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 • 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 branchedstructure
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:• 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
• 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