首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Beneficial forms of selenium (Se) and their impact on human health are a global topic of interest in public health. We are studying the genetic potential for Se biofortification of pulse crops to improve human nutrition. Lentils ( Lens culinaris L.) are an important protein and carbohydrate food and are a valuable source of essential dietary components and trace elements. We analyzed the total Se concentration of 19 lentil genotypes grown at eight locations for two years in Saskatchewan, Canada. We observed significant genotypic and environmental variation in total Se concentration in lentils and that total Se concentration in lentils ranged between 425 and 673 microg kg(-1), providing 77-122% of the recommended daily intake in 100 g of dry lentils. Over 70% of the Se was present as selenomethionine (SeMet) with a smaller fraction (<20%) as inorganic Se and very small amounts as selenocysteine (SeCys). We found that soils from the locations where the lentils were grown were rich in Se (37-301 microg kg(-1)) and that lentils grown in Saskatchewan have the potential to provide an excellent natural source of this essential element. Our analyses gave us a preliminary understanding of the genetic basis of Se uptake in lentil and indicated that any potential strategy for micronutrient biofortification in lentil will require choice of field locations that minimize the spatial variability of soil Se content.  相似文献   

2.
Selenium is an essential element in the human diet. Interestingly, there has been an increased consumption of dietary supplements containing this element in the form of either inorganic or organic compounds. The effect of using selenium as a dietary supplement in yogurt has been evaluated. For this purpose, different concentrations of inorganic Se (ranging from 0.2 to 5000 microg g(-1)) have been added to milk before the fermentation process. Biotransformation of inorganic Se into organic species has been carefully evaluated by ion-exchange, reversed-phase, or size-exclusion chromatography, coupled to inductively coupled plasma mass spectrometry (ICP-MS). Yogurt fermentation in the presence of up to 2 microg g(-1) of Se(IV) produces a complete incorporation of this element into proteins as has been demonstrated applying a dialysis procedure. Analysis by SEC-ICP-MS showed that most of them have a molecular mass in the range of 30-70 kDa. Species determination after enzymatic hydrolysis has allowed the identification of Se-cystine using two different chromatographic systems. The biotransformation process that takes place during yogurt fermentation is very attractive because yogurt can act as a source of selenium supplementation.  相似文献   

3.
施硒对茄子吸收转化硒和品质的影响   总被引：16，自引：4，他引：16  
盆栽试验结果表明,土壤施硒(0.15、0.60、3.00mg/kg)条件下,茄子的含硒量随施硒量的增加而显著增加。当施硒量为0.60和3.00mg/kg时,茄子无机硒转化成有机硒的比率下降,显著提高了茄子粗蛋白、粗脂肪和还原糖含量,增加了茄子的必需氨基酸总量,改善了茄子的品质。土壤施硒显著增加了茄子蛋氨酸、胱氨酸和丝氨酸的含量,但谷氨酸和脯氨酸的含量显著降低。  相似文献   

4.
The effect of two sources of Se, selenized yeast (Se-Y) and sodium selenite, added to total mixed rations (TMR) fed to cows on Se milk content and distribution in milk components was studied on three farms for 6 weeks. The maximal increase in milk Se was attained with Se-Y supplemented at 0.3 microg g(-1). The effect was immediate, with an increase of 9 microg L(-1) being observed after only 5 days, and remained steady until the last sample at day 40 of Se supplementation. Se distribution in milk components was constant, 53.6, 42.6, and 9.3% in whey, casein, and fat, respectively, and was unaffected by the form of supplementation. The effect of the level of Se-Y supplementation on milk Se was studied on two farms. Increasing dietary Se-Y from 0 to 0.5 microg g(-1) elevated milk Se content from 20 to 39 microg L(-1). Se-enriched cow's milk at different levels can be produced by varying dietary Se supplementation in the form of selenized yeast.  相似文献   

