共查询到20条相似文献,搜索用时 0 毫秒
1.
The water extractable (WE) arabinoxylans from two rye flours differing in baking quality were studied following sequential extraction with water at 4, 40, and 100 degrees C. Ammonium sulfate fractionation of the resulting WE fractions and subsequent analysis revealed substantial differences in the structure of the isolated materials. Furthermore, it allowed us to identify the factors contributing to arabinoxylan water extractability. Our results provide compelling evidence for the existence of separate polymers in rye WE arabinoxylans with different substitution degrees, ranging from quantitatively dominating, lowly substituted populations (arabinose to xylose ratio, Ara/Xyl approximately 0.5) to comparatively less abundant, highly substituted analogues (Ara/Xyl approximately 1.3). Generally, arabinoxylan water extractability was governed by the relative proportion of lowly and highly branched structures. A gradually increasing proportion of highly substituted populations was observed from cold to hot WE fractions. This was associated with the lower proportion of monosubstituted xylopyranosyl residues in the backbone, the higher proportion of disubstituted xylopyranosyl residues, and the higher level of substitution with feruloyl residues. Notable differences in the ratio of phenolic compounds to arabinose residues were observed between corresponding polymers isolated from rye flours of high and low baking quality, whereas the differences in their molecular weights were much less pronounced. 相似文献
2.
Verwimp T Van Craeyveld V Courtin CM Delcour JA 《Journal of agricultural and food chemistry》2007,55(5):1985-1992
The variability in rye flour alkali-extractable arabinoxylan (AE-AX) structures was examined by extensive fractionation and enzymic degradation studies. AX were isolated from destarched rye water-unextractables by sequential extraction with saturated barium hydroxide solution, water, 1.0 M sodium hydroxide, and water. The isolated AE-AX contained ca. 51% AX with an arabinose to xylose (A/X) ratio of 0.71. Fractionation of the isolated AE-AX by ethanol precipitation yielded a range of AE-AX fractions containing AX molecules with different A/X ratios and substitution patterns. Degradation of these structurally different AE-AX fractions by an Aspergillus aculeatus endoxylanase (XAA) and a Bacillus subtilis endoxylanase (XBS) resulted in AX fragments with various structural features. Further fractionation of the degraded AE-AX fractions by ethanol precipitation showed that a strong correlation exists between the structural features of the AX fragments, that is, average degree of polymerization (DP) of the xylan backbone, A/X ratio, and substitution pattern. Results indicated that the rye flour AE-AX consist of a continuum of structures rather than of two types of AX or two types of regions in the AX molecule. 相似文献
3.
Recent studies have indicated that some structural features of arabinoxylans, the major cell wall polysaccharides, might be potential quality markers in the selection of rye breeding materials. To specify the most appropriate characteristics, the differences in the structure of cell wall components were studied in two ryes with high and low breadmaking qualities. Two cell wall fractions were isolated from the outer layers of the grain (pooled shorts and bran fractions) by a consecutive water extraction with alpha-amylase (WE-A) and proteinase K (WE-P). Polysaccharides predominated in the WE-A fraction (approximately 64%, mainly arabinoxylans). By contrast, the WE-P fraction contained mostly protein (approximately 63%), and its level of polysaccharides was relatively low (approximately 18%). The 1H NMR and sugar analysis of the ammonium sulfate precipitated subfractions revealed that the WE-A was built of four arabinoxylan populations with marked structural differences (arabinose-to-xylose ratios, Ara/Xyl, of approximately 0.3, 0.5, 0.8, and 1.2). Instead, the arabinoxylans present in the WE-P were generally enriched in disubstituted xylopyranosyl residues. The ratio of phenolic components to arabinose residues in the WE-P fraction (indicated by 1H NMR) and the proportion of polymers with the highest molecular weights in the WE-A fraction (revealed by HPSEC) distinguished well two ryes with diverse breadmaking qualities. Much less obvious differences between both ryes were observed in the ratio of amide I to amide II band intensities of FTIR spectra for the WE-P and in the level of phenolic acids and ferulic acid dehydrodimers for both cell wall preparations. 相似文献
4.
