Transcript Chapter 9 Complex Carbohydrates

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
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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