Agriculture Handbook Research Articles

Dietary Magnesium Intake and Risk of Incident Hypertension Among Middle-Aged and Older US Women in a 10-Year Follow-Up Study

To assess the hypothesis that magnesium intake is beneficial in the primary prevention of hypertension, 28,349 female United States health professionals aged > or =45 years participating in the Women's Health Study (WHS), who initially reported normal blood pressure (systolic blood pressure <140 mm Hg, diastolic blood pressure <90 mm Hg, no history of hypertension or antihypertensive medications), were prospectively studied. A semi-quantitative food frequency questionnaire was used to estimate magnesium intake. During a median follow-up of 9.8 years, 8,544 women developed incident hypertension. After adjustment for age and randomized treatment, magnesium intake was inversely associated with the risk for developing hypertension; women in the highest quintile (median 434 mg/day) had a decreased risk for hypertension (relative risk 0.87, 95% confidence interval [CI] 0.81 to 0.93, p for trend <0.0001) compared with those in the lowest quintile (median 256 mg/day). This inverse association was attenuated but remained significant after further adjustment for known risk factors. In the fully adjusted model, the relative risks were 1.00 (95% CI 0.95 to 1.10), 1.02 (95% CI 0.95 to 1.10), 0.96 (95% CI 0.89 to 1.03), and 0.93 (95% CI 0.86 to 1.02) (p for trend = 0.03). Similar associations were observed for women who never smoked and reported no history of high cholesterol or diabetes at baseline. In conclusion, the results suggest that higher intake of dietary magnesium may have a modest effect on the development of hypertension in women.

Fatty acid composition and cholesterol content of beef and chicken meat in Southern Brazil

The aim of the present study was to analyze the fatty acid composition and cholesterol content of the beef and chicken meat most often consumed by a population of type 2 diabetic patients in Southern Brazil: for beef, semimembranosus and biceps femoris; and for chicken, drumstick and thigh. The moisture content (gravimetrically), protein content (Kjeldahl procedure), cholesterol content (HPLC or enzymatic methods), lipid content (gravimetric method) and fatty acid composition (gas chromatography) were analyzed in three different brands of these raw cuts in duplicate. The results were compared with data extracted from the United States Department of Agriculture (USDA) Handbook and Brazilian tables (TACO-UNICAMP and TBCAUSP 4.1). Chicken meat had a lower proportion of saturated (36.4±3.6%; P<0.001) and a higher proportion of polyunsaturated fatty acids (21.3±3.5%; P<0.0001) than beef (53.3±2.12 and 3.0±0.5%). Long chain omega-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic and docosahexaenoic were observed only in dark chicken meat (23±3 and 14±1 mg/100 g, respectively) and were found in less than 0.1 mg/100 g in beef cuts. The amount of gamma and alpha linolenic acids in biceps femoris (39/22 mg/100 g) was higher than in dark chicken meat (1/25 mg/100 g). A discrepancy was observed between the composition of the experimental meats and those reported in the USDA Handbook, mainly for beef. Total lipid content as well as PUFA and monounsaturated fatty acid (MUFA) levels were lower than the values reported in the USDA Handbook (26.5, 49 and 25% difference than USDA values, respectively) for beef. Chicken meat presents a more favorable fatty acid profile regarding serum cholesterol levels than beef cuts. Furthermore, the discrepancies observed between our experimental data and the USDA Handbook suggest that it is important to construct regional food composition tables.