Looking for potential quality indicators, which could be used in early selection of breeding materials, the structural features of cell wall arabinoxylans (AX) from outer layers of the grain (pooled shorts and bran fractions) were studied in two ryes with diverse breadmaking quality. The successive alkaline extraction of water-unextractable material with saturated Ba(OH)2, followed by water and 1 and 4 M NaOH, resulted in four purified fractions, Ba, BaH, 1Na, and 4Na, respectively, that became water soluble after their isolation. The AX present in these fractions constituted approximately 43, 12, 14, and 4% of their total amount recovered. Moreover, two xylan-enriched fractions, 1Na.P and 4Na.P (arabinose-to-xylose ratios, Ara/Xyl, of 0.07 and 0.19, respectively), were self-precipitated from both NaOH-extractable fractions. Polysaccharides of these fractions, containing mainly xylose, represented approximately 16 and 1% of AX recovered. In the BaH and 1Na, AX coexisted with beta-glucans, which predominated in the former protein-free fraction. On the contrary, hemicelluloses in the 1Na fraction were associated with protein as well. Further fractionation of the water-soluble materials by ammonium sulfate revealed that the parent AX populations in the Ba, BaH, and 1Na were composed of 3-4 subfractions with different degrees of substitution (Ara/Xyl of approximately 0.4, 0.8, and 1.1), whereas 4Na was almost totally built of highly substituted AX (Ara/Xyl of 1.1). Despite a comparable proportion of un-, mono-, and disubstituted xylopyranosyl residues in the chain of Ba(OH)2-extractable AX isolated from both ryes, the 1H NMR and Fourier transform infrared demonstrated the marked differences in their spectral profiles, suggesting different substitution patterns of these dominating polysaccharides. The high molecular weight population present in the Ba fraction also differentiated well two ryes with opposite breadmaking quality. 相似文献
5.
Figueroa-Espinoza MC Poulsen C Borch Søe J Zargahi MR Rouau X 《Journal of agricultural and food chemistry》2002,50(22):6473-6484
Water-extractable (WEP) and water-unextractable (WUP) pentosans were isolated from a rye flour. The effect of a commercial enzyme preparation, Grindamyl S 100 (GS100), containing pentosanase activities, was investigated on WEP, WUP, a mix of WEP and WUP, and the rye flour, with the aim to monitor the solubilization and depolymerization of high molecular weight arabinoxylans and the effect on the viscosity of the reaction medium. The effects of other hydrolyzing enzymes were also tested. Three xylanases were used: xylanase 1 (Xyl-1) from Aspergillus niger, the main activity present in GS100; xylanase 2 (Xyl-2) from Talaromyces emersonii; and xylanase 3 (Xyl-3) from Bacillus subtilis. Xyl-3 was used in combination with Xyl-1, (1,4)-beta-D-arabinoxylan arabinofuranohydrolase, endo-beta-D-glucanase, or ferulate esterase from A. niger, but no synergism was observed. GS100 and xylanases increased the arabinoxylan solubilization, Xyl-3 and Xyl-1 being those that presented the best yields of extraction without extensive depolymerization of water-extractable arabinoxylans. Both xylanases were affected by an inhibitor in rye flour. Flour treated with hot ethanol was used to study the oxidative gelation of flour extracts treated with xylanases, in the presence of laccase from Pycnoporus cinnabarinus. Two doses of xylanases were tested (0.5 and 2.5 units). Only the flour extracts treated with 0.5 unit of Xyl-1 thickened. 相似文献
6.
