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1

what are the 3 forms of nomenclature of triglycerides?

1 simplest: TGC that has only one type of FA attached to the 3 positions on the glycerol (simple glycerides)

2 mixed glycerides: more than one type of FA

3 position of each FA is numbered

2

what is sapoinification

hydrolyzing the fat

3

what is FAME?

FA methyl esters

4

how to determine overall FA composition of a fat?

1. saponify: hydrolyze the fat and react it with NaOH to release FA
2. methylate the FA to convert them to volatile FAMEs (FA methyl esters)
3. separate FAMEs using gas chromatography

5

what has GC analysis demonstrated?

that each natural fat source has a relatively consistent FA composition

6

fats from plants and fish tend to be...

oils (ie liquid at room temp)

7

what are TGC used as in plant seeds?

source of energy for germination

8

what are common primary plant sources of edible oils?

north america:
soybean
rapeseed (canola)
peanut

other locations:
olive
coconut
cocao and palm

9

are seeds and fruits of plants good or bad sources of lipid?

very good sources

10

what are the 3 most common sources of fats?

plants
animals
fish

11

fat in animal sources?

fat rendered as a by product of meat production (from trimmings and carcasses of cattle, hogs, sheep)

12

fat in fish sources?

fatty fishes such as sardines, herrings, menhaden

13

what are fats and oils classified by?

their fatty acid composition and distribution determined by gas chromatography

14

what are the 7 groups of fat classifications?

1 milkfat
2 lauric acid
3 oleic linoleic
4 linolenic
5 animal fat depot
6 marine oil
7 erucic

15

describe the milkfat group classification?

includes fat from milk of lactating ruminants (cow, goat, yak ,sheep, water buffalo)

major use: butter production

features: high levels of long chain sat FA
substantial portion of short chain (

16

why are some of the unsat FA in the milkfat group trans?

because of the biohydrogenation in the rumen by microorganisms

17

what is the short chain FA responsible for in the milkfat group?

1. rancid like odor
2. undesirable flavor in milk (due to enzymatic lipolysis)
2. desirable flavor of aged cheese (enhanced by microbial lipases)

18

what is the major use of milkfat group?

production of butter (water in oil emulsion)

19

sources of lauric acid C12 group? their distinguishing properties?

from species of palms (oil palm, coconut and babasu)

commonly known as tropical oils

distinguished by: high content of lauric acid. accounts for 40-50% of total FA content

20

saturation in lauric acid?

are they resistant to oxidative rancidity?

crystallization?

most FA are saturated = oils at room temp = resistant to oxidative rancidity

can be fractionally crystallized (fractionated) to produce distinct fat and oil fractions

21

why are palm and palm kernal oils (lauric acids) highly valued?

resistant to oxidative rancidity = their major use is as an oil or fat in baked goods = long oxidative shelf life

22

cottonseed, sunflower,safflower, olive, peanut and corn oil are what type of group?

oleic linoleic acid

23

compoisition of oleic linoleic acid group?

sat FA make up less than 20% of FA composition

predominant FA are long chain: oleic (C18:1) and linoleic (C18:2)

very little C18:3 = thus oils don't undergo reversion = relatively stable = can be turned into plastic edible fats by partial hydrogenation (shortenings)

24

describe the linolenic acid (C18:3) group

why are they categorized as industrial "drying oils"?

examples?

high quantities of linolenic acid (in conjuction with oleic and linoleic acid)

high in polyunsat FA

linolenic is very reactive and readily oxidized

categorized as industrial drying oils because they can polymerize into a hard film if applied as a thin layer on surfaces

ex: soybean, linseed, castor, hempseed, perilla oils

25

what is C18:1?

oleic acid

26

what is C18:2

linoleic

27

what is C18:3

linolenic (omega 3)

28

what is reversion?

how is this overcome by processing?

rapid transition from a bland, tasteless oil to a grassy, hay like fish flavour (common in unmodified processed soybean oil)

can reduce reversion by hydrogenation. Converts linolenic to oleic and linoleic acids

29

source of animal fat depot group?

lard from pigs, tallow from sheep and cattle

30

how does the fatty acid distribution on the glycerol affect physical properties of the animal fat depot group?

FA distribution animal fat depot group has higher ratio of di-saturated (gs2u) and tri-saturated (gs3 glycerides than oleic-linoleic acid group = causes melting point to be much higher than oleic-linoleic acid group, even though they have similar unsat FA levels

also influences plasticity and crystal formation in the fat (affects functionality)