LLIPIDSIPIDS

LIPIDSA water insoluble compounds, but soluble in ether, benzena, acetone and chloroformConsists of glicerol & 3 fatty acids. Forms: solid lipid

liquid fatEnergy contents 2.25 times higher than carbohydrate…….WHY??

ENERGY OF LIPIDS

• H:O higher than carbohydrate• They have higher Oxidation

potential Ex. Butiryic acid C3H7COOH (4:1)

Glucose C6H12O6 (2:1)

Classifition:

1. Simple lipids: esther, fatty acids and glicerol

2. Mixed lipids: simplelipid + other molecules such as N, S, P etc

3. Lipids obtained from hydrolysis

LIPID SYNTHESIS

CH2OH HOOC-R CH2-OOC-R

CHOH + HOOC-R CH-OOC-R + 3H2O

CH2OH HOOC-R CH2-OOC-R

Glicerol fatty acid fat water

Triacylglycerol Triglycerides

R-COO-CH2

R-COO-CH R-COO-CH2

• Triglycerides found in seeds and animal adipose.• Diglycerides found in plant leaves, one fatty acid is replaced by sugar (galactose).

PROPERTIES

Determined by structure of fatty acids:

1. Saturated (CnH2nO2)

2. Unsaturated (CnH2n-xO2)

SATURATED FATS

• Ex. Acetic acid CH3COOH

Butyric acid C3H7COOH

Caproic C5H11COOH

Caprylic C7H15COOH

Capric C9H19COOH

Lauric C11H23COOH etc

UNSATURATED

• They have double bounds

• Ex. Palmitoleic acid C15H29COOH

Oleic acid C17H33COOH

Linoleic acid C17H31COOH

Linolenic acid C17H29COOH

Arachidonic acid C19H31COOH

Most Common Fatty Acids in Di- and Triglycerides

Fatty acid Carbon:Double bonds

Double bonds

Myristic 14:0

Palmitic 16:0

Palmitoleic 16:1 Cis-9

Stearic 18:0

Oleic 18:1 Cis-9

Linoleic 18:2 Cis-9,12

Linolenic 18:3 Cis-9,12,15

Arachidonic 20:4 Cis-5,8,11,14

Eicosapentaenoic 20:5 Cis-5,8,11,14,17

Docosahexaenoic 22:6 Cis-4,7,10,13,16,19

CH3(CH2)nCOOH

Fatty Acid Isomers

Lipid Content of Feeds

ForagesFat content is low: 1 to 4% of dry matterHigh proportion of linolenic acid (18:3)Diglycerides in fats of leaves

GrainsFat content variable: 4 to 20% of dry matterHigh proportion of linoleic acid (18:2)Triglycerides in oils of seeds

CHEMICAL REATION OF FAT

1. HYDROLISISA. ENZYMATIK (in GIT)B. WITH ALKALI (SAPONIFICATION)

Lipid+alkaline glicerol salt alkaline

fatty acid

2. ANALYSISa. Saponification score- No.of mg

KOH needed to form 1 gr fatb. Fatty acids score- No.of mg KOH

needed to neutrilise free fatty acid from 1 gr of fat

c. Polenske score- No.of mg KOH neede to neutralise insoluble fatty acids from 5 gr of fat

CHEMICAL REACTION (CONT...)

d. Iodine score (unsaturation level) - gr iodine absorbed by 100 gr

lipid (each double bounds of fat can take 2 iodine atoms)

e. Ranacidity Test (level of rancidity)- Peroxida score (using KI)- Tiobarbiturate test- Oven Schaal test

CHEMICAL REACTION OF FAT

RANCIDITY

1. HYDROLITIC Presence of lipase causes this

reaction to form fatty acid+glicerol

NV of feed is not affected2. OXIDATIVE Occured by the presence of

oxigen Energi value of fat reduced

PREVENTION1. ANTIOXIDANTCompund preventing the occurence of

lipid oxidation (rancidity)# PRIMER (to stop chained

reaction of free radical formation to release H)

# SEKUNDER (to prevent the action of prooxidant)

2. HYROGENISATION---- lessreaktve3. Good storage