Individual contribution of grain outer layers and their cell wall structure to the mechanical properties of wheat bran 总被引:1,自引:0,他引:1
Antoine C Peyron S Mabille F Lapierre C Bouchet B Abecassis J Rouau X 《Journal of agricultural and food chemistry》2003,51(7):2026-2033
The mechanical properties of wheat bran and the contribution of each constitutive tissue on overall bran properties were determined on a hard wheat (cv. Baroudeur) and a soft wheat (cv. Scipion). Manual dissection allowed three different layers to be separated from wheat bran, according to radial and longitudinal grain orientations, which were identified by confocal laser scanning microscopy as outer pericarp, an intermediate strip (comprising inner pericarp, testa, and nucellar tissue), and aleurone layer, respectively. Tissue microstructure and cell wall composition were determined. Submitted to traction tests, whole bran, intermediate, and aleurone layers demonstrated elastoplastic behavior, whereas pericarp exhibited elastic behavior. By longitudinal orientation, pericarp governed 50% bran elasticity (elastic strength and rigidity), whereas, in the opposite orientation, bran elastic properties were mostly influenced by the other tissues. Regardless of test orientation, the linear force required to bran rupture corresponded to the sum of intermediate and aleurone layer strengths. According to radial orientation, the intermediate strip governed bran extensibility, but according to longitudinal orientation, all tissues contributed until bran disruption. Tissues from both wheat cultivars behaved similarly. A structural model of wheat bran layers illustrated the detachment of pericarp from intermediate layer within radial bran strips. 相似文献
7.
8.
《Soil Science and Plant Nutrition》2013,59(3):318-327
Abstract We examined the relationship between nitrogen (N) and phosphate (P2O5) surplus derived from agriculture and river water quality. We selected two river basins; one was a paddy farming area (Omoigawa) and the other was an intensive livestock husbandry area (Nakagawa). Nitrogen and P2O5 surpluses, defined as the difference between their input and output on regional farmland, from farmland in Omoigawa were twice those of Nakagawa; the surpluses came mainly from chemical fertilizer use. Although N and P2O5 surpluses in Nakagawa were lower, Nakagawa had a large amount of non-utilized livestock excreta, twice the N surplus on farmland in Nakagawa. Residual N and P2O5 in the river basin, caused by surplus and non-utilized livestock excreta, were approximately 20% and 40%, respectively, higher in Nakagawa than in Omoigawa. Outflows of N and P2O5 to river water were higher in Omoigawa than Nakagawa. By excluding domestic sewage N and P2O5 in river water, we calculated the loads of non-point source N and P2O5. Non-point source N and P2O5 were higher in Omoigawa than Nakagawa. This inverse result might be caused by the different source of residual N (i.e. chemical N fertilizer or livestock excreta). 相似文献
9.
10.
Rongxiao Yuan Huaming Guo Di Zhang Yuan Li Yilong Zhang Wengeng Cao 《Journal of Soils and Sediments》2017,17(12):2899-2911
Purpose
High groundwater arsenic (As) and salinity have been detected in aquifers of the Hetao Basin in Mongolia which have caused serious public health concerns. The objective of this study was to characterize the distributions of the soluble components in sediment in different lithologies and depths and to assess the relationship between soluble As in sediments and dissolved As in groundwater.Materials and methods
One hundred and one sediment samples and 13 groundwater samples were collected from four boreholes at varied depths. In addition to total chemicals and mineralogical phases of sediments, the soluble components (including major ions and As, Fe, and Mn) in sediments and dissolved chemicals in groundwater were analyzed.Results and discussion
Clay or silty clay had relatively higher EC values (189–805 μS cm?1) than aquifer sands (approximately 92–261 μS cm?1). The major soluble components were Na+, Ca2+, HCO3 ?, and SO4 2?, which were more variable in clay samples than fine sand samples. Soluble As concentrations ranged between 2 and 950 μS cm?1, and high contents generally occurred in clay sediments with high contents of soluble Fe and Mn. A comparison of chemicals between soluble components in sediments and dissolved species in groundwaters at matched depths showed that chemicals were preferentially partitioned into sediments at the mountain front and deep aquifers (>60 m), while partitioned into groundwater in the shallow aquifers (<60 m) of the flat plain. Arsenic was preferentially partitioned into groundwater in aquifers with relatively low dissolved SO4 2?.Conclusions
Groundwater components were mostly sourced from corresponding sediments. In clay sediments, As was desorbed from the surface sites along with other soluble components. Under reducing conditions, reduction of Fe oxides with high surface sites for As adsorption led to a weak association of As with other phases (such as carbonates), and therefore resulted in high dissolved As concentrations and low As partition between sediments and groundwater in deep aquifers.11.
