Chapter 3 Bask Grain Processing Industries — . . . ---- -

CONTENTS

Page Grain Processing Industries ...... 47 Milling Industries ...... 47 Feed Manufacturing ...... 49 Soybean Processing ...... 50 Basic Processes Used To Produce Grain Products ...... 50 Dry Milling and Corn ...... 50 Wet Milling Corn ...... 54 Soybean Processing ...... 57 Chapter 3 References ...... 57 Figures Figure Page 3-1. Grades Obtained in the processor Milling ...... 48 3-2. How Flour is Milled ...... + ...... 52 3-3. Production Flow Chart for a Typical Corn Tempering-Degerming System ...... 53 3-4. Block Flow Sheet ...... 54 3-5. Wet-Milling Process Flow Diagram...... 55 3-6. Typical Soybean Extraction Process Flow ...... 56

Tables Table ‘ Page 3-1. Active Capacity by Size Group ...... 48 3-2. Amount of Corn Used Annually for Dry Milled and Alkaline Cooked Products in the United States ...... 49 3-3. Estimated Dry Milling Product Quantities Classified According to End Use, 1977 ...... 49 3-4. Typical Proportion of Corn Products From a Degerming Dry Mill . . . . . 49 3-5. Shipment of Products of the Corn Refining Industry in the United States, 1983-85 ...... 50 Chapter 3 Basic Grain Processing Industries

Wheat, corn, and soybeans can be used in The basic uses for wheat, corn, and soybeans a variety of ways. They can be used directly in the United States are very similar to those in food for human consumption, as in the case in countries that import these grains. The basic of wheat flour and soybean oil. Products from processes used to produce wheat flour, corn these grains can also be mixed with other in- starch, soybean oil, and so on are similar every- gredients, as is the case with corn starch and where. Yet, differences in processing technol- corn sugars, to produce a multitude of prod- ogies exist, as do cultural preferences for cer- ucts for human consumption. Wheat and corn tain types of products. The specific physical are fed directly to animals or mixed with other and intrinsic attributes required of finished ingredients to produce balanced diets. Meal products for U.S. consumption may therefore produced during soybean oil extraction is used differ from those required for a specific prod- as a feed supplement to increase the protein uct in an importing country, even though the content of mixed feed. Byproducts from the basic processing technology is similar. various processes, such as millfeed produced When identifying the basic sanitary, physi- from wheat milling and steep-water concen- cal, and intrinsic requirements for wheat, corn, trates from corn wet milling, are used by the and soybeans, it is important that the technol- feed industry or for industrial use. In addition, ogy involved with producing the intermediate new uses for these grains are constantly being product and the quality required of the finished developed–for example, ethanol and biode- product be understood. This chapter thus pro- gradable plastics produced from corn. There- vides basic information on grain processing in- fore, the physical and intrinsic characteristics dustries and technologies. required of each grain vary; more important, they must be assessed in terms of their various commercial uses.

GRAIN PROCESSING INDUSTRIES

Three basic industries–milling (wheat and for the various byproducts. Thus each milling corn), feed manufacturing, and soybean proc- process entails almost complete utilization of essing—process wheat, corn, and soybeans. all the grain.

Wheat Milling Milling Industries Wheat is milled to remove the and germ Milling is a process by which kernel compo- and reduce the wheat kernel to flour to be used nents are separated physically or chemically. in various baked and nonbaked goods. Other Each milling process yields products indica- products of the process, e.g., vital , can tive of the grain being milled. Wheat is milled supplement other edible products. Millfeed, the to produce various types of flour. In the case material remaining after all the usable flour is of corn, dry or wet processes are used, and each extracted, is used by the feed industry either results in different products and byproducts. directly or as a feed supplement. The many products of milling can be used In general, 100 pounds of wheat will produce directly as food or as ingredients in another type 72 pounds of flour. The remaining 28 pounds of food product. Specialty uses of milling prod- is classified as millfeed (figure 3-1). In large flour ucts have also been developed, along with uses mills, 30 or more flour streams of varying com-

47 48

Figure 3-1. - Flour Grades Obtained In the Process In 1988, a total of 211 flour mills and 18 Du- of Milling rum mills were operating in the United States (5). The basic flour types produced and the daily production capacities from these mills are hard wheat flour (843,606 cwt), soft wheat flour (247,931 cwt), whole wheat flour (40,205 cwt), 14% 14% bran shorts and flour (96,540 cwt). Table 3-1 pro- vides a breakdown of the 211 hard, soft, and whole wheat flour mills by size and capacity. Twenty-four percent of mills in the United States produce 84 percent of all flour.