Soils and their distribution on Bambouto volcanic mountain, West Cameroon highland, Central Africa

Morphological, physical and chemical studies were carried out on soils of Mount Bambouto, a volcanic mountain of the West Cameroon highland. These studies show that the soils of this region can be divided into seven groups according to Soils Taxonomy USA [Soil taxonomy: a basic system of soil classification for making and interpreting soils surveys: USDA Agriculture Handbook 436: Washington, DC, US Government Pronting Office, 1975, 754]: lithic dystrandept soils, typical dystrandept soils, oxic dystrandept soils, typical haplohumox soils, typical kandiudox soils, tropopsamment soils and umbriaquox soils. A soils map of this region at scale 1:50,000 has been drawn up, using the seven soils groups above as soil cartography units. These soils are organised into of three main categories: soils with andic characteristics in the upper region of the mountain (lithic dystrandept soils, typical dystrandept soils and oxic dystrandept soils); ferrallitic soils in the lower part of the mountain (typical haplohumox soils and typical kandiudox soils) and imperfectly developed soils (tropopsamment soils and umbraquox soils).

Use of fractal scaling to discriminate between and macro- and meso-pore sizes in forest soils

Two-dimensional image analysis of soil porosity has been used to study four forest plots. The analysis yields the number n( a) of soil pores having greater area than a, and the number n( p) of pores having larger perimeters than p. Both distributions follow power-laws of the form n( a)∼ a − Da and n( p)∼ p − Dp , with different exponents in two scaling regimes. The two regimes are between 10–32 mm 2 ( Da1) and 32–100 mm 2 ( Da2) for pore areas, and from 11 to 21 mm ( Dp1) and 21 to 40 mm ( Dp2) for pore perimeter. In all cases, the regression used to obtain the Korcak exponent was statistically significant. The higher Korcak exponents ( Da2 and Dp2) correspond to larger pore areas and perimeters, and the lower ones ( Da1 and Dp1), to the smaller areas and perimeters. The inflection point between the two scaling laws is at 6.4±1.0 mm diameter for pore areas and 6.8±1.4 mm for pore perimeters and it lies close to the medium/coarse soil-pore limit of 5 mm equivalent diameter [US Soil Survey Division Staff, 1993. US Soil Survey Division Staff, 1993. Soil Survey Manual. Soil Conservation Service. US Department of Agriculture Handbook 18]. This coincidence could be used for soil macro-pore classification.

Use of fractal scaling to discriminate between and macro- and meso-pore sizes in forest soils

Two-dimensional image analysis of soil porosity has been used to study four forest plots. The analysis yields the number n ( a ) of soil pores having greater area than a , and the number n ( p ) of pores having larger perimeters than p . Both distributions follow power-laws of the form n ( a )∼ a − Da and n ( p )∼ p − Dp , with different exponents in two scaling regimes. The two regimes are between 10–32 mm 2 ( Da 1) and 32–100 mm 2 ( Da 2) for pore areas, and from 11 to 21 mm ( Dp 1) and 21 to 40 mm ( Dp 2) for pore perimeter. In all cases, the regression used to obtain the Korcak exponent was statistically significant. The higher Korcak exponents ( Da 2 and Dp 2) correspond to larger pore areas and perimeters, and the lower ones ( Da 1 and Dp 1), to the smaller areas and perimeters. The inflection point between the two scaling laws is at 6.4±1.0 mm diameter for pore areas and 6.8±1.4 mm for pore perimeters and it lies close to the medium/coarse soil-pore limit of 5 mm equivalent diameter [US Soil Survey Division Staff, 1993. US Soil Survey Division Staff, 1993. Soil Survey Manual. Soil Conservation Service. US Department of Agriculture Handbook 18]. This coincidence could be used for soil macro-pore classification.