P uptake by rye grass and alfalfa from smaller particle size of DCPD (≦ .18 mm) was larger than that from larger granules (0.4–0.5, 1.0–1.25, and 1.5–1.75 mm). Differences, however, became smaller with increasing time of contact. However powdered MCP was superior to all DCPD particles size fraction in an alluvial clay and a calcareous sandy clay loam indicating that under such alkaline reaction, the rate of dissolution is more limiting than the rate of immobilization. Results also indicate that the phosphate mobility in the highly calcareous was much lower than in the clay soil due to high pH and carbonate content. 相似文献
12.
13.
Nordlund E Aura AM Mattila I Kössö T Rouau X Poutanen K 《Journal of agricultural and food chemistry》2012,60(33):8134-8145
Rye bran and aleurone, wheat bran and aleurone, and oat bran and cell wall concentrate were compared in their in vitro gut fermentation patterns of individual phenolic acids and short-chain fatty acids, preceded by enzymatic in vitro digestion mimicking small intestinal events. The formation of phenolic metabolites was the most pronounced from the wheat aleurone fraction. Phenylpropionic acids, presumably derived from ferulic acid (FA), were the major phenyl metabolites formed from all bran preparations. The processed rye, wheat, and oat bran fractions contained more water-extractable dietary fiber (DF) and had smaller particle sizes and were thus more easily fermentable than the corresponding brans. Rye aleurone and bran had the highest fermentation rate and extent probably due to high fructan and water-extractable arabinoxylan content. Oat samples also had a high content of water-extractable DF, β-glucan, but their fermentation rate was lower. Enzymatic digestion prior to in vitro colon fermentation changed the structure of oat cell walls as visualized by microscopy and increased the particle size, which is suggested to have retarded the fermentability of oat samples. Wheat bran was the most slowly fermentable among the studied samples, presumably due to the high proportion of water-unextractable DF. The in vitro digestion reduced the fructan content of wheat samples, thus also decreasing their fermentability. Among the studied short-chain fatty acids, acetate dominated the profiles. The highest and lowest production of propionate was from the oat and wheat samples, respectively. Interestingly, wheat aleurone generated similar amounts of butyrate as the rye fractions even without rapid gas production. 相似文献
14.
The amount and composition of rhizo‐deposition as an important component of dissolved organic carbon (DOC) in forest soils is largely unknown. The objective of our study was to examine one component of DOC production in forest soils, namely rhizo‐deposition, under conditions of low, moderate, and high inorganic‐nitrogen (N) input. Two‐year‐old Picea abies saplings were incubated in hydroponic solution for a period of 2 weeks, comprising an adaptation and an experimental period of each 1 week. Treatments included 0 (zero N), 1, 10 (moderate N), and 100 (high N) mg N L–1 nitrogen addition split equally between nitrate and ammonium. Quantity and quality of dissolved‐organic‐carbon (DOC) production were investigated. Cumulative DOC production ranged between 3.7 and 8.8 mg C (g root dry weight)–1 (7 d)–1 and was significantly reduced in zero‐ and high‐N treatments. In turn, the specific UV absorbance as a measure of the aromaticity increased significantly in zero‐ and high‐N treatments, indicating a reduced contribution of microbial products to rhizo‐deposited C. Mineralization of rhizo‐deposited DOC was not significantly different between N treatments at day 1 of the experimental period, but by day 7, 69% of rhizo‐deposition in zero‐N hydroponic solution was mineralizable compared to 37%–49% for the moderate‐ and high‐N treatments. Increasing N input tended to result in decreased degradability. We conclude from this short‐term experiment that rhizo‐deposited DOC from Norway spruce displays a fast response to changes in inorganic N. 相似文献
15.