Short patent flour Dry Milling Corn so% The dry milling process requires the miller to remove the corn hull and germ without re- ducing the . The dry milling and alkaline cooking industries processed about 161 million bushels of corn in 1986. Total corn SOURCE: Wheat Flour Institute, “From Wheat to Flour,” revised ed., Washington, usage has ranged from a low of 154 million DC* 1981 bushels in 1975 to a high of 170 million bushels in 1982 (table 3-2). position and purity may be collected, grouped, and merchandised. Combining all the streams This process produces flaking grits, meals, results in a straight grade flour. The more highly , oil, and other products. Low-fat flaking refined flour streams are taken off separately grits are the highest valued grit product and and sold as patent grade flours. The remain- are used primarily in breakfast foods. General ing streams contain more bran and germ and food use accounted for 1,125 million pounds are considered clear flour. Raising the propor- of dry milling product in 1977, with breakfast tion of this that is included in the patent flour cereals using the most (table 3-3). lowers the quality of the remaining clear flour Table 3-4 shows the yield of primary and alter- (8). nate products produced by dry milling. Break- Flour is used in a variety of U.S. products. fast cereal is produced from large flaking grits. Fancy patent flour from soft is used in Coarse and regular grits are used by the brew- cake products. In the case of hard wheats, short ing industry, while corn meal is made from ma- patent is used in premium , standard pat- terial too small to make grits. Corn meal and ent in featured breads, medium and long pat- flour are made from finely ground starchy en- ent and straight in and rolls, and high dosperm and used in various baked goods, gluten flour in hearth breads and Kaiser rolls. snack foods, and mixes, but they also have in- Flour types and grades produced in non-U.S. Table 3-1.-Active Wheat Flour Capacity by Size Group mills vary by mill and by the type of flour (wheat, soft wheat and whole wheat flour) product. Hundredweights Number of Active Inactive The Association of American Feed Control per day mills capacity capacity Officials has defined eight different types of Under 200 ...... 21 2,371 — 200-399 ...... 22 6,415 — millfeeds: wheat bran, wheat feed flour, wheat 400-999 ...... 17 10,330 — germ meal, wheat mill run, wheat middlings, 1,000-4,999 ...... 61 168,670 — wheat shorts, wheat red dog, and defatted 5,000-9,999 ...... 48 317,200 – wheat germ meal (9). These products are used 10,000 & over ...... 42 615,750 – Total 211 1,120,736 — to feed cattle, poultry, and other small animals SOURCE: &fi//irrg and Baking News, Milling Directory/Buyers Guide” (Mer- as part of a formulated ration. riam, KS: Sosland Publishing Co., 19SS). 49

Table 3-2.—Amount of Corn Used Annually for Table 3-4.—Typical Proportion of Corn Products Dry Milled and Alkaline Cooked Products From a Degerming Dry Mill (percent) in the United States Product Yield Dry-milled Flaking grits ...... 12 and alkaline Total U.S. Coarse grits ...... 15 cooked products corn production Dry-mill share Regular grits...... 23 a Year (million bushels) (million bushels) (in percent) Coarse meal ...... 3 1975 . . . 154 5,841 2.6 Dusted meal ...... 3 1976 . . . 155 6,289 2.5 Flour ...... 4 1977 . . . 158 6,505 2.4 Oil ...... 1 1978 . . . 155 7,268 2.1 Hominy feed ...... 35 1979 . . . 158 7,928 2.0 Shrinkage ...... 4 1980 . . . 160 6,639 2.4 SOURCE: O.L. Brekke, “Corn Dry Milling Industry,” Corn” Culture, Processing, 1981 . . . 162 8,119 2.0 Products, G.E. Inglett (cd.) (West port, CT: AVI Publishing Co , Inc , 1970). 1982 . . . 170 8,235 2.1 1983 . . . 164 4,175 3.9 68 in 1986. Of these, 55 had daily capacities 1984 . . . 160 7,674 2.1 of under 12,000 bushels, 8 could handle be- 1985 . . . 161 8,865 1.8 tween 12,000 and 36,000 bushels, and 5 could 1986 . . . 161 8,253 2.0 ‘Year begins Sept. 1, process 36,000 bushels a day (4). The majority SOURCE: U.S Department of Agriculture (USDA), Economic Research Service, of corn dry mills are located in the midwest- “Feed Situation and Outlook Report,” FdS-302, Washington, DC, May 1987; USDA, Agricu/tura/ Statistics, 1986 (Washington, DC: U S Govern- ern and southeastern part of the United States. ment Printtng Office, 1986). The 13 largest mills have a combined estimated Table 3-3.—Estimated Dry Milling Product Quantities daily capacity of 445,000” bushels, about 69 per- Classified According to End Use, 1977 cent of the total corn usage for dry milling,

