LIPIDS • A water insoluble compounds, but soluble in ether, benzena, acetone andchloroform • Consists of glicerol & 3 fatty acids. Forms: solidlipid liquid fat • Energy 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: • Simple lipids: esther, fatty acids and glicerol • Mixed lipids: simplelipid + other molecules such as N, S, P etc • 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: • Saturated (CnH2nO2) • 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 CH3(CH2)nCOOH
Lipid Content of Feeds • Forages • Fat content is low: 1 to 4% of dry matter • High proportion of linolenic acid (18:3) • Diglycerides in fats of leaves • Grains • Fat content variable: 4 to 20% of dry matter • High proportion of linoleic acid (18:2) • Triglycerides in oils of seeds
CHEMICAL REATIONOF FAT • HYDROLISIS • ENZYMATIK (in GIT) • WITH ALKALI (SAPONIFICATION) Lipid+alkalineglicerol salt alkaline fatty acid
CHEMICAL REACTION (CONT...) 2. ANALYSIS • Saponification score- No.of mg KOH needed to form 1 gr fat • Fatty acids score- No.of mg KOH needed to neutrilisefree fatty acid from 1 gr of fat • Polenske score- No.of mg KOH neede to neutraliseinsoluble fatty acidsfrom 5 gr of fat
CHEMICAL REACTION OF FAT 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
RANCIDITY • HYDROLITIC Presence of lipase causes this reactionto formfatty acid+glicerol NV of feed is not affected • OXIDATIVE Occured by the presence of oxigen Energi value of fat reduced
PREVENTION • ANTIOXIDANT Compund preventing the occurence of lipid oxidation (rancidity) # PRIMER (to stop chained reaction offree radical formation to release H) # SEKUNDER (to prevent the action of prooxidant) • HYROGENISATION ---- lessreaktve 3. Good storage