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