Principles of Food Science and Processing Carbohydrate 2nd Lecture 2024 PDF

Principles of Food Science and Processing Carbohydrate 2 lecture nd Dr. Mohamed Elsaadany  Outline Definition Simple carbohydrates Complex carbohydrate Fiber Glycemic index Carbohydrate recommendation Grains...

Principles of Food Science and Processing Carbohydrate 2 lecture nd Dr. Mohamed Elsaadany  Outline Definition Simple carbohydrates Complex carbohydrate Fiber Glycemic index Carbohydrate recommendation Grains Wheat Rice Dr. Mohamed Elsaadany 2 1 Simple and Complex Carbohydrates Dr. Mohamed Elsaadany 3  Definition Carbohydrates  are organic compounds that contain carbon (C), hydrogen (H), and oxygen (O) in the ratio of two hydrogen atoms and one oxygen atom for every one carbon atom (CH 2 O).  Two or more sugar molecules can be assembled to form increasingly complex carbohydrates.  The two main types of carbohydrates in food are simple carbohydrates (sugars) and complex carbohydrates (starches and fiber). 4 Dr. Mohamed Elsaadany 4  Simple carbohydrates Simple Sugars or Simple carbohydrates  are naturally present as simple sugars in fruits, milk, and other foods.  Plant carbohydrates also can be refined to produce sugar products such as table sugar or corn syrup.  The two main types of sugars are monosaccharides and disaccharides. Monosaccharides consist of a single sugar molecule Disaccharides consist of two sugar molecules chemically joined together Monosaccharides and disaccharides give various degrees of sweetness to foods. The most common monosaccharides in the human diet are the following:  Glucose  Fructose  Galactose All three monosaccharides have six carbons, and all have the chemical formula C 6 H 12 O 6 , but each has a different arrangement of these atoms. 5 Dr. Mohamed Elsaadany 5  Monosaccharides Glucose  is the most abundant simple carbohydrate unit in nature. Also referred to as dextrose  glucose plays a key role in both foods and the body.  Glucose gives food a mildly sweet flavor.  It doesn’t usually exist as a monosaccharide in food but is instead joined to other sugars  In the body, glucose supplies energy to cells.  Glucose is virtually the only fuel used by the brain Fructose  Fruit sugar, fructose , tastes the sweetest of all the sugars and occurs naturally in fruits and vegetables.  Although the sugar in honey is about half fructose and half glucose, fructose is the primary source of its sweet taste.  Food manufacturers use high-fructose corn syrup as an additive to sweeten many foods Galactose  rarely occurs as a monosaccharide in food. It usually is chemically bonded to glucose to form lactose, the primary sugar in milk and dairy products. 6 Dr. Mohamed Elsaadany 6  Disaccharides Disaccharides: Disaccharides consist of two monosaccharides linked together. The following disaccharides are important in human nutrition: Sucrose (common table sugar) Lactose (major sugar in milk) Maltose (product of starch digestion) Sucrose  most familiar to us as table sugar, is made up of one molecule of glucose and one molecule of fructose.  Sucrose provides some of the natural sweetness of honey, maple syrup, fruits, and vegetables.  Manufacturers use a refining process to extract sucrose from the juices of sugar cane or sugar beets.  When a food label lists sugar as an ingredient, the term refers to sucrose. 7 Dr. Mohamed Elsaadany 7  Disaccharides Disaccharides: Lactose  or milk sugar, is composed of one molecule of glucose and one molecule of galactose.  Lactose gives milk and other dairy products a slightly sweet taste.  Human milk has a higher concentration (approximately 7 grams per 100 milliliters) of lactose than cow’s milk (approximately 4.5 grams per 100 milliliters), so human milk tastes sweeter than cow’s milk. Maltose  Maltose is composed of two glucose molecules. Maltose seldom occurs naturally in foods, but is formed whenever long molecules of starch break down.  Human digestive enzymes in the mouth and small intestine break starch down into maltose.  Maltose is fermented in the production of beer. 8 Dr. Mohamed Elsaadany 8  Oligosaccharides Oligosaccharides Oligosaccharides are short carbohydrate chains of 3 to 10 sugar molecules. Dried beans, peas, and lentils contain the two most common oligosaccharides—raffinose and stachyose.  Raffinose is formed from three monosaccharide molecules—one galactose, one glucose, and one fructose.  Stachyose is formed from four monosaccharide molecules—two galactose, one glucose, and one fructose.  The body cannot break down raffinose or stachyose, but they are readily broken down by intestinal bacteria and are responsible for the familiar gaseous effects of foods such as beans.  Human milk contains more than 200 different oligosaccharides,  For breastfed infants, oligosaccharides serve a function similar to dietary fiber in adults making stools easier to pass.  