Photocatalytic production and use of CLA-rich soy oil

A. Proctor & V.P. JainDepartment of Food Science

University of Arkansas

September 8th 2006Renewable Resources & Biorefineries Conference

University of York, UK

Introduction: CLA

• Conjugated linoleic acid

• Positional and geometrical isomers of linoleic acid• 28 different isomers (Adolf, 1999)• Found naturally – Beef

– Dairy products

CLA rumen biosynthetic pathway

α Linoleic acid(cis-9, cis-12 octadecadienoic acid)

cis-9, trans-11 CLA

Vaccenic acid(trans-11 octadecenoic acid)

Rate limiting step (Lawson et al, 2001)

Stearic acid(Octadecanoic acid)

Health Benefits of CLA

• Anticarcinogenic (Ha and others, 1987)

• Antimutagenic (Yeong and others, 1989)

• Antioxidant (Yeong and others, 1989)

• Decreases atherosclerosis (Ha and Pariza, 1987)

• Decreases body fat (Park and others, 1997)

• Enhances immune system (Yeong and others, 1989)

Health Benefits of CLA

• Human CLA needs are 3g/day to produce physiological effects (Ip et al. 1994)

• Actual human CLA intake 0.3g /day (Ip et al, 1989; Beaulieu et al. 2002)

• Increasing dietary animal fat to obtain desirable CLA levels is not recommended

Synthetic CLA

• Methyl esters– methyl ricinoleate (Berdeaux et al, 1997)

– methyl linoleoate photoisomerization (Seki et al., 1998)

• Vegetable oil linoleic acid– alkali isomerization (Iwata et al, 1999)

– base conjugation (Delmonte et al, 2003)

– ‘green’ photoisomerization of soy oil (Gangidi & Proctor, 2004)

Soy Oil for CLA production ?

• Soy oil composition- 50 % linoleic oil, for conversion to CLA

• Availability- 34mMT soy oil world supply (2005-2006)*

- 115mMT world vegetable oil supply (2005-2006)*

- 80% of US total oil intake is soy oil

* Oil Crops Situation and Outlook Report 2006

Outline: CLA-rich soy oil

1. Production and oxidative quality

2. Kinetics study

3. Frying study

1. CLA-Rich Soy Oil Production and Oxidative Quality

J. Ag and Food Chem. 2006 54: 5590-5596

Customized System

UV Lamp

Customized System

Reaction Vessel

Customized System

Immersion Well

Customized System

Customized System

•

Effect of Iodine Concentration – Processing(Jain & Proctor 2006)

700g fully refined commercial soy oil

• iodine concentration 0.1, 0.15, 0.25 %

• irradiation for 0 – 144 hours (duplicate)

• temperature 22-25 °C

• stirred with magnetic stirrer

CLA isomer: FAME analysis (triplicate) (Christie & others 2001; Ma & others 1999)

• total CLA• cis 9, trans 11 CLA• trans 10, cis 12 CLA• trans, trans isomers (8,10; 9,11; 10,12)

Lipid oxidation products • hydroperoxides: ATR FTIR (Ma & others 1999)• aldehyde carbonyls: 1H NMR (Ma & others 1999)• GC – MS: hexanal (Monsoor & Proctor 2004)

Effect of Iodine Concentration – Analysis

Effect of iodine concentration on total CLA Yields

0

5

10

15

20

25

0 50 100 150time (h)

CLA

(% to

tal o

il)

0.25 % Iodine0.15 % Iodine0.1% Iodine

LSD0.05 = 0.67

Effect of iodine concentration on cis 9, trans 11 CLA

0

0.4

0.8

1.2

1.6

2

0 50 100 150time (h)

CLA

(%to

tal o

il)

0.25 % Iodine0.15 % Iodine0.1 % Iodine

LSD0.05 = 0.05

Effect of iodine concentration on trans 10 cis 12 CLA

0

0.4

0.8

1.2

1.6

2

0 50 100 150time (hours)

CLA

(% to

tal o

il)

0.25 % Iodine0.15% Iodine0.1% Iodine

LSD0.05 = 0.05

Effect of Iodine Concentration on t, t (8,10; 9,11; 10,12) CLA

0

20

5CL

10ta

15

A (%

tol o

il)

0.25 % Iodine0.15 % Iodine0.1 % Iodine

LSD0.05 = 0.48

0 50 100 150time (h)

Dairy Beef Soy oil (Proctor & Jain 2006)

CLA fatty acid

c-9, t-11 CLA 0.6 0.1 1.8

t-10, c-12 CLA <0.01 0.02 1.7

Total CLA 0.7 0.6 23.8

CLA (%) content of bovine lipids and soy oil

t, t CLA also has major health benefits (Gavino 2002; Lai et al 2005)

