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The analysis of alpha tocopherol and other E-group vitamers in cereal grain foods

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Recent studies of cereal foods have been focused upon water soluble vitamins and many of these are relatively unstable during processing. Among the conditions that are important determinants of retention are processing steps of heating as well as pH.
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   Document: The Analysis Of Alpha Tocopherol And Other E.doc Author: Oliver Buddrick Save Date: 21/02/2015 Page of 4 THE ANALYSIS OF ALPHA TOCOPHEROL AND OTHER E-GROUP VITAMERS IN CEREAL GRAIN FOODS Oliver Buddrick, Hugh J. Cornell, Darryl M. Small and Paul D. Morrison Applied Chemistry, School of Applied Sciences, RMIT University, Melbourne, VIC 3001, Australia INTRODUCTION Tocopherols and tocotrienols are lipid-soluble compounds and these eight vitamer forms of vitamin E act as primary antioxidants in the body Schwartz et al.(2008). A variety of functions have been identified for and these include protective roles against the risk of a variety of diseases. Among the good dietary sources of the tocols are cereal and cereal based products as well as seeds along with vegetable oils Nanditha & Prabhasankar.(2009). AIM The purpose here has been to investigate methods for measurement of vitamin E in cereal foods. MATERIALS AND METHODS Oil sample preparation The standard reference tocopherol oil was purchased from National Institute of Standards and Technology (NIST). Alpha tocopherol was purchased from Sigma-Aldrich Germany. The palm oil was kindly supplied by Lembaga Minyak Sawit Malaysia. The wheat germ oil used was purchased at a local health food shop. The standard reference material was readily dissolved in the mobile phase (1ml/10ml) as well as palm oil and wheat germ oil. The dissolved oils were directly injected into the HPLC system.  HPLC analysis of tocols Samples were analysed using normal phase (NP)-HPLC. A Shimadzu instrument was fitted with fluorescence detector (excitation 290nm, emission 330nm) and an analytical column, 4.6mm   25cm, 5µm particle size: silica Supelcosil LC-Si, Supelco. Tocols were separated isocratically within 30min using a mobile phase consisting of 1:1:198 (v/v/v/) ethyl acetate/acetic acid/hexane and a flow rate 1.5ml/min. RESULTS AND DISCUSSION  HPLC analysis In considering alternative approaches to the measurement of the tocols, a variety of chromatographic methods were reviewed. Most of the procedures published in the past ten years have been based around HPLC. Whilst some have used reversed phase systems, the overwhelming number of reports have utilized normal phased combinations. The chromatographic method used in the current work was based upon that described by Zhimin Xu (2002). When a series of oil samples were analysed, effective separation of a number of vitamers forms of Vitamin E were well separated. Isocratic elution was possible and the resolution of the four samples (Figures 2-5) was achieved within 30 minutes. were eluted in the following order: α - tocopherol< α - tocotrienol<  - tocopherol<  - tocotrienol<  - tocopherol<  - tocotrienol< δ - tocopherol< δ - tocotrienol.   Document: The Analysis Of Alpha Tocopherol And Other E.doc Author: Oliver Buddrick Save Date: 21/02/2015 Page of 4 050000010000001500000200000025000000 1 2 3 4 5 6 Time (min)    A   b  s  o  r   b  a  n  c  e   Figure 1 .Chromatogram of α -tocopherol standard (Sigma) for normal phase HPLC   01000000200000030000004000000500000060000000 5 10 15 20 25 30 Time (min)    A   b  s  o  r   b  a  n  c  e   Figure 2 .Chromatogram of tocopherols and tocotrienols of palm oil for normal phase HPLC 01000000200000030000004000000500000060000000 5 10 15 20 25 30 Time (min)    A   b  s  o  r   b  a  n  c  e  Figure 3 .Chromatogram of tocopherols and tocotrienols of palm oil spiked with α -tocopherol for normal phase HPLC 1. α -tocopherol 2. α -tocotrienol γ.  -tocopherol 4.  -tocopherol 5. δ -tocopherol 1 2 4 5 3   Document: The Analysis Of Alpha Tocopherol And Other E.doc Author: Oliver Buddrick Save Date: 21/02/2015 Page of 4 01000000200000030000004000000500000060000000 5 10 15 20 25 30 Time (min)    A   b  s  o  r   b  a  n  c  e   Figure 4 . Chromatogram of tocopherols and tocotrienols of a wheat germ oil sample 01000000200000030000004000000500000060000000 5 10 15 20 25 30 Time (min)    A   b  s  o  r   b  a  n  c  e   Figure5 . Chromatogram of tocopherols and tocotrienols of a wheat germ oil sample spiked with α -tocopherol. CONCLUSIONS The method has proven reproducible and effective for the determination of tocopherols and tocotrienols in vegetable oils. The same method will be applied in the determination of vitamin E in cereal foods in future work. ACKNOWLEDGEMENTS We thank the GRDC for financial support through the award of a Grains Research Scholarship to Oliver. In addition, we are grateful to Dianne Mileo for her help in procuring chemicals as well as RMIT staff for providing training and support in the use of the instruments. Furthermore we want to thank friends and colleagues for support throughout the project 1. α -tocopherol β.  -tocopherol γ.  -tocotrienol 4.  -tocopherol 5. δ -tocopherol 6. δ -tocotrienol 1 4 6 5   3 2   Document: The Analysis Of Alpha Tocopherol And Other E.doc Author: Oliver Buddrick Save Date: 21/02/2015 Page of 4 REFERENCES Al-Saqer, J. M., Sidhu, H. S., Al-Hooti, S. N., Al-Amiri, H. A., Al-Othman, A., Al-Haji, L., Et Al. (2004). Food Chemistry, 85 (4), 579-583 Dewettinck, K., Van Bockstaele, F., Kühne, B., Van De Walle, D., Courtens, T. M., & Gellynck, X. (2008).  Journal Of Cereal Science, 48  (2), 243-257. Hidalgo, A., & Brandolini, A. (2010).  Journal of Cereal Science, 52 (2), 254-259. Nanditha, B., & Prabhasankar, P. (2009). Critical Reviews in Food Science and Nutrition, 49 (1), 1-27. Nielsen, M. M., & Hansen, A. (2008). Cereal Chemistry, 85 (2), 248-251. Schwartz, H., Ollilainen, V., Piironen, V., & Lampi, A.-M. (2008).  Journal Of Food Composition And Analysis, 21 (2), 152-161. Sen, C. K., Khanna, S., & Roy, S. (2007).  Molecular Aspects of Medicine, 28  (5-6), 692-728. Tiwari, U., & Cummins, E. (2009). Trends in Food Science & Technology, 20 (11-12), 511-520. Zhimin Xu. 2002.. John Wiley & Sons, Inc., New York. pp. D1.5.1-D1.5.12.
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