Chemistry and Improvement of Oxidative Stability of Soy Products

1
Chemistry and Improvement of Oxidative Stability
of Soy Products

• David B. Min
• Department of Food Science and Technology
• The Ohio State University
• Columbus, USA

2
Soy Products as Food Ingredient

• Good functionality
• Emulsifier
• Foaming
• Water activity
• Texture
• Nutritional qualityEssential fatty and amino
  acids
• Health benefits- Phytochemicals
• Economical Competitive price

3
Compositions () of Soy Products
4
Oxidation Effects of Soy Products

• Flavor Quality Consumer Acceptance
  
• Nutritional Quality Essential Fatty and Amino
  Acids. Vitamins
• Functional Quality Proteins and Lipids
• Health Risks Growth Retardation
• Heart
  Diseases
• Carcinogens

5
Activation Energy for Chemical Reactions

Reactions
Activation Energy

(Kcal/Mole) Protein Denaturation
100 Nonenzymatic Browning
Reaction 50 Enzyme Catalyzed
Reaction
10-15 Oxidation of Food Components
10-15
6
Oxidation of Food Components

• Triplet oxygen free radical oxidation
• Singlet oxygen oxidation

7
Molecular Orbital of Triplet Oxygen
Molecular
?
Atomic
Atomic
?
?
?
?
2Px 2Py 2Pz
2Pz 2Py 2Px
?
?
Energy
2S
2S
?
8
Mechanism of Triplet Oxygen Oxidation
14 13 12 11 10 9
C
H
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
2
2
3
3
INITIATION
- ? H
13 12 11 10 9
(
C
H
)
C
H
C
H
R
C
H
C
H
C
H
C
H
C
H
2
4
3
2
?
3O2
13 12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2
O
O
PROPAGATION
? H
?
9
(No Transcript)
10
Results of Soy Protein Oxidation

• Oxidation of amino acid side chains
• Protein-protein cross linkage
• Protein fragmentation
• Volatile compound formation

11
Protein Oxidation Mechanism
Protein cross linkage
R
O
R
O
R
O
P
P
P
P
P
P
N
C
C
N
C
C
N
C
C

O2

H
H
H
H
O
O
H
R
O
- OH
R
O
R
O
H
P
P
P
P
P
P
N
C
C
N
C
C
N
C
C
H
O
H
H
O

H
O
O
H
Peptide bond cleavage
12
Peptide Bond Cleavage
H
O
O
H
O

P
C
C
N
H
C
P
Diamide pathway
C
C
N
C
O
R
R
R
1
2
3

H
O
O
O
H
O
P
P
C
C
N
H
C
C
N
H
C
C
R
R
R
1
2
3
H
O
O
O
H
O

?-amidation pathway
P
P
C
C
N
H
C
C
C
C
N
H
2
R
R
R
2
3
1
13
Protein and Oxidized Lipid Compound Reaction
4-Hydroxy-2-nonenal from lipid oxidation
O
H
O
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
3
2
2
2
2
2
S
P
Protein-cystein -SH
O
H
O
O
H
O
P-lysine -NH2
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
C
H
H
3
2
2
2
2
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
2
3
2
2
2
2
H
N
P
Protein-histidine -NH
O
H
O
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
3
2
2
2
2
2
N
N
P
14
Protein Carbonyl Formation from Aldehydes
Malonaldehyde from lipid oxidation react with
protein amino groups (PNH2)
C
H
N
H
P
C
H
N
P
C
H
N
P
C
H
O
C
H
C
H
C
H

2
C
H
2
C
H
O
C
H
O
C
H
O
H
C
H
O
15
Browning Reaction between Protein and Carbonyl
Compounds of Lipid Oxidation
C
P
N
H
C
N
P
C
O
(
H
C
O
H
)
n
C
O
H
)
n-1
(
H
C
H
O
R

R
(
H
C
O
H
)
n
P
N
H
2
Lysine
R
C
H
N
P
C
H
O
O2
P
N
H
C
O
C
O
2
C
O
H
)
n-1
(
H
C
O
H
)
n-1
(
H
R
R
16
Singlet Oxygen Oxidation of Soy Products
17
Molecular Orbital of Singlet Oxygen
Molecular
?
Atomic
Atomic
?
?
?
?
2Px 2Py 2Pz
2Pz 2Py 2Px
?
Energy
?
2S
2S
?
?
1S
1S
?
18
Chlorophyll
H
C
H
H
C
R
2
C
H
C
H
H
C
2
3
3
N
N
M
chl a, R -CH3
H
g
H
N
N
chl b, R - CHO
C
H
3
H
C
3
O
C
O
C
H
2
3
C
H
2

C
O
2
C
H
C
H
C
H
C
H
3
3
3
3
19
Singlet Oxygen Formation by Sensitizer
Excited State
1Sen
K1- 20?108/sec ISC
Fluorescence K 2?108/sec
3Sen
hv
K1- 3?109/sec
Phosphorescence
3O2
K10- 104/sec
1Sen
Singlet Oxygen
Ground State
20
Sulfide Compounds from Soy Protein
O
O
-
-
Protein

