F&C starches

what is starch

complex carbohydrate (polysaccharide) made of thousands of glucose molecules linked by glycosidic bonds

function of starch in plants

to keep energy stored in seeds/roots for growth

function of starches in food

thickening, gelling, energy source

major sources in cereal grains

corn, wheat, rice, oats

major sources in roots

potatoes and tapioca

major sources in legumes

beans and peas

monomer

single unit of glucose

amylose

linear, forms gels

amylopectins

branched, cannot form gels

where are starch granules stored?

leucoplasts

what do starch granules contain

amylose and amylopectin

maltese cross

seen under polarized light due to crystalline (amylose) and amorphous (amylopectin) regions

starch gelatinization

process when starch granules absorb water, swell, and thicken when heated

cold water phase (Step 1)

dissolves in cold water and contains water-soluble nutrients/compounds

heating phase (step 2)

water enters granule (first amorphous then crystalline), hydrogen bonds break and granules swell, amylose leaks out and paste thickens

3rd step

thick, opaque sol

when theres higher amylose theres a what?

higher gelatinization temp.

when does gel formation (cooling process) happen after

gelatinization

what molecules realign

amylose

cereal starches have a high…

amylose, forms gels

root and waxy starches have a high…

amylopectin and no gels are formed

retrogradation

crystallization of amylose/amylopectin during storage

syneresis

loss of water from a starch gel 

whats an example of retrogradation?

bread staling

what should you mix starch with to prevent clumps in fat/oils

gravies, sauces

what should you mix starch with to prevent clumps in sugar

puddings, desserts

what should you mix starch with to prevent clumps in cold water

fats and sf products

moderate stirring=

smooth texture

excess stirring=

granules burst (thinner product)

what happens to starch with acids

breaks starch (thinner)

what happens to starch with sugar

competes for water (thinner)

what happens to starch with proteins

coats granules, delays swelling, weaker gel

pregelatinized starch modification

precooked and dried

pregelatinized starch purpose/used in

thickens in cold liquids, pudding

cross linked starch modification

chemically linked molecules

cross linked starch purpose/used in

stable under acid and heat, pizza/BBQ sauce

substituted starch modification

added chemical groups

substituted starch purpose/used in

prevents syneresis in frozen foods

acid modified starch process

heated with dilute acid

acid modified starch purpose/used in

forms strong gels when cooling, gummy candies