5.
A method of hydride generation atomic fluorescence spectrometry was applied to the determination of the selenium concentration of regular polished rice in China and selenium-enriched polished rice obtained by foliar application of selenium-enriched fertilizer in the forms of selenite and selenate. The average selenium content of regular rice was 0.025 +/- 0.011 microg g(-)(1). On the basis of a daily dietary rice intake of 300-500 g suggested by the China Nutrition Society, the total selenium intake from regular rice was calculated to be 7.5-12.5 microg per person per day for an adult. The selenium contents of rice were significantly increased to 0.471-0.640 microg g(-)(1) by foliar application of selenium-enriched fertilizer at rate of 20 g of Se ha(-)(1) in the forms of sodium selenite and sodium selenate. The selenium content of rice by application of a fertilizer of selenate was 35.9% higher than that by a fertilizer of selenite, which showed that Se-enriched fertilizer in selenate exhibited greater efficiency in increasing Se content in rice products. The Se-enriched rice products can increase daily Se intake on average by 100-200 microg of Se per day by the consumption of 400 g of rice products if the Se level of rice products is controlled at 0.3-0.5 microg of Se g(-)(1). Because rice is a staple food in China, selenium-enriched rice obtained by bioenrichment of selenium to increase the Se content of rice could be a good selenium source for the population in selenium-deficient regions.  相似文献   

6.
Selenium-enriched broccoli florets, harvested from plants grown on soil fertilized with four levels of sodium selenate, were evaluated for their free amino acid composition using alkylchlorformate derivatization, solid-phase extraction, and GC-FID or GC-MS. The selenium-enriched florets contained 0.4 (control), 5.7 (treatment A), 98.6 (treatment B), and 879.2 (treatment C) microg/g Se (dry weight). Twenty-one free amino acids were identified in the control and all three treatments. The total free amino acid content of the broccoli florets ranged from 178 mmol/kg (dry weight), for the control, to 479 mmol/kg (dry weight), for treatment C. Broccoli from treatment C contained the highest level of Se, had the most total free amino acids, and had an extremely high level of glutamine (Gln) when compared to the control and the other two treatments. In general, the smallest addition of Se to the soil (treatment A) induced increased levels of all detectable amino acids when compared to the control, whereas increased additions of Se (treatments B and C) produced mixed responses. Florets from treatment A contained the highest essential amino acid content.  相似文献   

7.
土壤增施蛋氨酸硒对厚皮甜瓜生理特性和品质的影响   总被引：3，自引：0，他引：3  
【目的】本研究探究了蛋氨酸硒对厚皮甜瓜生长与生理特性的调控作用,硒在厚皮甜瓜中的富集效益,以及硒在土壤中的变化趋势。【方法】以‘M135’厚皮甜瓜为试材,蛋氨酸硒为硒源,采用盆栽试验,以土壤本底硒为对照,通过向土壤中增施蛋氨酸硒使土壤中的总硒含量分别增加4、 10和16 mg/kg,研究了蛋氨酸硒对厚皮甜瓜生长、 产量、 光合特性、 产品品质及果肉硒含量的影响,对厚皮甜瓜不同组织器官中总硒含量的影响,以及对土壤中不同形态硒含量变化的影响。【结果】施硒4、 10和16 mg/kg均可显著提高甜瓜叶片光合色素含量、 叶片光合速率、 植株生长量以及甜瓜产量; 另外,不同浓度施硒处理还显著提高了果肉中有机硒、 无机硒、 可溶性糖、 可溶性蛋白、 游离氨基酸和维生素C的含量,并以10 mg/kg施硒处理的效果最佳。10 mg/kg施硒处理的单株产量比对照提高了19.53%,果肉中的可溶性糖、 可溶性蛋白、 游离氨基酸和维生素C的含量比对照分别提高了14.82%、 49.88%、 23.42%和25.03%,果肉中硒的总含量为44.74 μg/kg,其中有机硒含量36.87 μg/kg,占到总硒含量的82.91%,达到富硒标准。进一步的研究发现,虽然果肉中硝酸还原酶活力、 硝酸盐和亚硝酸盐含量均随施硒浓度的增加而增加,但4、 10和16 mg/kg施硒处理后的亚硝酸盐含量分别为1.499、 1.907和2.131 mg/kg,均远低于国家标准的上限(20 mg/kg)。对施硒后厚皮甜瓜不同组织器官中硒含量的研究发现,厚皮甜瓜各组织器官(根、 茎、 叶柄、 叶、 果皮、 果肉和种子)的总硒含量也随施硒浓度的增加而增加。对根、 茎、 叶柄和叶的比较发现,在未增施蛋氨酸硒时叶中的硒含量最高,其次为根、 茎和叶柄; 而增施蛋氨酸硒后则表现为根中最多,其次为茎、 叶和叶柄。对果皮、 果肉和种子的比较发现,各处理果实内各组织的总硒含量均表现为种子中最多,其次为果肉和果皮。对施硒后土壤中不同形态硒含量的研究发现,定植后未施蛋氨酸硒的上层土壤中总硒、 无机态Se6+的含量均呈下降趋势,土壤中有机硒和无机态Se4+的含量变化不大; 4、 10和16 mg/kg施硒处理的土壤中有机硒、 总硒以及无机态Se4+含量都呈先下降后趋于平缓的趋势,而无机态Se6+的含量则呈先上升后下降的趋势。【结论】土壤增施蛋氨酸硒后提高了厚皮甜瓜果肉的硒含量,增强了光合能力,促进了厚皮甜瓜植株的生长,从而提高了产量和综合品质,其适宜的土壤施硒浓度为10 mg/kg。  相似文献   