Quantity Wet Milling Corn Use (million Ibs) Brewing ... , , ...... 1,850 The amount of corn processed by the wet Food, general ...... 1,125 milling industry has increased from 155 mil- Breakfast cereals ...... 800 Mixes (pancake, cookie, muffins, etc.) . . . 100 lion bushels in 1960 to 645 million bushels in Baking ...... 50 1985, accounting for some 12 percent of domes- Snack foods...... 100 tic corn use (3). Breadings, batters, baby foods, etc...... 75 Fortified Public Law 480 foods ...... 485 Wet milling corn produces starch, oil, and Nonfood ...... 530 Gypsum board ...... 100 sweeteners (table 3-5). Corn starch is used in Particle, fiber board, plywood...... 40 food and nonfood products by the brewing and Pharmaceuticals, fermentation...... 200 baking industries; in the production of chemi- Foundry binders ...... 90 Charcoal binders...... 75 cals, drugs, and pharmaceuticals; by the paper Other (paper, corrugating, oil well industries; and in the production of ethanol. drilling fluids ...... 25 Sweeteners are used by the baking, beverage, Animal feed ...... 2,200 canning, and feed industries. Byproducts from Total ...... 6,190 the wet milling process, including the water SOURCE: R.J. Alexander, “Corn Dry Milling” Processes, Products and Applica- tions,” Corn Chernfstry and Technology, S.A. Watson and P.E. Ram. used to steep the corn prior to milling, are used stad (eds ) (St. Paul, MN American Association of Cereal Chemists, 1987), by the feed industry. dustrial uses. Corn oil obtained from dry mill- ing is used in food products and in industrial Feed Manufacturing uses. Hominy feed consists of all the byproducts Livestock and poultry consumed 85 percent such as hull fractions, inseparable mixtures of of domestic corn during the 1980s. Over the hull, endosperm, germ, germ meal, and corn past 5 years, swine consumed 34 percent of the cleanings. It is the single largest product sold corn; beef, 22.3 percent; dairy, 18.2 percent; by dry millers (6). poultry, 21.3 percent; and other classes of ani- The number of corn dry mills in the United mals, 5.1 percent. Wheat use in feed, on the States has dropped from 152 in 1965 to only other hand, is significantly lower. In 1985 wheat 50

Table 3-5.—Shipment of Products of the Corn Refining Industry in the United States, 1983-85 (thousand pounds)

Product 1983 1984 1985 Starch products (includes corn starch, modified starch, and dextrin)...... 4,018,905 4,182,866 4,225,171 Refinery products (includes glucose syrup, high-fructose corn syrup dextrose, corn syrup solids, and maltodextrins) ...... 16,005,529 17,921,126 20,341,535 High-fructose corn syrup ...... 9,707,041 11,502,324 13,920,406 Other products: Corn oil crude ...... 72,612 116,142 164,382 Corn oil refined ...... 399,919 407,456 382,234 Corn gluten feed ...... 7,391,069 8,739,730 8,811,476 Corn gluten meal 41% protein 19,115 20,272 18,503 60% protein ...... 1,383,129 1,635,228 1,609,112 Corn oil meal ...... 28,728 29,465 48,585 Steepwater ...... 211,937 300,770 282,333 Hydrol ...... 208,807 216,558 228,742 Ethanol (thousand gallons, 100%) ...... 325,000 375,000 425,000 SOURCE: Stanley A. Watson and Paul E. Ramstad (eds), CornChemistry and Teclrno/ogy (St Paul, MN: American Association of Cereal Chemists, 1987) and rye combined accounted for 16.9 percent Soybean Processing of total feed grain consumption by livestock. Soybean processing separates oil by solvent- Wheat and corn can be ground and fed to ani- extraction from the nonoil portion of the bean. mals or ground and mixed with other ingre- The soybeans are cleaned prior to being dients to produce a balanced diet for a particu- cracked, hulls are removed, and the cracked lar species. Each animal species has specific dehulled pieces are heated and rolled into dietary requirements; when corn and wheat are flakes. Crude oil is then extracted from the used, ingredients must be added to overcome flakes. After extracting the oil, the flakes can certain deficiencies in these grains (7). Feed be toasted and ground into meal products. concentrates, byproducts from wheat and corn milling processes, soybean meal, animal pro- The two major products from soybean proc- tein, and other byproducts are mixed with other essing are high-protein meal and oil. Food uses feeds or fed directly to livestock. of oil include shortening, margarine, and cook- ing and salad oils; nonfood uses include paint, The modern feed manufacturer blends ingre- varnish, resins, and plastics. Soybean meal, dients using a computer program designed to which is the largest product produced from this select the lowest priced ingredient that is a sig- process, is used by the feed industry as a pro- nificant source of the desired nutrients. For tein supplement unmanufactured feeds. most nutrients, published average values are used and any deviation from these values will render the feed deficient and affect animal per- formance.

