Andrew Proctor - University of Arkansas, US

Photocatalytic production and use of CLA-rich soy oil A Proctor & V.P Jain Department of Food Science University of Arkansas September 8th 2006 Renewable 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 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 Production and oxidative quality Kinetics study Frying study CLA-Rich Soy Oil Production and Oxidative Quality J Ag and Food Chem 2006 54: 5590-5596 1H NMR spectra of unirradiated oil with 200 ppm hexanal 12.0 11.0 10.0 9.0 8.0 ppm Aldehyde CHO range Unirradiated oil with 200 ppm hexanal, 0.15 % Iodine Partial GC - MS chromatograms: hexanal 2.0 3.0 4.0 5.0 6.0 Unirradiated oil, 0.15 % Iodine 2.0 3.0 4.0 5.0 6.0 Unirradiated oil with ppm added hexanal, 0.15 % Iodine 2.0 3.0 4.0 5.0 144 hours photoisomerized oil sample, 0.15 % Iodine 6.0 Significance • 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: * Linoleic acid CLA Kinetics CLA-isomers Irradiation cis-9, cis-12 linoleic acid A cis-9, trans-11 CLA, trans-10, cis-12 CLA, trans-9, cis-11 CLA, cis-10, trans-12 CLA B trans- , trans- CLA (8,10 : 9,11 : 10,12) C Soy oil C18:2 fatty acid profile during photo-irradiation 60 Linoleic acid cis-, trans- / trans-, cistrans-, trans- CLA Fatty acid conc (% total oil) 50 40 A 30 20 C 10 B 0 24 48 72 Time (h) 96 120 144 CLA-isomers: irradiation cis-9, cis-12 linoleic acid A second order kinetics cis-9, trans-11 CLA, trans-10, cis-12 CLA, trans-9, cis-11 CLA, cis-10, trans-12 CLA B zero order kinetics trans- , trans- CLA (8,10 : 9,11 : 10,12) C Kinetics • A to B reaction dependent on LA conc • B to C reaction is fastest as it achieves the most thermodynamically stable CLA form 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