fish Lipids

8/14/2019 fish Lipids

1/31

Lipids


2/31

Lipids

(generally soluble in organic solvents

Plant sources

(olive, palm)

No cholesterol

Animal sources

(butter, lard, tallow)

Triacylglycerol

Oils and Fats

SterolsWaxes

(monoesters)


3/31

Lipids

Definition of Lipids Naturally occurring biological substances made from C, H

and O of pronounced hydrophobicity that are soluble inorganic solvents but not water Petroleum distillates (e.g. hexane)

Chloroform Ethers Alcohols

Also classified as biological molecules containing fattyacids or the corresponding alcohols or sphingosine bases

Lipids have more C and H than carbohydrates, which is whythey generate more energy when utilized 2.25 timesmore = 9 kcal/g vs. 4 kcal/g.


4/31

Lipids

Biological roleA. Structural

- found in membranes

- protective barriers

B. Regulatory

- steroids/prostaglandins

- phospholipids

C. Storage

- triglyceride is

storage for energy

D. Vitamins

- solvent

- precursor


5/31

LipidsRole in foods

A. Calories (kcal)

energy


6/31

Lipids

Classification of lipids (structure)1) Simple lipids

Mono, Di and Triacylglycerols Waxes

2) Compound lipids Phospholipids Glycolipids Sphingolipids (amide to alcohol)

3) Derived lipids Free fatty acids Sterol esters Tocopherol (Vit-E) -carotene

Triacylglycerol

Glycerol

backbone Fatty acids


7/31

Lipids

1) Non-polar lipids

(neutral lipids) Fatty acids

Mono-, di-, & triacylglycerols

Waxes

Sterols

Carotenoids

Tocopherols

2) Polar lipids Glycerophospholipid

Glyceroglycolipid

Sphingophospholipid

Sphingoglycolipid

Classifications of lipids (polarity)Classifications of lipids (polarity)


8/31

Lipids

Structure & properties of fatty acids Fatty acid are composed of a hydrocarbon chain with

methyl group (CH3) on one end and a carboxyl group

(COOH) on the other. Basic properties common to most fatty acids

1. Most are even carbon #

2. Most are monocarboxylic acids

3. Most are part of triacylglycerides (triglycerides)


9/31

Lipids

NOMENCLATURE

1. Number of carbons C4-C24 most common

E.g. C8 = octa

C12 = dodeca2. Saturation

Saturated

(no double bonds)

Unsaturated

(double bonds) Mono (1 = bond)

Poly (>1 = bond)


10/31

Lipids

2. Saturation (cont.) No double bond = Anoic

E.g. C18:0

One double bond = Enoic E.g. C18:1

Two double bonds = Dienoic E.g. C18:2

Three double bonds = Trienoic E.g. C18:3

3. Geometric configuration

of double bonds Cis vs. Trans

Has an influence on

the fatty acid backbone

structure


11/31

Lipids

4. Position of double bonds Delta () system - count # of carbons to the = bond from the

COOH end E.g. 9-octadecenoic acid

Means: a) C18 = octadecenoicb) 1 double bond = octadecenoic

c) double bond is 9 carbons from the COOH end

Omega () system - count # of carbons to the = bond from the

CH3 end used for abbreviations of fatty acids

E.g. 9-octadecenoic acid would be C18:19

-3 therefore would mean that the = bond is 3 C from the CH3 end

-3, -6 and -9 the most common


12/31

Lipids

What is the name of this fatty acid using the delta & omegasystems?

H3C-(CH2)4-CH=CH-CH2-CH=CH-(CH2)7-COOH

Delta: ___________________________

Omega: __________________________

Common name is Linoleic acid (C18:2)


13/31

Lipids

Major fatty acids in foods Saturated

Palmitic (16:0) Stearic (18:0)

Monoenoic Oleic (18:19)

Dienoic Linoleic (18:26) 9, 12 - common in plants; some in animal

Trienoic Linolenic (18:33) 9, 12, 15

Tetraenoic Arachadonic (20:46) - 5, 8, 11, 14 - part of membrane phospholipids


14/31

Lipids

Factors affecting the properties of fatty acids1.Length of fatty acids

Longer chain length leads to increase in melting point and gives

more stable fatcrystals

Classes: C4 C8 - liquid @ room temperature (20-25)

These are water soluble good emulsifiers

C10 - C14 - viscous @ room temperature

C16 - C26 - solid @ room temperature

For example: C6:0 MP = -2C

C10:0 MP = 31.5C

C16:0 MP = 63C


15/31

Lipids

Factors affecting the properties of fatty acids2. Double bonds

An increase in double bonds decreases melting point

Example:

