Translation of Food Science Research Findings into Application Improvement of Soybean Oil Flavor

1
Translation of Food Science Research Findings
into Application Improvement of Soybean Oil
Flavor

• David B. Min
• The Ohio State University
• Columbus, Ohio

2
History of Soybean in America

• 1804 Soybean was first mentioned in American
  literature by James Mease
• 1911 Soybean imported from Manchuria was
  processed in America
• 1922 A. E. Staley encouraged farmers to grow
  soybean and the soybean was processed
• 1930 - 40 Soybean become wonder bean and
  important crop to farmers in America

3
Current Statistics of Soybean Oil in 2006

• Refined soybean oil is 47 billion dollars in USA
• Soybean oil represents the 80 of edible oils in
  USA
• Soybean oil is the major edible oil in the world
• Soybean is the major exporting agricultural crop
  in USA

National Agricultural Statistic Service, USDA
4
Compositions of Vegetable Oils
5
Soybean Oil Flavor Reversion

• The return of good deodorized soybean oil flavor
  to the undesirable flavor of crude oil within a
  very short period of time is termed flavor
  reversion
• The development of a characteristic beany and
  grassy flavor in soybean oil is commonly called
  reversion flavor.

Extraction
Crude soybean oil
Refining, Bleaching, Deodorization
Edible soybean oil
6
Soybean Oil Flavor Reversion

• Flavor reversion has been an important classical
  problem of soybean oil industry and the most
  extensively studied research subject in oils and
  foods since 1930.
• Flavor reversion makes soybean oil less
  acceptable to consumers and food manufactures.

7
National Soybean Processors Association

• Edward J. Dies, Chairman of the association
  invited 28
• scientists from government, academic and
  industry to discuss the flavor reversion in 1946
  .
• Dies told them I strongly emphasize the economic
• advantages of rapid solution of the flavor
  reversion in
• soybean oil. Let us solve it at the earliest
  possible
• moment. This meeting was to bring together
  the best
• research minds in the nation who are working
  on flavor
• reversion. We might be able to facilitate a
  free exchange
• of ideas and special collaboration among
  scientists to
• solve difficult flavor reversion problem in
  soybean oil

8
Soybean Oil Flavor Reversion Review in 1951 by K.
S. Markley

• Flavor reversion is a characteristic property in
  soybean oil.
• Flavor reversion occurs even at very low peroxide
  value of 2.
• M. M. Durkee reported that linolenic acid is the
  precursor of flavor reversion in 1936.
• 2-Pentenyl group of linolenic acid is responsible
  for flavor reversion.

9
Soybean Oil Flavor Reversion Review in 1951 by K.
S. Markley

• Antioxidants were not effective in flavor
  reversion.
• Phospholipid, light, and nonsaponifiable compound
  are responsible for flavor reversion.
• None of the physical and chemical methods was
  effective
• to prevent soybean oil flavor reversion.

10
Rutgers University Research on Flavor Reversion
in 1960-1980

• Changs group identified 2-pentyl furan in
  reverted soybean oil in 1966.
• Changs group also assumed that 2-pentenyl furan
  
• could be formed from linolenic acid.
• Changs group synthesized 2-pentenyl furan from
  tetrahydrofuran and n-butyl lithium.

11
Soybean Oil Flavor Reversion Review in 1980by E.
Frankel

• Linolenic acid, phospholipids, unsaponifiable
  compound, and light are responsible for reversion
  flavor.
• Antioxidants did not slow down or retard the
  flavor reversion of soybean oil.
• K. S. Markleys Review on Flavor Reversion of
  Soybean Oil in 1951

12
Flavor Reversion Review in 1985 by T. H. Smouse

• Linolenic acid theory
• Isolinoleic acid theory
• Oxidized polymer theory
• Phospholipid theory
• Nonsaponifiable theory
• Multivalent metal theory
• Furanoic acid theory

