Question

(b) The trans isomer of oleic acid is called elaidic acid and this is the main trans fatty acid formed in the partial hydrogenation of vegetable oils. Answer ALL the following; a. Draw the structure of elaidic acid. b. Explain why oleic acid melts at 4 °C but elaidic acid melts at 45 °C. c. Compare the effect of oleic acid and elaidic acid consumption on HDL cholesterol and LDL cholesterol. (c) In the human diet what are the main long chain o3 fatty acids and the main ob fatty acid? Account for differences in the 06:03 ratio in the typical Japanese diet, Mediterranean diet and the Western diet. (d) Describe how you would measure a lipids saponification value. Include a description of what the saponification value tells you about a lipid and how the saponification value of coconut oil would compare with the value for soya oil. (e) Describe the main reactions in lipid peroxidation. Include an explanation for why some fatty acids are more susceptible to oxidation and how antioxidants, such as butylated hydroxytoluene, retard oxidation. (f) Cis-trans isomerization can occur during the industrial hydrogenation of plant oils. Describe how this occurs and how hydrogenation can be accomplished without forming trans fats.

Answer 1

| Past bi (a) Structure of elaidic acid Hoy - perfect (6) The packing of the olefin is light in the I case of trans-isomer (elaidicacid). Hence Lit meets at higher temperature than the & cis-isomer Coleic acid). . cc) oleic acid consumes more LDL than HDL: I Elaidic acid consumes more HDL tesars LDLY Explanation". HDL is linear, LOL is branched.