C
H
C
H
S
C
H

Protein
1
C
H
C
H
S
C
H

2
3
O
2
2
3
2
2
O
O
O
H
-
Protein
Protein-
C
H
C
H
S
C
H

C
H
C
H
S
C
H
O
H
2
3
2
3
O
Protein-
Protein-
C
H
C
H
S
C
H

C
H
C
H
O

S
C
H
2
3
2
3
2
C
H
S
S
C
H
S
C
H
3
3
3
Disproportionation
2
S
C
H
S
S
C
H

C
C
H
S
C
H
C
H
S
S
H
3
3
3
3
3
3
21
H2S Formation from Soy Protein
O
O

-
-

Protein
1
C
H
S
H
Protein
C
H
S
H
O
2
2
2
O
O
O
H


-
-

Protein
H
H
C
H
S
H
Protein
S
O
H
C
H2S2
-
O
( )
2

Protein
H
C
S
H
S
H
Disproportionation
2H2S2
2H2S S2
22
Oxidation of Soy Protein Histidine Tryptophane
1O2
Protein
-
C
H
N
2
Protein
-
C2N2H3
C
H
C
O
O
H
2
N
H
Protein
CH2-COHNCNH2CO
Protein
-
C
H
Protein
-
2
C
H
1O2
2
O
N
C
H
O
N
H
H
23
Reversion Rancid Flavor Compounds from Soy Oil
24
2-(2-Pentenyl)-furan Formation from Linolenic
Acid by
1O2
1O2
C
H
C
H
C
O
O
H
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
2
2
6
2
3
2
2
O
O


C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
2
3
2
2
1O2
O
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
2
3
2
2
O
O
O
25
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
2
3
2
2

O
O
O
H
- OH

C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
2
3
2
2

O
O

C
H
C
H
C
H
C
H
C
H
C
C
H
C
H
C
H
3
2
2
2
2
O
O
C
H
C
H
C
H
C
H
C
H
C
C
H
C
H
C
H
3
2
2
O
H
O
H
- H2O

C
H
C
H
C
H
C
H
C
H
3
2
2
O
26
Triplet Oxygen Oxidative Stability Improvement of
Soy Products
27
Food Oxidation by Triplet Oxygen
14
13 12 11 10 9
C
H
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
2
2
3
3
INITIATION metal catalysts
- H

12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2

O
2
12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
2
4
3
2
O
O
PROPAGATION
H


28
12 11 10 9
C
H
C
H
C
H
C
H
C
H
C
H
R
(
C
H
)
C
H
2
2
4
3
O
HYDROPEROXIDE
O
- OH

DECOMPOSION
H
12 11 10 9
C
H
R
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
2
2
4
3
O

O

C
C
H
C
H
C
H
C
H
C
H
R
C
H
(
C
H
)
C
H

2
3
2
3
2
H
TERMINATION
H

C
H
(
C
H
)
C
H
(PENTANE)
3
2
3
3
29
Tocopherols in Soy Products
R
1
H
O
C
H
C
H
C
H
C
H
3
3
3
3
R
O
2
R
3
Tocohperols R1 R2 R3 ?-Tocopherol CH3 CH3 CH3
?-Tocopherol CH3 H CH3 ?-Tocopherol H CH3 CH3
d-Tocopherol H H CH3
30
Antioxidants in Soy Products

• Chlorogenic acid, caffeic acid, ferulic acid -
• Metal chelation and hydrogen donation
• Isoflavones
• Metal chelation and hydrogen donation

31
Chlorogenic Acid and Isoflavones in Soy Products
C
O
O
H
H
O
O
R
2
H
O
O
O
H
O
H
1
O
H
Chlorogenic acid
Isoflavones
R1 R2
Genistein OH OH Daidzein H OH
32
Singlet Oxygen Oxidative Stability Improvement of
Soy Products
33
Carotenoids
C
H
O
Apo - 8'- carotenal
b -
b -
Carotene
O
Canthaxanthin
O
34
Effects of ?-Apo-8-Carotenal, ?-Carotene or
Canthaxanthin on Soybean Oil Quality
Peroxide Value (meq/kg oil)
Storage Time (hr)
35
Total Quenching Rate Constant of Singlet Oxygen
by Carotenoids
Carotenoids Number of Conjugated
Quenching Rate Double Bonds
Constants ( M-1 sec-1) ?
-apo-8- Carotenal 10
2.86 ? 109 ? -
Carotene 11
4.60 ?
109 Canthaxanthin 13
1.12 ?
1010

36
Quenching Mechanism of ?- Carotene on Singlet
Oxygen
1O2 1?-Carotene 3O2 3?-Carotene
3 ?-Carotene
1?-Carotene
Energy Transfer
Radiationless Energy Transfer
37
Summary