PKSC 2010 Midterm EXAM
1. All enzymes are: proteins
2. Enzymes are catalysts that: lower the activation energy of a reaction
3. Enzymes are not by the reaction: changed
4. 2 types of enzymes: Endogenous-within a food product
Exogenous-added to a food product
5. Active site: small portion of the protein where catalysis takes place
6. Importance of tertiary structure for enzymes: protects the active site
7. What denatures protein?: Heat
pH
chemicals
mechanical
8. Lock and key theory: substrate fits into active spot on enzyme
,9. What affects tertiary structure of enzymes?: H bonds
ionic bonds
hydrophobic interaction
covalent bonds
10. Thermal processing: cooking
retorting cans
11. Each enzyme has an optimum: pH and temperature
12. What must you know to control enzyme activity?: pH and temp optimas
13. Endogenous enzymes are responsible for...: off flavor
14. Lipoxygenase: attacks fat and breaks into short chain of fatty acids
15. Lipoxygenase causes..: lipolytic/hydrolytic rancidity
bad smell/taste
16. If you blanch vegetables you'll..: inhibit enzyme activity
denatures lipoxygenase = store longer
, 17. What is peroxidase used for: indicator enzyme bc most heat stable
-->deactivate this, others deactivated
18. Z and D values for cooking: how hot and how long to apply heat
D value: time it takes to reduce enzyme activity by 1 log =rate at which enzymes are deactivated
Z Value: temperature interval for enzyme deactivation to occur by 1 log
1. All enzymes are: proteins
2. Enzymes are catalysts that: lower the activation energy of a reaction
3. Enzymes are not by the reaction: changed
4. 2 types of enzymes: Endogenous-within a food product
Exogenous-added to a food product
5. Active site: small portion of the protein where catalysis takes place
6. Importance of tertiary structure for enzymes: protects the active site
7. What denatures protein?: Heat
pH
chemicals
mechanical
8. Lock and key theory: substrate fits into active spot on enzyme
,9. What affects tertiary structure of enzymes?: H bonds
ionic bonds
hydrophobic interaction
covalent bonds
10. Thermal processing: cooking
retorting cans
11. Each enzyme has an optimum: pH and temperature
12. What must you know to control enzyme activity?: pH and temp optimas
13. Endogenous enzymes are responsible for...: off flavor
14. Lipoxygenase: attacks fat and breaks into short chain of fatty acids
15. Lipoxygenase causes..: lipolytic/hydrolytic rancidity
bad smell/taste
16. If you blanch vegetables you'll..: inhibit enzyme activity
denatures lipoxygenase = store longer
, 17. What is peroxidase used for: indicator enzyme bc most heat stable
-->deactivate this, others deactivated
18. Z and D values for cooking: how hot and how long to apply heat
D value: time it takes to reduce enzyme activity by 1 log =rate at which enzymes are deactivated
Z Value: temperature interval for enzyme deactivation to occur by 1 log
