Science Of Food- Exam 3 Review

uses of starch:

• Thickeners (in soups and sauces)

• Stabilizers

• Texturizers

• Water or fat binders (bread crumbs)

• Fat substitutes

• Emulsification aids

The plant’s cell unit for storing starch

starch granules

cereal sources of starch

wheat, rice, and corn

root starches sources

Potatoes, arrowroot,

cassava (tapioca)

other sources of starch include…

Dried beans, peas, sago

palm

uses of starch, such as corn starch, in the food industry

Thickening agent

Edible films

Dextrose

Starch syrups

main use of starch in food products

thickening agent

how do starches act as edible films in food products

Protective coating for

chewing gums

Bind foods such as meat

products and pet foods

Hold substances such as

flavor oils in chocolates

dextrose

Sweetener used in the

production of

confections, wine, and

some canned goods

starch syrups

Over ½ of the starch

produced in the US is

converted to syrup

(e.g., corn syrup)

step 1 of starch formation

gelatinization

what happens during gelatinization

When heated in liquid, starch

granules increase in

• Volume

• Viscosity

• Translucency

how does gelatinization of starches happen

When starch granules are added to a liquid, and the

liquid is heated, the hydrogen bonds holding the starch

together weaken

This allows water to penetrate the starch molecules

causing them to swell

factors impacting gelatinization

Amount of Water: Must be sufficient enough for starch

absorption

Temperature: Most starches gelatinize when heated

above 133°F–167°F

Timing: Just long enough to reach peak viscosity

Stirring: Stirring early = uniform consistency + no lumps;

Too long or vigorous = less viscosity

Acids: Reduce ability of starches to thicken

Sugar: Competes for available water, delays the onset of

gelatinization, and increases the required temperature

Fat/protein: Coats starch, preventing water absorption

second step in starch formation

gel formation

what happens during gel formation

a fluid starch becomes a semi-solid paste after cooling to <100F

3rd step in starch formation

Retrogradation

retrogradation characteristics

Happens as the gel cools/ages

• Seepage of water out of aging gel

• Syneresis or weeping

• Occurs due to contraction of the gel

• Amylose molecules tighten bonds

• Accelerated by freezing

• Prevention: Use foods immediately

fourth step of starch formation

Dextrinization

what is Dextrinization

THICKENING POWER DIMINSHED

Breakdown of starch molecules

Presence of dry heat

Smaller, sweeter-tasting dextrin molecules

Example:Lousisiana Gumbo flour

examples of thickened sauces

cheese sauce, white sauce, some gravies

examples of unthickened sauces

• Other Gravies

• Hollandaise

• Butter Sauce

• Fruit

• Barbecue

• Tartar

• Tomato Sauces

roux thickener

• Foundation of thickened sauces

• Equal parts fat and flour

• Three Types

• White

• Blond

• Brown

• As the roux cooks, it becomes darker and its

starchy taste lessens

Beurre manié thickener

• Equal parts butter and flour

• Mixture not cooked

• Slowly whisked into a

simmering sauce

• Use only small amount to

prevent taste from becoming

starchy

slurry starch thickener

• Combine starch and cool liquid

• Cornstarch or flour

• Mix into simmering liquid base

• Sauce thickens

• May yield starchy taste

• Less stable thickening

the worlds major food crops are

grains

grains that account for 95% of the worlds production…

corn, rice, wheat, barley

durum flour

flour with high protein content which helps to give pasta elasticity and maintain its shape while cooking

what does moist heat prep (boiling or simmering) do to starch

Cooking gelatinizes the starch. This occurs when heated

starch molecules absorb water and expand and can swell

2-3 times in volume.

example of a leavening agent

baking soda, which has sodium bicarbonate ********(Must have an acid ingredient added to the flour mixture)

baking powder chemical leavener consists of:

Baking soda

Acid(s)

****Inert filler such as cornstarch

yeast (leaving agent):

Found naturally in air, water, and living

organisms

Product CO2 through fermentation

what happens during proofing of bread

Changes during fermentation

►Dough doubles

►Becomes more acidic

►pH 6.0 – 5.5-5.0

can you freeze uncooked grains?

