Food Science and Properties Flashcards
Suspension
particles too large to go in solution and are suspended in solvent
Colloid system
mixture with one part dispersed into another
Foam
air is dispersed into a liquid
Emulsion
liquid dispersed into another liquid with which it is typically incapable of being mixed
Sol
solid dispersed into a liquid (gelatin)
Solid foam
air dispersed into a solid (meringue, bread, cake, ice cream)
Gel
liquid dispersed into a solid (gelatin, jam)
Solid emulsion
liquid in solid like butter or margarine…water in oil emulsion asa water droplets scattered un oil
Water freezes at:
Water steams at:
0 C, 32 F
110 C, 212 F
Add sugar or salt to ______ freezing point, and to ______ boiling point
decrease/lower, and to increase
Bacteria require a water activity of:
aW= 0.85-1.0
CANT SURVIVE BELWO 0.50
Chlorophyll
- Green
- fat-soluble
- stored in plastids in plant cell cytoplasm
Carotenoids
- yellow to orange-red
- fat soluble
- stored in plastids in plant cell cytoplasm
- heat and pH stable
Flavonoids
- anthocyanin (blue-red, purple)
- anthoxanthins (colorless, pale yellow)
- water soluble
chlorophyll turns ____ when exposed to acid
Pheophytin (olive green)
Cholorphyll turns ____ when exposed to alkaline
chlorophyllin (bright green)
Preserve green color by:
cooking uncovered
Anthocyanins turn ____ in acid and ____ in alkaline
red in acid, blue in alkaline
plant proteolytic enzymes (enzymes break down proteins):
Bromelain and Papain
What is the crispness of vegetables (state of turgor) due to?
The osmotic pressure of water-filled vacuoles
What is the limiting amino acid in soybeans?
Methionine
Protopectin (large,insoluble) is converted to _______ (ripe fruit) then converted to ________(overripe fruit)
Pectin; pectic acid
What accelerates ripening of fruits during storage?
Ethylene gas (avocado, naners, melons)
Which fruits ripen best at room temperature?
Avocados
Bananas
Pears
Tomatoes
Fruits low in vitamin C from darken rapidly when cut due to enzymatic action. How can this be prevented?
) Dip in citrus juice
) Add sugar before freezing
) Heat to boil
Anthoxanthins or flavones (white) are ________ in acid and _______ in alkaline.
Colorless; yellow
*Onions turn yellow in aluminum pan
Flavor of fruit is due to…?
acids, sugar and aromatic compound
The grade of fruits/vegetables is based on what?
Quality, firmness, color, maturity, freedom from defects, uniform size and shape
Canned Fruits & Vegetables
Grade A
desserts & salads (Fancy)
Canned Fruits & Vegetables
Grade B
Processed (Choice)
Canned Fruits & Vegetables
Grade C
Pudding and pies (standard)
Fresh Produce Grades (5)
Fancy, Extra #1, #1, Combination, #2
Baking at high altitudes:
- decrease leavening agent
- increase moisture
- increase protein (flour)
- decrease tenderizing agent (fat/sugar)
Overmixing:
tunnels, peaked tops, pale crust
Undermixing:
low volume, fat top, uneven texture
Low acid foods (>4.5) should be canned using:
pressure canner. reach 240 to destroy spores
veg, meat, bean, soup
High acid foods (< 4.5) should be canned using:
water bath canner
fruit, jam, jelly, salsa
Sugar _____ egg white foams
Sugar _____ starch gels
Sugar _____ in _____ reaction
- stabilizes
- tenderize
- for browning in Maillard rxn (sugar and amino acid)
Cereal products contain:
germ, bran, endosperm
Name the 8 different wheat flours.
graham
bread (hard wheat)
all-purpose (blend of hard and soft wheat)
pastry (soft wheat)
cake (soft wheat)
enriched with B vits, iron and folic acid
instant blending
self-rising
Place the following flours in order from strongest gluten and most protein to weakest gluten and least protein: all-purpose, cake, pastry, bread.
