and ash, although practically none of its starch. This corn meal is less nutritious and delicious in flavor than that used by the Indians and early settlers.
Let us now consider how this greatest of American crops is used. According to the U.S. Department of Agriculture, there is, on average, about 2,700,000,000 bushels of corn produced each year. Of this quantity only ten to thirteen bushels out of each hundred ever leave the farm on which they were grown. This leaves a surplus of about 276,000,000 bushels of grain, which is shipped to the great U.S. grain centers: Chicago, Kansas City, St. Louis, and Milwaukee. From these primary markets the corn is disposed of by essentially three routes – namely: milled products or cereals, exports, and products made of corn. A little over half of the corn surplus goes to the millers to be manufactured into the various cereal foods, which eventually find their way back to our cupboards, as well as to the cupboards of the rest of the world.
The texture of the cereal depends partly upon the kind of corn used and partly upon the process employed. The “flinty” varieties of corn usually produce a cereal or meal, coarse and granular. Cereals made of the soft varieties of corn are fine and floury. After removing the bran and germ, the machines crush the soft parts so that it passes through grading screens very readily, thereby forming the corn meal and the corn flour to which we are all used.
Indians discovered one of the methods that is still used in preparing corn. The grain is cooked with a small amount of lye or lime which loosens the corn hulls so that they can be washed off. The Indians probably used ashes instead of lye or lime. The product left is known as “lye hominy.” The small varieties of corn that “pop” have a rather wide use. The popped corn treated with butter, salt, sugar, or various other flavorings is an important ware of the street vendor.
The corn disposed of by the export route is a very small amount, being only about one percent of the total crop. However, we export about one-fourth of the total cornstarch manufactured in the United States, and a considerable portion of the cornstarch syrup goes to Great Britain, where it is used in making jams, preserves, jellies, and pickles.
Now we come to the most important phase of the use of corn: every third ear of the long train of corn rolling into the big markets is bound for the factories of the refiners. That is, after a little over one-half has gone to the millers and approximately a twelfth to overseas importers, the rest is used by the refiners by whom it is made into products known as “corn derivatives,” which are quite different from the products of the millers. The story of this process is one of the most interesting stories concerning corn. The entire process is one of separations and recombinations. To begin with, let us recall the nature of a grain of corn. The germ or embryo contains most of the oil of the kernel and some mineral matter, protein, fiber, and starch. The endosperm, or main body of the grain, contains most of the starch, together with some gluten or protein material. The pericarp, or hull, is a membranous, cellophane-like wrapper, which nature has provided to protect the germ and endosperm until called upon to produce a new cornstalk.
The shelled corn is received at the plant in boxcars holding about fifteen hundred bushels each. The corn goes first to large cylindrical wooden cleaning tanks with conical bottoms. These tanks (holding about two thousand bushels each) are called “steeping tanks.” In them the corn is soaked in warm water containing about 0.12% of sulfur dioxide. This sulfurous acid water is used for two reasons:
(1.) It prevents souring or fermentation of the corn during the steeping process.
(2.) It aids in the softening of the kernel by dissolving its protein and mineral salts.
After being steeped for about forty-eight hours, the kernel takes on a greatly softened and swollen appearance, having absorbed water to the extent of about one-half of its weight. The excess water in which the corn has been soaked is drawn off, boiled down to a thick concentrate, and finally incorporated into the “gluten feed,” of which we shall hear more later. We have now eliminated the soluble proteins and mineral matter from the grain, an amount of about three pounds of dry material per bushel of corn. If desired, hydrated lime may now be added to the diluted steep water. Calcium phitate then separates and can be filtered and washed. It is used as a calcium and phosphate supplement in baby foods, while the concentrated soluble portion goes into the “gluten feed.”
The calcium phitate can be hydrolyzed with acid under pressure to inositol, which is sometimes known as “muscle sugar,” since it is found in muscle as well as in the brain and heart. It is technically known as “hexahydrohexanydroxybenzene” and is edible.
Hexanitro-inositol can be made by treating the inositol with nitric acid. The result is an excellent detonator for explosives.