Some of these oligosaccharides also protect infants from diseases in the intestines.  Oligosaccharides in human milk also provide sialic acid, a compound essential for normal brain development. 9 Dr. Mohamed Elsaadany 9  Polysaccharides Polysaccharides  Polysaccharides ( poly meaning “many”) are long carbohydrate chains of monosaccharides.  Some polysaccharides form straight chains whereas others branch off in all directions.  Such structural differences affect how the polysaccharide behaves in water and with heating.  The way the monosaccharides within them are linked makes the polysaccharides either digestible (e.g., starch) or indigestible (e.g., fiber). Starch  Rich sources of starch include (1) grains, such as wheat, rice, corn, oats, millet, and barley; (2) legumes, such as peas, beans, and lentils; and (3) tubers, such as potatoes, yams, and cassava.  Starch imparts a moist, gelatinous texture to food. For example, it makes the inside of a baked potato moist, thick, and almost sticky.  The starch in flour absorbs moisture and thickens gravy.  Starch takes two main forms in plants: amylose and amylopectin.  Amylose is made up of long, unbranched chains of glucose molecules, whereas  amylopectin is made up of branched chains of glucose molecules. 10 Dr. Mohamed Elsaadany 10  Polysaccharides Polysaccharides Wheat flour contains a higher proportion of amylose, whereas cornstarch contains a higher proportion of amylopectin. In the body, amylopectin is digested more rapidly than amylose. Although the body easily digests most starches, a small portion of the starch in plants may remain enclosed in cell structures and escape digestion in the small intestine. Starch that is not digested is called resistant starch. Some legumes, such as white beans, contain large amounts of resistant starch. Resistant starch also is formed during the processing of starchy foods. 11 Dr. Mohamed Elsaadany 11 Polysaccharides 12 Dr. Mohamed Elsaadany 12  Polysaccharides Polysaccharides Glycogen  Glycogen is composed of long, highly branched chains of glucose molecules.  Its structure is similar to amylopectin, but glycogen is much more highly branched.  Living animals, including humans, store carbohydrate in the form of glycogen ,  Although some organ meats, such as kidney, heart, and liver, contain small amounts of carbohydrate, meat from muscle contains none. This is because after an animal is slaughtered, enzymes in the muscle tissue break down most glycogen within 24 hours.  Glycogen play an important role in our bodies as a readily mobilized store of glucose.  Most glycogen is stored in skeletal muscle and the liver.  If necessary, liver glycogen can provide as much as 100 to 150 milligrams of glucose per minute to the blood at a sustained rate for up to 12 hours.  Normally, the body can store only about 200 to 500 grams of glycogen at a time.  Some athletes practice a carbohydrate-loading regimen, which increases the amount of stored glycogen by 20 to 40 percent above normal 13 Dr. Mohamed Elsaadany 13  Polysaccharides Polysaccharides  Fiber  Dietary fiber consists of indigestible carbohydrates (such as cellulose, or soluble and insoluble fiber) and lignins.  Although not digested by the human gastrointestinal system it can enhance the process of digestion and provide other health benefits.  Functional fiber refers to isolated, indigestible carbohydrates that have beneficial physiological effects in humans. Examples of functional fiber pectins, gums and resistant starches, chitin and chitosan, and commercially produced nondigestible polysaccharides.  Total fiber is the sum of dietary fiber and functional fiber.  Cellulose, hemicellulose, pectins, gums, and beta-glucans (ß-glucans) all are indigestible  Dried beans, peas, and lentils contain short-chain carbohydrates called oligosaccharides, which are also considered to be dietary fiber.  Whole-grain foods such as brown rice, rolled oats, and whole-wheat breads and cereals; legumes fruits; and vegetables are all rich sources of dietary fiber 14 Dr. Mohamed Elsaadany 14  Polysaccharides Polysaccharides Fiber Cellulose  In plants, cellulose makes the walls of cells strong and rigid. It forms the woody fibers that support tall trees  Cellulose is made up of long, straight chains of glucose molecules.  Grains, fruits, vegetables, and nuts all contain cellulose. Hemicelluloses Hemicelluloses are composed of a variety of monosaccharides with many branching side chains. The outer bran layer on many cereal grains is rich in hemicelluloses, as are legumes, vegetables, and nuts. Pectins  Found in all plants, but especially fruits, pectins are gel-forming polysaccharides.  When fruit becomes overripe, pectin breaks down into monosaccharides and the fruit becomes mushy.  When mixed with sugar and acid, pectin forms a gel used to add firmness to jellies, jams, sauces, and salad dressings. 