RUSLE C-factors for slope protection applications

Despite the fact that the Universal Soil Loss Equation (USLE) was originally developed to estimate erosion rates for agricultural lands, both the USLE and its successors (RUSLE Versions 1.06, 2.0) are increasingly applied to non-agricultural land disturbances. For these non-agricultural applications there is little consensus in the erosion-science community concerning which covermanagement factor (C-factor) values should be used to account for the effects of various slope-protection materials. The purpose of this study is to derive appropriate RUSLE C-factor values from the rainfall-simulation study data collected at the Texas Department of Transportation – Texas Transportation Institute, Hydraulics and Erosion Control Laboratory (TTI) and the San Diego State University, Soil Erosion Research Laboratory (SERL), and to evaluate the utility of such values. RUSLE C-factor values were calculated for over 50 erosion-control products, straw mulch, and several vegetation types for various research conditions. The C-factor values were then compared with the few values provided by the manufacturers of erosion-control products. The C-factor values for straw mulch and the several vegetation types were compared with analogous USLE C-factor values found in Agricultural Handbook 537 (Wischmeier and Smith, 1978) and values calculated using RUSLE2. One-way ANOVA tests and a Tukey test identified a significant difference between the C-factors calculated with the SERL methods and the USLE C-Factors and a second significant difference between the SERL method C-factors and values provided by product manufacturers. To test the spatial and temporal variability of C-factors, monthly values were calculated using RUSLE2 for 49 U.S. cities. A two-factor, without replication, ANOVA test was used to determine that the temporal and spatial variability of C-factor values is statistically significant. As a result of the lack of available C-factors for specific products, the SERL method at best provides a “quick and dirty” C-factor estimation. These values provide a soil-loss ratio useful for comparing the surface protection of similar erosion control products. The results of this study should assist USLE and RUSLE users by increasing awareness of the high variability of available C-factor values and highlight the need for product-specific C-factor values in RUSLE2. Additional

River Weed Growing Epizoically on Freshwater Mussels

LITTLE, E. L. 1971. Atlas of United States trees, volume 1: conifers and important hardwoods. Miscellaneous Publication 1146, United States Department of Agriculture, Washington, D. C. LITTLE, E. L. 1979. Check list of the United States trees (native and naturalized). Agricultural Handbook 541, United States Department of Agriculture, Washington, D. C. ROBERTSON, K. R., AND Y. T. LEE. 1976. The genera of Caesalpinioideae (Leguminosae) in the southeastern United States. Journal of the Arnold Arboretum 57:1-53. SPENCER, C. 1947. Propagation of thornless honeylocust. Journal of Forestry 45:715-722. STUBBENDIEK, J., AND C. ELVERNE. 1989. Common legumes of the Great Plains: an illustrated guide. University of Nebraska Press, Lincoln. TOWNSEND, A. M. 1989. The search for salt tolerant trees. Arboricultural Journal 13:67-73. VINES, R. A. 1960. Trees, shrubs and woody vines of the southwest. Universisty of Texas Press, Austin. WATSON, L. 1981. An automated system of generic descriptions for Caesalpinioideae, and its application to classification and key-making. In: Polhill, R. M., and P. H. Raven, editors. Advances in legume systematics, part I. Royal Botanic Garden, Kew, United Kingdom. Pp. 65-80.

Using biological criteria and indicators to address forest inventory data at the state level

The Santiago Declaration identified seven criteria and 67 indicators for assessing the conservation and sustainable management of temperate and boreal forests. Data collected by the Forest Inventory and Analysis (FIA) program of the US Department of Agriculture Forest Service can be used to directly address at least 11 biological indicators. The FIA program has conducted periodic inventories of forestland for several decades. These inventories provide statistical estimates of forest area, timber volume, growth, removals, and mortality. Recent legislation has mandated that the Forest Service inventory the forestland of the US on an annual basis measuring the entire set of national sample plots over a 5-year period. This paper identifies which criteria and indicators can be addressed by FIA data; the scale at which it may be appropriate to use these data; and how recent changes will impact the Forest Service’s ability to provide information needed to address these indicators. Data from the two most recent inventories of Iowa (1974 and 1990) and Minnesota (1977 and 1990) are used to show how criteria and indicators relate to trends in forest composition and extent, timber resource utilization, and the population size of native and non-native trees. These two states have distinctly different forest resources, ranging from sparse to dense, and provide a good test of the effectiveness of using forest inventory data to provide criteria and indicator information at the state level. Analysis of the data for the last two inventories of Iowa and Minnesota reveals that the area of timberland has increased by 34 and 8%, respectively, while growing-stock volumes have increased by 47 and 23%. Volumes of most native species increased over the period, especially for pioneer species such as Juniperus virginiana L. [ Little (1979). Agricultural Handbook No. 541, USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Ft. Collins, CO] (eastern red cedar). A notable exception was the 52% decline of Ulmus americana L. (American elm) due to the spread of Dutch elm disease. The number of non-native species also increased. In Iowa, the estimated number of live Ulmus pumila L. (Siberian elm) trees, a non-native species, went from 0 in 1974 to 675×10 3 in 1990. During the 1990 inventory of Minnesota another non-native species, Ailanthus altissima (Mill.) Swingle (tree of heaven), was sampled for the first time.

