Nutrient Data Laboratory Research Articles

Food Science Education Publications and Websites

Bird We invite readers to submit print or electronic resources that they would like to share with other readers. Please submit the full text of the articles or the URL for the website and an annotation of not more than 100 words. We welcome your comments and resources. Material should be submitted to: Jim Bird, Science & Engineering Center, Fogler Library, Univ. of Maine, Orono, ME 04469 or e-mailed to Jim.Bird@umit.maine.edu. CRIS Current Research Information System. USDA. Available at http://cris.csrees.usda.gov/ (accessed 8/18/2006) CRIS includes a searchable database of ongoing or recently completed projects supported by grants from the USDA. Users can search the database by an assisted search interface that includes a fill-in form or by a professional search that utilizes Boolean operators and field-directed commands. A detailed classification code system can be used with both search interfaces. Each record includes performing institution and principal investigator(s); a brief description of the funded project, giving objectives, approach, and progress; and a list of publications that have resulted from the research. There are also a CRIS pending projects database and a database of multistate projects. Hooker, P. 2005. Mineral analysis of whole grain total cereal. J Chem Ed 82(8):1223-5. The author describes an experiment that was implemented in the chemistry curriculum at Westminster College, Salt Lake City, Utah. The procedure for iron, calcium, and zinc analysis is discussed. Supplementary information, including instructor notes, is available in this issue of Journal of Chemical Education online (subscription required). Laminack, J, Dainello, F, Vestal, TA, Wingenbach, G. 2006. Experiential education employed to demystify food irradiation as a viable technology for food industry professionals. HortTechnology 16(2):318-23. The authors describe a professional development short course for food industry personnel and extension agents. Focusing on the course effectiveness, the article includes information on participants' perceptions, knowledge and understanding, and levels of concern about food safety and irradiation. The authors note that the short course increased food safety knowledge among participants as well as changing perceptions and attitudes. Lemar, L, Haytowitz, D, Bingham, M, Cutrufelli, R, and Thomas, R. 2006. The Nutrient Data Laboratory web site gets a new look. J Food Comp Analysis 19:S96-9. This paper describes the redesigned Nutrient Data Laboratory (NDL) web site (http://www.ars.usda.gov/ba/bhnrc/ndl (last updated 7/26/2006). Through this site users can access the USDA National Nutrient Database for Standard Access (release 18), the full text of articles (1996–present) by NDL staff as well as poster sessions and presentations, and a current list of research programs and projects. Riverol, C, Andrade, S, and Cooney, J. 2005. A laboratory course on real-time control for food engineers. Int J Eng Ed 21(4):668-75. The authors describe a laboratory course that utilizes real-time control experiments focusing on fuzzy control. It is noted that this laboratory course is preceded by a 1-year course titled “Application of Artificial Intelligent [sic] (AI) in Food Processing.” MATLAB software is used for laboratory experiments. Distance learning is briefly discussed, as is student feedback. Taylor, A and Sajan, S. 2005. Testing for genetically modified foods using PCR. J Chem Ed 82(4):597-8. The authors describe an experiment that can be used in biochemistry or analytical chemistry courses. Using PCR, students evaluate “…commercially-available cornmeal products for the presence of the CaMV 35S promoter… ” (p.597). This is a 2-week experiment that also includes a case study on genetically modified foods. Supplementary information, including instructor notes and the case study, is available in this issue of Journal of Chemical Education online (subscription required). University of Nebraska, Lincoln. Center for Science, Mathematics, & Computer Education. Food science labs. http://scimath.unl.edu/labs/food.html (accessed 8/14/2006) The experiments listed on the site are appropriate for high school science classes and are the result of a grant for the inclusion of food experiments in science classes. Contributors include Nebraska science teachers and others. A contact e-mail is given for comments on the experiments. Included are experiments on digestive enzymes, DNA isolation from an onion, chromatography, vitamin C analysis, and food microbes.

The Nutrient Data Laboratory Web site gets a new look

The Nutrient Data Laboratory Web site, along with all Agricultural Research Service (ARS) Web sites, has a new look. The basic appearance is similar to the United States Department of Agriculture Web site, but with some navigational categories unique to ARS sites. The purpose of these changes is to make ARS Web sites more uniform in navigation, enhancing overall ease of use. Navigation tools now found on our Web site include links to: About Us, Research, Products & Services, People and Places, News and Events, Partnering, and Careers. Partnering, a section recently added to the Web site, includes information detailing our numerous research collaborations with scientists in educational institutions, research laboratories, the food industry and other federal agencies as well as our award-winning partnerships for technology transfer. The online search program, our most frequently accessed feature, remains prominently displayed on our Home Page, continuing to give users fast access to nutrient information on a specific food. This popular program has been upgraded, supporting enhanced search techniques and the capability to customize portion sizes for food component reports. The NDL Web site is the principal means of dissemination of food composition data from the National Nutrient Databank System and receives an average of over 110,000 visitors per month.

