2009 Annual Report
Objective 2: Develop and evaluate spectral fingerprinting and chromatographic profiling methods to characterize components in lipid soluble, water soluble, and intermediate fractions of food materials. Sub-objective 2.A.: Develop spectral fingerprinting methods for identification of plant materials and individual components using direct analysis (no prior chromatographic separation) and pattern recognition algorithms. Sub-objective 2.B.: Develop chromatographic profiling methods for identification and quantification of individual components in plant materials.
Objective 3: Develop methods to determine variability of biologically active components in food materials through profiles and/or fingerprints.
Objective 2: Spectral fingerprinting methods will be developed based on ultraviolet and visible molecular absorption (UV/Vis), infrared (IR), near-infrared (NIR), and mass spectrometric (MS) detection. The overlapping complex spectra will be interpreted using pattern recognition programs. The patterns will be used to determine the sensitivity of the different detection systems for discriminating between plant materials based on genera, species, variety, growing year, growing site, and processing conditions. These methods will be developed using 3 food materials and 3 botanical supplement materials. Repeat samples will be examined over a period of years to determine the stability of the spectra and the ability to compare spectra of new materials to archived spectra. The phenolic and vitamin content of the plant materials will also be determined using chromatographic profiling using LC-DAD-ESI/MS. This will make it possible to determine which compounds are contributing most to differences arising from the various growing factors.
Objective 3: The spectral fingerprints can be used with nested analysis of variance to determine the relative variance contributed by each growing factor: species, variety, site, year, plant-to-plant variation, and analytical uncertainty. Samples will be obtained from collaborators across the country and representing a variety of foods and botanical supplements. UV/Vis, IR, and NIR spectra will provide variance data for the integrated chemical composition of the plant materials and MS will provide variance data for specific masses and, with the assistance of chromatographic profiling, specific compounds of health interest.
Spectral fingerprints for broccoli samples consisting of 2 different cultivars and 7 different growing conditions were compare using 6 different spectral methods: fourier transform infrared (FT-IR), fourier transform near-infrared (FT-NIR), molecular absorption in the ultraviolet region (UV), molecular absorption in the visible region (Vis), mass spectrometry with positive ionization (MS+), and mass spectrometry with negative ionization (MS-). All 6 methods provided statistical differentiation between the cultivars and the growing conditions. Based on analysis of variance, the UV and Vis gave the best discrimination, followed by the group of FT-NIR, MS+, and MS-, and finally FT-IR.
Chinese (Panax ginseng) and American (Panax quinquefolius) Ginseng roots were purchased locally and a project to discriminate between the two species using UV, MS, and FT-NIR fingerprints is underway.
This work was supported in part by an interagency agreement with the Office of Dietary Supplements (ODS) at the National Institutes of Health (NIH).
Luthria, D.L., Natarajan, S.S. 2009. Influence of sample preparation on the assay of isoflavones. Planta Medica. 75:704-710.
Brisibe, E.A., Umoren, U.E., Brisibe, F., Magalhaes, P.M., Ferreira, J.F., Luthria, D.L., Wu, X., Prior, R. 2009. Nutritional characterization and antioxidant capacity of different tissues of Artemisia Annua L. Food Chemistry. 115:1240-1246.