Antioxidants

Question 1

Which antioxidant is this?

Answer 1

BHA

Question 2

Which antioxidant is this?

Answer 2

BHT

Question 3

Which antioxidant is this?

Answer 3

TBHQ

Question 4

Which antioxidant is this?

Answer 4

PG

Question 5

Which antioxidant is this?

Answer 5

AP

Question 6

What is the formula of the propagation step?

Answer 6

R-O-O. + R-H —–> R-O-O-H + R.

Question 7

The relative rates of autoxidation FOR C18 FA ARE :
C18:0
C18:1
C18:2
C18:3

Answer 7

1
100
1200
2500

Question 8

T or F : autoxidation takes place 2,500 times faster in linolenic acid than in stearic acid

Answer 8

true –> C18 (x1); C18:1 (x100); C18:2 (x1200); C18:3 (x2500)

Question 9

Name the factors that can initiate the oxidation of FA

Answer 9

Heat, radiant energy, enzymes, divalent metal ions and singlet oxygen.

Question 10

What is the 2 most important property of the antioxidants?

Answer 10

1. the property of donating a hydrogen more readily than a fatty acid
2. the poor tendancy of the antioxidant radical to react with oxygen

Question 11

T or F : Alph tocopherol (Vit. E) has the strongest antioxidant properties among the tocopherols compounds

Answer 11

false

Question 12

T or F : Antioxidants cannot retain their functionality forever

Answer 12

T

Question 13

Metal ions catalyze the autoxidation reaction by:
A. Abstracting hydrogen from hydroperoxides
B. Forming singlet oxygen
C. All of them
D. None of them

Answer 13

C

Question 14

What stage of the oxidation is lenghted by the use of antioxidants

Answer 14

induction

Question 15

Why vegetable oil less susceptible to oxidation than animal fat?

Answer 15

because of the presence of the vitamin E (natural antioxidant)

Question 16

What is the reaction of the propagation ?

Answer 16

ROO˚ + RH –> ROOH + R˚ –> R˚ + O2 –> ROO˚

Question 17

What is the formula of the initiation?

Answer 17

Homolytic cleavage : RH –> R˚ + H˚

Question 18

What is the reaction that occurs with the hydroperoxide during monomolecular reactions

Answer 18

ROOH –> RO˚ + OH˚

Question 19

What is the reaction that occurs between the hydroperoxides during bimolecular rxn?

Answer 19

2ROOH –> ROO˚ + RO˚ + H20

Question 20

What are the three singlet oxygen reactions

Answer 20

Question 21

Explain the excitation and formation of singlet oxygen from chlorophyll

Answer 21

Question 22

What is the maximum concentration of antioxidants?

Answer 22

200 ppm