Intro to Food Science final

components of egg

yolk, albumen, shell membranes, air cell, shell

yolk purpose

nutrient dense to nourish chick

germinal disk

in yolk, dark means fertilized

albumen (egg white)

made of water and protein (3g), contains chalaza and vitelline membrane

chalaza

holds yolk in content to the center of the thick egg white

vitelline membrane

the membrane surrounding the egg yolk attached to the chalaza

inner and outer membrane

protect the egg against bacterial invasion

air cell

provides chick with air for its first breath which it needs to break out of the shell

shell

protects internal components of egg from bacteria

shell pores

allows air exchange

cuticle (bloom)

a waxy coating on an eggshell that seals the pores from bacterial contamination and moisture loss

how egg structure changes with aging

egg whites thin, chalazae become weaker, vitelline membrane around yolk weakens and eventually breaks, air cell increases in size as moisture and carbon dioxide escape through the shell

inspection of eggs

U.S. poultry division requires egg products to be wholesome, unadulterated, truthfully labeled

restricted eggs

eggs that don't pass inspection can't be sold whole to consumer

grading of eggs

evaluates appearance and freshness, uses AA, A and B

candling

A method determining egg quality by examining eggs placed against a light

haugh units

fresh egg whites, the thick albumen, (AA) will stand up tall and firm whereas older egg whites will spread out.,

egg substitutes

removing entire yolk to replace with vegetable oil or just cholesterol and fat from yolk. ultrapasteurized good for undercooked foods

value-added eggs

special nutrient content or conditions under which hens are raised - lower cholesterol and increase omega-3 acids & vit E

nutritional content of egg

1 large egg = 1/4 c.

75 kcal

7g of protein

5g of fat

186mg cholesterol

fat soluble vitamins

functions of eggs in foods

emulsifying (lecithin phospholipid), binding, foaming, color, interfering, clarifying

binding in eggs

high protein content makes good adhesive

how to create a good egg foam

whip egg whites into fine bubbles, room temperature, deep bowl, separate yolk, add sugar last, acid helps foaming by denaturing proteins

interfering (eggs)

used to block the formation of crystals

clarifying (eggs)

when heated, albumen can attract other particles that may be clouding the liquid, raising them to surface for removal

effects of cooking on eggs

temperature low and cooking time short, overheated proteins are tough & rubbery

coagulation temperatures egg

whites coagulate at 140 but yolk coagulates at 144ºF

ferrous sulfide ring

when overboiled, sulfur in egg white and iron in yolk combine

dry heat preparations eggs

fried eggs, scrambling, omeletes, baking

moist heat preparation eggs

hard/soft boil, coddling, poaching, custards, microwaving

proper storage of eggs

eggs begin to deteriorate as soon as they're laid, refrigeration will delay changes in eggs that occur over time

vegetable

part of plant you eat

fruit

flower of plant has seeds mature ovaries

cell wall

rigid, structure, made of cellulose, lignin, fibers and hemicellulose

parenchyma cells

house different fluids and pigments and have intracellular air spaces

pigments

carotenoids, chlorophyll and flavonoids

carotenoids

heat stable- cartens (orange), xanthophylls (yellow) and lycopene (deep red)

pectin

sticky substance holds cell walls together, used in food industry for gelling, emulsifying, stabilizing, thickening

phenolic compounds

reacts with oxygen and browns, includes tannins

tannins

a phenolic compound in unripe fruit that causes astringent taste

phytochemicals

nonnutrative functional food in plants considered to have health benefits

acids in fruits/veggies

immature/under ripe fruits and veggies have higher levels of acidic compounds so they are more tart

blanching

briefly dipping vegetables in boiling water to destroy enzymes via denaturation to limit enzyme browning

grading of fruits and vegetables

quality can change quickly, determined by freshness, ripeness, color, shape, size, uniformity and freedom from bruises or signs of decay

grading of canned/frozen f&v

A (color, tender, flavor, uniform), B, C

flavonoids

color change and variation with pH and added cooking methods

changes of f/v during cooking

pectin, fibers and proteins break down and cells can freely pickup water and lose solutes lead to soft texture/structure, flavor components may be lost

enzymatic browning

certain plants are more susceptible when peeled/sliced (phenol to melanin)

goals when preparing f/v

preserve nutrients

storage of f&v

continues respiration after harvest, refrigeration slows respiration, no airtight bags

ethylene gas f/v

apples, pears and bananas give off ethylene gas when ripe and can speed up ripening/deterioration of other fruit

danger zone

40-140ºF

proper thawing (4)

refrigerate, under running water, microwave followed by immediate cooking, part of cooking process

cross contamination

the spreading of pathogens from one food to another

natural

no official definition, FDA's only guidance is that nothing artificial or synthetic has been included

organic

certified by USDA

fortification

adding nutrients that weren't there to begin with

enrichment

adding back nutrients that were lost

food allergy

immune system responds to specific protein in food as harmful, may be life threatening

food intolerance

digestive system has problems e. lack of enzyme

food sensitivity

mild immune response, not as severe, less specific and delayed symptoms

water activity

higher aw, more perishable because of bioactivity

subjective testing

sensory evaluations: triangle tests, paired comparisons, ranking, dilution, descriptive

objective testing

does not rely on personal judgement but rather clear tests: microscope, viscometer, texture analyzer, spectrophotometry

senses to evaluate food

taste, sight, aroma

disaccharides in food

carbohydrates; two molecules (sucrose is glucose + fructose)

monosaccharides in food

one molecule; glucose, fructose, galactose

complete protein

all essential (9) amino acids

saturated fats

solid, animal 9 kcal/g

unsaturated fats

liquid, plant

protein

4kcal/g, amino acids + nitrogen

carbohydrates

sugars, starches, fibers, plants, 4kcal/g, CHO

lipids

fatty acids, steroids

fats

9kcal/g, phospholipids make them good emulsifiers

conduction

direct heat transfer

convection

transfer heat by air or liquid, hot air rises, cool air sinks

radiation

transfer heat with waves of particles

induction

transfer of heat "without contact" - flat surface with coils underneath

moist heat cooking (general)

allows even heating, soften foods and makes them tender, color, nutrients and flavor lost

parts of cereal grain

husk, bran covering, endosperm, germ

husk

chaff: protective outer layer, not consumed

bran covering

contains fiber, minerals and aleurone layer (vitamins)

endosperm

starch, we eat

germ

embryo, B & E vits, fat so makes it susceptible to spoilage

flour

fine powder obtained from chrushing carypsis, refined flour is only endosperm

gluten

gliadin + glutenin: protein found in grains, important for structure of baked goods, in endosperm

grains that contain gluten

wheat, barely, oats, rye and triticale

liquid functions baking

gluten is formed once its hydrated, activates yeast

sugar functions in baking

volume, moistness, tenderness, flavor

salt functions in baking

limits yeast growth by absorbing moisture (preserves), flavor enhancer

fat functions in baking

interacts with gluten development by lubricating the dough to prevent it from absorbing too much water, develops tender crumb

eggs functions in baking

enhances structural integrity

physical leavening

air, steam

biological leavening

yeast, bacteria

types of yeast

active/dry, inactive, fresh/compressed, instant

chemical leavening

baking soda and baking powder

quick breads

bake immediately after mixing, no proofing, leavened by air/steam/co2, baked at very high temperatures

yeast breads

kneaded, proofed (yeast produces co2) (sometimes twice), cooked for 2-3 hours

kneading

develops gluten to maximum potential, hard to overknead

adding too much flour kneading

will slow fermentation, be dry and heavy finished product