Complex Carbs Ch 9 Day B

Functions of complex carbohydrates

• Structure- in baked goods and other products• Cellulose forms the framework for fruits and veggies• Pectins and gums provide texture for jelly and gummy candies, ice cream etc

Starch

• Polymers of glucose (>500 glucose molecules)• Linked by alpha-1-4• Digestible

• Present in plant materials as “starch granules”• Starch molecules in the form of densely packed bundles• Visible in sliced potato with food color•

Starch

Linear

Branched

Alpha 1,6

Amylose

• Molecules contribute to gel formation:• Linear chains• Orientation parallel to each other• Moving close enough together to bond ( hydrogen bonds)

Amylopectin

• Branched molecules give viscosity to cooked paste• Side chains /bulky shape• Keep them from bonding together• Not contribute to gel formation

• Doesn’t get as organized as amylose, • It thickens but does not gel

• (Tumbleweed analogy)

Starch granules

Contain both linear amylose and branched amylopectin

Eg) corn starch, 1,3 amylose: amylopectin

( ratio depends on type of starch)

Starch

• soluble in cold water…..but• Gelatinization• Heat + water• Starch granules swell and eventually burst

• Starch molecules absorb water

• Examples:• Raw vs cooked

• Potato, rice, pasta

Gelatinization

• Raw STARCH

Heat and Water

When starch is heated in water the bonds joining amylose and amylopectin are weakened

That allows water molecules to move in and form “H” bonds( water pushes the Hydrogen bonds apart)

• Starch = alpha -1,4,1-6= digestible

• Cellulose = beta-1,4= indigestible• Cows can digest this….people cannot

• Both are linear chains of glucose units

Functions of complex carbohydrates (polysacchr)• Bind, Stabilize• Hold batters to foods when deep fried• Carageenan- stabilizes cocoa in chocolate milk• Guar and xanthan gums improve consistency of gluten free baked goods• Keep compounds, mixtures and solutions from changing state

• Fat replacers• Regular vs light mayo

Functions of complex carbohydrates

• Thicken- Starch• Starch must be heated to allow starch to swell and take up water• Heating breaks intermolecular bonds exposing polar structures that attract water.• Gelatinization- thickening a liquid with starch• Gelatinization point- temperature of maximum swelling

• Holds the most water• Has greatest thickening power

• Too much heat will break down (hydrolyze) the starch• Too high heat• Heating too long

• Salt and sugar will interfere with gelling• Sugar decreases strength and viscosity• Salt has different effects on different starches

Functions of complex carbohydrates

• Pectins• Used to thicken jams and jellies• Found in skins of fruits and vegetables• Sold as powder or liquid

Thickened Starch Mixtures

Types• Sol—a thickened liquid• Paste—thickened starch mixture that has little fl ow but isspreadable• Gel—a rigid starch mixtureProperties• Retrogradation—gel becomes firm as it cools (Lemon pie)• Syneresis—water leaks out of gel during storage• Viscosity—resistance to flow• Gelatinization—starch granules absorb water and swell,causing thickening of liquids

Retrogradation

• After gelatinization= upon cooling and storage• Linear amylose- chains orient back to crystalline zones ( intermolecular H-bonding)• Syneresis (loss) of water

• Toughening food, gritty texture• eg stale bread, gritty starch pudding

• Can be partially reversed by heating• Especially mashed potatoes• Will not completely return like original due to starch molecule explosion

• Better to store bread in freezer than refrigerator. Freezer locks in moisture

• Stability- ability of a thickened mixture to remain constant over time and temperature changes.

• Waxy maize starch is as thick when hot as it is cold• Corn starch has more thickening power than flour, but unstable with

prolonged heat

• Flour might be better choice for gravy not served right away

Starch appearance

• Opacity- how much something blocks light• Translucency- how much light passes through something

• Translucent: corn starch, potato starch, arrowroot• Good for fruit sauces

• Wheat flour good for white foods.

Starch texture

• FDA does not require identification of sources of modified starches• wheat,corn, or soy ( corn most common in US)• Most modified by hydrolysis

• Cross linked starch- designed to be more resistant to acids and separation in the freeze / thaw process• Used in baby foods, salad dressings , cream corn, fruit pie fillings

• Modified starches- stabilize condiments, sauces and relishes

Thickening Sauces with starchAvoiding lumps:• Cold water paste:• Slurry- uncooked liquid and starch

• Starch and Fat• Roux- cooked fat and starch paste• Beurre manie- equal parts butter and flour

• Starch and Sugar• Starch and sugar then add liquid• Used in sweet sauces and puddings

Nutrition of Complex Carbs

= digestible starches and indigestible fiber4 cal/g beta glucose= fiberMost abundant/ economical most abundant Should provide ½ + daily cal feel full, aids eliminationGlucose is only energy brain can use lowers risk of colon cancerExcess CHO stored as glycogen plant cell wall materialBody uses stores w/in 2hrs heavy exercise linear glucose chainsSkipping meals slows brain and organ storesIf no carbs… body goes into ketosisKetosis- elevated ketones damages kidney

Nutritional Functions of CHO

• Provide energy• Bulk for digestion• Tie up bile acids( decreasing reabsorption)• Lowers cholesterol levels in the blood• Promotes utilization of fat

• Half of carbs should be whole grain sources