Oxidation Analysis

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

1000 1500 2000 2500 3000 3500

0% I2, 0 hour

0.1% I2, 144 hours

0.15% I2 , 144 hours

0.25% I2, 144 hours

Hydroperoxide peaks absent(3400 to 3600 cm-1)

ester C=O1750 cm-1Hydrocarbons

ATR – FTIR spectra of photoisomerized oil samples for hydroperoxide peaks

Conjugated = bond

1H NMR spectra of 144 hour photoisomerized oil for proton peaks of aldehyde carbonyl

12.0 11.0 10.0 9.0 8.0

ppm

Aldehyde CHO range

144 hours photoisomerized oil sample, 0.15 % Iodine

1H NMR spectra of unirradiated oil of aldehydecarbonyl proton peaks

8.09.010.011.012.0

ppm

Aldehyde CHO range

Unirradiated oil , 0.15 % Iodine

1H NMR spectra of unirradiated oil with 200 ppm hexanal

8.09.012.0 11.0 10.0

ppm

Aldehyde CHO range

Unirradiated oil with 200 ppm hexanal, 0.15 % Iodine

Partial GC - MS chromatograms: hexanal

6.05.04.03.02.0

6.05.04.03.02.0

6.05.04.03.02.0

Unirradiated oil, 0.15 % Iodine

Unirradiated oil with 1 ppm added hexanal, 0.15 % Iodine

144 hours photoisomerized oil sample, 0.15 % Iodine

• trans, trans major isomers produced

• t, t CLA also has health benefits

• c, t & t, c CLA levels greater than in dairy/meat

• long processing time

• ‘apparently’ relatively oxidatively stable:

Significance

*Linoleic acid CLA

2. Kinetics

CLA-isomers Irradiation

cis-9, cis-12 linoleic acid

cis-9, trans-11 CLA, trans-10, cis-12 CLA, trans-9, cis-11 CLA, cis-10, trans-12 CLA

trans- , trans- CLA(8,10 : 9,11 : 10,12)

A

B

C

Soy oil C18:2 fatty acid profile during photo-irradiation

0

10

20

30

40

50

60

0 2

Fatty

aci

d co

nc (%

tota

l oil)

. Linoleic acidcis-, trans- / trans-, cis-trans-, trans- C

4 48 72 96 120 144Time (h)

LA

A

B

C

CLA-isomers: irradiation

cis-9, cis-12 linoleic acid

cis-9, trans-11 CLA, trans-10, cis-12 CLA, trans-9, cis-11 CLA, cis-10, trans-12 CLA

trans- , trans- CLA(8,10 : 9,11 : 10,12)

A

B

C

second order kinetics

zero order kinetics

• A to B reaction dependent on LA conc.

• B to C reaction is fastest as it achieves the most thermodynamically stable CLA form

Kinetics

3. CLA-rich soy oil and frying

C18 fatty acids in photoisomerized soy oil, and oil extracted from potato chips fried in CLA-rich soy oil (n=4)

Photoisomerized oil (%) Oil extracted from chips (%)

Linoleic Acid 31.46a 30.87a

Linolenic Acid 4.73a 4.64a

c 9, t 11 CLA 1.78a 1.79a

t 9, c 11/c 10,t 12 CLA 2.74a 2.81a

t 10, c 12 CLA 1.75a 1.81a

t, t CLAb 14.73a 14.55a

Means with different letters within rows differ significantly, p<0.05Fatty acids expressed on total oil w/w basisbt,t CLA consists of t,8, t,10 CLA, t,9,t,11 CLA & t,10, t,12 CLA

PV of RBD & CLA rich oil &these oils extracted from potato chips after frying

PV (Meq / 1000g sample)

RBD soy oil (control) 1.0b

CLA-rich soy oil (control) 0.9a

Oil extracted from chips made with CLA-rich oil 1.0b

Oil extracted from chips made with RBD oil 0.9a

CLA-rich soy oil after frying 1.0b

Values are means, n=4. Means with different letters within a column differ significantly, p<0.05

• Oil Composition stable at frying temperatures

• FA composition in chip similar to that of oil

• Frying oil and extracted oil was oxidative stabile

Significance

• Pr

RESEARCH ISSUES

ocessing:

inor compounds:and oxidation compounds:

long processing time, processing modifications: USDA NRI grant 2006-2009

• MiodoGC-MS studies

• Shelf Life:oxidation stability studies

• Oxidation chemistry:oxidation/polymerization mechanisms