13
T. H. Smouses Opinion on Flavor Reversion in
1985

• T. H. Smouse reported No known method is
  available to prevent flavor reversion of soybean
  oil. Although much has been learned since 1930s,
  we do not know how to make soybean oil that will
  not revert.
• Light has a much more adverse effect in soybean
  oil than other oils and reduces the flavor
  stability of soybean oil to the point where
  reversion flavor is observed in a few hours of
  storage

14
What is the next approach to solve the Flavor
Reversion of Soybean Oil ?
15
The Ohio State University Research on Soybean Oil
Flavor Reversion

• Extremely fast Activation energy for
  flavor reversion reaction is very low.
• Antioxidants were not effective in flavor
  reversion Flavor reversion is not radical
  reaction.
• At very low peroxide value of 2.
• Peroxide value Flavor reversion requires
  oxygen.
• The oxygen involved in flavor reversion requires
  low activation energy to react with soybean oil
  fast.
• The ordinary triplet radical oxygen requires high
  activation energy to react with soybean oil.

16
Oxygen History

• 1772 Scheele Priestley Discovered
  Oxygen 1811 Avogadro Oxygen is a Diatomic
  Molecule 1848 Faraday Oxygen is a
  Paramagnetic Molecule 1934 Herzberg
  Observation of Singlet Oxygen 1969 Foote
  Wexler Rediscovered Singlet Oxygen  

17
Food Oxidation

• Triplet oxygen free radical oxidation
• Singlet oxygen non-free radical oxidation

18
Triplet Oxygen Oxidation
19
Electronic Configuration of Triplet Oxygen
Molecular
?
Atomic
Atomic
?
?
?
?
2Px 2Py 2Pz
2Pz 2Py 2Px
?
Energy
?
2S
2S
?
20
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
Energy
- 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
K109/sec
21
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
(K 1 M-1sec-1)
O
?
(K 107 M-1sec-1)
.
O
H
O
C
(
C
H
)
H from
3
3
?
C
(
C
H
)
3
3
O
C
H
3
O
C
H
3
22
13 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
Peroxide value
O
- OH
?
H
13 12 11 10 9
(
C
H
)
C
H
C
H
C
H
C
H
C
H
C
H
R
C
H
3
2
2
4
O
?
C
H
(
C
H
)
C
HO
3
2
4
C
H
(
C
H
)
C
H
3
3
2
3
23
Singlet Oxygen Oxidation
24
Electronic Configuration of Singlet Oxygen
Molecular
?
Atomic
Atomic
?
?
?
?
2Px 2Py 2Pz
2Pz 2Py 2Px
?
Energy
?
2S
2S
?
?
1S
1S
?
25
Reaction of 3O2 and 1O2 with Linoleic Acid
Antioxidant effects
OOH


3O2
- H
R
R
R
1
R
R
R
1
2
1
2
2
OOH
1O2
O
R
R
2
R
1
2
R
H
O
1
OOH
No antioxidant effects
R
R
2
1O2
1
gtgtgt
in reaction with soybean oil
3O2
26
The Ohio State University Research on Soybean Oil
Flavor Reversion

• Extremely fast Activation energy for
  flavor reversion reaction is very low.
• Antioxidants were not effective in flavor
  reversion Flavor reversion is not radical
  reaction.
• At very low peroxide value of 2.
• Peroxide value Flavor reversion
  requires oxygen.
• The singlet oxygen requires low activation energy
  to react with soybean oil.

Singlet Oxygen meets all the requirements for the
flavor reversion reaction of soybean oil
27
Singlet Oxygen Formation in Foods

hn
3O2 Chlorophyll 1O2

28
Chlorophyll as Photsensitizer
H
C
H
H
C
CH
2
3
C
H
C
H
H
C
2
3
3
N
N
H
M
g
H
N
N
C
H
H
C
3
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
29
Excitation and Deactivation of Chlorophyll under
Light
Excited State
1Chlorophyll
K1-20?108/sec ISC
Fluorescence K 2?108/sec
3Chlorophyll
hv
K1-3?109/sec
Phosphorescence
3O2
K10-104/sec
1Chlorophyll
Singlet Oxygen
Ground State
30
Singlet Oxygen Trapping
O
O
CH3
1O2
H3C
H3C
CH3
N
CH3
N
H3C
H3C
CH3
H
O