8.
黄颡鱼的含肉率及肌肉营养价值研究   总被引：9，自引：0，他引：9  
采用常规方法测得广西桂江黄颡鱼的含肉率为 83.88% ;每 1 0 0 g肌肉 (干样 )中含粗蛋白85.96g,粗脂肪 5.0 4 g,粗灰分 5.57g,氨基酸总量为 70 .2 1 g,必需氨基酸含量 2 7.39g,含钙 39.58mg,磷 1 87mg,铜 0 .33mg,锌 5.33mg,铁 4 .75mg,锰 3.0 3mg,硒 74 7.0 6μg。综合分析结果认为 ,广西桂江的黄颡鱼是营养价值较高的优质鱼类  相似文献   

9.
Accumulations of selenium in kelp Laminaria japonica cultured in seawater was achieved by adding selenite (Na2SeO3) with or without N-P (NaNO3 + NaH2PO4) nutrients at different concentrations. Biotransformation of selenium in the kelp was investigated through measuring the selenium of biological samples and different biochemical fractionations. The results showed that the optimal selenite-enrichment concentration is 200 mg L(-1), which can allow the kelp to accumulate a total selenium content from 0.51 +/- 0.15 to 26.23 +/- 3.12 microg g(-1) of fresh weight (fw). Selenium composition analysis of kelp (control group) showed that selenium is present as organic selenium, which is up to 86.22% of the total selenium, whereas inorganic selenium is barely 4.85%. When L. japonica was exposed for 56 h in seawater containing 200 mg L(-1) Na2SeO3, the organic selenium was 16.70 microg g(-1) of fw (68.23%) and inorganic selenium was 4.71 microg g(-1) of fw (19.26%). The capability of accumulation of selenium was further enhanced by adding N-P nutrients to the selenite-enriched medium. Total selenium is increased to be 33.65 microg g(-1) of fw at optimal concentration of N-P nutrient (150 mg L(-1) NaNO3 and 25 mg L(-1) NaH2PO4), whereas the inorganic selenium was not increased and remained at 4.597 microg g(-1) of fw (13.36%), and the increased part of selenium was organic selenium. This implied that kelp L. japonica could effectively transform inorganic selenium into organic selenium through metabolism.  相似文献   

