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1 Cereal Grains, Legumes and Oilseeds 1211 Steven C Seideman, PhD Extension Food Processing Specialist Cooperative Extension Service University of Arkansas.

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Presentation on theme: "1 Cereal Grains, Legumes and Oilseeds 1211 Steven C Seideman, PhD Extension Food Processing Specialist Cooperative Extension Service University of Arkansas."— Presentation transcript:

1 1 Cereal Grains, Legumes and Oilseeds 1211 Steven C Seideman, PhD Extension Food Processing Specialist Cooperative Extension Service University of Arkansas

2 2 Cereal Grains, Legumes and Oilseeds This module covers some of the basic cereal grains, legumes and oilseeds- their production, composition, processing and ultimate use. This module covers some of the basic cereal grains, legumes and oilseeds- their production, composition, processing and ultimate use. It is a brief summary of Chapter 17 Cereal Grains, Legumes and Oilseeds from the book FOOD SCIENCE by Norman N. Potter and Joseph H. Hotchkiss. Published by Kluwer Academic/Plenum Publishers, New York. It is a brief summary of Chapter 17 Cereal Grains, Legumes and Oilseeds from the book FOOD SCIENCE by Norman N. Potter and Joseph H. Hotchkiss. Published by Kluwer Academic/Plenum Publishers, New York.

3 3 Cereal Grains

4 4 Cereals Cereals are plants that yield edible grains. Cereals are plants that yield edible grains. They are consumed worldwide and make up a majority of the worlds calories and 50% of protein consumption. They are consumed worldwide and make up a majority of the worlds calories and 50% of protein consumption. Rice is the worlds most important food with wheat not far behind. Over 90% of rice is grown in Asia where it is consumed. Rice is the worlds most important food with wheat not far behind. Over 90% of rice is grown in Asia where it is consumed. In the U.S., corn is the leading grain but most is used for animal production while wheat is used directly for human consumption. In the U.S., corn is the leading grain but most is used for animal production while wheat is used directly for human consumption.

5 5 Photo courtesy of USDA

6 6 Cereal Grains Wheat, rice and corn production worldwide is on the order of 525 million tons annually. Wheat, rice and corn production worldwide is on the order of 525 million tons annually. The principle cereal grains grown in the U.S. include corn, wheat, oats, sorghum, barley, rye, rice and buckwheat. The principle cereal grains grown in the U.S. include corn, wheat, oats, sorghum, barley, rye, rice and buckwheat.

7 7 Composition of Some Cereals Grains (%) Grain Grain Corn Corn Wheat Wheat Oats Rice Oats Rice Moisture Carbohydrates Protein Fat

8 8 Physical Characteristics of Grain Starchy endosperm- main part of the grain or kernel. Starchy endosperm- main part of the grain or kernel. Protective outer layers- bran or hull Protective outer layers- bran or hull Embryo or germ- typically located at the bottom of the kernel. Embryo or germ- typically located at the bottom of the kernel.

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11 11 Milling of Cereal Grains In most milling operations, the hulls are removed which are largely indigestible by humans. The dark-colored bran is also removed. In most milling operations, the hulls are removed which are largely indigestible by humans. The dark-colored bran is also removed. The germ, which is high in oil, is enzymatically active and under certain conditions would be likely to produce a rancid condition in the grain. The germ, which is high in oil, is enzymatically active and under certain conditions would be likely to produce a rancid condition in the grain. Thus, the main component of interest is the starchy, proteinaceous endosperm. Thus, the main component of interest is the starchy, proteinaceous endosperm. Since the bran is rich in B vitamins and minerals, it is a common practice to add these back to processed grains from which they came. This is known as enrichment. Since the bran is rich in B vitamins and minerals, it is a common practice to add these back to processed grains from which they came. This is known as enrichment.