TMPD
TAN
31
ESR Spectrum of 2,2,6,6-Tetramethyl-4-Piperidone-N
-Oxyl (TAN)
3370 G 3390 G
3410 G
32
Singlet Oxygen Oxidation of Soybean Oil
33
Soybean Oil Purification by Chromatography
Soybean oil
Silicic acid
Sugar
Charcoal-Celite
Silicic acid
Vacuum
Purified soybean oil
34
Identified Compounds in Soybean Oil

• Phospholipids
• Tocopherols
• Monoglycerides
• Diglycerides
• Oxidized polymers
• Free fatty acids
• Chlorophylls

Purified soybean oil
35
Light Box for Soybean Oil Flavor Study
36
Effect of 0 and 5 ppm Chlorophyll on
2-Pentenylfurans in Soybean Oil
0 ppm
             
No beany flavor
5 ppm
2-Pentenylfuran
Trans-2-heptenal

Strong beany flavor
37
Mass Spectrum of 2-Pentenylfuran
38
2-Pentenylfuran from Linolenic Acid by 1O2
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
(
C
H
)
C
O
O
H
2
2
2
6
3
2
2
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
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
3
2
2
2
O
1O2
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
39
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
H
C
H
C
H
C
C
H
C
H
C
H
C
3
2
2
O
H
O
H
- H2O
C
H
C
H
C
H
C
H
C
H
3
2
2
2-(2-pentenyl)-furan
O
40
Chlorophyll Effect on the Reversion Flavor of
Soybean Oil under Light at 10oC
Reversion Flavor Intensity
Storage in Hours
41
Carotenoids
CHO
Canthaxanthin
42
Effects of ?-Apo-8-Carotenal, ?-Carotene or
Canthaxanthin on Soybean Oil Oxidation under
Light
Peroxide Value (meq/kg oil)
Storage Time (hr)
43
Effects of ?-Apo-8-Carotenal, ?-Carotene or
Canthaxanthin on Soybean Oil Oxidation under
Light
Peroxide Value (meq/kg oil)
Storage Time (hr)
44
Diagram for Singlet Oxygen Oxidation of Soybean
Oil and Prevention Mechanism by Carotenoids
Q Carotenoids
A
hv
3O2
ISC
Sen
AO2
1O2
1Sen
3Sen
kr
kO
(Chlorophyll)
Q
Q
kQ
Q
kd
kQ
Sen
kox-Q
Sen
3O2
3O2
QO2
dAO2
ko3O2
k rA
K

ko3O2kQQ
k rA (kox-Q kQ)Q kd
dt

45
Quenching Mechanism of b-Carotene
1/ Peroxide Value ( 1/ M )
1/ Soybean Oil (1/ M)
46
b-Carotene Quenching Rate Constant of Singlet
Oxygen

K 4.60 ? 109 M-1 sec-1
47
Conclusions
48
Singlet Oxygen Formation in Soybean Oil by
Chlorophyll under Light
Excited State
1Chlorophyll
K1-20?108/sec ISC
Fluorescence K 2?108/sec
3Chlorophyll
hv
K1-3?109/sec
Phosphorescence
3O2
K10-104/sec
Singlet Oxygen (1O2)
1Chlorophyll
Ground State
49
2-Pentenylfuran Formed from Linolenic Acid and
Singlet Oxygen
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
C
H
(
C
H
)
C
O
O
H
2
2
2
6
3
2
2
1O2
K3?107/sec
C
H
C
H
C
H
C
H
C
H
3
2
2
O
50
Flavor Reversion Free Soybean Oil
Excited State
1Chlorophyll
K1-20?108/sec ISC
Fluorescence K 2?108/sec
3Chlorophyll
hv
K1-3?109/sec
Phosphorescence
3O2
K10-104/sec
Singlet Oxygen (1O2)
1Chlorophyll
Ground State
51
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