《European Journal of Soil Biology》2008,44(1):92-100
Elevated copper (Cu) concentrations have been shown to decrease the microbial activity in soils. Plants can have beneficial effects on the biological activity of soils mainly through their root exudates. In this study we investigated the impact of various plant species with different Cu tolerance levels on the microbial activity in two soils with low (10 mg/kg) and high (180 mg/kg) copper concentrations. The soil was a Kahangi Sandy Loam. Three different plants, Agrostis capillaris ‘Parys’ tolerant for Cu, Agrostis capillaris ‘Highland’ non-tolerant and Helianthus annuus tolerant and a hyper-accumulator for Cu were used. To increase the Cu availability to plants, EDTA was added to some of the pots 20 days after sowing. The effect of Cu contamination on the biological activity of soil in the presence and absence of plant growth was evaluated by measuring the dehydrogenase activity, the microbial biomass, the basal respiration, and the potential nitrification.Results show that plants increased the microbial activity in the low Cu soil. In the high Cu soil the microbial activity seemed to be related to the plant health. With the Cu-tolerant Agrostis capillaris ‘Parys’, the microbial activity increased faster than with the other plant species. Up to 50 days after sowing, the tolerant grass Agrostis capillaris ‘Parys’ had a higher plant biomass and was much healthier than the non-tolerant grass. Later on the growth of the non-tolerant Agrostis capillaris ‘Highland’ recovered, and the microbial activity of the soil reached close to those recorded for the soil treatments with the Cu-tolerant plant species. The addition of EDTA delayed the increase in microbial activity even further. The proportion of microbial biomass carbon in the organic fraction was higher in the low Cu soil than in the high Cu soil, with ratios ranging from 1.3 to 3.3 and from 0.5 to 1.7 respectively. The basal respiration rate in the original soil was significantly lower in the high Cu soil than in the low Cu soil, and was generally increased by the presence of plants. 相似文献
16.
1981-2020年黄土旱塬区冬小麦田耗水组分特征及其影响 总被引:1,自引:1,他引:0
深入理解农田耗水组分特征对提高干旱地区作物产量和水资源利用效率具有重要意义。该研究利用1981-2020年西峰国家农业气象试验站冬小麦定位观测资料,分析黄土旱塬区冬小麦田耗水组分特征及年代际变化规律,并探究其对叶面积指数(Leaf Area Index,LAI)、干物质积累分配和转运、产量及水分利用效率(Water Use Efficiency,WUE)的影响。结果表明:近40年研究区冬小麦田全生育期耗水量平均为315 mm,生育期降水和休闲期土壤贮水消耗占比分别为69.4% 和30.6%,不同年代、不同生育阶段耗水组分存在差异,起身-开花期是休闲期土壤贮水消耗的主要时期;随着年代际推移,LAI、干物质量、产量及WUE均呈现增加趋势,其中LAI增加主要受年际降水的调控作用,且与耗水组分中生育期内降水增加密切相关,而近10年(2011-2020年)受生育期降水增加及抗旱高产品种影响,冬小麦干物质量、产量及WUE显著增加(P<0.05)。研究成果可为黄土高原旱作农业水资源高效利用提供参考。 相似文献
17.
Substrate quality and decomposition (measured as CO2 release in laboratory microcosms) of fresh leaf litter and fine roots of Cupressus lusitanica, Pinus patula, Eucalyptus grandis and native forest trees were studied. Changes in litter chemistry in each forest stand were analysed by comparing fresh leaf litter (collected from trees) and decomposed litter from the forest floor. Elemental concentrations, proximate fractions including monomeric sugars, and cross polarisation magic-angle spinning (CPMAS) 13C NMR spectra were analysed in leaf litters, decomposed litter and fine roots. Leaf litters and fine roots varied in their initial substrate chemistry with Ca concentration in leaf litters being higher than that in fine roots. In each stand, fine roots had a higher acid unhydrolysable residue (AUR) (except for the Pinus stand), higher holocellulose concentration and lower concentration of water-soluble extractives (WSE) and dichloromethane extractives (NPE) than fresh leaf litter. Likewise, 13C NMR spectra of fine roots showed lower alkyl and carboxyl C, and higher phenolic (except P. patula), aromatic and O-alkyl C proportions than leaf litters. Compared with fresh leaf litter, decomposed litter had lower concentrations of potassium, holocellulose, WSE, NPE, arabinose and galactose, similar or higher concentrations of Mg, Ca, S and P, and higher concentrations of N and AUR. CPMAS 13C NMR spectra of decomposed litter showed a higher relative increase in signal intensity due to methoxyl C, aromatic C, phenolic C and carboxylic C compared with alkyl C. In a microcosm decomposition study, the proportion of initial C remaining in leaf litter and fine roots significantly fitted an exponential regression model. The decomposition constants (k) ranged between 0.0013 and 0.0030 d−1 for leaf litters and 0.0010-0.0017 d−1 for fine roots. In leaf litters there was a positive correlation between the k value and the initial Ca concentration, and in fine roots there was an analogous positive correlation with initial WSE. Leaf litters decomposed in the order Cupressus>native forest>Eucalyptus∼Pinus, and fine roots in the order Pinus>native forest>Cupressus∼Eucalyptus. In each stand the fine root decomposition was significantly lower than the leaf litter decomposition, except for the P. patula stand where the order was reversed. 相似文献
18.