BASIC PROCESSES USED TO PRODUCE GRAIN PRODUCTS

To fully understand the quality requirements company within the United States and among of each industry, a general knowledge of the countries around the world. basic technologies used to process the various grains is important. Since such technologies Dry Milling Wheat and Corn are similar worldwide, general descriptions are provided in this section. Modifications of and The basic process used to mill wheat and corn improvements to these will vary by individual involves cleaning, conditioning, grinding, and 51

sifting. In the case of dry milling corn, degerm- Wheat Milling Process ing also takes place. After tempering, wheat is moved to an ento- leter, which consists of discs revolving at high Samples are taken from each incoming ship- speed that crack unsound wheat kernels and ment of wheat and corn and tested. The char- separate them from the grain stream. Wheat acteristics of the wheat determine how it will flows from the entoleter to the grinding bin, be handled, since different types are usually where it is held and metered into the mill itself. blended before milling to meet various flour re- quirements. Figure 3-2 provides a simplified wheat milling flowchart, and figure 3-3 is a dry Corrugated rolls are used to break the wheat corn milling flowchart. The sequence, number, into coarse particles. The initial set of these (re- and complexity of different operations will vary ferred to as the “first break” rolls) break the somewhat between mills. kernel into very coarse pieces. These rolls can be adjusted for spacing as well as speed to The first step in milling involves cleaning the achieve the exact milling surface desired, de- grain to remove weed , other grains, and pending on the type of wheat and its condition. material such as sticks, stones, dirt, and other As many as four to six break rolls, with succes- debris. This involves the use of scalpers to re- sively smoother surfaces, can be used to fur- move large material, aspiration to remove fine ther reduce the kernel into flour. material, and screens. Magnetic separators can also be used to remove any metal from the grain. The coarse pieces of wheat and bran pro- duced from the first break are sifted over a ser- Disc separators are used to catch individual ies of bolting cloths or screens to separate larger kernels and reject larger or smaller ones, thus from smaller particles. Sifters consist of as creating a uniform kernel size for milling. In many as 27 frames of bolting cloth with meshes the case of wheat, the grain passes through a that grow progressively smaller from top to bot- scourer that throws the kernels against a sur- tom. Larger material is shaken off at each step face, buffing each one and breaking off the and the finer flour sifts to the bottom. The beard. Air currents remove the dust and 1oo- coarse pieces are sized and carried to the sec- sened particles of the bran coat. ond set of break rolls. The second break rolls are spaced closer together, producing a finer Wheat and corn are conditioned prior to mill- material, This material is then sent to a sifter ing. This process, called tempering, involves and the process repeats itself. adding moisture. Tempering is done to aid in removing the bran from the endosperm dur- Flour is obtained from each break roll and ing grinding, since the outer bran layers are sifting operation. However, fragments of en- brittle and must be toughened. Wheat is held dosperm, bran, and germs called middlings re- in tempering bins for usually 8 to 24 hours, de- main after each sifting. These are sent to puri- pending on the type of wheat. The percent of fiers, where air removes bran particles and moisture added, the amount of soaking time, bolting cloth is again used to separate coarser and the temperature differ for soft, medium, fractions by size and quality. The coarse mate- and hard wheats. Corn is injected with steam rial is then sent to reduction rolls and again or sprayed with warm water in a tempering sifted (8). chamber. This may occur in one to three stages before the corn finally reaches 18- to 24-percent The process of grinding, sifting, purifying, moisture. The moist corn is then held in the and reducing is repeated many times until the tempering bin for up to 6 hours, Corn moisture, maximum amount of flour is obtained. Each holding time, and the temperature during con- process results in a separate flour stream. For ditioning are critical for obtaining correct mois- example, flour is produced from each break and ture gradients in the kernel. middlings reduction (first, second, third, etc.). . -. . . - - -

