1. BROWNING
b) Michelle, a Research and Development (R&D) manager is concerned that her potato
flakes are an undesirable golden brown colour as soon as they are produced. The
potatoes are peeled, steam-cooked, mashed then dried on heated drums. Her
proposed
solution is to conduct the drying under a nitrogen atmosphere to limit oxidation and to
use sugar syrup.
i) What do you think is the most likely mechanism of browning?
(1 mark)
ii) Do you think her solution is likely to be effective? Explain and justify your answer.
(5 marks)

2. QUESTION 5
The appearance of a brown discolouration in bananas or potatoes is due to an
enzymatic
reaction.
a) Discuss the substrates, enzymes and chemical reactions that occur in either
bananas
or potatoes.
(10 marks)
b) Between apples and potatoes, which are more sensitive to browning if they are
stacked? Explain why.
(2 marks)
c) Discuss how you would control such browning reaction by chemical methods.
(8 marks)

3. QUESTION 3
a) Answer either part i) or part ii)
i) Write an account on caramelisation in sugar systems.
ii) Discuss the role of sugars and amino acids in Maillard reaction.
(10 marks)
b) Non-enzymatic browning can be controlled by several methods depending on the
nature
of food and situation. Discuss the mechanisms of the following methods of controlling
non-enzymatic browning:
i) removal of reducing sugars
(4 marks)
ii) removal of amino acids or proteins
(3 marks)
iii) application of sulphites.
(3 marks)

4. QUESTION 3
a) Discuss the following:
i) Initial reaction of Maillard reaction (condensation stage).
(3 marks)
ii) Basic chemical reaction of caramelisation.
(3 marks)
iii) Enzymes in enzymatic browning.
(4 marks)
b) Enzymatic browning can be prevented or controlled by several methods depending
on
the nature of fruit or vegetable and the situation. Discuss all possible physical and
chemical methods which can be used to control enzymatic browning.
(10 marks)

5. QUESTION 5
The appearance of a brown discolouration in bananas or potatoes is due to an
enzymatic reaction. Discuss the substrates, enzymes and chemical reactions that occur
in either bananas or potatoes. Between apples and potatoes, which are more sensitive
to browning ifthey are stacked? Explain why. Discuss how you would control such
browning reaction bychemical methods.
(20 marks)

6. QUESTION 6
b) Explain what is meant by enzymatic browning? What are the conditions required for
enzymatic browning to occur and how would you prevent this from occurring.
(10 marks)
d) Explain how Maillard reaction is different from caramelisation.
(3 marks)

7. d) Discuss any two (2) of the following:
i) Initial reaction of Maillard reaction (Aldol condensation stage)
ii) Basic chemical reaction in caramelisation
iii) Control of non-enzymatic browning by using sulphite
(6 marks)
c) Enzymatic browning is an undesirable occurrence in fruits like banana when they are
cut or injured. Suggest three (3) chemical methods to inhibit this problem.
(6 marks)