10.
Brassica carinata protein isolates were hydrolyzed using the digestive enzymes trypsin, chymotrypsin, and carboxypeptidase A in order to obtain hydrolyzates with a high Fischer's ratio. The proteases were immobilized using two glyoxyl-agarose supports of different porosity, 4 and 10% agarose gels, in order to evaluate the effect of substrate diffusion into the support containing the enzyme on the hydrolytic process. Reaction time, substrate concentration, and the enzyme to substrate ratio were optimized in an attempt to increase the Fischer's ratio in the resulting hydrolyzates. Gel filtration chromatography of a hydrolyzate with a degree of hydrolysis of 36% yielded a fraction that represented 31% of the total hydrolyzed proteins and had a Fischer's ratio of 28.3 with a phenylalanine + tyrosine content below 1.5%. This material could be used for preparing special diets when there is a need to increase the supply of branched amino acids and/or reduce the intake of aromatic amino acids.  相似文献   

11.
The quality of Tombul (Round) hazelnut, grown in the Giresun province of Turkey, was determined by measuring proximate composition, minerals, vitamins, dietary fiber, amino acids, and taste active components (free amino acids, sugars, and organic acids). Fat was the predominant component in Tombul hazelnut (approximately 61%). The major minerals were potassium, phosphorus, calcium, magnesium, and selenium. Hazelnut was also found to serve as an excellent source of vitamin E (24 mg/100 g) and a good source of water soluble (B complex) vitamins and dietary fiber. The major amino acids were glutamic acid, arginine, and aspartic acid. The three nonessential amino acids and the essential amino acids contributed 44.9 and 30.9% to the total amino acids present, respectively, while lysine and tryptophan were the limiting amino acids in Tombul hazelnut. Twenty-one free amino acids, six sugars, and six organic acids were positively identified; among these, arginine, sucrose, and malic acid predominated, respectively. These taste active components may play a significant role in the taste and flavor characteristics of hazelnut. Thus, the present results suggest that Tombul hazelnut serves as a good source of vital nutrients and taste active components.  相似文献   

12.
The earthworm is one of the typical saprophagous organisms that has been successfully used to convert organic waste into biomass. Indeed, vermicomposting occurs throughout the world. More recently, research on pharmaceuticals derived from earthworms, known as green biomedicine, has been increasing. As a result, earthworms have become an international medicine, even though their original utilization in traditional medicine has been known for thousands of years. With the development of biomedicine, scientists have rediscovered the medicinal value of earthworms related to many chemical components, including (1) earthworm proteases (lumbrokinase, collagenase, superoxide dismutase, cholinesterase, catalases, glycosidases); (2) metal-binding protein (metallothionein, calmodulin-binding protein); (3) other active proteins including those with proliferative improving activity like lysenin, eiseniapore, antitumor proteins, and glycoprotein; (4) active peptides (gut mobility regulation peptide, antibacterial peptide); (5) earthworm metabolites (carbamidine, lumbrinin, lumbrofobrin, terrestrolumbrolysin); (6) special organic acids (succinic acid, lauric acid, and unsaturated fatty acid) and (7) other components such as purin, vitamin B, tyrosine and Se. In this paper, we mainly describe earthworm fibrinolytic enzymes and antibacterial peptides in particular.  相似文献   

13.
The amounts and compositions of free, conjugated, bound, and total phenolic acids were determined in 175 samples of wheat flour grown on a single site in 2005. The highest contents of total phenolic acids were found in flours of winter wheat (1171 microg/g) with average levels of 658 microg/g total phenolics across all of the wheat genotypes. Winter wheats showed a range of >3.5-fold across the concentration range for total phenolic acids. Spelt genotypes displayed the narrowest (1.9-fold) range of total phenolic acid concentration. The concentrations of phenolic acids in the different phenolic acid fractions were in the order bound > conjugated > free, with bound phenolic acids making up around 77% of the total phenolic acid concentration and free phenolic acids constituting between 0.5 and 1%. The results indicate that there is genetic diversity in phenolic acid content and that it should be possible to selectively breed for lines with high contents of phenolic components.  相似文献   