Beef Retail Cut Composition: 2. Proximate Analysis

The proximate composition of the separable lean of beef retail cuts as influenced by USDA quality grade and external fat trim level was determined. Carcasses (n=20) were selected from two commercial packing plants, one in the Texas Panhandle and the other in Nebraska, by trained Texas A&M University personnel. Ten USDA Choice and 10 USDA Select, yield grade 2 and 3 carcasses were selected to reflect the approximate distribution found in the U.S. beef supply. Thirteen cuts (in sets of four) were fabricated and assigned to one of four treatments: (1) 0.3 cm external fat trim, raw; (2) 0.0 cm external fat trim, cooked; (3) 0.3 cm external fat trim, cooked; and (4) 0.6 cm external fat trim, cooked. Retail cuts assigned to the cooked treatment were braised, broiled or roasted. Proximate analysis on the separable lean was done to determine fat, moisture, protein, and ash content. Trimming cuts of external fat before cooking had few (P<0.05) effects on chemical fat, moisture, protein or ash content within a cut. However, separable lean from the Choice quality grade retail cuts had higher (P<0.05) chemical fat contents than Select cuts. The lipid content for separable lean from most cuts in the present study was lower than that currently reported in Agriculture Handbook 8–13. Lipid retention was not affected by USDA quality grade or trim level. Therefore, health conscious consumers attempting to reduce fat intake by consuming only separable lean should make their selection based on USDA quality grade rather than external trim level.

Beef Retail Cut Composition: 1. Separable Tissue Components

Carcasses (n=20) were selected from two commercial packing plants, one in the Texas Panhandle and the other in Nebraska, by trained Texas A&M University personnel. Ten USDA Choice and 10 USDA Select, yield grade 2 and 3 carcasses were selected to reflect the approximate distribution found in the U.S. beef supply. Thirteen cuts (in sets of four) were fabricated and assigned to one of four treatments: (1) 0.3 cm external fat trim, raw; (2) 0.0 cm external fat trim, cooked; (3) 0.3 cm external fat trim, cooked; and (4) 0.6 cm external fat trim, cooked. Retail cuts assigned to the cooked treatment were braised, broiled or roasted. Both the cooked and raw cuts were dissected into separable lean, external fat, seam fat, and waste (heavy connective tissue and bone). USDA quality grade or trim level did not significantly affect the cooking yields of most cuts. Retail cuts that were braised had lower cooking yields than cuts that were roasted or broiled. Dissection data suggested that percentage separable lean increased as cuts were trimmed progressively of external fat cover. Cooked USDA Choice retail cuts had a higher percentage of seam fat than Select retail cuts. Arm roasts had the least separable lean, as well as the most seam fat and waste, even if all the external fat was removed before cooking. These data will be a potential source of information to be used by USDA in Agriculture Handbook 8-13 and the National Nutrient Data Bank, the most widely used resource for nutritional information in the U.S.