no-freezing alters the protein

structure in such a way that any baked product will not rise

as high

for 1 cup of cooked pasta how much dry pasta should you use

2 oz or ½ cup of short pasta

2 oz or a bunch about ½ inch. in diameter of long pasta

grains husk

rough outer covering

bran part of the grain

Hard outer covering under husk

• Protects endosperm

• Excellent source of fiber and

minerals

endosperm portion of the grain

• Largest portion of grain (~83%)

• Contains starch

germ layer of a grain

• Embryo

• Fat, incomplete protein, vitamins,

and minerals

flour

Fine powder from crushing endosperm of the grain

flour is a good source of…

Fibers, phytochemicals, lignans(antioxidants),

phytoestrogens along with vitamins mentioned earlier

uses of flour

Breads and baked products

Thickener

cereal grains can be used as

pasta, breakfast cereal, alcoholic beverages, and animal feeds

why do starches expand when cooked

Starch gelatinizes—absorbs water and expands 2–3×.

what makes pasta “high protein”

Made by adding soy, wheat germ, dairy

20-100% more protein

what happens to heating time when cooking grains in a microwave

Heating times not significantly reduced; follow

manufacturer’s directions

which nutrients are lost during the process of refining grains

Thiamine (B1) - 77%

• Riboflavin (B2) - 80%

• Niacin - 81%

• Vitamin B6 - 72%

• Pantothenic Acid- 50%

• Folate - 67%

• Vitamin E - 86%

*starch remains

macaroni(pasta nomenclature)

Generic term for all dried pasta

• If eggs are added (at least 5.5% egg by wt.), pasta is

called noodles

fanciful pasta

Pressed into unusual shapes

• Ex: dinosaurs

difference between dough and batter

batter mixtures contain more water than dough

component that affects the rising of baked goods

yeast

simplest flour mixture…

Flour and water

ingredients that can be added to a flour mixture

Milk, fat, eggs, sugar, salt, flavoring, leavening agents

optional ingredients in baked goods…

sugar, acid

categories of cookies(determined by fluidity of batter or dough)

Bar * Dropped

Pressed Molded

Rolled Icebox/Refrigerator

categories of cakes

shortened cakes

Aka butter or conventional cakes,

leavened with baking powder or

baking soda

■ Cake made with fat

unshortened cakes

Aka sponge or foam cakes, leavened

with beaten egg whites Cake made

without added fat

chiffon cakes

Shortened and unshortened hybrid

■ Cake made from fat from vegetable oil

and egg yolks and combine with

foamed egg whites

how does volume increase in cake baking

Volume increases by expanding air, steam and CO2

how does structure set in cakes

Heat flows from edges toward the center of pan, so

cakes become rounded at the top as their interiors

continue to rise after the outside portions of the cake

have started to set.

what happens as structure sets in shortened cakes

Protein coagulates

■ Starch gelatinizes

what is gluten

the protein portion of some grains

such as wheat, rye, or barley and the flour

made from these grains.

what makes up gluten

gladin, and glutenin

what percent of flour is dough forming (makes gluten)

85%

what is kneading

part of gluten formation:

Compresses and stretches dough

Evenly distributes yeast

Warms dough

Increases fermentation and CO2 production

Yields a smooth, stretchable dough

Avoid excess kneading

Too much kneading results in sticky, lumpy dough with little elasticity

when should 1st proofing of yeast happen

in a covered bowl, after an hour in an 85 degree humid, undisturbed place

where to store fresh baked bread

Cool completely, wrap and store in a dry, cool

place away from the sun

refrigeration is Not recommended in less humid areas, can

speed staling

Freeze in two layers of plastic wrap for 2-3 months

straight dough mixing method

Place all ingredients in bowl at the same

time, mixed, rise once or twice

sponge mixing method for dough

Combine yeast, water, and ~1/3 of flour;

allow to ferment in warm place 0.5-1 hour;

add remaining ingredients

batter mixing method for dough

Simplest; combine ingredients; beat via hand

or electric blender

rapid mixing method for dough

Mixes in bread maker

overfermentation

First rise is done when doubled in size,

two fingers in dough leave indentation

► As gluten stretches it becomes weaker

► Results in

► Coarse grain

► Pale color

► Sour odor

► Poor flavor

biological leavening agents

Yeast and bacteria

chemical leavening agents

Baking powder and baking

soda yield CO2 when the alkali reacts

with an acid in the presence of liquid

fundamental ingredients of yeast breads

Flour

Liquid

Sugar

Salt

Yeast