Hafize Dilek Tepe 《Journal of plant nutrition》2017,40(9):1287-1299
Boron (B) is one of the essential nutrients for the growth of plants, but its high concentrations are toxic for plants. Thus, B toxicity is a big challenge in crop cultivation. Nitric oxide (NO) is a small signaling molecule that has cytoprotective roles in plants. We investigated whether exogenous sodium nitroprusside (SNP), which is a NO donor, may succeed to alleviate B-induced toxicity in wheat cultivars. Seedlings were grown for 10 days in a growth chamber at 25°C with 16 hr light–8 hr dark photo cycle. After high B application, the effects of SNP on growth parameters; electrolyte leakage (EL); changes in reactive oxygen species [contents of hydrogen peroxide (H2O2), malondialdehyde (MDA), and proline]; the activities of antioxidant enzymes [glutathione peroxidase (GSHPx), glutathione reductase (GR), and glutathione S-transferase (GST)] and nitrate reductase (NR); and low molecular weight organic acid (LMWOAs) contents and also chlorophyll and total carotenoid contents were investigated in both shoots and roots of two different wheat cultivars. All experiments were carried out in triplicate. 0.2 mM SNP application ameliorated the chlorophyll and total carotenoid contents, and growth parameters such as shoot length, root length, and fresh weight in both wheat cultivars exposed to B stress. SNP reduced the B-induced lipid peroxidation, EL, and proline and H2O2 content in wheat cultivars. SNP application also increased the activities of NR and antioxidant enzymes, including GSHPx, GR, and GST in wheat cultivars exposed to B toxicity. All of the tested LMWOAs including succinic, propionic, butyric, oxalic, formic, malic, malonic, and benzoic acids were increased by SNP treatment in the shoots and roots of both wheat cultivars exposed to B toxicity. In conclusion, results obtained from this study have demonstrated that interactive effects of SNP with B considerably reduced the toxic effects of B in wheat cultivars. 相似文献
19.
基于川麦冬活性成分高和重金属含量低的有机无机肥最佳配施方案 总被引:1,自引:1,他引:0
20.
Müller C Hemmersbach S Slot GV Hofmann T 《Journal of agricultural and food chemistry》2006,54(26):10076-10085
Recent investigations demonstrated that the reaction of odor-active thiols such as 2-furfurylthiol with thermally generated chlorogenic acid degradation products is responsible for the rapid aroma staling of coffee beverages. To get a clear understanding of the molecular mechanisms underlying this aroma staling, the existence of putative phenol/thiol conjugates needs to be verified in coffee. The aim of the present study was therefore to synthesize such conjugates for use as reference substances for LC-MS screening of coffee. To achieve this, catechol, 3-methyl-, 4-methyl-, and 4-ethylcatechol, pyrogallol, hydroxyhydroquinone, 5-O-caffeoylquinic acid, and caffeic acid, respectively, were reacted with 2-furfurylthiol in the presence of iron(III) chloride and air oxygen. After purification, the structures of 25 phenol/thiol conjugates were identified by means of LC-MS/MS and 1D/2D NMR experiments. Using these compounds as reference materials, four conjugates, namely, 3-((2-furylmethyl)sulfanyl)catechol, 3-((2-furylmethyl)sulfanyl)-5-ethylcatechol, 4-((2-furylmethyl)sulfanyl)hydroxyhydroquinone, and 3,4-bis((2-furylmethyl)sulfanyl) hydroxyhydroquinone, were identified for the first time in coffee brew by means of HPLC-MS/MS(MRM). These findings clearly demonstrate catechol, 4-ethylcatechol, and hydroxyhydroquinone as the primary thiol trapping agents involved in the aroma staling of coffee beverages. 相似文献