Intro to Foods- Exam 2

fruits: classification

classified according to the type of flower from which they develop

drupes

food with seeds encased in pit (peaches, cherries)

pomes

fruits with seeds in central core (apples, pears)

aggregate fruits

develop from several ovaries in one flower (blackberries)

multiple fruits

develop from a cluster of several flowers (pineapples, figs)

fruits usually treated as vegetables

tomato, squash, okra, green beans, cucumbers, nuts (rhubarb is vise versa)

fruits: pectic substances

protopectin → pectin → pectic acid (no gel → gel → no gel)

enzymatic browning

• phenolic compounds, polyphenol oxidase enzymes, oxygen, browning produces melanin

• sulfites, sorbates, and benzoate prevent browning in dried fruits

• denature enzymes (blanching), reduce pH (acid), lower temp, coat with sugar (seal), adding antioxidants

antioxidants (fruits)

protect against oxidative damage, vitamins a c e

polyphenols (fruit)

lower risk of cardiovascular disease and dementia, make blood vessels relax → better blood flow

fruit processing

• extraction

• clarification- remove cloudiness

• deaeration- remove trapped air

• pasteurization- quick exposure to high heat

• concentration/ additions

fruit heating

• change color

• protopectin → pectin → pectic acid

• degrade cellulose to hemicellulose

• denature cell-membrane proteins

preserves

whole fruits

conserves

mixture of fruits (citrus) nuts and raisins

jellies

cooked fruit with pectin and sugar

marmalade

juice with thin slices of fruit (citrus) and rind

fruit butter

thick and smooth puree of long cooked fruit, less sweet

what causes sugar crystallization

• too much sugar

• not enough acid

• overcooking (delay in sealing)

failure to gel causes

• improper balance of pectin, sugar, and acid

• overcooking

what can lead to fermentation

• glasses not well sterilized

• stored in warm damp place

• not completely sealed

climacteric fruits

• increased phase of respiratory rate right before becoming fully ripe

• continue to ripen after being harvested

• apple (ethylene gas which spoils others), avocado, peach

non climacteric fruit

• best ripened fully before being harvested

• blueberry, cherry, grapes

fats contribute…

• flavor

• color

• texture

• mouthfeel (creaminess)

fats heat transfer

transfer heat to foods without burning

fats emulsions

• liquid diapered in another lliquid

• oil in water (salad dressing)

• water in oil (butter)

• dispersed or discontinuous (oil)

• dispersion medium or continuous (water)

• emulsifier (surfactant, reduces liquid’s surface tension, increases wetting and blending

• more viscous as they increase stability

fats melting point

• degree of saturation (more saturation = more energy to break)

• length (longer = more energy)

• cis-trans configuration (trans = more energy)

• crystalline structure (more crystals = more energy)

fats plasticity

• hydrogenated has more plasticity

• ability of solid to hold shape and be molded

• spreadability

fats solubility

• generally insoluble

• dissolve in organic compounds (benzene, chloroform, ether)

role of butter

mouthfeel, aeration of dough, emulsification, flavor extender

clarified butter

• removed milk solids (almost 100% fat)

• ghee

• higher smoke point

margarine

• made from soybean, corn, safflower, canola

• 80% fat, 16% water, 4% milk solid

shortening

• hydrogenated plant oils

• mono/diglycerides for increased plasticity

high smoke point oils

• avocado, almond

• ideal is 420

low smoke point oils

canola, grape seed, unrefined olive, sesame

olive oils

• extra virgin- strongest, olives first pressing, least acidic

• virigin- not more than 2% acidity

• pure- blend of virgin and refined, 1% acidity

• light- sautéing, baking, and salad dressings

• olive-pomace- less expensive, cold pressing and solvents

lard

fat from swine, grainy at room, hard in fridge

tallow

animal fat from beef cattle or sheep

suet

solid fat around kidneys and loin of beef or sheep

interesterification

rearranges fatty acids on the glycerol molecule within triglycerides, smaller fat crystals and smoother consistency

fat sub

• sub- physical and sensory without cal

• mimetics- smooth and creamy, high protein

• analogs- characteristics with lower cal, alter digestibility

• extenders- optimize functionality so less fat required

frying

• 375 (olive, corn, vegetable)