The softened corn is now passed through mills, which do not grind, but merely loosen the germ and hull from the main body of the grain. These broken kernels next fall into one end of the oblong iron tanks called “germ separators,” where the suspended mass passes slowly along, allowing the germs to float and overflow at the opposite end, while the heavier portions (the hull, the starch, and the gluten) fall to the bottom. The large proportion of oil in the germ causes it to float off from the remaining portion of the corn grains. This eliminates another portion of the grain, namely the “germ.”
The germ is washed free of starch, dried thoroughly, and finally forced through hot squeezers where the oil is pressed from the solid portion. The dry germ is made up of about fifty percent oil. Each bushel of corn then yields about one and one-half pounds of crude oil. The material left after the oil is expelled is ground and either mixed with the ”gluten feed” or sold separately as oil cake meal to feed hogs, cattle, or poultry. In its raw state, the corn oil is used in the manufacture of soaps, glycerin, liniments, dyes, paints, varnishes, oilcloth, and various other products. Another product of the crude oil is a kind of gum. By a vulcanizing process this gum is converted into a substitute for rubber and is used in the manufacture of many products from artgum to bath sponges. However, the major portion of the crude oil is processed and refined to yield other products.
The process of refining the crude oil from the squeezers includes filter pressing to remove any fine particles, allowing the filtered product to settle in large tanks from which the clear oil is then drawn off and refined. Refining is accomplished by removing the fatty acids and passing the oil through refrigerators, clarifiers, filters, and sterilizers. A part of this refined oil is then packed and sold as a cooking oil. Another portion is used as salad oil. Having an agreeable taste, odor, and color, it is equal to the olive oil used for similar purposes.
The corn oil’s value as a cooking oil lies in the fact that it has a high smoking temperature; that is, it can be heated to a high temperature without smoking. This means that when it is used for frying, there is no disagreeable odor of burnt fat in the kitchen. Corn oil does not readily absorb flavors. Consequently it can be strained and used over again and again for cooking – one time, perhaps, to fry potatoes, another time for frying doughnuts, a third time for frying onions, a fourth time for fish, and so on. Foods fried in corn oil, if cooked at the proper temperatures, are neither soggy nor indigestible, since the high temperature to which corn oil can be heated, causes it to quickly form a crisp crust, which seals in the flavors and prevents the absorption of fat. It may also be used as a shortening for cake and pastry or as a fat in popping corn.
Another portion of the refined oil is treated by the hydrogenation process to yield a high grade of shortening. Hydrogenation is the process of the passing of hydrogen into the oil in the presence of a catylist, usually finely divided nickel. A catylist has been described as “a chemical parson,” since it aids in the union of two substances without any permanent change within itself. The oil unites with the hydrogen and forms a product similar to lard. The nickel can be recovered and used again.
Returning to the endosperms and hulls which we left settling in the oblong tanks: we pass the liquid stream containing these parts through buhr mills, where the entire remaining portion is ground very fine. This mixture is first passed over copper sieves, and finally, over silk bolting cloth where all the hull and fibrous materials are removed, while the starch and gluten pass through as a milky suspension in water.
The starch and gluten are separated by being passed over long inclined tables about two feet wide and 120 feet long. The heavier starch settles to the bottom, while the lighter gluten passes off the end into large settling tanks, where the gluten is concentrated, pressed to remove water, combined with the hulls, dried, ground very fine, and added to the gluten feed.
If desired, the gluten may be dried separately to make a special cattle feed known as “Corn Gluten Meal,” which is sold with a guarantee of a minimum protein content of forty percent. The value of these various livestock feeds depends largely on their protein content.
Each bushel of corn yields thirty-nine pounds of starch. The pure corn starch which was deposited on the tables is removed by flushing off with pure water, filtered by suction, washed, and finally scraped off. This starch cake contains about forty-five percent moisture and can be used for either of two purposes: it can be sent to the starch vacuum dryers, or it may be used to make corn sugar or corn syrup as desired.