12 12 Cereal Grains Typically cereal grains contain a moisture of % if properly dried. When the moisture content is higher than this, they must be dried or they may mold or rot in storage before they can be used. Typically cereal grains contain a moisture of % if properly dried. When the moisture content is higher than this, they must be dried or they may mold or rot in storage before they can be used. Cereal grains contain about two-thirds carbohydrate, most is in the form of digestible starches and sugars. Cereal grains contain about two-thirds carbohydrate, most is in the form of digestible starches and sugars. The operations of milling generally remove much of the indigestible fiber and fat from these grains when they are to be consumed for human food. The operations of milling generally remove much of the indigestible fiber and fat from these grains when they are to be consumed for human food.

13 13 Wheat Wheat is classified into one of two types – Hard wheat is higher in protein than soft and produces a stronger dough used for bread-making. Soft wheat is better for batters and cake baking. Wheat is classified into one of two types – Hard wheat is higher in protein than soft and produces a stronger dough used for bread-making. Soft wheat is better for batters and cake baking. Wheat milling is basically a succession of pulverizing steps to break down the endosperm. Wheat milling is basically a succession of pulverizing steps to break down the endosperm.

14 14 Photo courtesy of USDA

15 15 Photo courtesy of USDA

16 16 Photo courtesy of USDA

17 17 Conventional Wheat Milling Milling is a progressive series of disintegrations followed by sieving. The disintegrations are made by rollers set progressively closer and closer together. The first rollers break open the bran and free the germ from the endosperm. The second and third rollers further pulverize the brittle endosperm and flatten out the semiplastic germ. The flakes of bran and flattened germ are removed by the sieves under the first few sets of rollers. Milling is a progressive series of disintegrations followed by sieving. The disintegrations are made by rollers set progressively closer and closer together. The first rollers break open the bran and free the germ from the endosperm. The second and third rollers further pulverize the brittle endosperm and flatten out the semiplastic germ. The flakes of bran and flattened germ are removed by the sieves under the first few sets of rollers.

18 18 Conventional Wheat Milling The pulverized endosperm is run through successive rollers set still closer together to grind it into finer and finer flour, which is sifted under each set of rollers to remove the last traces of bran. The pulverized endosperm is run through successive rollers set still closer together to grind it into finer and finer flour, which is sifted under each set of rollers to remove the last traces of bran. As flour is progressively milled, it becomes whiter in color, better in bread-making quality but lower in vitamin and mineral content. As flour is progressively milled, it becomes whiter in color, better in bread-making quality but lower in vitamin and mineral content.

19 19 Uses of Wheat Flour The uses of wheat flour in the baking industry include the making of breads, sweet doughs, cakes, biscuits, doughnuts, crackers and the like. The uses of wheat flour in the baking industry include the making of breads, sweet doughs, cakes, biscuits, doughnuts, crackers and the like. Another use of wheat flour and courser milled fractions of wheat are alimentary pastes such as macaroni, spaghetti and other forms of noodles and pasta. Another use of wheat flour and courser milled fractions of wheat are alimentary pastes such as macaroni, spaghetti and other forms of noodles and pasta.

20 20 Uses of Wheat Flour Alimentary pastes are mostly milled wheat flour and water. The wheat is usually hard durum and is milled to yield course particles called semolina. Alimentary pastes are mostly milled wheat flour and water. The wheat is usually hard durum and is milled to yield course particles called semolina. Alimentary pastes may also contain eggs, salt and other minor ingredients. Alimentary pastes may also contain eggs, salt and other minor ingredients. They differ from bakery doughs in that alimentary pastes are not leavened. They differ from bakery doughs in that alimentary pastes are not leavened. Alimentary pastes are usually made with 100 parts wheat flour/ 30 parts water, mixed, and extruded into thin sheets, cut into noodles or other shapes and then dried. Alimentary pastes are usually made with 100 parts wheat flour/ 30 parts water, mixed, and extruded into thin sheets, cut into noodles or other shapes and then dried.

21 21 Rice Rice is unusual compared to other grains in that it is not ground into flours before consumption. Worldwide, rice is primarily consumed as an intact grain. Rice is unusual compared to other grains in that it is not ground into flours before consumption. Worldwide, rice is primarily consumed as an intact grain. The milling process is designed to remove only the outer bran layer and hull without breaking the kernel. The milling process is designed to remove only the outer bran layer and hull without breaking the kernel. It is often used in the U.S. as a carbohydrate source for making beer because its bland flavor. It is often used in the U.S. as a carbohydrate source for making beer because its bland flavor.

