FATS 2 Flashcards
whats the smoke point?
(350-450°F): temperature at which fat or oil
begins to smoke
whats flash point
(~600°F): temp at which wisps of fire streak
the surface of heated fat or oil
whats the fire point
(~700°F): temp at which heated substance
bursts into flames and burns for >5 sec
wat are triglycerides
glycerol + fatty acids
whats glycerol
acrolein smoke with sharp, offensive odor
how should fats be fried
stable heat in 100% fat; smoke point above 420F
what should you avoid when frying
surface moisture and temps that are too low (below 375 may lead to excessive fat absorption)
why should particles of food or breading that break off be
filtered out daily?
Darken oil’s color and lower smoke point
Why do foods fry best in oil that has been used at
least once?
because oils pick up proteins and sugars from foods
that have been fried in them
+ provide substrates for the Maillard reaction
what has to be broken to release the fat so it can lump
together and be churned into butter
Phospholipid layers emulsifying the fat globules in milk
whats used to make butter
Cream that floats to the top from unhomgenized milk
what does milk fat consist of
triglycerides surrounded by protein + phospholipid membrane
what does milk fat membrane allow for
dispersion of fat in
aqueous phase
whats maragine made from
partially hydrogenated vegetable oils
whats shortening made from
Plant oils that have been hydrogenated to become more
solid and pliable
what are the three extraction methods for oils
cold-pressing, expeller-pressing, chemical solvents
whats cold pressing
mechanical pressing
*Usually, unrefined
whats expeller pressing
squeezing at very high pressures
how do chemical solvents work
chemical removal using non-polar (fat-soluble) solvent
*Majority of commercial vegetable oils
describe the flavor, nutritional value, smoke point and rancidity of unrefined oils
full flavor of the plant source
*Slightly higher nutritional value
*Have low smoke point, can’t expose to high heat
*More prone to rancidity (lower shelf-life)
describe the smoke point, aroma and flavor of refined oils
*Low-aroma, bland-flavor
*Higher smoke points
whats removed from refined oils
naturally present gums,
resins, pigments, soil, free fatty acids
why do some oils partially crystalize when stored in the fridge
because some fatty acids have higher melting points
what does partially crtsalzing create
cloudiness (still perfectly edible and reversible
at warmer temps)
whats winterization the removal of
removal of high-melting point
triglycerides to prevent cloudiness at cold temps
what are fat mimetics
mimic sensory and/or physical properties
what are fat mimetic based from
carb- or protein-based
*Cannot replace fat on one-to-one basis
what do carb-based fat replacers bind
water, swell, mimic texture, mouthfeel, and opacity fat
what are protein-based fat replacers broken into
microscopic particles that mimic mouthfeel and
texture of fat
Olestra (Olean®) is a lipid-based fat replacer that is so big it cannot be digested. what is it made of
glycerol portion of triglyceride is replaced with sucrose which can bind 6,7, or 8 fatty acids
what are the two types of rancidity
hydrolytic and oxidative
what does water break down in hydrolytic ranicty
large fat molecules into smaller ones
what does the the double bond of unsaturated fatty acid reacting with oxygen in oxidative rancidity result in
two or more shorter
molecules
when does hydro rancidity occur
if food is not rid of surface moisture, or from
water found on frozen food to be fried
what is hydro rancidity catalyzed by
lipases and heat
when does oxidative randcity occur
when food is exposed to oxygen in the air
what increases suspectidty to randicidty in oxidative
Higher degree of unsaturation
whats the first step of oxidative rancidity
Initiation: formation of free radical
what occurs during the second step
Propagation: free-radical chain reactions
what occurs during the third step
Termination: formation of non-radical products