• too low: extra fat absorption, gummy

• too high: polymerization, darken, smokes excessively, greasy (free fatty acids)

rancidity

chemical spoilage or degradation of fats and oils that causes foods to develop foul odors, stale tastes, and unappealing textures

soup

liquid food that may or may not contain solid ingredients

stews

more solid than soups

broth

stock made from meat and water with little to no flavor, seldom reduced and not a strong flavored as stocks

stock

foundational thin liquid of many soups, produced when meat or vegetables are reduced and strained

white stock

liquid from simmering bones of beef, veal, chicken, or pork

brown stock

stock resulting from browning bones and/or meat prior to simmering them

meat stock

• raw/ aged is most flavorful

• meat and bones in 3 inch sections to increase surface area

• vegetables in last 30 minutes to avoid bitter and overcooking

fish stock

• head, tail, and backbone

• no more than 30 min

storage of soups

• cool before putting in fridge to prevent raising temp

• use within 5 days

• freeze to last longer

• simmer stored stock for at least 10 minutes before serving

clear and thin soups

• clear: remove particles

• thin: consistency between clear and thickened (broth based onion, noodle, or miso)

thickened soup

cream, puree, sauce, noodles (egg drop, minestrone, chowder)

cream soups

adding cream/ milk to puree made from meat, vegetables or fish (bisque)

avoid curdling

• tempering (add hot soup to milk and mix)

• don’t boil before adding dairy

• add acid to milk

gelatins

• protein extracted from collagen in animal hides, bones, and connective tissue

• low in tryptophan making it an incomplete protein

phases of gel formation

• hydration: absorbes 5 to 10x weight in water, in cool water to avoid clumping

• dispersion: hot water added to disperse protein granules (100F) proteins denature and unfold

• gelation: cooling, gel turned to solid-like gel within 1-6 hours, proteins aggregate

factors influencing gel formation

• concentration is 1-2% (1 T per 2 C)

• too much gelatin is rubbery, too little it wobbly

• quicker cooling leads to faster setting

• sugar delays gelling and weakens structure

• acid weakens gel, optimal pH between 5 and 10

• enzymes and solid ingredients (fruits/ nuts) weaken (pineapple, kiwi)

• milk and water strengthen gel from additional minerals

gel storage

• dried = cool, dry place

• serve within 24 hours

• syneresis (lose water over time)

• lose shape at high temp

starch

• complex carb

• thickener, stabilizer, texturized, water/fat binder, fat-sub, emulsifier sweetener (dextrose and syrups),

starch structure

• amylose: linear

• amylopectin: branched

• high amylose gel

• high amylopectin no gel but gummy (waxy starches)

starch characteristics: gelatinization

• gelatinization: increase volume, viscosity, and translucency

• water allows absorption

• heating beyond gelatinization decreases viscosity

• too much stirring is rupturing

• acid, sugar, and fat all weaken/ delay gelatinization (sugar fights for water and fat coats starch)

starch characteristics: gel formation

• fluid starch (sol) turns to gel

• dependent on available amylose

starch characteristic: retrogradation

• during cooling when amylose and amylopectin recrystallize and lose structure to realign themselves (syneresis)

starch characteristics dextrinization

• breakdown starch into smaller, sweeter molecules (dry heat)

• lose thickening power (gumbo thin but better flavor)

starch alterations

• pregelatinizated

• cross-linked: waxy starches with incorporated amylose to reject weeping

• oxidized starches: less viscous but more clear (marshmallows)

mother sauces (5)

• white sauce (béchamel): milk

• brown sauce (espagnole): brown stock

• hollandaise: butter

• tomato

• veloute: chicken or fish stock

sauce ingredients

• liquid

• thickening agent

• seasonings

preparing thickened sauces

roux: cooking equal parts fat and flour (then liquid)

beurre manie: blending equal butter and flour (bit by bit)

slurry: combining starch and cool liquid (gradually added)

preparing un-thickened sauces

• degreasing: separate liquid from fat

• deglazing: take leftovers without fat and add liquid

• reduction: evaporate water

• straining

• seasoning

sauces issues

• too thick: decrease thickener and heat

• too thin: increase thickener and heat

• lumpy: decrease thickener, increase mixing

• grainy: increase mixing, raise pH (reduce precipitation)