22 22 Photo courtesy of USDA

23 23 Rice Milling Rice milling begins with whole grains of rice being fed by machine between abrasive disks or moving rubber belts. These machines, known as shellers or hullers, do not crush the grains but instead rub the outer layer of hull from the underlying kernels. Rice milling begins with whole grains of rice being fed by machine between abrasive disks or moving rubber belts. These machines, known as shellers or hullers, do not crush the grains but instead rub the outer layer of hull from the underlying kernels. The hulls are separated from the kernels by jets of air and the kernels, known as brown rice, move to another abrasive device called a rice-milling machine. The hulls are separated from the kernels by jets of air and the kernels, known as brown rice, move to another abrasive device called a rice-milling machine.

24 24 Rice Milling Here the inner layers of bran and germ are dislodged by the rubbing action of a ribbed rotor. The endosperms with bran and germ removed can now be further polished to a white, high glossy finish. Here the inner layers of bran and germ are dislodged by the rubbing action of a ribbed rotor. The endosperms with bran and germ removed can now be further polished to a white, high glossy finish. As in the case of wheat, the higher the degree of milling or polishing, the lower are the remaining vitamin and mineral contents. This is particularly serious in the case of rice because entire populations depend on rice as the principle item of diet. As in the case of wheat, the higher the degree of milling or polishing, the lower are the remaining vitamin and mineral contents. This is particularly serious in the case of rice because entire populations depend on rice as the principle item of diet.

25 25 Enrichment Rice can be enriched in one of two ways; Rice can be enriched in one of two ways; 1)Coat the polished rice with the enrichment mixture (thiamin, niacin and iron) and then coat the grains with a waterproof film material. 1)Coat the polished rice with the enrichment mixture (thiamin, niacin and iron) and then coat the grains with a waterproof film material. 2)Parboiling whole rice including the hulls, bran and germ in water for 10 hr at 70C. This causes the B vitamins and minerals from the hulls, bran and germ to leach into the endosperm. The rice is then dried, milled and polished. This is often referred to as converted rice.

26 26 Corn Corn is consumed as both whole kernels ( a vegetable) or as a flour. Corn is consumed as both whole kernels ( a vegetable) or as a flour. Popcorn pops because the moisture expands upon heating and explodes because it cannot escape. Popcorn pops because the moisture expands upon heating and explodes because it cannot escape. Corn can be dry-milled like wheat or wet-milled. Wet milling is popular and is used to make corn syrups and high fructose corn syrup Corn can be dry-milled like wheat or wet-milled. Wet milling is popular and is used to make corn syrups and high fructose corn syrup

27 27 Corn Corn is milled to remove hulls and germ, both of which can be fed to livestock. The germ is an important source of corn oil. Corn is milled to remove hulls and germ, both of which can be fed to livestock. The germ is an important source of corn oil. Corn can be dry milled similar to wheat where the end product is corn meal or if further refined, corn flour. In this process, the hulls and germ are also removed and the endosperm reduced in size. Corn can be dry milled similar to wheat where the end product is corn meal or if further refined, corn flour. In this process, the hulls and germ are also removed and the endosperm reduced in size.

28 28 Photo courtesy of the USDA

29 29 Photo courtesy of USDA

30 30 Photo courtesy of USDA

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32 32 Wet Milling of Corn In wet milling, corn kernels are placed in large tanks of warm water with generally an acid and sulfur dioxide as a preservative. In wet milling, corn kernels are placed in large tanks of warm water with generally an acid and sulfur dioxide as a preservative. The softened kernels are then run through an attrition mill to break up the kernels. The pasty mass is then pumped to settling troughs. Here is where the oil rich germ floats to the top, is skimmed off to be pressed for oil. The softened kernels are then run through an attrition mill to break up the kernels. The pasty mass is then pumped to settling troughs. Here is where the oil rich germ floats to the top, is skimmed off to be pressed for oil. The watery slurry is then filtered to remove the hulls. The watery slurry is then filtered to remove the hulls.

