Food Science

Question 1

Define the process of denaturation

Answer 1

• Happens in protein molecules
• Chemical bonds that hold the molecule together break
• Makes the molecule change shape

Question 2

What are the 4 ways in which denaturation is caused?

Answer 2

• via heat
• by adding acids
• air bubbles
• mechanical agitation

Question 3

Define the process of coagulation

Answer 3

• Denatured protein are larger and take up more space
• Because of this they knock into other denatured molecules
• This makes them join together in large groups
• As they coagulate, the protein molecules trap and hold water in food pockets between them
• This changes the appearance and texture of the food

Question 4

Give 4 examples of food that denature and/or coagulate in different ways

Answer 4

• eggs via heat
• meats when marinated in acids (e.g. lemon/lime juice)
• whisked sponge mixtures (adding air bubbles)
• agitating egg whites for meringue

Question 5

How does gluten produce a light and risen texture in baked foods?

Answer 5

• Gluten is a protein formed when 2 other proteins combine with water
• The dough is kneaded which makes gluten give it plasticity allowing it to be stretched, shaped and elastic
• This is because long gluten molecules are coiled
• As the dough is kneaded the gluten straightens out
• It needs to be able to stretch so that the C02 can expand and make it rise

Question 6

What is enzymic browning?

Answer 6

An oxidation reaction that takes place in some foods, mostly fruit and vegetables, causing the food to turn brown and have a negative effect of the sensory and nutritional characteristics of the food.

Question 7

How can enzymic browning be prevented?

Answer 7

• Placing the fruits and vegetables in a water bath reduces the foods’ contact with oxygen.
• Some fruits can also have lemon juice added to them to prevent this