14.
Crops grown in seleniferous soil may accumulate selenium (Se) to levels considered highly toxic for animal and human consumption. Furthermore, higher Se content in plant tissues leads to considerable deterioration in product quality. Application of organic amendments plays an important role in improving soil physical, chemical, and biological conditions and influencing nutrient availability. A field trial was conducted to evaluate the effect of organic amendments, namely poultry manure (PM), sugar cane press mud (SCPM), and farmyard manure (FYM), on Se uptake and grain quality of wheat and oilseed rape grown on a seleniferous soil in Punjab, India. Selenium accumulation by wheat and oilseed rape grains decreased significantly (75%–95%) with the application of PM and SCPM, while FYM application resulted in a significant decrease (23%) only in case of wheat grains. The amount of Se associated with seed proteins varied in proportion to its uptake under different treatments. Quality of wheat grains improved considerably with respect to total soluble sugars, reducing sugars, starch, lipids, and sulfur concentrations only after application of SCPM and PM. Treating a Se‐contaminated soil with organic amendments significantly increased the oil concentration and changed the proportion of various fatty acids in rape grains. It is concluded that applying organic amendments to Se‐contaminated soils can alleviate the deleterious effects of Se and restore the nutritional quality of grains.  相似文献   

15.
为实现亚麻籽饼粕中分离蛋白的综合加工利用,该文以冷榨亚麻籽饼粕为原料,对其进行脱胶脱脂处理,采用超声辅助水提法分别提取亚麻籽分离蛋白和脱胶脱脂亚麻籽分离蛋白,并对理化性质、结构及功能特性进行分析比较。结果表明,冷榨亚麻籽饼粕和脱胶脱脂亚麻籽饼粕中蛋白质质量分数分别为37.52%±0.04%、37.47%±0.02%。采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳测定亚麻籽分离蛋白和脱胶脱脂亚麻籽分离蛋白的分子质量,显示10～55 kDa之间有明显谱带,其中水溶性低分子质量的白蛋白（10、14、15及17 kDa）和盐溶性高分子质量的球蛋白（30、33、35、40、45及55 kDa）谱带最为明显。氨基酸的种类各检测到17种,含有丰富的必需氨基酸和非必需氨基酸。傅里叶变换红外光谱测定的2种蛋白质的二级结构稳定性一般;由扫描电镜和X-射线衍射可知亚麻籽分离蛋白比脱胶脱脂亚麻籽分离蛋白的微观孔隙率低,结构中都较缺乏结晶度或有序排列。2种蛋白的两亲性与大豆分离蛋白相比,亲水/油特性突出,亲油性是大豆分离蛋白的2倍多。通过对不同pH（2～11）和盐离子浓度（0～1.25 mol/L）下溶解度、起泡性、泡沫稳定性、乳化活性及乳化稳定性的测定,显示两者具有良好的碱溶性,脱胶脱脂亚麻籽分离蛋白的起泡性、乳化活性及乳化稳定性均优于亚麻籽分离蛋白,而泡沫稳定性恰好相反,该研究结果有利于拓宽2种分离蛋白在健康食品领域中的应用前景,为食品中的应用提供有益参考和数据支撑。  相似文献   

16.
Analyses of chemical residues in animal tissue matrices require multistep sample preparation. To simplify this process, a methodology was developed that combines sorbent extraction and solid-matrix time-resolved luminescence (TRL); it was applied to tetracycline screening in milk. Reported here is an effort to extend its application to tissue matrices, illustrated by oxytetracycline (OTC) screening in catfish muscle. Extraction and enrichment are accomplished by immersing small C18 sorbent strips into tissue homogenates for 20 min, followed by a 3 min rinse in water and a 2 min dip in a reagent solution. After desiccation, TRL is measured directly on the sorbent surface. Tissue particulates no longer interfere via attenuation or scattering, rendering centrifugation and filtration unnecessary. The integrated TRL intensity shows a linear dependence on OTC concentration in the 0-8 microg/g range (R2 = 0.9992) with a 0.026 microg/g limit of detection. To screen OTC at 2 microg/g, the U.S. regulatory tolerance level, a threshold is established at x2-3sigma2, where x2 and sigma2 are the mean and standard deviation, respectively, of the TRL signals from 15 samples fortified at 2 microg/g. Among 45 blind samples randomly fortified at 0-4 microg/g, 41 were screened correctly and 4 negative samples were presumed positive. This method has the potential to improve throughput and save assay costs by eliminating acids, organic solvents, centrifugation, and filtration.  相似文献   

