lipids Flashcards
what is the diff between fats and oils?
fats solid, oils liquid at room temp
crude oil is _____% TAGs, ___% non-TAG
93-98; 2-7
TAGs prefer the __ conformation
chair
C 4:0
butyric acid (milk)
C 10:0
capric acid (milk)
c 12:0
lauric acid (coconut, palm kernel)
C 14:0
myristic acid (milk)
C 16:0
palmitic acid (palm, milk)
C 18:0
stearic acid (milk)
C 18:1
oleic acid (olive oil, milk)
C 18:2
linoleic acid (sunflower, canola, soybean)
C 18:3
linolenic acid (flaxseed, borage)
C 20:5
eicosapentaenoic acid
C 22:6
docosahexaenoic acid
C 22:5
docosapentaenoic acid
TFAs are found in:
dairy/animal fat and also hydrogenated vegetable oils
_____ oil is found in rapeseed and mustard
erucic acid
lauric oils are particularly important for _____
soap making
______ have wide melting points ranging from -40 to 40 degrees C
milk fats
Palmitic oils are widely grown in ___ and are rich in ___
Malaysia; beta carotene
what is vegetable butter derived from?
palmitic, stearic, oleic acids (saturated–>solid)
animal fats have lots of _____ TAGs, giving them a high ___
fully saturated; melting point
the most common type of vegetable oils are ___, that make up _____%
oleic/linoleic; 80-90
why shouldn’t you use olive oil for high temp frying?
the high amount of monounsaturates means that it oxidizes easily with metal elements in pan
very high unsaturation leads to _____ and development of ___ flavour
auto-oxidation; rancid
this type of oil is used for its excellent drying properties in the paint industry
linolenic oils (camelina, flax)
C 22:1
erucic acid (edible oils in china and india, industrial oil in NA)
the genetic mod of rapeseed developed in uni of Sask; must have
canola
marine and fish oils have very __ melting points because of the presence of ___
low; PUFAs
what are the 3 major vegetable oils?
palm, rapeseed, soybean
what are the steps of industrial production of vegetable oil?
seed collection/cleaning, extraction of crude oil (pressing, solvent extraction), refining
what needs to be removed in the refining process of crude oil?
phospholipids (degumming), free f.a. (alkali neutralization with NaOH), undesirable colour (bleaching), undesirable odours (deodorizing)
what is the miscella?
oil and solvent mix after pressing/extraction (solvent must be evaporated to get crude oil)
what is lecithin?
an emulsifier used in degumming
what are soapstocks?
sodium salt of free f.a. after the neutralization process
what are the diff chem tests of fats and oils?
acid value, saponification value, iodine value, smoke point
a higher smoke point = ___ for frying
better
what is the iodine value? It is expressed as _____
degree of unsaturation; # I (g) absorbed by 100g oil
what is the saponification value? It is defined as __
f.a. chain length and amount of TAGs; # mg KOH needed saponify 1 g oil/fat
What is the acid value? The test involves a titration with ___
free f.a. content; KOH
a higher molecular weight oil will result in a ___ SV
lower
fully saturated lipids have an IV of ___
0
what is the smoke point?
temp at which fat/oil produce first visible smoke (200 degrees is min for optimum frying characteristics)
what is the flash point?
when oil heated too high, ignites and catches fire
what is lipid oxidation?
rxn between oxygen and lipids–>generates peroxides, aldehydes, ketones
what determines rate of oxidation?
how quickly e- may be extracted from f.a., leading to free radicals (easier with db bonds)–>light and temp affect
what are some ways to prevent lipid oxidation?
reducing PUFAs through hydrogenation and replacement with SA, exclude o2 and light, add antioxidants, create physical barrier (encapsulation)
how do antioxidants neutralize free radicals?
by donating one of their own e-
Examples of antioxidants include:
BHA, TBHQ, tocopherols, carotenoids, ascorbates, flavonoids
what is GRAS status?
generally recognized as safe
amount of TFA on label can be labeled as 0g if
0.2
what is a replacement for hydrogenation?
modification through fractionation
good TFAs that are a family of isomers of octadecdienoic acid (18:2)
CLAs (conjugated linoleic acids)
where are CLAs generated? How?
rumen of animals; process of bacterial isomerization
positional isomers vs. geometric isomers?
positional: pos. of conjugated db bonds
geometric: cis/trans
what is the most common CLA isomer (there are 24 in total)?
octadeca-cis-9, trans-11-dienoic acid
what are some potential health effects of CLAs?
anticarcinogenic, prevent cardio disease, reduce fat deposit, protect against bone loss
what are the physical properties of oils/fats?
crystallization/melting profile, spreadability, texture
fats exist in a _______
fat crystal network (aggregated spherulites and non-aggregated forms)
> length = ___ MP; cis = __ MP; db bond = ___ MP
> ;
what are the main functions of fats and oils in foods?
dietary import, flavour/mouthfeel/palatability, cooking medium for heat transfer, food structure, emulsions, baking
what are the essential fatty acids? what are the food sources?
alpha linolenic, linoleic; fish/soy/canola/flax/sunflower oils
