IV C Principles of food production Flashcards
continuous phase
medium surrounding all parts of the dispersed phase
what are dispersion systems?
mixture of solids, liquids, gases
dispersed phase
distributed throughout the colloidal system
a dispersion is classified according to?
the STATE OF MATTER in each phase of the dispersion (i.e. gas liquid solid) OR the SIZE of dispersed particles (small, large, clumps)
whipped egg whites are?
gas in liquid: foam
sponge cake is?
gas in solid: suspension
mayonnaise is?**
LIQUID IN LIQUID: EMULSION
gravy is?
solid in liquid: sol
custard is?
liquid in solid: gel
small particles are?
a true solution (i.e. sugar, salt)
large particles are?
a colloidal dispersion (protein, cooked starch)
clumps of molecules are?
suspension, separates upon standing (fat, uncooked starch)
how to change the degree of dispersion
apply heat or beat
what is an interface?
line that forms between two immiscible liquids (water and oil)
vegetables are usually (acid/basic) with a (high/low) pH
vegetables: slightly acid, high pH
how should vegetables be processed?
at a temperature HIGHER THAN 212F TO DESTROY BOTULISM
___________ can be used to can low acid vegetables; why?**
PRESSURE COOKER; reaches temperature higher than 212F
relationship between pressure and temperature***
pressure raises temperature
if the pH is low/acidic, how should they be canned?**
canned in a BOILING WATER bath
____ are sometimes pickled with vinegar or _____***
beets; vinegar or acetic acid - lowers the pH
acid causes ___ when green vegetables are overcooked or canned
loss of color
what happens when acid is added to green vegetables?**
molecule becomes PHEOPHYTIN (brown or olive green), color fades
what happens when alkaline is added to green vegetables?*** (3 things)
1) intense green color = CHLOROPHYLLIN
2) becomes MUSHY (alkaline softens cellulose)
3) WATER-SOLUBLE VITAMINS LOST
how to prevent color from fading in green vegetables?***
cook for SHORT TIME- LEAVE LID OFF FOR FIRST FEW MIN to allow escape of volatile acids
baking soda- acidic or alkaline?**
alkaline
cream of tartar- acidic or alkaline?***
ACIDIC
when adding cream of tartar to angel food cake, it maintains a white color. WHY?**
acid prevents the Maillard browning reaction
acid in angel food cake has what affect on the volume?***
LARGE volume by STABILIZING EGG WHITE FOAM
acid in angel food cake has what affect on the crumb?***
TENDER crumb
angel food cake without cream of tartar becomes…?**
TOUGH, YELLOW, SMALL CAKE
what are enzymes?
catalysts to facilitate chemical reactions
enzymes are what type of molecule? what does this mean?***
proteins- activity will be affected by temperature and pH
two types of browning reactions- where do they occur?**
1) enzymatic = cut surfaces of fruit
2) Maillard = browning of bread or baked goods
what happens with enzymatic reaction in ripening of fruit?***
starch –> sugar, softens
what causes the browning on cut surfaces of fruit?***
enzymatic oxidation
what will acid do to enzymes?***
lowers pH = inhibits enzymes = prevents browning
what should you do to vegetables before freezing?***
BLANCH to destroy enzymes –> put in and out of water quickly
how to get more rapid browning?
increase pH to 6 or higher, increase temp, decrease water content
what is conduction?**
heat moves from one particle to another by CONTACT/TOUCHING
good conductors are?***
COPPER, black cast iron, aluminum
bad conductors are?***
glass, stainless steel
example of conduction –>
meat kept warm on dish sitting on heated pellet
what is convection?**
heated air MOVED WITH THE FAN
what is induction?**
use of ELECTRICAL MAGNETIC VIBRATIONS TO EXCITE THE MOLECULES OF METAL COOKING SURFACES
how does induction work for heating?***
NO open flame; surface DOES NOT get hot…..PAN ITSELF is the original generator of the cooking heat
what is radiation?***
INFRARED WAVES coming from glowing heat (gas flame, charcoal, electrical element, toasting, broiling)
what is microwaving?***
radiation followed by conduction
a microwave affects what type of molecules? how far does it heat into the food?***
water molecules; 2” into food
what is standing time of a microwave?**
subsequent distribution of heat by conduction when the magnetron is turned off –> why you have to let it sit!
what’s a disadvantage of microwaving?***
UNEVEN heat
steak on a grill, meat braising in a steam-jacketed kettle = what type of heating?**
conduction + radiation
— steak on a grill = touching the grill (conduction), radiation from heat moving upward
what are engineered foods?
variety of natural and/or synthetic ingredients
advantages of engineered foods?
consistent; LONG SHELF LIFE
what are meat analogs?**
isolated SOY PROTEIN (ex: imitation bacon bits)
properties of meat analogs?***
less fat than meat, about 50% protein
what are seafood analogs?***
SOY BLENDED WITH FISH (ex: imitation crab meat)
what are vegetable blends?***
feeds people in underdeveloped countries; incaparina and CSM
what is incaparina?**
used to feed people in underdeveloped countries; vegetable blend of maize, sorghum, cottonseed flour
what is CSM?***
used to feed people in underdeveloped countries; Corn Soy Milk + vitamins and minerals
where do molds grow?
warm, dark, damp conditions; grow best on acid, neutral, sweet foods
are molds harmful? should you get rid of them, if so how?
- usually don’t produce harmful substances
- boil to destroy
yeasts need what to grow?
water, energy, acid medium in oxygen
how are yeasts destroyed?
boiling
what do bacteria need to grow? at what temperature?**
MOISTURE, NEUTRAL FOODS; 68-113F
how are bacteria destroyed?
temperatures of pasteurization (145F for 30 min)
bacteria danger zone is?**
41-135F
can microorganisms grow in frozen foods?
no- prevented by cold temperatures and lack of water
do enzymes work in frozen foods?
slow action, but noticeable over time
what is dehydrofreezing?
dried to 50% of weight and volume, then frozen
how should you thaw potentially hazardous foods?**
1) in refrigerator
2) submerge under running cold water @70F or lower
if you thaw foods in the microwave, when should you cook them?
immediately
what prevents growth of microorganisms in dried foods?
low water content
do enzymes work in dried foods?
inactivated by blanching
what is freeze drying?
frozen first, then water is evaporated without melting crystals (sublimation)
how long do canned foods last?
up to a year
how are foods canned? why?***
1) if pH is low, acid is high = boiling water
2) if pH is high, acid is low = pressure cooker (to increase temperature)
relationship between acid and bacterial growth***
high acid foods, less bacterial growth
best pH for bacteria to grow
neutral
how is botulism best destroyed?***
heat in acid (remember: pressure cooking for the veggies that aren’t high in acid to increase temperature)
calcium compounds are additives in canning used as…?**
HUMECTANTS
what are humectants?***
1) retain MOISTURE
2) increase FIRMNESS, TENDERNESS
what is aseptic canning?
food sterilized outside of can, then aseptically placed in sterile cans which are sealed in an aseptic environment
what is irradiation?
COLD STERILIZATION to KILL most harmful BACTERIA in foods other than milk (temperature does not raise much even though large amounts of energy are used)
what are BHA and BHT?**
ANTIOXIDANTS for fatty products
what role do acids play in chemical preservation?***
denature bacterial proteins - interfere with moist or neutral
what role do sugar and salt play in chemical preservation?***
make water unavailable
