Food Lipids Previous Exam I

University of Kentucky, Department of Animal & Food Sciences, FSC 640

1. Which would have a higher melting point, trans, 9-oleic acid or cis, 9-oleic acid. Also compare the melting points of cis,9-oleic acid and cis, 3-oleic acid. Explain in detail why these differences in melting points occur. (9 pts.)

2. Explain the deoderization process used in edible oil refining. When does it occur in the overall refining process, and why it is located at this point in the process ? (11 pts.)

3. Explain the difference between selective and nonselective hydrogenation. What are the key processing conditions and corresponding oil characteristics from each method? (13 pts.)

4. You have an oil that is composed predominately of linoleic acid. HPLC analysis show large content of hydroperoxides (approximately 40% of the total ) in this oil on the #10 and #12 carbons (60% on other carbons). Explain the process of how these hydroperoxides were formed. (13 pts.)

5. What are the main characteristics that an antioxidant must have to be effective? Describe the chemical structure of any common antioxidant and how these primary characteristics apply to it. Also describe two other physical characteristics that can effect its utilization in food systems. Describe a type of food system that corresponds to each situation. (11 pts.)

6. Describe two ways that oxidizing lipids can cause protein crosslinking? In the journal article discussed in class, what were two analytical methods used to measure changes in the protein due to exposure to lipid oxidation products (not TBA values)? (11 pts.)

7. Describe any two methods of measuring lipid oxidation products. Discuss the advantages and shortcomings of each method you choose. ( 11 pts.)

8. Describe the degumming process used in refining of edible oils. What are the primary compounds removed, how does the chemistry of these compounds contribute to their removal. Also discuss potential problems with the process. (11 pts.)

9. What is the difference between random and direct interesterification? Explain the difference in the end products using each method. What are some possible benefits for modifying fats and oils by interesterification? (9 pts)