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Lipids: Triglycerides, Phospholipids,

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the lipids in foods or body fat, both of which, are composed of TG ... oleic acid (C18:1) polyunsaturated (PUFA) fatty acids. 2 or more double bonds ... – PowerPoint PPT presentation

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Title: Lipids: Triglycerides, Phospholipids,


1
Lipids Triglycerides, Phospholipids, Sterols
2
Lipids
  • Lipids are the family of compounds that includes
  • Triglycerides fats oils
  • Phospholipids
  • Sterols

3
Some key definitions
  • Fats
  • the lipids in foods or body fat, both of which,
    are composed of TG
  • TG (also called triacylglycerols)
  • chief form of fat in the diet
  • major storage form of fat in the body

4
Building Blocks of Triglycerides
  • Glycerol
  • an alcohol
  • a 3C chain as the backbone for TG
  • Fatty Acid
  • an organic acid composed of a carbon chain with
    hydrogens attached with an acid group (COOH) at
    one end a methyl group (CH3) at the other end.

5
TG made from glycerol 3 FA
6
Classification of Fatty Acids
  • Saturated fatty acids
  • Monounsaturated fatty acids
  • Polyunsaturated fatty acids
  • omega-6 fatty acids
  • omega-3 fatty acids
  • Trans fatty acids

7
Saturated Fatty Acids
  • FA carrying the maximum possible number of
    hydrogen atoms
  • ex stearic acid (C180)
  • It is fully loaded with hydrogen atoms contains
    only single bonds between its carbon atoms
  • A saturated fat is composed of TG in which all FA
    are saturated

8
Unsaturated Fatty Acids
  • FA that lacks hydrogen atoms so have at least one
    double bond between carbons
  • monounsaturated (MUFA) fatty acids
  • one double bond
  • oleic acid (C181)
  • polyunsaturated (PUFA) fatty acids
  • 2 or more double bonds
  • linoleic acid (C182)
  • linolenic acid (C183)

9
  • See Tables C-1 C-2 in Appendix C for names,
    chain length sources of fatty acids commonly
    found in foods

10
Degree of Unsaturation
  • Affects firmness of fats at room temperature
  • Influences stability

11
Hydrogenation of Fats
  • A chemical process by which H are added to MUFA
    or PUFA
  • Reduces of double bonds making fats more
    saturated
  • More solid (spreadable at room temperature)
  • More resistant to oxidation (prolongs shelf life)

12
Essential Fatty Acids
  • Body can make all but 2 FA
  • a-Linolenic Acid omega 3 FA
  • Linoleic Acid omega 6 FA
  • Must be supplied by the diet
  • Found in vegetable oils, seeds, nuts, fish
    marine foods

13
Essential FA Families
  • Omega-3 FA
  • A PUFA in which the first double bond is 3
    carbons away from the methyl end of the carbon
    chain
  • Omega-6 FA
  • a PUFA in which the first double bond is 6
    carbons from the methyl end of the carbon chain

14
Omega-3 FA Family
  • a-Linolenic Acid
  • Primary FA in omega-3 family
  • Sources vegetable oils, nuts, seeds, vegetables
  • Eicosapentaenoic Acid (EPA) Docosahexaenoic
    Acid (DHA)
  • Omega 3-PUFA synthesized from linolenic acid
  • Present in fatty fish

15
Omega-6 FA Family
  • Linoleic Acid
  • Primary FA in omega-6 family
  • Arachidonic Acid
  • Can be made from linoleic acid
  • Becomes EFA if deficiency of linoleic acid
  • Dietary sources meats

16
Essential Fatty Acids
  • Needed for cell membrane structure to make
    eicosanoids
  • hormone like substances which help regulate blood
    pressure, blood clotting, blood lipids immune
    responses to injury infection
  • Include prostaglandins, thromboxanes,
    leukotrienes

17
Summary
  • Triglycerides
  • Predominant class of lipids both in foods in
    the body
  • Contain glycerol fatty acids
  • 4 class of fatty acids
  • Essential fatty acids
  • linolenic a-linoleic acid
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