Let us first trace the course of the starch through the vacuum dryers and dry starch process. The vacuum dryer consists of a large horizontal cylinder surrounded by a steam jacket. The wet starch is put in the cylinder and stirred by revolving agitators while a vacuum is maintained, causing the moisture to pass out quickly and at a low temperature. This starch, coming from the vacuum dryers is the starting material for all the dry starches. Just as the kernel is a starting point for a whole series of products, namely corn gluten feed, oil meal, corn oil, cornstarch, cereals, etc., each with many uses, so cornstarch itself is the beginning of another series of manufactured products known as “corn derivatives.” This starch can be used for any purpose where a thick boiling starch is being used, regardless of whether the starch be tapioca, potato, rice, or wheat.
As it comes from the driers, about twenty percent of it is in the form of pellets, while eighty percent is powdered. The powdered starch is separated from the pellets by passing it over silk bolting cloth. The powdered starch may be put in cartons, labeled, and sold as “Powdered Starch.”
The fine state of subdivision of the starch aids in putting the starch into solution and makes it cook up smoothly. Since this starch is often used in pudding mixtures, in the making of custards and ice cream, to thicken sauces and gravies, etc., it is necessary that it be very fine to insure an even mixture. It blends well when used in flours, cosmetics, and baking powders. Canners use it as a thickener in canned soups and vegetables, while candy makers use it in gumdrops and in candied orange slices.
The colloidal nature of starch makes it useful in many industries. The ability of starch to swell when cooked, producing a clear neutral jelly, makes it useful as a paste to hold the chemicals in dry cell batteries, explosives, asbestos, soap, and briquette manufacture. By special fermenting processes, starch can be converted into butyl alcohol, which is used as a solvent for Duco varnish. Starch forms the main body of the wet yeast cake, acting as a binder for the yeast cells. In table salt, powdered sugar, and baking powder a small percentage of starch prevents caking up and holds the chemicals apart to prevent weakening, as in the case of baking powders. The candy makers also use corn starch for molding purposes since it has the ability to hold an imprint and absorbs excess moisture from the candy centers as they are poured, in such candies as those with cream centers, marshmallow centers, and bon bons. In these candies, starch is used because of its jelling quality and its ability to hold water in both its cooked and uncooked conditions, rather than for its food value.
The raw starch coming from the driers is about 12% moisture, 87.5% starch, and 0.5% protein and ash. This starch is used primarily as a sizing in paper and textile manufacturing. The cooked starch has the ability to fill up the space between particles, binding them tightly together. When sized in this way, the finished paper or cloth has great tensile strength, as well as a smooth, durable finish. This starch is known as “thick boiling starch,” since it makes a thick paste when boiled in water. This thick tenacious character gives it the ability to fill and bind wood pulp and fiber without adding much weight. Hence it acts as an adhesive and does not penetrate deeply into the pores of the wood or cotton fibers.
Manufacturers of adhesives use considerable amounts of raw starch. They are primarily interested in the ability of starch to change to dextrin. Dextrin is a white to yellowish-brown powder. When mixed with water it is an excellent adhesive. The gum on the back of gummed paper and postage stamps is made of dextrin. It is also used in ink, library paste, mucilage, glues, and adhesives; for strengthening fiber and finishing fabrics; as a size for cloth, carpets, and twine; for the thickening colors for printing calicoes and other textiles; in fireworks called “sparklers”; as a core binder for foundries; and as a glaze for rice and coffee. The usual procedure of preparing it is to cook the starch suspended in water in the presence of an acid such as hydrochloric, or sulfuric, or diastase, or any agent capable or hydrolyzing the starch into dextrins. Hydrolysis is the name given to any reaction in which water is one of the reactants. The viscosity or thickness of the paste is determined by the length of time this hydrolysis proceeds. When the desired point is reached, the acid is neutralized with soda, or if diastase is used, the temperature is raised to 190º F., thereby destroying the hydrolyzing enzyme. By variations of this process, pastes and adhesives of various types and qualities can be produced.
