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United States Department of Agriculture

Agricultural Research Service


Location: Food Composition and Methods Development Laboratory

2013 Annual Report

1a. Objectives (from AD-416):
Objective 1: Develop and evaluate procedures for quantitative extraction and/or fractionation of food materials by polarity. Sub-objective 1.A.: Develop an extraction procedure for sequential fractionation of the major groups of components from plant materials. Sub-objective 1.B.: Develop optimized extraction procedures for accurate quantification of individual phytochemicals in plant materials. 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. Temporary Objectives: Objective 1: Conduct an independent and outside evaluation of the IT capabilities of the Food Composition and Methods Development Laboratory coordinated with the Nutrient Data Laboratory and the Food Surveys Research Group; include an assessment of whether cloud computing or local data storage is the optimal approach for the next 5-10 years of anticipated data collection, storage, and dissemination. Objective 2: Implement changes to update and modernize the IT infrastructure of the Food Composition and Methods Development Laboratory that links to the Nutrient Data Laboratory and Food Surveys Research Group.

1b. Approach (from AD-416):
Objective 1: Methods will be developed for the quantitative extraction of macro and micro components from plant materials using commercial, high pressure/temperature extraction instrumentation. Soybeans will be tested initially as they contain both lipid soluble and highly polar molecules of health interest. Sequential and parallel extraction will be investigated. Extracted materials will be characterized using liquid chromatography with diode array and electrospray ionization/mass spectrometric detection (LC-DAD-ESI/MS). The new method will be applied to foods and botanical materials. In addition, optimized methods will be developed for specific families of compounds such as water-soluble vitamins, lipid-soluble vitamins, phenolic acids, and flavonoids. 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. Temporary Approaches: Approach 1: Submit names of individuals to the BHNRC with expertise to evaluate existing and future needs for evaluating food composition data arising from analysis in the laboratory. Assessment will include how to work more effectively in sharing compositional information across the various laboraties within the BHNRC. Approach 2: Replace as needed hardware and software needed to evaluate food composition information generated by the FCMDL and for sharing quality compositional information with the NDL and the FSRG.

3. Progress Report:
In collaboration with Thermo Scientific and support from the Office of Dietary Supplements (NIH), FCMDL is continuing to establish an in-house database for phytochemical compounds, primarily the flavonoids, using high resolution mass spectrometry. The new database contains their exact mass, chemical formula, structure, full mass spectra, and molecular absorption spectra. The database will be used to facilitate identification of chemical components in future analysis of food materials and will save significant time and resources. In collaboration with the National Small Grains and Potato Germplasm Research Unit of USDA in Aberdeen Idaho, FCMDL continues to work on the determination of phenolic acid content in nine key fractions of ground corn (cooked slurry, liquified slurry, fermented mesh, whole stillage, thin stillage, condensed distillers solubles, wet distillers grain, and distillers dried grains with solubles) collected from three commercial plants in Iowa. This study will allow processors to identify the changes in the phenolic acids content in the byproduct. A manuscript has been submitted. In collaboration with the Western Wheat Quality Lab of USDA at Washington State University and the Department of Nutrition and Food Science at the University of Maryland, the effect of cooking on tocopherols and carotenoids in white and whole wheat breads was investigated. The phytochemical content in different fractions of flour, dough, and bread (upper crust, central crumb, and bottom crust)were analyzed. We are currently summarizing the initial results. In collaboration with the Department of Chemistry and Center for Innovation in Chemistry at Khon Kaen University in Khon Kaen, Thailand, VACs were extracted from 3 species of lemongrass (Cymbopogon citrates, C. nardus, and C. winterianus) by classical microhydrodistillation (MHD) and modern accelerated solvent extraction (ASE). Ensuing analysis by gas chromotography-mass specrmetry (GC-MS) identified sixteen VACs. GC-flame ionization detection was used for the quantification of five VACs (citronellal, citronellol, geraniol, citral, and eugenol) to compare the extraction efficiency of the two different methods. The results showed that the ASE technique is more efficient than MHD, as it results in improved yields and significant reduction in extraction time due to the automated extraction capabilities.

4. Accomplishments
1. Differentiation of organically and conventionally grown vegetables. Controversy exists as to whether organically grown produce offers increased nutrition compared to the same cultivars grown conventionally. Scientists at USDA in Beltsville, MD, in collaboration with the Department of Nutrition and Food Chemistry at the University of Maryland, have developed a fast analytical method that can detect chemical differences in organically and conventionally grown vegetables in 1 minute using flow-injection mass spectrometry (FIMS) following a simple methanol-water extraction. The project revealed that there are chemical differences between organically and conventionally grown basil, peppermint, and sage sold in the US market. However, the chemical differences have not been shown to be of nutritional significance.

2. Phenolic profiles of purple radish. Anthocyanins are common flavonoids that have been linked to resistance to cancer, diabetes, infections, inflammation, and neurological diseases. Scientists at USDA in Beltsville, MD, analyzed purple radishes (Raphanus sativus L.), a plant bred to provide high anthocyanin content, by high performance liquid chromatography (HPLC) with high resolution mass spectrometry (HRMS)detection. Thet detected 57 acylated anthocyanins, 45 observed for the first time. This study showed the presence of a large variety of anthocyanins and the necessity of HPLC-HRMS to provide the sensitivity and specificity for their identification.

