2.11 Emulsification Lipids: Bile Acids

• Emulsifier

  • a substance that can disperse and stabilize water-insoluble substances as colloidal particles in an aqueous solution.
• Bile acid

  • Cholesterol derivative that functions as an emulsifying agent that makes dietary lipids soluble in aqueous environment of the digestive tract.
• Bile

  • A fluid containing emulsifying agents secreted by the liver, stored in the gallbladder, and released into the small intestine during digestion
• 2 types of Bile acids:

  • Simple bile acid
  • Complex bile acid
• Simple bile acid

  • Are steroid monocarboxylic acids, obtained by oxidation of cholesterol.
• Simple bile acid differs from cholesterol in 2 aspects:

  • They are tri- or dihydroxy cholesterol derivatives.
  • The carbon 17 side chain of cholesterol has been oxidized to a carboxylic acid.
• Complex bile acid

  • Have enhanced emulsifying ability stemming from one end of the molecule being strongly hydrophilic (the amino acid bearing carbon chain) and the rest of the molecule (the steroid nucleus with its small attachments) being largely hydrophobic.