17.
为了明确叶面喷施亚硒酸钠对黑豆硒吸收转运特征及籽粒硒形态的影响,采用小区试验在黑豆结荚兴盛期进行一次性叶面喷施亚硒酸钠(施硒量分别为0、6、12、18和24 mg·m-2)处理,分析比较不同浓度亚硒酸钠处理下黑豆产量、各器官硒含量、籽粒有机硒转化率和品质性状的差异。结果表明,各施硒水平对黑豆各器官总硒含量均有提升作用,在24 mg·m-2硒处理时各器官总硒含量最大,根、茎、荚和籽粒硒含量分别较对照提高了8.74、8.37、9.85和65.21倍,硒处理后各器官总硒含量呈现籽粒>根≈荚>茎的特点。籽粒中硒以有机硒形态存在,且有机硒转化率随着亚硒酸钠浓度的增加呈下降趋势,在0、6、12、18和24 mg·m-2施硒处理时,有机硒含量分别为0.071 4、1.101 8、1.510 6、1.811 1和2.093 5 mg·kg-1,有机硒转化率分别为94.52%、84.81%、70.30%、60.11%和52.43%。叶面喷施亚硒酸钠显著提高了黑豆籽粒蛋白质含量和分离蛋白硒含量,但对脂肪含量的影响较小,在24 mg·m-2硒处理时蛋白质含量和分离蛋白硒含量分别较对照增加了2.4个百分点和117.35倍,分离蛋白硒含量占有机硒和总硒含量的比例分别为90.29%和47.39%。适宜浓度亚硒酸钠叶面喷施对黑豆产量具有促进作用,但浓度过高导致增产效果减弱。综上,叶面喷施亚硒酸钠可提高黑豆各器官总硒含量,但黑豆籽粒有机硒转化率随喷施浓度的增加呈下降趋势,且黑豆籽粒有机硒主要以蛋白质形式存在。本研究结果为应用外源硒强化技术生产富硒黑豆提供了科学依据。  相似文献   

18.
外源硒矿粉对玉米硒累积及矿质元素吸收的影响   总被引：3，自引：1，他引：3  
【目的】通过生物强化的方法获得生物安全形态的有机硒,是实现人体科学补硒的重要途径。研究外源硒矿粉在生产中的合理施用量及其对作物的影响,可为富硒农产品生产提供理论与技术指导。【方法】以玉米为试材,以湖北恩施的富硒矿粉(总硒含量为180 mg/kg)为硒源进行田间试验,研究了玉米对外源硒的吸收与转化及施硒对玉米矿质元素吸收的影响。设5个施硒处理: Se 0 (CK)、 750 (Se1)、 1500 (Se2)、 2250 (Se3) 和3000 g/hm2 (Se4)。于玉米大喇叭口期和成熟期取样,测定玉米不同部位总硒含量以及玉米籽粒中总硒、 有机硒及矿质元素含量。【结果】土壤施用富硒矿粉对玉米籽粒产量和总生物量没有显著影响,但可显著增加玉米籽粒及各器官硒含量。随硒施用量由0增加到3000 g/hm2,玉米籽粒中硒含量由14.2 μg/kg 增加到350.3 μg/kg。除Se2处理外,玉米根系中的硒含量在收获期高于抽穗期,而玉米茎和叶中的硒含量在收获期低于抽穗期。玉米不同器官对硒的富集能力依次为根叶籽粒茎,而玉米对硒的转移系数大小顺序亦为叶籽粒茎。与对照相比,施硒使玉米籽粒中有机硒含量显著增加,不同施硒处理玉米籽粒中有机硒含量范围为12.9~302.6 μg/kg,随土壤施硒量增加,有机硒占总硒的比例从86.87%增加到90.84%,不同处理之间有机硒所占比例差异不显著。玉米籽粒总硒、 有机硒与各器官硒含量之间均表现出显著的相关性,其中籽粒中有机硒与不同生育期根中硒含量达到极显著相关水平。施硒可显著抑制玉米籽粒对Na的吸收,对K、 Ca、 Mg、 Fe 的吸收无显著影响,一定的施硒水平下,可促进玉米籽粒对Mn、 Cu、 Zn的吸收。【结论】施用外源硒矿粉对玉米生物量与籽粒产量无显著影响。随施硒量增加,玉米籽粒中总硒含量和有机硒含量与对照相比显著增加,但对玉米籽粒中的有机硒与总硒的比例没有显著影响。一定施硒水平下,可促进玉米籽粒对Mn、 Cu、 Zn的吸收。以纯硒施用量为750~1500 g/hm2作为硒矿粉在富硒玉米生产中的推荐施硒量。  相似文献   

