Food Proteins

Question 1

define protein

Answer 1

long chain of amino acids joined by peptide bonds

Question 2

what are the roles of protein

Answer 2

cell signalling
cell adhesion
immune response
growth and repair

Question 3

what are the sources of protein in food

Answer 3

animals
plants
algae
microorganisms

Question 4

structure of a protein

Answer 4

primary
secondary
tertiary
quaternary

Question 5

how are proteins classified

Answer 5

by their structure
- fibrous, globular, intermediate

by their composition
- simple, conjugated, derived

Question 6

what are the structural properties of proteins useful for in terms of their function

Answer 6

gelatination

• cross linking to form tertiary structure, traps water to form a rigid structure
• reversible = fibrous protein e.g gelatine
• irreversible = globular protein

stabilising emulsions and foams

• interfacial properties are exploited
• egg and milk proteins are used to stabilise oil-in-water emulsions

form films

• act as a moisture barrier to enhance shelf life
• used for biodegradable packaging and to improve mechanical handling properties

Question 7

what occurs during protein denaturation

Answer 7

• the secondary, tertiary and quaternary structures are lost due to the bonds holding them together being broken

Question 8

what are the causes of protein denaturation

Answer 8

heat
cold
pH change
chemicals
high pressure

Question 9

what are the effects of protein denaturation

Answer 9

loss of solubility
loss of activity
loss of the active site
changes in functionality