Suyatno Rindang Farmasis

Food Lipids

Lipids

Ÿ"Lipids consist of a board group of compounds that are generally soluble in organic

solvents but only sparingly soluble in water…." "…Glycerol esters of fatty acids, which

make up 99% of the lipids of plant and animal origin have traditionally been called fats

and oils"

Lipids are non-polar (hydrophobic) compounds, soluble in organic solvents.

Fatty acids consist of a hydrocarbon chain with a carboxylic acid at one end

Non-Polar Polar

Saturated Fatty Acids

Systematic name	Trivial name	Shorthand designation	Molecular wt.
butanoic	butyric	4:00	88,1
pentanoic	valeric	5:00
hexanoic	caproic	6:00	116,1
octanoic	caprylic	8:00	144,2
nonanoic	pelargonic	9:00	158,2
decanoic	capric	10:00	172,3
dodecanoic	lauric	12:00	200,3
tetradecanoic	myristic	14:00	228,4
hexadecanoic	palmitic	16:00	256,4
heptadecanoic	margaric (daturic)	17:00	270,4
octadecanoic	stearic	18:00	284,4
eicosanoic	arachidic	20:00	312,5
docosanoic	behenic	22:00	340,5

Mono-Unsaturated Fatty Acids

Systematic name	Trivial name	Shorthand designation	Molecular wt.
cis-9-tetradecenoic	myristoleic	14:1(n-5)	226.4
cis-9-hexadecenoic	palmitoleic	16:1(n-7)	254.4
cis-9-octadecenoic	oleic	18:1(n-9)	282.4
tr-9-octadecenoic	elaidic	tr18:1(n-9)	282.4
cis-11-octadecenoic	vaccenic (asclepic)	18:1(n-7)	282.4
cis-11-eicosenoic	gondoic	20:1(n-9)	310.5
cis-13-docosenoic	erucic	22:1(n-9)	338.6

Systematic name	Trivial name	Shorthand designation	Molecular wt.
9,12-octadecadienoic	linoleic	18:2(n-6)	280.4
6,9,12-octadecatrienoic	γ-linolenic	18:3(n-6)	278.4
9,12,15-octadecatrienoic	α-linolenic	18:3(n-3)	278.4
6,9,12,15-octadecatetraenoic	stearidonic	18:4(n-3)	276.4
5,8,11,14-eicosatetraenoic	arachidonic	20:4(n-6)	304.5
5,8,11,14,17-eicosapentaenoic	EPA	20:5(n-3)	302.5
4,7,10,13,16,19-docosahexaenoic	DHA	22:6(n-3)	328.6

Phospholipids

ŸPi is in turn esterified to OH of a polar head group (X): e.g., serine, choline,ethanolamine, glycerol, orinositol.

ŸThe 2 fatty acids tendto be non-identical. They may differ in length and/or the presence/absence of doublebonds.

Sphingolipids

ŸSphingolipids are derivatives of the lipid sphingosine, which has a long hydrocarbon tail, and a polar domain that includes an amino group.
ŸThe amino group of sphingosine can form an amide bond with a fatty acid carboxyl, to yield a ceramide.

Sphingomyelin

Ÿ Sphingomyelin, a ceramide with a phosphocholine or phosphethanolamine head group, is a common constituent of plasma membranes

A cerebroside is a sphingolipid (ceramide)with

amonosaccharide such as glucose or galactose as

polar head group.

Attributes of Food Lipids

ŸThree major functions in foods

–Energy and health

–Influence food flavors

Ÿfree fatty acids contribute flavors

Ÿlipids act as solvents for carrying hydrophobic

flavors and aromas (and nutrients)

–Texture

ŸSolid vs liquid

ŸEmulsions

Attributes determined by types and positions of fatty acids on glycerol backbone

Plant Triglycerides

– Coconut, palm oil richer in 8:0-16:0

Cocoa butter

– ~ equal 16:0, 18:0, 18:1

–sn-2 primarily unsat’d (U)

–sn-1,3 mostly sat’d (S)

Coconut oil

–80% of triacylglycerols are trisaturated

ŸLauric at sn-2

ŸOctanoic at sn-3

ŸMyristic or palmitic at sn-1

ŸPeanut Oil

–

~40% oleic; 40%linoleic

–sn-2 largely unsat’d

– Soybean oil similar

Olive Oil

–~75% oleic

–sn-2 99% unsat’d

–homogeneous

Animal Triglycerides

Ÿ Beef Fat (tallow)

– ~ equal 16:0, 18:0, 18:1

– sn-1,2,3 sat’d (S) &

unsat’d (U)

–Pig fat (lard) similar

Cocoa Butter vs Animal Fat

ŸCompare cocoa butter vs tallow (beef fat)Ÿ

–fatty acid composition quite similar roughly equal C16:0, C18:0, C18:1

cocoa butter tallow

Cocoa butter homogeneous: melts sharply at body temp; Tallow heterogeneous:

solid/liquid over wide temp range

Animal Triglycerides

bovine milk fat
cod oil

ŸMilk Fat - Large number of short-chain fatty acids Marine Oils

– affects cheese flavor – Long-chain unsaturated fatty acids

– causes milk rancidity

Summary of Fatty Acid Profiles

ŸPlant fats/oils:

–sn-2 largely unsaturated fatty acid (C18:1 & C18:2)

–some plant oils contain high unsaturated fatty acid contents (peanut, soybean, olive, Canola)

–other plant oils significantly saturated (cocoa butter)

–coconut and palm oil primarily saturated— rich in C8:0- C16:0

ŸAnimal fats/oils:

–broader range of fatty acids/triglycerides found

milk fat (short chains) vs fish oils (long, polyunsat’d)

–sn-2 often saturated, greater variation in positions

Properties
Crystallization

ŸCrystallization/Melting is balance

– entropic considerations

favor increased molecular motion

and

– attractive intermolecular interactions

favor packing molecules close together

Melt (liquid)

crystal (solid)

Melting Point

ŸLonger chain fatty acids pack better than shorter chains

– M.P.long > M.P.short

ŸSaturated fatty acids pack better than unsaturated

– M.Psat’d > M.P.unsat’d

Trans fatty acids pack better than cis

–M.Ptrans > M.P.cis

–hydrogenation increases M.P.

Melting Point Trends

Fatty A cid	Comm on N ame	M.P
8:00	Caprylic acid	16ºC
16:00	Palmitic acid	63ºC
18:00	Stearic acid	69ºC
20:00	Arachidic acid	75ºC
18:1Δ9 (cis)	Oleic acid	13ºC
18:2Δ9,12 (ci s)	Linoleic acid	-5ºC
18:3Δ9,12,15 (ci s)	Linolenic acid	-11ºC
18:1Δ9 (trans)	Elaidic acid	46ºC
18:2Δ9,12 (trans)	Linolelaidic acid	28ºC