Quality-control materials in the USDA National Food and Nutrient Analysis Program (NFNAP)

The US Department of Agriculture (USDA) Nutrient Data Laboratory (NDL) develops and maintains the USDA National Nutrient Databank System (NDBS). Data are released from the NDBS for scientific and public use through the USDA National Nutrient Database for Standard Reference (SR) ( http://www.ars.usda.gov/ba/bhnrc/ndl ). In 1997 the NDL initiated the National Food and Nutrient Analysis Program (NFNAP) to update and expand its food-composition data. The program included: 1) nationwide probability-based sampling of foods; 2) central processing and archiving of food samples; 3) analysis of food components at commercial, government, and university laboratories; 4) incorporation of new analytical data into the NDBS; and 5) dissemination of these data to the scientific community. A key feature and strength of the NFNAP was a rigorous quality-control program that enabled independent verification of the accuracy and precision of analytical results. Custom-made food-control composites and/or commercially available certified reference materials were sent to the laboratories, blinded, with the samples. Data for these materials were essential to ongoing monitoring of analytical work, to identify and resolve suspected analytical problems, to ensure the accuracy and precision of results for the NFNAP food samples.

Sampling and initial findings for a study of fluoride in drinking water in the United States

The role of fluoride in reducing the risk of dental caries, especially among children, is well recognized and is the basis for current intake recommendations. The US Department of Agriculture, Nutrient Data Laboratory conducted a comprehensive study of the fluoride content of US drinking water, as part of the US National Fluoride Database and Intake Assessment Study, a collaborative effort with the University of Minnesota, the University of Iowa College of Dentistry, and Virginia Polytechnic Institute and State University. The sampling method involved: serpentine ordering of the US population by census region, division, and county; dividing the population into 72 equal population size zones; and randomly selecting one county per zone and two residences per county. Participants were recruited by phone to provide two tap water samples, 3–4 months apart; samples ( n = 2 8 8 ) were analyzed by the direct read method. Well water averaged <20 mcg fluoride/100 g, municipal water averaged 100–110 mcg fluoride/100 g, and the national average across sources was 71 mcg fluoride/100 g. These nationally representative data for drinking water will support public health research on the impact of fluoride on bones and teeth and will provide a foundation for assessment tools in the dental and medical communities.

USDA Nutrient Data Laboratory

USDA Nutrient Data Laboratory

Fluoride content of municipal water in the United States: what percentage is fluoridated?

Recently, a study was conducted to look at the trace element content of municipal waters sampled around the United States. This was a collaborative project defined by representatives of the Nutrient Data Laboratory and the Food Composition Laboratory of the United States Department of Agriculture. As part of the study, the fluoride content of nationally representative water samples was measured since water is one of the principal sources of fluoride in the US diet. This study served as a pilot for planning a more extensive future nationwide sampling. Samples were analyzed using a separate reference electrode and ion selective electrode with TISAB II buffer. The calibration range was from 0.5 to 3.0 ppm. Accuracy of the method was validated by analyzing NIST SRM 2671a Fluoride in Freeze-Dried Urine. Results from the municipal water study clearly showed that the distribution of fluoride in US municipal waters is bi-modal. That is to say, because of the fact that ambient levels are typically extremely low, the concentration of fluoride is basically quantized. Either the water is fluoridated and contains approximately 1 ppm of fluoride or it is not fluoridated with undetectable fluoride concentration. The distribution of these data make it difficult to assign a meaningful average value useful to health professionals and consumers to assess fluoride intake. This study revealed that approximately 40% of the water samples from this nationwide sampling were fluoridated with a mean concentration of 1.01±0.15 μg/ml.