Fuzzy class membership approach to soil erosion modelling

To optimize the use of the available land and water resources of a watershed for sustainable agricultural production, soil erosion assessment and conservation are essential. The Universal Soil Loss Equation (USLE) is a widely accepted model (Wishmeier and Smith, 1965. Predicting Rainfall Erosion Losses from Cropland (Agricultural Handbook No. 282). USDA. Washington, D.C.) for assessing soil erosion and to account for the most important factors. Conventional approaches to classification are designed to assign a given area element (pixel) to a single erosion class. However, the soil and other physical parameters might vary spatially within a pixel and it may not correspond entirely to a single erosion class. To determine the loss of information on the susceptibility to erosion a fuzzy class membership approach was used to assign partial grades to the erosion classes. In the present studies, a spatially distributed approach was used to consider the influence of the spatial variation in the soil and other physical parameters in soil erosion assessment in the study area, Kalyanakere sub-watershed Karnataka, India, using the USLE model. The emphasis of the studies was laid on the use of a fuzzy class membership approach in soil erosion classification, and to develop a criteria table specifying the erosion parameter values related to erosion susceptibility classes from available literature to apply fuzzy class membership approach for the classification. Salient features of the approach and the results of the study are presented in this paper.

Simulation and testing of self-similar structures for soil particle-size distributions using iterated function systems

Particle-size distribution (PSD) is a fundamental soil physical property. The PSD is commonly reported in terms of the mass percentages of sand, silt and clay present. A method of generating the entire PSD from this limited description would be extremely useful for modeling purposes. We simulated soil PSDs using an iterated function system (IFS) following Martı́n and Taguas [Martı́n, M.A., Taguas, F.J., 1998. Fractal modeling, characterization and simulation of particle-size distribution in soil. Proc. R. Soc. Lond. A 454, 1457–1468]. By means of similarities and probabilities, an IFS determines how a fractal (self-similar) distribution reproduces its structure at different length scales. The IFS allows one to simulate intermediate distributional values for soil textural data. A total of 171 soils from SCS [Soil Conservation Service, 1975. Soil taxonomy: a basic system of soil classification for making and interpreting soil surveys. Agricultural Handbook no. 436. USDA-SCS, USA, pp. 486–742] were used to test the ability of different IFSs to reconstruct complete PSDs. For each soil, textural data consisting of the masses in eight different size fractions were used, and different PSDs were predicted using different combinations of three similarities. The five remaining data points were then compared with the simulated ones in terms of mean error. Those similarities that gave the lowest mean error were identified as the best ones for each soil. Fifty-three soils had an error less than 10%, and 120 had an error less than 20%. The similarities corresponding to the sand, silt and clay fractions, i.e., IFS {0.002, 0.05}, did not, in general, produce good results. However, for soils classified as sand, silt loam, silt, clay loam, silty clay loam and silty clay, the same similarities always produced the lowest mean error, indicating the existence of a self-similar structure. This structure was not the same for all classes, although loams and clays were both best simulated by the IFS {0.002, 0.02}. It is concluded that IFSs are a powerful tool for identifying self-similarity in soil PSDs, and for reconstructing PSDs using data from a limited number of textural classes.

By Soil Survey Staff, Soil Taxonomy A Basic System of Soil Classification for Making and Interpreting Soil Surveys Second Edition, 1999, United State Department of Agriculture, Natural Resources Conservation Service Agriculture Handbook Number 436, (869pp.)

By Soil Survey Staff, Soil Taxonomy A Basic System of Soil Classification for Making and Interpreting Soil Surveys Second Edition, 1999, United State Department of Agriculture, Natural Resources Conservation Service Agriculture Handbook Number 436, (869pp.)

Assessment of the arachidonic acid content in foods commonly consumed in the American diet.