19.
In some regions of the world, where the bioavailability of selenium (Se) in soil is low and/or declining (e.g., due to use of high-sulfur fertilizers), there is increased risk of adverse affects on animals and human health. In recent years, increased research attention has focused on understanding the relationships between Se contents in foods and supplements and their nutritional benefits for animal and humans. The objective of this study was to use a species-unspecific isotope dilution and reverse phase ion pairing-inductively coupled plasma-mass spectrometry techniques for the identification and quantification of Se species in biofortified grains (i.e., wheat and triticale), flour, and wheat biscuits. The information on Se species was used to gain an understanding of the bioavailability of Se in biofortified and process-fortified wheat biscuits used in a clinical trail. The major Se species identified in biofortified and process-fortified samples were selenomethionine (76-85%) and selenomethionine selenoxide (51-60%), respectively. Total plasma Se concentrations in the biofortified Se exposure group were found to increase throughout the 6 month trial period (mean=122 microg L(-1) at 0 months to 194 microg L(-1) at 6 months). In contrast, the trial group exposed to process-fortified Se biscuits showed little increase in mean total Se plasma concentrations until 4 months of exposure (mean=122 microg L(-1) at 0 months to 140 microg L(-1) at 4 months) that remained constant until the end of the trial period (mean=140 microg L(-1) at 4 months to 138 microg L(-1) at 6 months). The difference in total Se plasma concentrations may be due to the presence and bioavailability of different Se species in biofortified and process-fortified biscuits. An understanding of Se speciation in foods enables better understanding of pathways and their potential benefits for animals and humans.  相似文献   

20.
A flow-through experimental wetland system has been under investigation since 1996 to remove selenium (Se) fromagricultural drainage water in the Tulare Lake Drainage Districtat Corcoran, California, U.S.A. The system consists of ten cellswhich have dimensions of 15 × 76 m continuously flooded andvarious substrates planted. The objectives of this article are topresent the overall performance in Se removal after establishingthe wetland for three years, and to examine factors affecting Seremoval with special attention to accumulation in the sediments.In 1999, The wetland cells reduced Se from inflow water by 32 to65% in concentration and 43 to 89% in mass. Vegetationplays an important role in Se removal as non-vegetated cellshowed the least removal of Se. The inflow drainage water wasdominated by selenate (Se(VI), 91%) with smaller percentages ofselenite (Se(IV), 7%) and organic Se (org-Se(II-), 2%). Theoutflow water from the cells contained an average of 47% Se(VI),32% Se(IV) and 21% org-Se indicating reduction processesoccurring in the wetland cells. The surface sediment appears as alarge sink of Se removal. The highest Se concentration was foundin fallen litter, followed by the fine organic detrital layer onthe sediment surface. The sediment Se concentration dramaticallydecreased with increasing sediment depth. The mass distribution of Se, however, was sediment (0-20 cm) > fine detrital matter >fallen litter. Fractionation of surface sediment (0-5 cm) reveals that elemental Se was the largest fraction (ave. 47%) followedby organic matter-associated Se (34%). Soluble, adsorbed, and carbonate-associated Se accounted for 1.2, 3.1 and 2.5% ofthe total sediment Se, respectively. The major Se sink mechanism in the cells is the reduction of selenate to elemental Se andimmobilization into the organic phase of the sediments.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号