33 33 Wet Milling of Corn The watery slurry now containing the starch and protein fractions is passed through high speed centrifuges to separate the heavier starch from the lighter protein fraction. The watery slurry now containing the starch and protein fractions is passed through high speed centrifuges to separate the heavier starch from the lighter protein fraction. The starch is dried to yield corn starch. The starch is dried to yield corn starch. The protein fraction is dried and referred to as corn gluten or zein which is commonly used for animal feed. The protein fraction is dried and referred to as corn gluten or zein which is commonly used for animal feed.

34 34 Corn Syrup Corn syrup is made from the corn starch fraction that has been exposed to acid or starch-splitting enzymes. Corn syrup is made from the corn starch fraction that has been exposed to acid or starch-splitting enzymes. This hydrolyzed starch contains varying proportions of dextrins, maltose and glucose and is used as a sweetner. This hydrolyzed starch contains varying proportions of dextrins, maltose and glucose and is used as a sweetner.

35 35 Barley, Oats and Rye Barley, oats and rye are primarily used for animal feed. Barley, oats and rye are primarily used for animal feed. Barley and rye also provide sources of fermentable carbohydrate in the production of fermentable beverages. Barley and rye also provide sources of fermentable carbohydrate in the production of fermentable beverages. The flour from rye can be used to make flour for breads but cannot be used by itself because the protein content is too low. The flour from rye can be used to make flour for breads but cannot be used by itself because the protein content is too low. Most oats used for human consumption are in the form of rolled oats, an ingredient in breakfast cereals. Most oats used for human consumption are in the form of rolled oats, an ingredient in breakfast cereals.

36 36 Barley, Oats and Rye Barley is also used to produce barley malt. In this process, the barley seed is allowed to germinate to a sprout. The dried barley sprout is now called barley malt and is used in the brewing industry to help digest starchy material into sugars for rapid yeast fermentation. The malt also adds a distinctive flavor to beer. Malt further adds flavor to breakfast cereals and malted-milk concentrates. Barley is also used to produce barley malt. In this process, the barley seed is allowed to germinate to a sprout. The dried barley sprout is now called barley malt and is used in the brewing industry to help digest starchy material into sugars for rapid yeast fermentation. The malt also adds a distinctive flavor to beer. Malt further adds flavor to breakfast cereals and malted-milk concentrates.

37 37 Breakfast Cereals Most breakfast cereals are made from the endosperm of wheat, corn, rice and oats. Most breakfast cereals are made from the endosperm of wheat, corn, rice and oats. In ready to eat breakfast cereals, the endosperm is broken down or ground into a mash and then converted into flakes by squeezing the broken grits or mash between rollers. The mash can be extruded into a number of different shapes or the endosperm can be kept intact as kernels to be puffed as in the case of puffed rice. In ready to eat breakfast cereals, the endosperm is broken down or ground into a mash and then converted into flakes by squeezing the broken grits or mash between rollers. The mash can be extruded into a number of different shapes or the endosperm can be kept intact as kernels to be puffed as in the case of puffed rice.

38 38 Breakfast Cereals In all cases, the flaked, formed or puffed cereals must be oven-cooked and dried to develop the toasted flavor and to obtain the crisp, brittle textures desired. In all cases, the flaked, formed or puffed cereals must be oven-cooked and dried to develop the toasted flavor and to obtain the crisp, brittle textures desired. This crispness requires that many ready-to- eat cereals be dried to 3-5% moisture content. This crispness requires that many ready-to- eat cereals be dried to 3-5% moisture content.

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41 41 Baking Science

42 42 Baking Science Baking, by definition, refers to the application of heat in an oven. This is a very strict definition for baking. It can also include all the reactions and processes that occur before the item is placed in an oven. Baking, by definition, refers to the application of heat in an oven. This is a very strict definition for baking. It can also include all the reactions and processes that occur before the item is placed in an oven.