Arachidonic acid (AA) is an extremely important fatty acid involved in cell regulation. When provided in the diet, it is cogently incorporated in membrane phospholipids and enhances eicosanoid biosynthesis in vivo and in vitro; however, controversy exists as to the levels of AA in food and in the diet. This study determined the amount of AA in cooked and raw portions of beef (rib eye), chicken (breast and thigh), eggs, pork (loin), turkey (breast), and tuna; it compared these results to values published in Agriculture Handbook No. 8 (HB-8). The cooked portions were prepared as described in HB-8. With the exception of chicken thigh and tuna, the levels of AA (w/w) in the selected foods analyzed were significantly higher, in general, than those values published in HB-8. The greatest differences were observed in beef (raw and cooked), turkey breast (raw and cooked), and pork (cooked) where AA levels were twice that of the values in HB-8. In contrast, the AA and n-3 fatty acid contents in tuna were almost half the HB-8 values. The present data indicate that HB-8 tends to underreport the amounts of AA in a number of foods commonly consumed in the American diet, and new initiatives should be considered to validate and update the current database for fatty acid composition of foods.

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.

Information from USDA's Nutrient Data Bank

The United States Department of Agriculture's Nutrient Data Bank contains a wealth of information on the composition of foods. These data are made available to the public through Agriculture Handbook No. 8, Composition of Foods: Raw, Processed, Prepared, its computerized form—the USDA Nutrient Data Base for Standard Reference, and other publications. Food components in Agriculture Handbook No. 8 include proximate components, minerals, vitamins, fatty acids, cholesterol, phytosterols, and amino acids. Other tables and data sets containing food components of special interest such as vitamins D and K, selenium, and sugars, are also available. This paper describes how to obtain the data in either printed or electronic form. Information on obtaining the data through the Nutrient Data Bank Bulletin Board or the Internet is also presented.

Erosivity Index Values for Northern Mississippi

Annual rainfall erosivity (R) values during 1982 to 1992 were computed from 29 standard recording rain gages in or adjacent to the 21.3 km2 Goodwin Creek Watershed near Batesville, Mississippi, using Brown-Foster, McGregor-Mutchler, Agriculture Handbook 282, and Agriculture Handbook 537 procedures. The computations were made to determine the adequacy of previously recommended erosivity values for northern Mississippi. Computed R values were substantially higher than interpolated values given in Agriculture Handbooks 282 and 537, or the Users Guide for the Revised Universal Soil Loss Equation (RUSLE). The interpolated value from the iso-erodent map used in RUSLE is only about 5790 MJmm(hah)1. The average annual R value computed with the Brown-Foster equation for the 29 rain gages was 7968 MJmm(hah)1 for all storms with no limitations on storm size or intensity parameters, 7719 MJmm(hah)1 for all storms but with a limitation of 64 mm/h on the I30 parameter of the energy-intensity (EI) product, and 7515 MJmm(hah)1 where (1) storms less than 13 mm were excluded unless the storms contained 15-min rainfall intensities of 25 mm/h or more, and (2) the maximum 30-min intensity in the EI product was limited to 64 mm/h. This latter R value was still 30% higher than the R value obtained from the Users Guide for RUSLE. Various limitations that have previously been recommended for use in calculating R values were found to affect R totals from less than one to less than 4%. This is the second study in northern Mississippi, on different intensively gaged watersheds, that has shown significantly higher measured R values than previously recommended. Results from these studies also have been supported by measurements taken at Holly Springs, Mississippi, during erosion related research during a 25-year period. These results indicate that R values in the mid-south should be recomputed using modern rainfall data to replace existing iso-erodent index maps in which estimates of erosivity often were based on regression equations rather than measured values. Preparation of a standard erosivity map for the complete eastern United States also is recommended, especially considering the availability and ease of analyzing modern rainfall computations, and the advantage of having a standard erosivity map based on measurements.