Food and Dietary Supplement Databases for What We Eat in America–NHANES

Relative strengths and potential approaches for improvement of food and dietary supplement databases used for tabulating intakes from the dietary component of the What We Eat in America-National Health and Nutrition Examination Survey (NHANES) are discussed. The U.S. Department of Agriculture's Nutrient Data Laboratory develops and maintains the Nutrient Databank System (NDBS) and many nutrient-specific and population-specific databases. NDBS contains data for approximately 8,000 foods and approximately 115 components; tables for compounds of special interest are also available. Nutrient databases need constant revision because of a constantly changing food supply. The completeness of analytical data varies from nutrient to nutrient. The National Center for Health Statistics developed and maintains a database of dietary supplements based on label information. To date, no verification of ingredients has been undertaken. The development of a dietary supplement database containing analytical values would require extensive resources but would be valuable. Databases for vitamin and mineral supplements are compatible with food databases. Databases for botanicals and other supplements include nonnutrient constituents that may not be documented in food composition databases. Gaps in food and dietary supplement composition data exist because of limited resources, changing availability of foods and products and the advent of new compounds of health interest. More data are needed on nutrients and other bioactive constituents in foods and dietary supplements. Analytical methods do not exist for all ingredients or active constituents in foods and dietary supplements. Research needs for further development of meaningful food and dietary supplement databases are similar.

Individual Sugars, Soluble, and Insoluble Dietary Fiber Contents of 70 High Consumption Foods

As part of the continuous efforts of the Nutrient Data Laboratory, Agricultural Research Service (ARS), USDA in updating and expanding the carbohydrate data in its database, foods were selected based on dietary fiber content and frequency of consumption. They were analyzed by a commercial testing laboratory under a USDA contract. Individual sugars, soluble and insoluble dietary fiber values of 70 foods in six food groups were reported. Foods included 14 baked products, 10 cereal grains and pastas, 19 fruits, seven legumes, 10 cooked vegetables, and 10 raw vegetables. Except for cereal grains/pasta and legumes, most other foods contained fructose and glucose; sucrose was found in almost all except baked products, which were the most predominant source of maltose. Fruits contained the most total sugar and cereal, grains/pasta the least. Legumes contained the highest amount of total dietary fiber. All these commonly consumed foods, with the exception of cooked white rice, contained both soluble and insoluble dietary fiber. The percent of soluble and insoluble fiber varied across food groups, even within each group. Comparison of data from the commercial laboratory with those of the same food analyzed in the Food Composition Laboratory using different methods indicated there was good agreement between high-performance liquid chromatographic and gas chromatographic methods for the determination of individual sugars. Total dietary fiber as calculated from the sum of soluble and insoluble fiber according to AOAC Method 991.43 and total dietary fiber from direct analysis using a single enzyme-gravimetric method showed high variability ( r 2<0.8) for three of the six food groups, but good agreement for others.

Development of a Multi-nutrient Data Quality Evaluation System

The U.S. Department of Agriculture's (USDA) Nutrient Data Laboratory (NDL) has redesigned the software of the USDA Nutrient Databank to provide a system for data acquisition, compilation, and dissemination, and as part of this system has developed a module to facilitate the evaluation of analytical data quality. USDA's first data evaluation procedures were developed as a manual system to assess the quality of analytical data for iron, selenium and carotenoids in foods. These procedures have been modified and expanded for multi-nutrient data quality evaluation. The same five evaluation categories; sampling plan, number of samples, sample handling, analytical method and analytical quality control, from the original work have been maintained but the evaluation questions have been made more objective. The rating scales for each category have been changed from discrete steps to a more continuous scale. These ratings are combined to give a Quality Index (QI), and Confidence Code (CC) that is disseminated with the nutrient data to indicate the level of confidence in the value. The algorithm for combining ratings from the five categories was revised from earlier systems to avoid the possibility that the aggregation of several mediocre data points would together, merit the highest CC.