43 43 Classifications Baked items can be placed in one of four categories. Baked items can be placed in one of four categories. 1)Yeast-raised goods –breads, etc leavened by CO 2 from yeast fermentation 1)Yeast-raised goods –breads, etc leavened by CO 2 from yeast fermentation 2)Chemically leavened goods-layered cakes, doughnuts, biscuits etc that are raised by CO 2 from baking powders and chemical agents. 2)Chemically leavened goods-layered cakes, doughnuts, biscuits etc that are raised by CO 2 from baking powders and chemical agents. 3)Air-Leavened goods- angel cakes and sponge cakes made without baking powder 3)Air-Leavened goods- angel cakes and sponge cakes made without baking powder 4)Partially leavened goods- pie crusts, certain crackers, where intentional leavening agents are used yet a slight leavening occurs from expanding steam and other gases during the oven-baking operation. 4)Partially leavened goods- pie crusts, certain crackers, where intentional leavening agents are used yet a slight leavening occurs from expanding steam and other gases during the oven-baking operation.

44 44 Baking Ingredients and their Function The following goes through the major baking ingredients and how they function

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47 47 Gluten and Starch of Wheat Flour The principle protein in wheat flour is called gluten. The principle protein in wheat flour is called gluten. Gluten has the property of when moistened and worked by mechanical action, it forms an elastic dough. This is accomplished by forming linkages between protein molecules. The more the dough is worked, the more linkages are formed. This is the reason that doughs are kneaded when a strong dough is required. However, the gluten can weaken and breakdown under excessive mechanical agitation such as over-mixing. Gluten has the property of when moistened and worked by mechanical action, it forms an elastic dough. This is accomplished by forming linkages between protein molecules. The more the dough is worked, the more linkages are formed. This is the reason that doughs are kneaded when a strong dough is required. However, the gluten can weaken and breakdown under excessive mechanical agitation such as over-mixing.

48 48 Gluten and Starch of Wheat Flour Wheat starch does not form elastic films like gluten but rather gelatinizes when moistened, forming a paste material. Wheat starch does not form elastic films like gluten but rather gelatinizes when moistened, forming a paste material. The character of the dough or batter depends on the type of flour used. Real rigid doughs are made from flours with a high gluten content (hard wheat) and make good bread. The character of the dough or batter depends on the type of flour used. Real rigid doughs are made from flours with a high gluten content (hard wheat) and make good bread. Flours with a lower gluten content (soft wheat) make better batters that are less chewy and more tender. Flours with a lower gluten content (soft wheat) make better batters that are less chewy and more tender.

49 49 Leavening Agents Yeast and baking powders are not the only leavening agents. Water in dough or batters turns to steam in the oven and the expanding steam contributes to leavening. Yeast and baking powders are not the only leavening agents. Water in dough or batters turns to steam in the oven and the expanding steam contributes to leavening. Air in the dough or batter also expands when heated and contributes to leavening. Air in the dough or batter also expands when heated and contributes to leavening.

50 50 Yeasts There are two forms of yeast used in baking- moist pressed cakes and dehydrated granules. There are two forms of yeast used in baking- moist pressed cakes and dehydrated granules. Both contain billions of living cells (Saccharomyces cerevisiae). Both contain billions of living cells (Saccharomyces cerevisiae). When rehydrated, both forms begin metabolism and fermentation. When rehydrated, both forms begin metabolism and fermentation. In fermentation, simple sugars are converted to carbon dioxide gas and alcohol In fermentation, simple sugars are converted to carbon dioxide gas and alcohol The heat of the oven kills the yeast and inactivates its enzymes thus stopping fermentation. The heat of the oven kills the yeast and inactivates its enzymes thus stopping fermentation.

51 51 Baking Powders Baking powders contain particles of sodium bicarbonate and some acid (like monocalcium phosphate) and generate CO 2 by the following reaction; Baking powders contain particles of sodium bicarbonate and some acid (like monocalcium phosphate) and generate CO 2 by the following reaction; 3CaH 4 (PO4) 2 + 8NaHCO 3 3CaH 4 (PO4) 2 + 8NaHCO 3 Monosodium Phosphate + Sodium bicarbonate bicarbonate Equals Equals Ca 3 (PO 4 ) 2 +4Na 2 HPO+8CO 2 +8H 2 O Tricalcium phosphate+ Disodium phosphate+Carbon dioxide+ water dioxide+ water

