Download Food chemistry lesson 2 worksheet

IB Chemistry SL
Name:_______________________
Food Chemistry Lesson #2
Objectives for this lesson- Compare the structural features of the major synthetic antioxidants in food.
 Discuss the advantages and disadvantages associated with natural and synthetic antioxidants.
 List some antioxidants found in the traditional foods of different cultures that may have health
benefits.
 Distinguish between a dye and a pigment.
 Discuss the safety concerns associated with the use of synthetic colorants in food.
 Compare the two processes of non-enzymatic browning (Maillard reaction) and caramlization that
cause the browning of food.
 Define a genetically modified food.
 Discuss benefits and concerns of GM foods.
 Describe a dispersed system of food.
 Distinguish between the following types of dispersed systems: suspensions, emulsions and foams
in food.
 Describe the action of emulsifiers.
Read pages 425-443 in your text.
Use your notes and your text to answer the following questions.
1. Which are more cost effective, synthetic or natural antioxidants?
2. Draw the structure of a phenol.
3. What is a tertiary butyl group? Draw the structure of 2-BHA.
4. Identify the antioxidants from page 425 that have both a phenol and a tert butyl group.
5. What are conjugate bonds? Draw a portion of β-carotene to illustrate this type of bonding.
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6. Which vitamin is produced from β-carotene?
7. Where are flavonoids found? What are three positive health benefits that flavonoids may have?
8. Compare and contrast the advantages of natural and synthetic antioxidants in the table below.
Natural Antioxidants
Synthetic Antioxidants
Advantages
Disadvantages
9. Why do foods have color? (discuss in terms of the absorption of light)
10. Distinguish between the terms pigment and dye.
11. Read page 430.
(a) Why are synthetic dyes added to food?
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(b) List two concerns pertaining to synthetic food dyes.
12. Describe the process of enzymatic browning. Give an example of this type of browning.
13. Answer the following questions pertaining to caramelization.
(a) Describe the composition of foods that undergo this type of browning.
(b) How does this process begin?
(c) What are two types of products of this process?
(d) When do undesirable effects occur?
(e) At what temperature does caramelization begin for
i) fructose ___________ii) sucrose ___________
(f) Could boiled foods be caramelized? Explain.
(g) What is an example of caramelization?
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14. Answer the following questions pertaining to Maillard Browning.
(a) Is this process a single reaction or a series of reactions?
(b) What is the composition of foods that undergo this type of browning?
(c) What is the first step in the process?
(d) How does the size of the sugar relate to the rate of reaction?
(e) Why does lysine react faster than the other amino acids?
(f) Why does milk brown readily (to make caramels for example)?
(g) Which amino acid browns the least?
(h) Why does Maillard Browning decrease the nutritional content of foods?
(g) What are some examples of Maillard Browning?
15. What does genetic engineering involve?
16. Describe the GM food, the Flavr Savr tomato. What are the advantages of this tomato?
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17. Complete the table below.
Benefits of GM Food
Concerns around GM Food
1.
1.
2.
2.
3.
3.
4.
4.
5.
5.
6.
6.
18. Sketch a dispersed system showing the dispersed phase and the continuous phase.
19. Why does milk appear white?
20. What is meant by the term kinetically stable?
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21. Complete the table below.
Food Type
Continuous
Phase
Dispersed Phase
Type of
Dispersed
System
Ice Cream
Bread
Jam
Salad dressing
Soda
Whipped Cream
Butter
22. Define the following terms:
(a) Emulsifier
(b) Hydrophobic
(c) Hydrophilic
23. Sketch (a) an emulsifier molecule.
(b) A drop of oil surrounded by emulsifier molecules
24. Give two examples of emulsifiers, the food where they are found, and the type of food mixture where
they are often used.
25. What is a stabilizer? How is it different from an emulsifier? Give an example.
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