3. Phenolic acids in potato skins. Many of the bioactive compounds of potential health interest are found in the peels/skin/rinds of fruits and vegetables, materials usually thrown away as waste. Scientists at USDA in Beltsville, MD, used HPLC-UV and HPLC-MS methods to detect phenolic acids in potato peels using pressurized liquid extraction (PLE). The concentrations of the phenolic acids were more than tenfold higher in the peels than in the edible portion (tuber). The results varied significantly depending on the extraction parameters and optimum parameters were identified. The results suggested that phenolic acids are found predominantly in the potato peels and have the potential of providing a value added product for potato growers and processors.

4. Chemical fingerprinting for detection of adulterated botanical supplements. The popularity of botanical supplements to augment the US diet has provided a strong economic impetus for adulteration. Ginkgo biloba extract is a frequently used supplement that purportedly provides enhanced cognitive function. Scientists at USDA in Beltsville, MD, measured 22 flavonol glycosides in three NIST reference materials (SRM 3246, 3247, and 3248) and 20 commercially available supplements using HPLC-MS. Half of the commercial supplements were found to be adulterated with one of two inexpensive compounds (quercetin or quercetin rutinoside). Analysis was easily accomplished with a simple methanol-water extraction and direct analysis by UV spectrophotometry. This method provides the analyst with an inexpensive method for detecting adulterants.

5. Flavonoids in Ber fruit. Scientists at USDA in Beltsville, MD, in collaboration with the National Centre of Excellence in Analytical Chemistry at the University of Sindh in Sindh, Pakistan, measured the flavonoid profiles for the fruit of four species of ber (Ziziphus mauritiana Lam k), a fast growing tree native to Pakistan. The fruit are eaten raw and are high in vitamins, second only to guava for vitamin C content. This is the first systematic analysis of phenolic compounds in this fruit. Three different methods were compared and the optimized method allowed identification and quantification of 12 flavonoids, nine for the first time, and 9 phenolic acids. These data establish the potential health benefits of this fruit and enhance its potential for the international market.

Review Publications
Luthria, D.L. 2012. Optimization of extraction of phenolic acids from a vegetable waste product using a pressurized liquid extractor. Journal of Functional Foods. 4:842-850.

Sun, J., Chen, P. 2012. UHPLC/HRMS analysis of African mango (Irvingia gabonensis) seeds, seed extracts, and African mango based dietary supplements. Journal of Agricultural and Food Chemistry. 60:8703-8709.

Sun, J., Long-Ze, L., Chen, P. 2013. Recent applications for HPLC-MS analysis of anthocyanins in Food materials. Current Analytical Chemistry. 9:397-416.

Memon, A.A., Memon, N., Bhanger, M.I., Luthria, D.L. 2013. Assay of phenolic compounds from four species of Ber (Ziziphus mauritiana L.) Fruits: Comparision of three base hydrolysis procedure for quantification of total phenolic acids. Journal of Functional Foods. 139:496-502.

Cross, A.J., Harnly, J.M., Ferrucci, L.M., Risch, A., Mayne, S.T., Sinha, R. 2012. Developing a heme iron database for meats according to meat type, cooking method and doneness level. Food and Nutrition Sciences. 10:4236.

Lou, Y., Wang, T.T., Teng, Z., Chen, P., Sun, J., Wang, Q. 2013. Encapsulation of indole-3-carbinol and 3'3'-diindolylmethane in zein/carboxymethyl chitosan nanoparticles with controlled release property and improved stability. Food Chemistry. 139(1-4):224-30.

Zhao, Y., Niu, Y., Xie, Z., Shi, H., Chen, P., Yu, L. 2013. Differentiation of leaf and whole-plant samples of di- and tetraploid Gynostemma pentaphyllum (Thunb.) Makino using flow-injection mass spectrometric(FIMS) fingerprinting method combined with chemometric approaches. Analytica Chimica Acta. 5:1288-1297.

Gao, B., Qin, F., Chen, P., Shi, H., Liangli, L. 2012. Differentiating organic from conventional peppermints using chromatographic and flow-injection mass spectrometric (FIMS) fingerprints. Journal of Agricultural and Food Chemistry. 60:11987-11994.

Sun, J., Liu, X., Yang, T., Solvin, J., Chen, P. 2013. Profiling polyphenols of two diploid strawberry (Fragaria vesca) inbred lines using UHPLC-HRMSn. Analytical Biochemistry. 5:2945-53.

Harnly, J.M., Luthria, D.L., Chen, P. 2012. Detection of adulterated Ginkgo biloba supplements using chromatographic and spectral fingerprints. Journal of Association of Official Analytical Chemists International. 95:6.

Jumepaeng, T., Prachakool, S., Luthria, D.L., Chanthai, S. 2013. Determination of antioxidant capacity and a-amylase inhibitory activity of the essential oils from citronella grass and lemongrass. International Food Technology. 20:481-485.

Gao, B., Lu, Y., Chen, P., Liangli, Y. 2013. Differentiating Organic and Conventional Sage by Chromatographic and Mass Spectrometry Flow-Injection Fingerprints. Journal of Agricultural and Food Chemistry. 61:2957-2963.

Last Modified: 09/25/2017
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