GID 221E Food Chemistry I Midterm Examination 2 ( 2003 )

1.  Explain how fatty acids are given systematic names and what are the differences in omega (ω) fatty acids? Give one example. (7 points)    Systematic names of fatty acids are given by considering the carbon numbers (1   point)  and  by  a  suffix  -noic  acid  (1  point).  If  there  is  a  double  bond  in  the   structure then “enoic acid” suffix (1 point) is given. If double bond is more than   one ; 2- dienoic, 3- trienoic suffixes (1 point) are used.   When counting starts from CH3 (methyl end) of the chain (2 point), then suffix ω is   used.   ω-9  Oleic acid, ω-6  Linoleic acid , ω-3  Linolenic acid (1 point for one example)    2.  Which property of lipids allows us to determine the presence of double bonds?  (5       points)    Halogen addition reactions: We can determine the number of double bonds in an   oil/fat by their iodine number (5 points).


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