bread (strong gluten, 11.8% PRO)
all-purpose (less gluten, 10.5% PRO)
pastry (weaker gluten, 7.9% PRO)
cake (least and weakest gluten, more starch, 7.5% PRO)
Contains gluten:
wheat (farina, bulgur, durum, orzo), barley, rye
No gluten:
amaranth, millet, teff, buckwheat, quinoa, corn, rice, sorghum
Pregelatinized starches
dont need to be heated in water on per to expand
Dextrinization
starch broken down into sugars (increased sweetness, decreased thickening)
Gelation
starches cooked in liquid and starch granules absorb liguid
Retrogredation:
amylose and amylopectin in cooked gelatinized starch re-from hydrogen bonds causing liquid to gel
milk made up of:
water, CHO, fat, protein with water making 87% of its composition
Milk is :
80% casein, 20% whey
Homogenization:
breaks up milk fat globules into smaller ones permanently dispersed in colloid system
Pasteurized:
destroys pathogens, inactive bacteria
High temperature short-time pasteurization (HTST)
heating milk to 161 F fr 14 sec and rapidly cooling milk
Ultra pasteurization
heats milk to 280 for 2 seconds and extends shelf life
Egg white coagulates at:
140 F and completely coagulated at 158F
Egg yolk coagulates at:
Whole beaten egg coagulates:
Scrambles egg with milk coag:
144 F
156 F
180 F
Egg coagulation slowed by____ and sped up by_____
adding sugar, adding salt/vinegar
Whipped egg whites are stabilized with:
acid or sugar
Tender meats prepared with:
dry heat (broiling, roasting, grilling, frying)
Older cuts of meat prepared with:
moist heat (stewing, braising)
Tender meat:
near the backbone (short loin, rib, sirloin)
Tough meat:
lower leg, flank, neck (chuck, brisket, shank)
5 factors that influence lipid’s melting point:
length of carbon chain, saturation, configuration, crystalline formation, fatty acids
Lipids with higher melting points have:
More carbons, less to no double bonds, and are trans (cis have lower melting point), beta crystals (beta have higher mp than alpha)
hydrogenation:
makes fats and oils more solid at room temp by adding hydrogen, breaking double bonds
Interesterification
alters how fatty acids are arranged on triglycerides making it creamier
Winterization
oil chilled and fatty acids are crystalized; these are removed. oil remains clear at refri temp
Rancidity
fats broken down by water, heat, light
Fat is:
tenderizing ingredient. can also coat gluten resulting in tender crumb
Polymerization:
fatty acids link together during frying, making oil viscous and prone to foaming
Fats and oils smoke point:
420 F or higher better for frying
Leavening:
air, CO2, steam
Flour and eggs:
Fat and sugar:
structural
tenderizing
Conventional mixing method:
creams fat with sugar, add eggs, then alternate liquid and flour
Quick mixing method
adds fat and milk to dry ingredients, mix, add eggs mix again
Muffin method
mix liquid and dry ingredient separately and combine until dry are moistened
Pastry method
cuts fat into dry ingredients, then add liquid while mixing
Pour batter
Drop batter
Soft dough
Stiff dough
1:1 (liquid to flour)
1:2
1:3
1:4
Kefir:
add bacteria and yeast to milk
Spray drying:
particles in liquid/slurry, turned to droplets and then powder. (milk powder, instant coffee)
Curing
large amounts of salt
Dehydration
removing at least 80% water
Tunnel drying:
Freeze drying:
- remove moisture
- frozen to gas state (skips liquid state)
Food additives:
must be approved by FDA, direct or indirect
common ones: sugar, salt, corn syrup, dextrose
Anti-caking:
prevent moisture absorption
silicate. iron ammonium citrate, silicon dioxide, sodium stearate, sorbitol
Preservatives:
antimicrobals or antioxidants
sodium benzonate, propionates, sulfites, nitrates
Emulsifiers
lecithin, disodium phosphate
Flavor enhancers
used to enhance food without adding flavor of its own, added at sub-threshold level
salt acids, MSG, sugars
Fortification:
Enrichement:
- adding vit or minerals that present naturally in food or adding back in greater amount
- replacing vitamins and minerals lost during processing
Sequestrants
sequester trace minerals to prevent deterioration EDTA (calcium disodium)
Conduction
direct transfer of heat
Convection
transfer of heat by air or liquid
Induction
transfer of heat without contact
radiant heat
transfer of heat in forms of eaves
Maillard reaction
between sugar and amino acid and results in browning when heated; creates flavors and colors
browning meat with dry heat, egg or milk wash in pastry
Caramelization
no amino acid, but does use sugar. Caramelization and maillard are considered non-enzymatic browning