52

\

I

[ 53

I

SOURCE: Richard J Alexander, “Corn Dry Mdling: Processes, Products, and Applcatlons” m Corn ChemLsiYY and Technology (St Paul, MN: American Asaoaatlon of Cereal Chemists, 1987)

Figure 3-4 shows an example of a milling proc- large mills, there can be 30 or more separate ess with four breaks. In this case, 12 different streams. flours are produced–four from each break and Some mills, in addition to producing flour, eight from each reduction (2). produce vital , essentially a pow- Flour from each point in the process has dif- dery product containing 75 to 80 percent pro- ferent characteristics and baking properties and tein with a bland flavor that is able to absorb can be combined in many different ways. Flour water 2.5 times its dry weight. This product is from the first few middlings separations is the relatively simple to produce in that flour is most highly refined. After each additional proc- washed with water and then dried. Vital wheat ess the flour contains more bran and germ. In gluten is used as a supplemental ingredient in 54

a 5 mesh/inch sieve is considered large flaking grits. Material that will not pass through the 3,5 mesh/inch sieve is recycled for retemper-

Breaking Purified ing and degermination. Whatever passed through the 5 mesh/inch sieve is then sieved

1BK using 6 and 10 mesh/inch sieves. Anything pass- rolls ing through the 6 but not the 10 mesh/inch sieve 2BK is considered brewers and coarse grits. If there rolls are any attached germs or pericarps, the mate- 3BK rolls rial will be roller-milled.

4BK Several sets of corrugated rollers are used in rolls a manner similar to that described in the wheat milling section. Smaller numbers of corruga- tions are used for the first break to produce coarse grits. Second and third break rolls use more corrugations, resulting in more finely SOURCE: Canadian International Grams institute, “Gram& Oil seeds, Handling, Mar- keting, Processing,- 3rd ad, rewed, Winnipeg, MB, Canada, 1982 ground products. After grinding, the material is sifted and then aspirated to remove free pericarps. breadmaking especially by commercial bakers. Through-stock containing germs is aspirated It is added to a dough that requires additional to remove loose pericarps and then sent to grav- protein to develop properly. ity tables for separation. The germ fractions can then be dried and sent to an oil expeller or sol- Corn Dry Milling Process vent oil extraction process to recover the crude Determination is the process by which the oil. The germ meal remaining after the crude corn kernel is broken apart into endosperm, oil has been extracted is used in hominy feed. germ, and pericarps (6). Although a few com- The material other than the germ separated panies use impact mills or granulators, about with the gravity table is recycled back to the 90 percent of the dry mills producing flaking first break rolls to be processed with the grits use the Bean degermer almost exclusively. tail-stock. This is a cone-shaped mill with rows of small conical protrusions that rotate within an outer Wet Milling Corn conical surface that also has protrusions. This process causes corn-on-corn rubbing to remove Corn is first cleaned by screening and aspi- germs, pericarps, fines, and a few small grits ration to remove dust, , cobs, stones, and called through-stock. Tail-stock consists primar- so on, similar to the processes described for ily of grits that are free of attached germs and dry milling (figure 3-5). After cleaning, the corn pericarps. is moved on to the refining process (3). After degerming, through-stock is normally As in dry milling, corn must be tempered. wetter than the tail-stock and must be dried. This is accomplished by placing the grain in This is accomplished by rotary steam-tube steeping tanks and adding water containing sul- dryers that quickly heat the products to 140 to furous acid that has been heated to 125 ‘F. Corn 160 ‘F. After drying, the stock is cooled to 90 is held in steeping tanks for 22 to 50 hours. Dur- to 100 ‘F. ing this time the water is recirculated and re- heated. Tail-stocks consisting of large pieces of en- dosperm are aspirated to remove loose peri- Water is used to transport the corn from the carps. The material is then sieved. Material steeping tanks to holding bins. It is screened passing through a 3.5 mesh/inch sieve but not off prior to the wet corn being placed in the 55