• gritty: reduce salt and cooking, decrease lactose (crystallization)

parts of grain/ kernel/ berry (caryopsis)

• protective outer husk (chaff), not consumed

• bran covering (fiber, minerals, aleurone- b vitamins)

• starchy endosperm; flour

• germ: embryo, fat (quick spoilage), b vitamins, vitamin E

top grains

1. corn

2. rice

3. wheat

4. barley (malt liquor), sorghum, millet (gluten-free, starch), oats, rye

whole grain

entire kernel: bran, germ, and endosperm

• whole wheat flour

• bulgur (cracked wheat)

• amaranth

• buckwheat

refined grains

• stripped of bran and germ during milling

• removed fiber is not replaced

• enriched with thiamin, riboflavin, niacin, folic acid, iron

• white flour, rice, and bread

gluten grains

• wheat

• ancient wheat (einkorn, emmer, gamut, spelt)

• barley (malt)

• oats

• rye (bread, less protein than wheat)

• triticale (new, wheat and rye hybrid, higher protein and lysine content, but sticky dough)

gluten-free grains

• chia seeds (omega 3, maybe promote weight loss and blood glucose control)

• corn

• amaranth (superfood)

• buckwheat

• millet

• quinoa

• rice

• sorghum

• teff (high protein and essential amino acids)

cooking cereal grains

1. gelatinize starch

2. improved flavor (dextrinization)

3. softens texture (typically indigestible)

moist heat!

• must rinse, soak, and let stand

pilaf

cooking cereal grains

saute in oil and aromatics

perishable

• high concentration of water and protein

• fish, seafood, meat, eggs, dairy

• watery fruits and vegetables

semi perishable

• store for months under proper conditions

• potatoes, carrots, beets, turnips, onions, apples

nonperishable

nuts, cereals, tea leaves, pastas, dried beans

conventional drying

• sun drying

• heat evaporates water

spray drying

fine spray of liquid is dried in mid air (powder)

freeze drying

freeze food, place in vacuum, sublimation takes out intermediate liquid phase and goes straight from solid to vapor

sulfer dioxide prevents enzymatic browning

curing

using salt and drying to perserve

fermentation

microorganism preserve/ change texture, flavor (kombucha)

pickling

preserves by acidification

edible coating

barrier to moisture and oxygen (wax, starches, sugars in candy and cheese)

canning

high heat eliminates o2 and denatures enzymes in sterilized jars

hot pack (heated in liquid prior to jars)

cold pack (fill jar then add boiling water)

1. boiling water (low pH, fruits, tomatoes)

2. pressure (high pH, beans)

pasteurization

high temperature for short period of time, doesn’t cook but still kills microorganisms

ohmic heating

electrical current is passed through food generating enough heat to destroy microorganisms (liquid eggs, sauces, juices)

irradiation

• disrupts dna of microorganism (can’t multiply and cause diseases)

• similar to x-ray/ airport bag check

• can cause slight flavor/ nutrient change

high pressure processing

pressure inactivates cells of microorganisms (guacamole)

ozonation

using ozone to disinfect/ sanitize

composition of meat

protein, fat, carbohydrate (very little), vitamins and minerals (b vitamins, iron, zinc, copper, phosphorous)

structure of meats

• muscle tissue (protein)

• connective tissue (collagen-movement and elastin; collagen will melt and form gel, elastin should be cut out)

• adipose (fatty) tissue (cover fat vs intramuscular marbling fat)

• bone (landmark for cuts of meat)

tender meats

rib, short loin, sirloin

dry heat

tough meats

chuck, round, ground meat, flank, brisket

moist heat

meat cooking

• protein denatures, collagen melts, water is lost

• larding: insert fat into slits

• barding: tying sheets of fat or bacon for moisture

• changes flavor: protein coagulation, breakdown of fats, organic acids