18:0 = 70C18:1 = 15C

18:2 = -5C

18:3 = -11C


16/31

Lipids

Factors affecting the properties of fatty acids

3. Cis vs. Trans Cis has lower melting point than Trans

Cis produces a kink in the fatty acid chain which creates a more

open fatty crystal structure

Kink

Melting Point

18:1c 15C

18:1t 44 C

18:2c -5 C

18:2t 29 C

18:3c -11 C18:3t 71 C


17/31

Lipids

Arrangement of fatty acids on triacylglycerides1. Not random (usually)

2. Specificity controlled

3. General pattern

The arrangement can significantly affect physical properties of fat

LC : Long chain; SC: Short chain

Position Plant Mammal Milk Bird Fish

1 S S S S S-LC

2 U U S U U

3 U LC U or SC S or U LC


18/31

Lipids

% 16:1

Consistency

SSS

SSU

SUS

SUU

USU

UUS

Cocoa Butter

62.00

hard sharp mp

0.03

0.01

0.81

0.15

0.01

0.01

Tallow

64.00

greasy broad mp

0.28

0.16

0.32

0.18

0.02

0.03

High mp

Low mp

Importance of sn position; Cocoa butter vs. Tallow


19/31

Lipids

Important Compound Lipids1. Phospholipids Make up cellular membranes Lipid molecules that contain a phosphate

group attached to a functional group Have both hydrophobic

(fatty acids) and hydrophilic

(phosphate and functional

group) portions

Good emulsifiers May have a protective effect

against ulcers (milk PL)


20/31

Lipids

2. Glycolipids Contain at a minimum one sugar

Some may also have a phosphate group (glycosphingolipids)

Found in all tissues of animals

Have same solubility characteristics as regular lipids

3. Sterols Made of four fused hydrophobic rings with a hydrophilic OH group

Not so important as a food ingredient but important for dietary reasons Cholesterol in animal foods

Can contribute to coronary heartdisease (arteriosclerosis)

300 mg/day the recommended intake limit


21/31

Lipids

4. Fat substitutes Sucrose fatty acid polyesters

Olestra (Procter and Gamble Co.) 6-8 fatty acids (>C12) esterified to sucrose

Caloric free due to its bulky structure and because lipases cannot

hydrolyze it

May lead to loss of fat soluble vitamins and can give diarrhea

Approved for use in frying oils (snacks)

Sucrose and polyol fatty acid esters

1-3 fatty acids esterified to sucrose or a polyol (e.g. sorbitol) Have caloric value (polyol fatty acid esters only about 1.5 kcal/g)

Used as emulsifiers and stabilizers


22/31

Triacylglycerol

Sterols

Wax

(bees wax)


23/31


24/31

Compound Lipids

Phospholipid

Glycolipid

Sugar unitPhosphategroup


25/31

Derived Lipids

Sterols Carotene


26/31

Peptide based liquid

Tube or oral feeding Efficient energy utilization

MCT OIL (Novartis nutrition) unable to digest or absorb

conventional fats Less enzymes and bile acids

for digestion


27/31

Fish Lipids

Fish are classified as lean, semi-fatty or fatty. Fish that store lipids only in the liver as lean and fish

storing lipids in fat cells distributed in other body tissues as

fatty.

Typical lean species are bottom-dwelling ground fish likecod, and hake.

Fatty species include pelagic such as herring, mackerel

and sprat.

Some species store lipids in limited parts of their bodytissues only, or in lower quantities than typical fatty

species, and are consequently termed semi- fatty species

(e.g. barracuda, mullet and shark).


28/31

Type of lipids in fish

The lipids present in teleost fish species may be

divided into two major groups: Phospholipids

The phospholipids make up the integral structure of the unit

membranes in the cells; thus, they are often called structural

lipids.

Triglycerides The triglycerides are lipids used for energy storage in fat

depots, usually within special fat cells surrounded by a

phospholipid membrane and a rather weak collagen network. The triglycerides are often termed depot fat. A few fish

have wax esters as part of their depot fats.


29/31

Fish & Mammals lipids

Fish and mammalian lipids differ mainly in that

fish lipids include up to 40 percent of long-chain

fatty acids (14-22 carbon atoms) which are highly

unsaturated. Mammalian fat rarely contains more than two

double bonds per fatty acid molecule while the

depot fats of fish contain several fatty acids withfive or six double bonds.


30/31

Lipids: marine & freshwater fish

The percentage of polyunsaturated fatty acids

with four, five or six double bonds is slightly lower

in the polyunsaturated fatty acids of lipids from

freshwater fish (approximately 70 percent) Lipids from marine fish (approximately 88

percent).

However, the composition of the lipids is not completelyfixed but can vary with the feed intake and season


31/31

THANK YOU!!!!

fish Lipids

Documents

Transcript of fish Lipids