15 Dr. Mohamed Elsaadany 15  Polysaccharides Polysaccharides Fiber Like pectin, gums and mucilages are thick, gel-forming fibers that help hold plant cells together. The food industry uses plant gums (gum Arabic, guar gum, locust bean gum, and xanthan gum, for example) and mucilages (such as carrageenan) to thicken, stabilize, or add texture to foods such as salad dressings, puddings, pie fi llings, candies, sauces, and even drinks. Psyllium (the husk of psyllium seeds) is a mucilage that becomes very viscous when mixed with water. It is the main component in the laxative Metamucil and is added to some breakfast cereals. Lignins Not actually carbohydrates, lignins are indigestible substances that make up the woody parts of vegetables such as carrots and broccoli and the seeds of fruits such as strawberries. 16 Dr. Mohamed Elsaadany 16 characteristics of soluble and insoluble fiber 17 Dr. Mohamed Elsaadany 17  Health Effects of Fiber Health Effects of Fiber  Foods rich in dietary fiber contain a variety of fibers as well as vitamins, minerals, and other phytochemicals that offer important health effects.  High fiber foods are often lower in sugar and fat than refined wheat products, making them more healthy choices  It minimize fat, calories, and sugar intake 18 Dr. Mohamed Elsaadany 18  Recommended Intake of Carbohydrate  Recommended Intake of Carbohydrate  Recommended Dietary Allowance (RDA) for carbohydrate of 130 grams per day has been set for individuals age 1 year or older.  The RDA for carbohydrate rises to 175 grams per day during pregnancy and 210 grams per day during lactation.  choose and prepare foods and beverages with little added sugar. Although the Acceptable Macronutrient  many sources suggest that added sugar intake should be lower than 25 percent.  The Dietary Guidelines for Americans also recommends that we choose foods such  as whole grains, vegetables, fruits, and cooked dry beans and peas as staples  in our diet and to consume at least half of all grains as whole grains.  Fruits, vegetables, and whole grains, along with legumes, are good sources of fiber.  The Adequate Intake (AI) value for total fiber is 38 grams per day for men ages 19 to 50 years and 25 grams per day for women in the same age group.  This AI value is based on a level of intake (14 grams per 1,000 kilocalories) that provides the greatest risk reduction for heart disease.  The Daily Value for fiber used on food labels is 25 grams. 19 Dr. Mohamed Elsaadany 19  Glycemic Index of Foods Glycemic Index of Foods  The glycemic index measures the effect of a food on blood glucose levels.  Foods with a high glycemic index cause a faster and higher rise in blood glucose, whereas foods with a low glycemic index cause a slower rise in blood glucose.  Foods rich in simple carbohydrates or starch but low in fat or fiber tend to be digested and absorbed rapidly. This rapid absorption causes a corresponding large and rapid rise in blood glucose levels.  Other foods—especially those rich in dietary fiber, resistant starch, or fat—cause a less dramatic blood glucose response accompanied by smaller swings in blood glucose levels. 20 Dr. Mohamed Elsaadany 20 Glycemic Index of Foods 21 Dr. Mohamed Elsaadany 21 2 Grains Dr. Mohamed Elsaadany 22  Structure of Cereal Grains The structure is similar in all grains. Each kernel of grain is composed of three parts: 1- The germ, 2- Endosperm, and 3- Bran If all are present in a grain, it is a whole grain, such as whole wheat Corn, Rice, Millet, Sorghum Barley, oats,..etc. 23 Dr. Mohamed Elsaadany 23 23  The germ Germ:  is the inner portion of the kernel, composes approximately 2.5 % of the seed  Initiated the sprouting of the seeds  Contains: - Highest percent lipid ( 6–10 % lipid), Causes rancidity - Antioxidants - Vitamins E,B - Minerals - Enzymes 24 Dr. Mohamed Elsaadany 24 24  The endosperm  It represents the greatest percentage of the kernel and is contain: - Starch (high amount) - Protein matrix.  Contain lowest fat than germ and  Lower in fiber than the bran  composes approximately 83 % of the seed 25 Dr. Mohamed Elsaadany 25 25  Bran  It is the layered, outer coat of a kernel and consists of: - An outside pericarp layer, offering protection to the seed  CONTAINS: - Insoluble dietary fibre (xylans, cellulose and hemicellulose - Antioxidants bound to the cell walls (phenolic acid) - Proteins - Vitamins - Lipids &plant sterols - Minerals (iron) & phytic acid  The bran is often removed by abrasion or polishing in the milling process and may be used in many foods or animal feed. 26 Dr. Mohamed Elsaadany 26 26  Composition of Cereal Grains  Carbohydrate: (79–83 %) of the dry matter of grain. It exists predominantly as starch  Lipid (fats and oil): 1–7 % of a kernel.  Ex: wheat, rice, corn, rye, and barley contain 1–2 % lipid; oats contain 4–7 %.  