Etiket Arşivleri: Midterm

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).

GID 221E Midterm Examination I


Answer all questions listed from 1 to 8:

1. Write the systemic and trivial names of two saturated and unsaturated fatty acids.

2. What is iodine value?

3. What are the factors affecting the rate of autooxidation reaction?

4. What is an emulsion? How can we make such systems stable?

5. Describe the effect of antioxidants in foods. Name three synthetic antioxidants.

6. How do the amino acids join to each other to form into a long chain polypeptide? Show this reaciton using the chemical structures of three aminoacids.

7. What is denaturation? What are the factors resulting in denaturation?.

8. What is isoelectric point of proteins? Answer only 4 questions listed from 9 to 15:

9. Explain the function of amylase in breadmaking.

10. Explain the function of protease enzyme in food production.

11. Explain the application of commercial pectolytic enzymes in fruit and vegetable juices.

12. Explain the functions of oxidoreductases in food systems.

13. What are the functions of lipases in dairy products?

14. What is the action of glucose oxidase? Explain the importance of this enzyme in egg powder and meat products?

15. Which enzymes can be used as indicators of food quality? Give examples for each.