Vitamin B-6 requirements of humans

Vitamin B-6, also referred to as vitamin B 6, is the generic descriptor for all 3-hydroxy-2-methylpyridine derivatives possessing the biological activity of pyridoxine. Convincing evidence of the essentiality of the vitamin was demonstrated when hyperirritability and epileptiform-type seizures were reported in infants fed autoclaved commercial liquid formula low in vitamin B-6; administration of the vitamin corrected these symptoms. Vitamin B-6 status and requirements have been assessed using several methodologies. Dietary assessment usually consists of 24-h recall and/or 2–7-d intake records with nutrient composition being estimated using values given in the US Department of Agriculture's Handbook 8 series. Frequently used biochemical assessment methodologies include xanthurenic acid excretion after a tryptophan load, urinary 4-pyridoxic acid level, urinary and plasma total vitamin B-6 levels, erythrocyte alanine and aspartate aminotransferase activity coefficients, and plasma pyridoxal-5′-phosphate concentration. The most accepted vitamin B-6 status parameter is plasma pyridoxal-5′-phosphate concentration; however, more than one method should be utilized in evaluating status. The minimum vitamin B-6 requirement of men as evaluated by different researchers using various methodologies seems to be about 0.65 to 1.25 mg/d; similar estimates have been made for women. Estimates of vitamin B-6 requirements of pregnant and lactating women range from about 2.1 to 7.6 mg/d; pregnancy may affect many of the parameters utilized for assessing vitamin B-6 status. Controlled feeding studies utilizing infants, children, and adolescents are mainly lacking. Recommended Dietary Allowances (RDAs) for vitamin B-6 have existed since 1968; these RDAs are based primarily on protein intake. A few other countries also have recommended intake values for the vitamin. Vitamin B-6 metabolism and requirements may be altered in several diseases and pathological conditions. The symptoms for some but not all patients with these diseases/conditions have been reported to improve when therapeutic doses of the vitamin are given. Vitamin B-6 has been shown to be toxic. Dosages above 200 mg pyridoxine hydrochloride/d are not recommended.

Seeds of woody plants in North America

A revised edition of Agriculture Handbook 450 issued by the U.S. Forest Service, this encyclopedia of woody plant seeds covers 386 genera, adds more than 1,000 literature citations to the original, and treats all aspects of collection, storage, and germination.

Nutritive composition of Al-Nokel grape fragments and the potentiality of making evaporator-concentrate

A study was designed to produce evaporator-concentrated juice from Al-Nokel grapes and to contrast the proximate, physical and elemental composition of the fresh fruits (edible portion), single strength juice and the concentrate. Also, changes during storage in physicochemical (reducing sugars, sucrose, ascorbic acid and acidity), microbial and sensory characteristics were studied to determine the effect of storage time and storage temperature on the quality. The Al-Nokel grape cultivar is grown on a commercial level in the Al-Nokel area in Al-Madina Al-Monawara City, the South-Eastern region of Saudi Arabia. Proximate analysis indicated that the protein, lipid and ash contents of the edible portion of Al-Nokel grapes found in this study were approximately in agreement with the literature values (FAO, (1982) Food Composition Tables for the Near East. FAO, Rome; Paul & Southgate, (1978) The Composition of Foods. Elsevier/North-Hall, New York) but the total sugar content was higher than those reported in the literature and by Wall & Merrill (1975) Composition of Food, Agricultural Handbook no. 8. Consumer and Food Economics Institutes. Agricultural Research Service, US Department of Agriculture, Washington, DC. The edible portion of the fruit was found to be rich in potassium and magnesium while the fresh extracted juice was a fair source of potassium, magnesium and iron. The decrease in sucrose and ascorbic acid and the increase in reducing sugars were linearly related to the storage time. The increase in the reducing sugars was due to the hydrolysis of the sucrose under these conditions. The results of sensory evaluation indicated that panellists were not able to detect any significant changes in the quality attributes after 2 months of storage at various temperatures. However, after 6 months of storage there was a significant difference ( p < 0.05) in colour, flavour and overall acceptability between samples stored at 25°C and those stored at 1 and 5°C. Microbial analysis revealed that the concentrates stored at the three various temperatures were microbially stable through the storage period, and showed the absence of aerobic plate counts, coliforms, sporeformers and yearsts and moulds.