To make lump or gloss starch, the powdered starch is moistened, mixed, and finally compressed in cylinders at 800 pounds pressure for several days. After pressing, it is slowly dried in open trays to give it the crystalline lump structure of gloss starch. The cooking of starch with steam under pressure makes the starch partly soluble – a form which makes it suitable for laundry use.
Several other products are prepared for laundry purposes by blending the starch with various chemicals. These chemicals add to the starch’s ability to give a smooth, satiny, pliable finish to garments, as well as facilitating the ironing process and easing the removal of dirt from a soiled garment.
Thin boiling starches are prepared by letting the starch stand in a wet state with a little acid at a moderate temperature. This process makes the starch partially soluble. When the conversion has reached the desired stage, the starch is filtered, washed, and dried.
Thin boiling starches are used as sizing agents of greater penetration and weighting qualities than could be obtained by using the ordinary thick starches. The ordinary starch cooks into a viscous jell when used up to eight ounces per gallon. Above this concentration, the solution is so thick that it cannot possibly flow or penetrate below the surface of a fiber or a fabric. A thin boiling starch solution with a concentration as high as three pounds per gallon can produce a free flowing sizing agent capable of adding great weight to a fabric or a paper.
In the weaving of cloth, thin boiling starch plays an important role as a sizing agent for the warp yarns (the yarns running lengthwise of the cloth), which form the skeleton or body through which the filler yarns are woven. Without sufficient and proper sizing, these warp yarns become weak and their fibers become loose with continual shuttle friction, causing a shedding of lint and even breakage during the weaving process. The sizing adds tensile strength to the warp yarn giving it a smooth finish, which reduces frictional resistance. A sizing must be easily washed out, since if it is not thoroughly removed from the raw cloth, it is impossible to print or dye the cloth evenly.
Let us now turn to the use of starch in the making of corn syrup and corn sugar. When starch is cooked or digested under steam pressure in the presence of acid, it hydrolyzes or combines with water to produce a sugar know as “dextrose.” In the making of corn syrup, the starch, suspended in water, is put into a large bronze boiler with a little muriatic acid, where it is steam cooked for a few minutes at a pressure of thirty-five pounds per square inch.
The cooking is controlled, so that only about forty-two percent of the starch is converted into sugar, the remainder staying in the unconverted form of dextrin. Dextrin gives the corn syrup its viscous character and prevents the sugar from crystallizing. As soon as the proper point of conversion is reached, the material is blown into a large wooden tank, where soda is added to neutralize the acid, forming a small quantity of ordinary salt, carbon dioxide, and water. The acid which acts as a catylist, causes the starch and water to combine without entering, itself, into the reaction. The neutralized syrup is filtered to remove impurities, then decolorized and clarified over bone charcoal, and finally boiled down under a vacuum into a thick syrup of the concentration desired (usually containing about thirty-five percent dextrose and forty-eight percent dextrins, with the rest being mostly water). By blending this corn syrup with cane sugar and/or flavors, such as refiner’s syrup, vanilla, maple, or sorghum, the various table syrups are produced. Corn syrup is used in making “Karo Syrup” and because of its colloidal properties is used in candy making, baking, preserving, and canning fruits.
The process of making corn sugar is very similar to that of the making of corn syrup. In making corn sugar, however, the conversion is carried to the point where all the possible hydrolysis of starch to dextrose is obtained. The process is accomplished by using a larger quantity of acid and cooking the mixture at a higher pressure for a longer time than that required for the production of corn syrup. The sugar is neutralized, filtered, boiled down to a syrup, and then poured into pans. As it cools, the sugar crystallizes into a solid cake which, in turn, is cut into chips and sold as “70% Corn Sugar,” which means it contains 70% dextrose. By boiling out the water, one can produce 80% Corn Sugar. This type of sugar is used both by caramel makers and in the leather industry.