The lipid is 72–85 % unsaturated fatty acids (oleic acid and linoleic acid)  Protein: 7–14 % of the grain.  Cereals are low in the amino acid's tryptophan, methionine and lysine (it remains the limiting amino acid in cereals) 27 Dr. Mohamed Elsaadany 27  Composition of Cereal Grains Vitamins: 7–14 % of the grain.  B vitamins—thiamin (B1), riboflavin (B2), and niacin (B3).  These vitamins may be lost in the milling process and so are added back through the process of enrichment.  Today, there is less prevalence of the once deadly diseases beriberi and pellagra, due to cereal enrichment with thiamin and niacin, respectively Minerals:  are naturally present at higher levels in whole grains than in refined grains  Fortification:  The addition of Zinc, calcium as well as vitamins may also be added at levels beyond/not present in the original grain. Water: 10–14 % of the grain  If a flour is high in protein content, it absorbs a lot of added water compared to low protein flour. 28 Dr. Mohamed Elsaadany 28  Wheat  Wheat is classified in various according to:  Types  Color  Hardness  According to the type  they are classified as:  Hard wheat  Soft wheat  Durum wheat 29 Dr. Mohamed Elsaadany 29  Wheat - Hard wheat:  The characteristics of Hard wheat is as follows: - More protein - More water absorption power (WAP). - Good mixing capacity (easy to mix). - Fermentation tolerance. - Good gas retention power. Mainly used for yeast products. - Soft wheat:  The characteristics of Soft wheat is as follows: - Less protein - Less water absorption power (WAP). - Poor mixing capacity. - Fermentation tolerance. - Poor gas retention power. 30 Mainly used to make biscuits, cakes and pastries. Dr. Mohamed Elsaadany 30 Wheat  According to the color they are classified as:  Red wheat  White wheat  This variation due to the environmental factors 31 31 Dr. Mohamed Elsaadany 31  Wheat: Milling Process  Milling means conversion of wheat into flour.  Food and Drug Administration (FDA) Specify milling “flour (72%).  (Whole Grain - Refine Grain).  Two methods of milling:  1- Stone milling / home milling  2- Roller flour milling  Flour:  The flour obtained is called as green flour  It contains the high moisture and  Slightly yellowish color due to xanthophylls  Not suitable for making bakery products  (poor water absorption power, poor baking quality) 32 32 Dr. Mohamed Elsaadany 32  Bleaching: Bleaching:  To remove the color through oxidation process Bleaching agent:  Chlorine,  Chlorine dioxide or benzyl per oxide  The bleached flour is creamish white in color. Maturing: (oxidation process)  Objective: To improve flour quality  By using some chemicals like: 1- Potassium bromate, 2- Ascorbic acid 33 33 Dr. Mohamed Elsaadany 33  Wheat flower composition Starch:  -Starch is not soluble in water until starch is heated to about 140 F with six times of its weight of water  -Starch + water = is called gelatinization.  -Starch combines with lipid and gluten to retain the gas during fermentation. Moisture - More moisture in the flour it will: -Reduce the storage life. -Induce insect infestation (it may get fungus and bacteria -Reduce the Water Absorption pour (WAP) of the flour. Protein  Flour contadins soluble and insoluble proteins Albumin Globulin Gliadin ( viscous behavior) Glutenin (elastic)  The quality of the flour is decided by the gluten content. 10-11.5% for bread making 7 -10 % for cake and biscuits 34 34 Dr. Mohamed Elsaadany 34  Rice  It is considered to be the main food for about half population of the world, especially in the eastern parts of Asia as in China, Japan, India.  Rice may be eaten as the whole grain, or polished.  Whole rice (unpolished)is more subject to rancidity and favors deterioration, as well as insect infestation compared to polished, white rice.  Enriched rice should not be rinsed before cooking, or the added vitamins and minerals will be washed away - Enrichment of rice: (Ca, Fe, VitD,B1, B2, B3) Achieved by two primary methods: 1- The rice coated with a powder of thiamin and niacin, dry it, and then coated with iron before and dried again. 2- Enrichment through involves parboiling or “converting” rice 1- This process allows water-soluble bran and germ nutrients to travel to the endosperm by boiling or a pressure steam treatment. 2- As a result, nutrients are retained when the outside hull is removed. 35 3- Following the steaming process, rice is subsequently dried and polished. 35 Dr. Mohamed Elsaadany 35  Corn  Corn is a staple cereal food of many people and nations, although the majority of corn is used for animal feed. Lacking in the two essential amino acids: 1- Tryptophan and 2- Lysine  Corn usages:  For use in bread making, corn needs to be combined with other flour,  such as wheat flour. 36 36 Dr. Mohamed Elsaadany 36 THANKS! Any questions? Dr. Mohamed Elsaadany 37