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