A 99.5 to 100% pure dextrose mixture is prepared by agitating the highly converted and concentrated sugar liquor in large cylindrical crystalizers. During this agitation (which takes about four days), the crystallization process takes place. The heavy liquor, containing the crystals of pure dextrose, is then run into centrifugal machines that separate the crystals from the liquor. The crystals are washed in the centrifugal basket with pure water until nothing remains but the crystallized dextrose. The crystals are removed from the basket and dried before being sacked. This sugar is used principally in the manufacture of candy, carbonated beverages, ice cream, and bakery products. The uncrystallized liquor (called the “hydrol”) mentioned above, corresponds to the molasses obtained in the manufacture of cane sugar.
Some people have the erroneous idea that corn syrup and corn sugar occur as such in the original corn. One should remember, however, that it is the starch in the corn which is the real source of the dextrose and the syrup. (Thirty-three pounds of start in each bushel of corn can be converted into thirty-seven pounds of dextrose as syrup or twenty-five pounds of pure corn sugar).
It is interesting to note that this method of producing corn syrup and dextrose is similar to the action of the human stomach on starch. In the stomach, starch is changed into dextrose by the chemicals present – the main one being hydrochloric acid (that is, the same chemical used in producing dextrose). The fact that corn syrup is the product of the acid digestion of starch by a chemical reaction similar to the digestive process of the human stomach is evidence of its ease of assimilation and its natural food value. Corn syrup is more easily digested than starch, cane sugar, or beet sugar since it already exists in a form necessary for immediate use in the blood stream, where it furnishes quick energy.
When dextrose is taken by mouth it requires no digestive effort and furnishes fuel in a minimum of time. It is the sugar of the blood – the fuel that furnishes energy for every muscular effort. It has already been noted that athletes and other persons expending great energy use dextrose regularly.
So far, we have considered some of the derivatives of corn as obtained by chemical and physical treatment. Let us now turn to some products which are based on the fermentation processes, namely: butanol, ethanol (or grain alcohol), methanol (or wood alcohol), and acetone. The full account of these derivatives can be found in the October 1928 issue of Industrial and Engineering Chemistry in an article entitled “Butanol Fermentation Process” by C.L. Gabriel of the Commercial Solvents Corporation.
The process, as described in this article, is dived into four stems – the preparation of meal and mash, the building of cultures, the fermentation, and the distillation. It goes like this: shelled corn is cleaned and run to the mill, where its bran and germ are removed and a meal is prepared from the endosperm or starch part of the grain. Live steam under pressure is used to cook the meal into a smooth mash. After several hours of steaming, it is forced through coolers directly into 50,000-gallon capacity fermenters, where it arrives at a temperature of approximately 98º Fahrenheit.
Meanwhile, cultures of the proper bacteria have been built up in the laboratories and culture rooms. A few drops of bacilli in the spore form, the resting stage of the bacteria, have been activated by heat and used to inoculate a test tube of corn mash; this, in turn, forms the inoculants for a small flask, then for a larger one. Up to this stage, the operations have been carried out in laboratory incubators. The large flasks are now taken to the culture room, where their contents are used to inoculate 100 gallons of mash in each vessel; next, the fermenting contents of these tanks are run into tanks containing 1,000 gallons of corn mash. Finally, the contents of these containers are used to seed or inoculate more than 40,000 gallons of corn mash in each fermenter. It is important to note that each of the five steps in building up the culture has required about twenty-four hours of time and absolutely sterile conditions. Sterile conditions are necessary since wild yeast (that is, bacteria or molds from the air) might enter the mash, producing undesirable products. Also the selection of active cultures, and the elimination of sluggish cultures, has been in progress during each step of the process.
Soon after the inoculation of the 40,000 gallons of mash, gas begins to evolve from the “brew”; its volume increasing until it literally pours through a six-inch pipe and sterile water seal. The cultures rapidly progress in their work of changing starch into solvents, hydrogen, and carbon dioxide. In forty-eight hours their task completed and their food supply exhausted, the bacilli return to the spore stage.
