Lipids: Triglycerides, Phospholipids,

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Lipids Triglycerides, Phospholipids, Sterols
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Lipids

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

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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

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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.

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TG made from glycerol 3 FA
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Classification of Fatty Acids

• Saturated fatty acids
• Monounsaturated fatty acids
• Polyunsaturated fatty acids
• omega-6 fatty acids
• omega-3 fatty acids
• Trans fatty acids

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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

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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)

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

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Degree of Unsaturation

• Affects firmness of fats at room temperature
• Influences stability

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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)

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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

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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

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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

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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

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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

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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