Figure 3-5. - Wet-Milling Process Flow Diagram (showing equipment arrangement for the separation of the major components --steepwater, germ, fiber, gluten, and cornstarch)

Multiple-stage fiber wash system

I I I

Multiple-stage starch washing system

SOURCE: James B Mag, “Wet MWng: Process and Products” In Corn Chamisby and Technology (St bin, From the holding bin the corn moves into The material remaining in the flotation tanks grinders that break up the kernel. Water is again is screened to separate fiber from starch and added and the material is transported to flota- gluten. About 30 to 40 percent of all the starch tion tanks, where the germ floats to the top. The is separated at this stage. The remaining mate- germs are recovered, washed, and screened. rial is further processed, washed, and screened The recovered germs are then dried and fur- to separate more starch and gluten. Starch is ther processed to remove the oil, purified by washing and can be dried, treated 56

Figure 3-6.—Typical Soybean Extraction Process Flow n

Seed Preparation

I

Meal grinder

Meal to-storage

*Alternative - A crown desolventizer toaster dryer cooler may be furnished in Ileu of desolventizer toaster and dryer cooler

SOURCE’ Crown Iron Works, 1987. 57 with chemicals to modify the starch to meet The moisture content of the soybeans being various requirements, and then processed for processed must be between 9.5 and 10 percent. its various uses. The gluten is also washed and The cracked soybeans are first heated to about then dried, forming corn gluten meal. 140 ‘F and then proceed through a series of rollers, where they are flaked, Following a cool- Corn steepwater is processed to remove the ing period, the flakes are exposed to continu- corn solubles by evaporation. The corn solu- ous extraction with hexane to reduce the oil bles removed during this process are used remaining in the soybean flakes to 0.5 percent directly by the feed industry or in the produc- or less. The extracted flakes are then trans- tion of corn gluten feed. The corn germ meal ported to dryers and held at 208 ‘F for approx- remaining after the oil is extracted is also used imately 10 minutes to drive off any residual hex- in the feed industry, ane. From the dryer, the flakes are moved to a toaster for a 90-minute toasting at 220 ‘F. Soybean Processing Then the flakes are cooled and moved to the Soybeans are first cleaned to remove dust, grinder for reduction into the ultimate soybean- weed seeds, stones, and so on. Then they are meal-sized product. cracked by means of corrugated rolls and Crude soybean oil extracted from the meal moved to the dehuller (l). The hulls are drawn contains impurities that can affect its quality off between the first and second cracking rolls and must be removed. The various processes by dehulling equipment, using air suction (fig- used to remove objectionable impurities are de- ure 3-6). Screens remove any portions of the signed to minimize the effect on the finished seeds that have been removed with the hulls. oil and the loss of oil. hulls are transported to a grinder, where they can be kept separate or recombined with the extracted meal.

CHAPTER 3 REFERENCES

1. Brekke, O. L., “Edible Oil Processing-Introduc- 5. Milling and Baking News, “1988 Milling Direc- tion,” Handbook of Soy Oil Processing and Uti- tory/Buyers Guide” (Merriam, KS: Sosland Pub- lization, D.R. Erickson, et al. (eds.) (St. Louis, lishing Co., 1988). MO, and Champaign, IL: American Soybean As- 6. Paulsen, M. R., “Grain Quality Attributes for sociation and the American Oil Chemists’ Soci- Corn Dry Milling,” background paper prepared ety, 1980). for the Office of Technology Assessment, U.S. 2, Canadian International Grains Institute, Congress, Washington, DC, 1988. “Grains & Oilseeds Handling, Marketing, Proc- 7. Perry, T. W., “Grain Attributes for the Feed In- essing,” Zrd cd., revised, Winnipeg, MB, Can- dustry,” background paper prepared for the Of- ada, 1982. fice of Technology Assessment, U.S. Congress, 3. May, J. B., “Wet Milling: Process and Products,” Washington, DC, 1988, Corn Chemistry and Technology, S.A. Watson 8. Pomeranz, Y., and Schellenberger, J. A., Bread and P.E. Ramstad (eds.) (St. Paul, MN: Amer- Science and Technology (Westport, CT: AVI ican Association of Cereal Chemists, 1986). Publishing Co., Inc., 1971). 4. h4iZling and Baking News, “1987 Milling Direc- 9, wheat Flour Institute, “From Wheat to Flour, ” tory/Buyers Guide” (Merriam, KS: Sosland Pub- revised cd., Washington, DC, 1981. lishing Co., 1987).

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