Chapter 9 Complex Carbohydrates Two Names for Complex

Chapter 9 Complex Carbohydrates

Two Names for Complex Carbohydrates • 1. Polysaccharides- a chain of many sugar units or saccharides • 2. Macromolecules- very large molecules that contain hundreds or thousands of atoms each

Four Types of Complex Carbohydrates • • 1. Starches 2. Cellulose 3. Carbohydrate Gums 4. Pectin

Cellulose • A polysaccharide made from large amounts of β-D-glucose • Some animals use cellulose as a food source • Humans lack the digestive enzymes to break down cellulose • Cellulose is a fiber and forms the rigid structure of plants

Carbohydrate Gums • Polysaccharides that are soluble in water and extracted from plants • Used to thicken and stabilize mixtures and trap color and flavor by protecting them from moisture absorption, evaporation, or chemical oxidation • Ex. Gum arabic, karaya gum, gum tragacanth, gum agar, carageenan, algin

Pectin • Complex carbohydrates that are found in plant cells and made of chemical derivatives of sugar called sugar acids • Found naturally in fruits • It can produce a strong gel that is stable to near 100ºC • In the presence of sugar, pectin dehydrates, and acid will thicken pectin • Pectin is a key component in jams and jellies

Functions of Complex Carbohydrates in Food Preparation • 1. Provide structure • 2. Bind ingredients together • 3. Act as absorbing agents or thickeners

Providing Structure • Flour provides the majority of bulk and structure for baked goods and other food products • Starch is the main component of wheat flour • Starch thickens when heated and gels when cooled so that foods with starch can take and hold different shapes • Cellulose provides structure for fruits and vegetables • Pectins and gums give texture to jams, jellies and ice cream

Binding Agents • Amylose molecules work better than amylopectin molecules at holding batters to vegetables and meats when they are deep fried • If the batter-dipped food is allowed to sit for about 20 minutes prior to frying then the binding will be increased • Carageenan is a gum used to bind cocoa in chocolate milk and stabilizes ice cream and other dairy products

Thickening Agents • Starch is used to thicken liquids and is usually combined with them in food preparation • Starch must be heated first to break its intermolecular bonds in order to mix with liquids by forming hydrogen bonds

Examples of Starch Mixtures • Sols- ex. pancake, waffle, and muffin batter, white sauce and gravy • Pastes- ex. water or milk combined with starch. This paste can be stirred into hot broth without lumping and is used to thicken soups and stews • Gels- amylose forms more stable gels than amylopectins • Slurries- uncooked mixtures of water and starch

Viscosity • The resistance of a mixture to flow • Viscosity is tested by using line-spread sheets • Line spread sheets have a sample placed in the middle of marked lines of concentric circles and however far the sample flows is how viscous the sample is • Gels are more viscous than pastes, pastes are more viscous than sols

Stability • The ability of a thickened mixture to remain constant over time and temperature changes • A stable sauce can be frozen or reheated and still look and taste the same as when first prepared • Waxy maize starch is a very stable starch

Opacity vs. Translucency • Opacity- the ability of an object to block light • Translucency- the measure of how much light can pass through an object

Complex Carbohydrates and Nutrition • Complex carbohydrates provide 4 calories of energy per gram. • The brain uses glucose as its energy source • Cellulose, or fiber, aids in hunger satiety, digestion, and elimination • Fruits, vegetables, and grains all have fiber

Nutritional Functions of Starches • Provide energy • Provide bulk for digestion • Tie up bile acids and decrease its reabsorption • Lower blood cholesterol levels and fight atherosclerosis • Promote the use of fat