40 terms

Deep Fat Frying

Desirable characteristics (color, texture, flavor)
bland, buttery, flavor of the food being fried
crispy, crunchy
golden brown
Undesirable characteristics (taste, texture, color)
rancid, painty, grassy
soggy, oily
what should be kept to a minimum? how can this be acheived?
fat abs
-done by using fresh, non-deterioriated oil at the optimum temp during the entire frying period
what happens during the dehyration process? 2
water is transferred from interior to the surface of the item, where it is converted to steam (which is why the products will eventually float=are lighter after water leaves)
at the same time, heat from the periphery of the item is conducted to the interior
--summing: water transferred to item surface for conversion to steam AND heat is conducted to the interior
What does the proper temp depend on? 2
the type of food being cooked and its moisture content
what happens if the frying temp is too low?2
prolongs contact of food with oil, slows browning
what happens if frying temp is too high 2
faster deterioration of oil
crossbonding of CHO and proteins at surface, causing excessive browning before food is cooked
with too high of frying temp, what causes excessive browning before food is cooked?
cross bonding of CHO and proteins at surface (sugar amine reactions)
desirable characteristics of oils5
bland flavor, colorless, high smoke point, odorless, no emulsifiers (they would be breakdown prods=mono/diglycerides...want JUST trigs so that donw't break fast)
what are the color changes as oils are heated?
pale yellow to amber to brown
what happens to the surface tension as heated oil deteriorates? what does this cause to ahppen
suften decreases
-causes viscosity to increase and foaming occurs
what happens to the smoke point as heated oil deteriorates
what accumulates as heated oil deteriorates 4ish
fatty acids, glycerol (fat breakdown subs), mono-diacylglyerides
as oil is heated and deteriorates, what happens to the individual fat molecules?
they unite in long chains or polymers
when oils are heated, what may happen to the unsaturated molecules?
may become cyclic compounds (oxidative ranc)
as oil is heated, what rapidly deteriorates? so what accumlates
the fat
fas, glycerol, mono/diacylglycerides accum
what does a trig break down into when it is deteriorated when heated
glycerol and 3 fatty acids
what does glycerol break down into when fat deteriorates?
acrolein and 2 h2o
what is acrolein
blue gas that is irritating to mucous membranes
what is the relationship between percent glycerol in an oil and the smoke point of the oil?
lower the percent glycerol, higher the smoke point
what is the smoke point? and the appearance of what is seen at this point
temp at which oil can be heated before the appearance of acrolein
what is a characteristic observation of when the smoke point is reached
then flash point=becomes ignited volatiles
which oil has the highest smoke point?
safflower 509
soybean smoke point
canola smoke point
sunflower spt
peanut oil spt
cottonseed smpt
safflower smpt
extra virgin olive oil smpt
define rancidity . what speeds both kinds up?
deterioration in quality of fat/oil or fat-containing foods
heat, lightspeeds
what is hydrolytic rancidity. ex? how do you avoid?
when water causes it.
in butter/dairy foodsd
=avoid by fryin prods with less water in batter, etc
causes of oxidative rancidity5
unsat fat, light, heat, metals (iron), enzymes
four techniques for storing fats and oils
no light, no oxygen, low temp, use antioxidants (TBHQ, citric acid)
2 antioxidant examples. how are these related to fats and oils?
TBHQ, citric acid
useful for storing fat/oil to prevent rancidity
3 oil extraction methods
solvent (usually hexane)
what is RBD
refined, bleached, deodorized
rules for deep fat frying7
maintain constant temp
use stainless steel
use deep pans (/tall sides)
use minimum time
remove food particles from oil
minimize water, batter
avoid excessive load
what material of pan should be used? why?2 and what shouldnt be used/why
stainless steel
(iron is a prooxidant)
fat is more easily removed from steel
what could cold, wet food do if it is put into hot fat? so how should you change this?
cause steam bubbs to form, causing fat to overflow the container
--food should be as dry as possible