Lipids

Lipids

1. elemental composition

   • carbon hyrogen oxegon

2. chemical structure

   • triglyceride
     • 3 faty acid molecules , 1 glyceride

3. classification

   • saturated
     • full quota of hydrogen
     • no double bond
     • animal sources-butyric acid -butter
     • solid at room temp
     • increase blood cholesterol levels
   • mono unsaturated
     • only some are saturated with hydrogen
     • liquid at room temp
     • one double bond
     • plant sources-oleic acid (olive oil)
   • polyunsaturated
     • none are saturated with hyrogen
     • more than one double bond
     • soft/liquid at room temp
     • plant sources -linoleic acid(two double bonds)

4. essential fatty acids

   • cannot be made in body
   • linoleic + arachidonic
   • cell membranes
     • essential for growth
   • counteract hardening of cholestorol in artieries so reduce conary heart disease

5. cis /tans fatty acids

   • cis fatty acids
     • polyunsaturated
       • hydrogen above or below carbon chain
   • trans fatty acid
     • polyunsaturated
       • hydrogen either side of double bond -opposite side of carbon chain

6. cis/trans fatty acids in diet

   • reduce cholestorol
   • heat changes cis to trans
   • trans-bad-increase CHD

7. classification

   • animal
     • meat cream butter cheese
   • plant
     • cereals,veg oils,soya beans,margarine
   • marine
     • salmon mackeral herring trout

8. properties

   • melting point
     • solid fats melt when heated
       • 30-40
   • smoke point
     • decompose when overheated
       • glycerol changes to acrolein
         • solid fats-200
           • oil-250
         • blue haze-acrid smell
   • flash point
     • overheated-vapour rises which can burst into flames
       • solid fats-310
       • oils-325
   • solubility
     • insoluble water-soluble organic solvents
   • rancidity
     • oxidative
       • more common
       • unpleasant rancid smell
       • oxegon combines with carbon atom at double bond
     • hydrochloric
       • unpleasant smell
       • in freezer-enzymes
       • enzymes hrolose lipids changing to fatty acid and glycerol
   • absorb flavour quickly
   • emulsions
     • oil and water mixed-seperate layer
       • immiscibile
     • shaken vigourously-oil go in water for short time
       • seperate gagain
     • pernament emulsion
       • 3rd substanc
         • emulsifying agent
     • lowers surface tension-oil and water
     • hydrophilic head and hydrophobic tail
       • hydrophobic-oil
       • hydrophilic-water
       • stabilises mixture

9. fatty acid

   • organic compund

10. omega 3 fatty acid

    • prevent conarary heart disease,stroke,lower blood pressure

11. functions

    • heat,energy
    • adipose tissue-insulation
    • proctect organs
    • supple fat solouble vitiamins a d e k
    • provide essential fatty acids

12. digestion

    • hydrolysis-breaks down triglyceride
      • liver-bile slats-emulsify lipid
      • pancras-lipase-hydrolysis
      • intenstinal lipase continues breakdown

13. absorbtion

    • large molecules-cant go into blood
    • lacteals absorb fatty acid and glycerol
    • lacteals carry fatty acid and glycerol to thoracic duct and empty into blood

14. utilisation

    • oxidise in liver-heat and energy
    • energy reserve-adipose tissue
    • adipose tissue protect orgas

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