The fermented mash is then dropped into reservoirs where it is run at a rate of more than 50,000 gallons per hour through continuous steam stills. The mash entering these stills contains a very small percentage of solvents, but the distillate contains at least 50% solvents. The slop free of solvents is discharged at the bottom of the still. Storage tanks receive the mixture containing about 50% water, 30% butanol, 15% acetone, and 5% grain alcohol. Kettle stills are now used to separate and purify these substances. Anhydrous butanol, acetone, and 95% grain alcohol are obtained when the water is eliminated. These three compounds are stored in tanks until they become the contents of car tanks and drums to fill the demand of users located in various parts of the globe.
The hydrogen and carbon dioxide produced weigh one and one-half times that of the fermentation solvents. Each fermentation gives off more than 150,000 cubic feet of a mixture that is approximately half hydrogen and half carbon dioxide. At the beginning of the industry, this enormous volume of gas was wasted.
Finally, by strenuous research, it was discovered that when hydrogen and carbon dioxide were passed over certain catalysts under a pressure 4,500 pounds and at an elevated temperature, methanol could be formed. So now, the gas coming from the fermenters is run to a gas holder after which it is scrubbed under pressure to remove some of the carbon dioxide. Three volumes of hydrogen combine with one volume of carbon dioxide to form a molecule of methanol and one of water. This is then distilled and yields a product of practically one hundred percent methanol. The methanol obtained by this process is purer than that obtained by the distillation of wood. It was originally called “wood alcohol” because of its source, but is now technically known as “methanol.”
These three alcohols: butanol, ethanol, and methanol as well as acetone are excellent solvents. You are most likely familiar with the use of ethanol and methanol as an anti-freeze. The above process was originally started for the purpose of producing acetone to be used as a solvent for cordite, a high explosive used in the First World War. After the war the fermentation plants had huge quantities of butanol in their tanks, which was considered to be a “white elephant.” Efforts were made to salvage it. Small amounts of it had been used in place of fusel oil when the latter became almost unavailable due to the prohibition in Russia and the United States.
Through intense research it was found that butyl acetate, a substance produced by the reaction of butanol and acetic acid, the acid in vinegar, could be substituted quite satisfactorily for many of the uses of fusel oil and amyl acetate. Fusel oil is composed mainly of amyl alcohols used in preparing the amyl acetate. In fact, the purity of the butanol gave it considerable advantage over fusel oil.
Ethanol will react with acetic acid in a similar manner to give ethyl acetate. In 1933, forty-one million pounds of 85% ethyl acetate and thirty-three million pounds of butyl acetate were produced in the United States and largely used as solvents in the lacquer industry. Lacquer as used for automobile finishing is usually a mixture of nitrocelluse, resins, plasticizers, pigments, and solvents.
Acetone is used as a solvent in lacquers, plastics, smokeless powders, paints, varnish removers, etc. Today, the plants are no longer run for the manufacture of acetone but for the more valuable butanol.
This industry uses over 30,000 bushels of corn per day, and in converting this amount of raw materials into solvents, more than 600 tons of coal and fifteen million gallons of water are required daily.
Recently there has been established, at Atchison, Kansas, an experimental plant for the production of alcohol. This alcohol is frequently designated “industrial” or “power” alcohol, since it is used for other than beverage purposes. For the most part, this alcohol is “denatured” that is, rendered unfit for beverage purposes by adding certain substances such as, methyl alcohol, benzene, or pyridine. Ethyl or grain alcohol should not be confused with methyl or wood alcohol. The latter is violent poison, when taken internally, and gives poisonous vapors, which should not be inhaled.
The above plant was designed to convert corn into alcohol in an effort to alleviate the corn surplus and consequently raise the price paid to farmers. The alcohol is being used to blend with gasoline in an effort to conserve our petroleum supplies. A 5% alcohol is being sold as “Agrol 5” at a few service stations in Nebraska, Kansas, Iowa, and South Dakota. Since it has the same antiknock value as regular gasoline, it is being sold at the same price.
