1. Complex carbohydrates Ch 9 A

2. Types of complex carbohydrates • Starches • Cellulose • Gums • Pectins • others

3. Starches • Polymers of sugar • Most abundant complex carb in the diet • Most have 100 to several 1000 glucose units in chains

4. 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.

5. 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 arrowrootplant

6. Two basic structures of starch • Amylose- units are linked linear • Amylopectin- units have a branched structure

7. 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

8. Cellulose • A polysacchride

9. 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)

10. Carbs: polysaccharides • Sources: • Seaweed • Microbial products • Plant exudates • Plants • Different from simple sugars: • Usually insoluble in water and tasteless

11. Carbohydrates: Polysaccharides • Agar* • Alginates* • Carrageenan* • Xanthan gum • Gum Arabic/ acacia gum • Pectins • Starch • Cellulose, hemicellulose * ( not in text materials)

12. 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

13. Chocolate Milk • Purchase choc milk does not separate • Nestle Quick milk will separate

14. Carbohydrates: Polysaccharides ( other) • Xanthan gum • Extracted from bacteria (xanthomonascampestris) • From cabbage spoilage bacteria • Used to control viscosity ( thickness) • Used as a suspending agent ( salad dressing) • Provides Loaves structure in wheat-free bread

15. 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

16. 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

17. Lab: which fruits contain pectin? • Target: Observe the concentration and effect of pectin • Apple • Peach • Pear • Blue Berries • Grapes • Straw berry

19. Thickened Starch Mixtures • Types • • Sol—a thickened liquid • • Paste—thickened starch mixture that has little flow 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 flow • • Gelatinization—starch granules absorb water and swell, • causing thickening of liquids