Transcript Complex carbohydrates

Complex carbohydrates
Ch 9 A
Types of complex carbohydrates
• Starches
• Cellulose
• Gums
• Pectins
• others
Starches
• Polymers of sugar
• Most abundant complex carb in the diet
• Most have 100 to several 1000 glucose units in chains
Starches ( cont)
• Wheat is main source in the US
• Also found in
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rice,
corn,
potatoes,
and oats
• Any grain or seed is high in starch.
Starches ( less commonly used)
• Rye
• Sorghum
• Soy
• Tapioca -is a starch extracted from cassava root.
• Arrowroot- is an easily digested starch extracted from the roots of the
arrowroot plant
Two basic structures of starch
• Amylose- units are linked linear
• Amylopectin- units have a branched
structure
Starch is nature’s carb supply
• Plants produce starches in packets called granules
• Not soluble in cold water
• Size and shape vary from plant to plant
• Rice = smallest granule
• Potato = largest granules
• Varying starches varies performance of starches in foods
• Starches with mainly amylopectin are called waxy starches
Cellulose
• A polysacchride
polysaccharides
• High molecular weight polymers or long chains of monosaccharide
units
• (Eg. cellulose and starch = polymers of glucose)
• Form part of cellular structure and firmness of tissues
• ( Eg. cellulose , pectins, and gums)
• Energy reserve for animals and plants
• (Eg. glycogen, starch)
Carbs: polysaccharides
• Sources:
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Seaweed
Microbial products
Plant exudates
Plants
• Different from simple sugars:
• Usually insoluble in water and tasteless
Carbohydrates: Polysaccharides
• Agar*
• Alginates*
• Carrageenan*
• Xanthan gum
• Gum Arabic/ acacia gum
• Pectins
• Starch
• Cellulose, hemicellulose
* ( not in text materials)
Carbohydrates: polysaccharides
• Agar, Alginates, Carrageenan
• Extracted from seaweed
• Suspending and thickening agents
• Salad dressings, puddings, pie fillings, ice cream, sherbet and icings
• Cocoa particles suspend in chocolate milk
Chocolate Milk
• Purchase choc milk does not separate
• Nestle Quick milk will separate
Carbohydrates: Polysaccharides ( other)
• Xanthan gum
• Extracted from bacteria (xanthomonas campestris)
• From cabbage spoilage bacteria
• Used to control viscosity ( thickness)
• Used as a suspending agent ( salad dressing)
• Provides Loaves structure in wheat-free bread
Carbohydrates: Polysaccharides ( other)
• Gum Arabic ( acacia gum)*
• Plant exudates from the bark of a certain tree (acacia trees)
• Jelly beans: thickening agent
• Beer : stabilizer for foam head
*Expensive polysaccharide
Carbohydrates: Polysaccharides
Pectins- C6H10O7
(polygalacturonic acid metyl ester)
• Naturally found in plant tissue
• Lemons, oranges, apples
• Soft fruits not a good source
• Considered a food additive GRAS
• Generally regarded as safe
• Used as jelling agents in jams and jellies
• Hydrocolloidal that binds with water to create gel / thickener
• Contribute to viscosity (resistance flow) of ketchup
and tomato paste
• Overall mouth feel of foods
• Help maintain particles in suspension in OJ and unclarified apple juice
Lab: which fruits contain pectin?
• Target: Observe the concentration and effect of pectin
• Apple
• Peach
• Pear
• Blue Berries
• Grapes
• Straw berry
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Thickened Starch Mixtures
Types
• Sol—a thickened liquid
• Paste—thickened starch mixture that has little fl ow but is
spreadable
• Gel—a rigid starch mixture
Properties
• Retrogradation—gel becomes fi rm as it cools
• Syneresis—water leaks out of gel during storage
• Viscosity—resistance to fl ow
• Gelatinization—starch granules absorb water and swell,
causing thickening of liquids