Effects of heat on proteins

Question 1

List the effects of dry and moist heat

Answer 1

Coagulation
Colour change
Proteins can become indigestible

Question 2

Give an example of coagulation that can occur in proteins under both dry and moist heat

Answer 2

Egg whites coagulate at 60 degrees Celsius

Egg yolks coagulate at 68 degrees Celsius

Question 3

Give an example of a colour change that can take place in proteins under both dry and moist heat

Answer 3

Myoglobin (red pigment) in meat changes to haematin (brown pigment)

Question 4

How can proteins become indigestible under both dry and moist heat?

Answer 4

If proteins are over cooked they become indigestible

Question 5

What happens to proteins under dry heat?

Answer 5

The Maillard reaction occurs e.g. the roasting of beef

Question 6

What happens to proteins under moist heat?

Answer 6

Meat tenderises

Question 7

How does meat tenderise under moist heat?

Answer 7

Collagen in meat converts to gelatine which causes the fibres to tenderise