At present prices, corn is too high to use profitably as a raw material. Dr. Christensen, who is technical director at the Atchison plant, has discovered that 60 to 75 cents is the maximum price that can be paid for corn, depending somewhat on the market for the by-products mill feed, and dry ice. Four and one-half pounds of dry ice, or solid carbon dioxide, are produced with each gallon of alcohol. This plant is equipped to manufacture 10,000 gallons of ethyl alcohol from 4,000 bushels of corn per day.
Ethyl alcohol is produced by the fermentation of sugars. It is possible to produce alcohol from any material containing fermentable sugars, or materials such as starch or cellulose, which can be converted to fermentable sugars. Since many farm wastes contain these materials, it is perfectly possible to produce alcohol from such fruits as apples, grapes, or watermelons, but the cost of gathering and transportation is prohibitive.
Dr. Christensen has tried carloads of cull sweet potatoes, molasses, rice, grain sorghums, rye, oats, and barley in an effort to find a cheaper source of raw material than corn at the present prices.
So far, we have considered some of the uses of the corn grain. Let us turn briefly to the corn stalk, itself. Since wood and corn stalks are both largely made of cellulose, the question naturally arises, cannot corn stalks be converted into a material similar to wood? This has been done. Research work done at Iowa State College in cooperation with the U.S. Bureau of Standards at Ames, Iowa, has proved that wood-like materials ranging from soft, light, insulating board to material harder than teak wood can be made from corn stalks. Also such things as window sashes can be pressed from the pulp. Paper, rayon, cellophane, gun cotton, brushing lacquers, varnish, and many other things have been made from corn stalks. Of these, only one is in commercial production at the present time – this being insulating board.
Insulating board is a light, springy material, formed from fibrous material much larger in size and less refined than that in paper. It is manufactured in sheets one-half inch or seven-sixteenths inch thick, four feet wide, and six, eight, ten, or twelve feet long. It is being used in house construction as a sheathing material, as a plaster base, and as a substitute for lath and plaster. It has been successfully used on the outside of small buildings such as chicken houses and summer cottages. When used in this manner it must be kept well painted to prevent weathering. The development of mechanical refrigerators has resulted in the use of enormous amounts of this insulation. Since about 25% of the sound falling on it is absorbed, we also find it being used in acoustical work.
Three types of board have been produced, known as cooked, steamed, and mechanical board. A preliminary step, common in the production of all these boards, is the shredding of the corn stalk to give rather coarsely shredded, rather than finely shredded, divided material. In the cooked process, the stalks are digested in water at fifty pounds per pressure per square inch for four hours. For steamed pulp the shredded pressure per square inch for four hours. For steamed pulp the shredded material is steamed for four hours. Next we find each kind of material going through a rod mill – a revolving cylinder containing heavy rods that crush and tear the pulp into pieces not over two inches long. After adding about 3% of rosin soap the pieces go through an attrition mill, composed of two steel plates held together by a stiff spring, so that considerable pressure is applied to the pulp as it goes through the machine. The pulp emerges in small bundles of fibers not over three-quarters of an inch long. During this time the pulp has become more or less hydrated, giving it a certain stickiness. The amount of hydration depends on the amount of cooking and refining; the pressure-cooked pulp being most easily hydrated. The quantity of hydration is an important factor in determining the strength and density of the finished board. In general, the more hydrated the pulp, the stronger and denser the boards. If the pulp becomes highly hydrated it may be difficult to form a board and the finished board may be too dense to supply the necessary insulating properties.
Next, aluminum sulfate is added to the suspension of pulp to fix the size, then it is collected on a screen, passed through a press roll to remove some of the water, and finally through a continuous dryer, when it is cut ready for use.
I have attempted to give you the details of a few of the products of corn which are being produced commercially today. The future of the various industries noted here depends on many factors: for example, the starch manufacturer’s objection to the importation of sago and tapioca starch duty free, since it competes directly with corn starch. Without doubt, research will find new products that can be produced from such relatively cheap pure substances as starch and corn sugar. It seems that the use of starchy materials for the production of alcohol as a fuel has only begun. Our petroleum supplies certainly will run out some time. We should begin now to plan for that day; and certainly the products of corn will play an important role in that planning.