52 52 Eggs Eggs can function as a principle structure builder in cakes and also contribute to nutrition, flavor and color of the finished product. Eggs can function as a principle structure builder in cakes and also contribute to nutrition, flavor and color of the finished product. Like gluten, egg whites are a mixture of proteins that forms films and entraps air when whipped and on heating, it coagulates to produce rigidity. Like gluten, egg whites are a mixture of proteins that forms films and entraps air when whipped and on heating, it coagulates to produce rigidity. The yolks of eggs contain similar proteins. The yolks of eggs contain similar proteins. Eggs are important to use when working with low- protein flours as in the case of angel cakes and sponge cakes. Eggs are important to use when working with low- protein flours as in the case of angel cakes and sponge cakes.

53 53 Shortening Unlike flour and eggs, which are structure builders and tougheners, shortening is a tenderizer. The beating of shortening in some recipes is called for to entrap air prior to the incorporation of other ingredients to finish the batter. When the batter is baked in the oven, the shortening melts and releases the air bubbles which contribute to the leavening action of baking powders and expanding steam. The melted shortening then deposits around the cell walls of the coagulating structure to contribute a tenderizing effect and lubricate the texture. Unlike flour and eggs, which are structure builders and tougheners, shortening is a tenderizer. The beating of shortening in some recipes is called for to entrap air prior to the incorporation of other ingredients to finish the batter. When the batter is baked in the oven, the shortening melts and releases the air bubbles which contribute to the leavening action of baking powders and expanding steam. The melted shortening then deposits around the cell walls of the coagulating structure to contribute a tenderizing effect and lubricate the texture.

54 54 Sugars Sugar, like shortening, is a tenderizer in baked goods. It also adds sweetness and in the form of sucrose, provides additional fermentable substrate in yeast raised goods. Sugar, like shortening, is a tenderizer in baked goods. It also adds sweetness and in the form of sucrose, provides additional fermentable substrate in yeast raised goods.

55 55 Legumes and Oilseeds

56 56 Legumes and Oilseeds Legumes are flowering plants having pods which contain beans or peas. Legumes are flowering plants having pods which contain beans or peas. Legumes include various peas and beans, most of which are low in fat but soybeans are the exception. Legumes include various peas and beans, most of which are low in fat but soybeans are the exception. The term oilseed is applied to those seeds, including soybeans, which are processed for their oil. The term oilseed is applied to those seeds, including soybeans, which are processed for their oil. Oilseeds include peanuts seed, cottonseed, sunflower seed, rapeseed, flaxseed, linseed and sesame seeds. Oilseeds include peanuts seed, cottonseed, sunflower seed, rapeseed, flaxseed, linseed and sesame seeds. Both legumes and oilseeds contain considerably more protein than cereal grains. Both legumes and oilseeds contain considerably more protein than cereal grains.

57 57 Legumes and Oilseeds Legumes (beans and peas) and oilseeds are much higher in protein than grains and oilseeds are much higher in fat than grains. Legumes (beans and peas) and oilseeds are much higher in protein than grains and oilseeds are much higher in fat than grains. Soybeans are legumes that have oilseed characteristics. Soybeans are legumes that have oilseed characteristics.

58 58 Soybeans Soybeans are very versatile food products used for both animal and human foods. Soybeans are very versatile food products used for both animal and human foods. Soybeans can have up to 23% fat. Soybeans can have up to 23% fat. Soy protein is quite extensively used for animal feed as a protein source. Soy protein is quite extensively used for animal feed as a protein source.

59 59 Photo courtesy of USDA

60 60 Peanuts Peanuts contain 25% protein and 50% oil. They are used mainly to produce peanut butter (50% of the crop). Peanuts contain 25% protein and 50% oil. They are used mainly to produce peanut butter (50% of the crop). They can also be used to make flour and used for oil. They can also be used to make flour and used for oil.

61 61 Photo courtesy of USDA

62 62 Conclusions From this series, you should have learned; From this series, you should have learned; 1)The types, composition, structure and processing of cereal grains 2)How breakfast cereals are made 3)The science of baking 4)The category of legumes and oilseeds.

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