The Identification of Key Foods for Food Composition Research

The United States Department of Agriculture's (USDA) National Food and Nutrient Analysis Program (NFNAP) was initiated to update existing component values and to add data on new foods and components to reflect today's marketplace and needs for data. The USDA Nutrient Database for Standard Reference contains data for about 6040 foods for over 100 compounds. To develop a full nutrient profile for each food costs approximately $12 000 (six analytical samples×$2000 per sample). To determine food sampling priorities, the Nutrient Data Laboratory (NDL) has used the Key Foods approach to generate a list of 666 foods. This method utilizes existing nutrient profiles and nationally representative food consumption survey data collected by USDA in the Continuing Survey of Food Intakes by Individuals 1994–1996 (CSFII) and by The U.S. Department of Health and Human Services (USDHHS) in the National Health and Nutrition Examination Survey (NHANES). One premise of the project is that more samples will be collected and prepared for those foods which provide important amounts of nutrients of public health significance to the diet and not every sample will be analyzed for all the nutrients currently in NDL's nutrient databases. Even though the list of 666 Key Foods is much more manageable, procedures to set priorities for analysis are still needed. To accomplish this, two approaches were developed. One is based on a point system, and the other on nutrient consumption data. Based on an analysis of the two approaches, the nutrient consumption approach was chosen to be the primary method of selecting foods for analysis. This paper reports details of the two methods to modify the existing Key Foods list to determine new and specific priorities for NFNAP efforts. This program represents a comprehensive approach to collect baseline nationally representative data. Results will be used to update the USDA Nutrient Database for Standard Reference and to establish future priorities for frequency of updates.

Trace Element Composition of Municipal Waters in the United States: A Comparison of ICP-AES and ICP-MS Methods

A collaborative project was outlined by representatives of the Nutrient Data Laboratory and the Food Composition Laboratory of the United States Department of Agriculture. The purpose of the project was to obtain trace element (Ca, Cu, Fe, Mg, P, K, Na, Mn, Zn, Co, Cr, Ni and V) composition data for municipal waters sampled around the United States during three different seasons. Several sub-goals were outlined: (1) Compare inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) methods for the direct determination of nutritionally important elements in water; (2) Compare data from this study with a national, probability-based sampling plan, to existing published data in U.S. Department of Agriculture's Standard Reference Database SR-13; (3) Consider the variability of values comparing different locations; (4) Evaluate seasonal variability; (5) Conclude as to whether or not this high consumption product is a reasonable source of trace elements in the human diet. Results from the study indicated that the excellent detection capability of ICP-MS provided Cr, Ni and V results at the ppb level and also provided P and K data, all of which will be significant positive additions to USDA's Standard Reference Database SR-13. Correlation studies comparing ICP-MS and ICP-AES data showed excellent agreement (Ca, Cu, Mg, Na R=0.99+; K R=0.96). No real significant seasonal variability was identified during the course of the study. This study highlighted the fact that water is not a significant source of most trace elements in the U.S. diet.

Key Foods: Setting Priorities for Nutrient Analyses

The Nutrient Data Laboratory is responsible for developing authoritative nutrient data bases that contain a wide range of food composition values for the United States’ food supply. This requires, in addition to other activities, updating and revising the USDA Nutrient Data Base for Standard Reference, the electronic counterpart to Agriculture Handbook No. 8, and supplying nutrient values for the Nationwide Food Surveys. However, with more than 5,200 food items in the data base and a complete nutrient profile costing approximately $2,000 for one sample, the analysis of every food item for every nutrient to meet user requirements is impossible. Consequently, priorities for analyzing foods and nutrients must be determined. Procedures using food consumption data and nutrient values for developing the Key Foods list are explained. Key Foods have been identified as those food components that contribute up to 80% of any one nutrient. When total nutrient contributions from these 527 Key Foods are aggregated, they account for approximately 90% of the nutrient content of the U.S. diet for the 30 nutrients examined. These Key Foods will form the core of the USDA future nutrient analyses contracts. The list of Key Foods as major food contributors of various nutrients is presented.

Determination of Sugars, Starches, and Total Dietary Fiber in Selected High-Consumption Foods

A general scheme has been developed to determine sugars, starches, and total dietary fiber (TDF) in half-gram freeze-dried subsamples of various foods (or wet samples containing about 0.5 g dry matter). Duplicate subsamples are extracted for free sugars with 80% methanol, dried, derivatized to their trimethylsilylated oximes or ethers, and quantitated by gas-liquid chromatography (GLC). Residues after 80% methanol extraction are incubated with a solution containing amyloglucosidase in acetate buffer. Hydrolyzates are centrifuged, and duplicate aliquots are removed for glucose determination by GLC. Starch content is calculated as glucose (g/100 g) x 0.9. Remaining hydrolyzates are diluted with 4 volumes of 95% ethanol, left at room temperature for 1 h, and then filtered through glass crucibles matted with Celite filter aid. The weight of dry residues are corrected for residual crude protein and ash, and the resulting values are taken to be the TDF content of a sample. A variety of high-consumption foods selected by the Nutrient Data Laboratory of the Agricultural Research Service were analyzed for carbohydrate fractions by this method. Values for total sugar and dietary fiber were compared with those obtained by a commercial laboratory using different methods.