Extraction and Characterization of Starch from Alkaline Cooked Corn Masa

Starch granules undergo structural and morphological changes during food processing unit operations as they interact with other food ingredients. This study was conducted to isolate and characterize starch granules from corn masa. A proteolytic enzyme, thermolysin, was effective in separating and isolating starch granules from endosperm proteins present in masa. The efficiency of starch extraction using thermolysin was 74% (w/w), and subsequent analyses showed that the isolated granules were free of contaminants. Starch samples were characterized using light microscopy, SEM, DSC, and XRD. Starch granules isolated from masa had undergone internal structural changes and some granules (≈40%) lost birefringence during nixtamalization. These internal changes occurred, in most cases, without visible alterations in general granular morphology. Nixtamalized granules underwent changes mostly consistent with a “heat-moisture treatment” process.     

干湿交替对水稻土碳氮矿化的影响

通过室内培育试验,研究干湿交替条件下长期不同施肥处理水稻土微生物生物量和理化性状变化对土壤C、N矿化的影响机制.结果表明,与连续淹水(Cw)处理相比,干燥处理不仅显著地提高了所有施肥处理土壤有机C的矿化速率,其幅度为78%～204%,而且也提高了各处理土壤微生物生物量C和N,其幅度分别为55%～77%和57%～72%;干燥后淹水处理土壤有机C矿化速率的提高幅度为74%～95%,呈先降低再升高的趋势.土壤N的矿化在干湿交替过程的干燥处理中降低34%～78%:干燥后淹水过程仅使NPK处理的升高21%,而CK和NPKOM处理分别降低5%和13%.在培养过程中土壤Eh值仅在-60～60 mV范围时,与土壤微生物生物量C之间有显著的负相关关系.在干湿交替的干燥过程,随土壤pH值的升高土壤微生物生物量C有增加的趋势,在淹水条件下土壤pH值则仅与NPKOM处理土壤微生物生物量C之间有明显的负相关关系.干湿交替条件下土壤 pH和 Eh 值、微生物群落组成和数量与有机质的矿化之间的相互作用关系复杂,三者间的作用机理需进一步研究.     

Evaluation of Methods for Control of Ammonia Volatilization from Surface-Applied Nitrogen Fertilizers to Sugarcane Trash in North Queensland

Micrometeorological and microplot experiments were conducted in the field of freshly harvested green cane in Queensland,Australia.Results showed that high ammonia loss of fertilizer N could occur under relatively dry conditions when urea or commercial product of mixture of urea and muriate of potash were applied to the surface of sugarcane trash.The moisture content in the trash and the pH of fertilizer were two important factors controlling the processes of urea hydrolysis and ammonia volatilization.Most of the N in the soil was transformed to the nitratel-nitrite from after 70 days of fertilizer application.No significant leaching was found.Urea-free N fertilizers had higher N recoveries compared to urea-containing fertilizers.     

氮、磷的农业非点源污染防治方法

非点源污染最主要的影响就是使水体富营养化、水质变差,从而影响到生产、生活、社会与经济的发展,其中氮、磷的农业非点源污染又是最主要的。经过30多年的研究,非点源污染研究逐渐从初期的定性化研究转向定量化,由统计、调查与机理研究转向实用治理研究。就众多的防治方法来看,大体可以分为两大类,即“源”(Source)防治和“汇”(Sink)防治。     

土壤微生物量碳氮作为土壤肥力指标的探讨

通过对不同肥力水平黑土、棕壤、黄棕壤、红壤土壤微生物量碳氮的比较,研究和探讨土壤微生物量碳氮与土壤肥力的关系。结果表明:有机肥或无机肥施入土壤均能增加土壤微生物量C、N的含量,且有机肥与无机肥配合有显著的正交互作用。土壤微生物量C、N从北到南的地带性变化规律不强。BC/BN及TC/TN从北到南逐渐减小,BC/TC及BN/TN从北到南逐渐增加。相关分析结果表明:土壤微生物量C、N与全C、全N均呈极显著相关,可以作为指示土壤肥力的重要指标。     

植物吸收对模拟污水净化系统去除氮、磷贡献的研究

采用炉渣、沸石和土壤为基质,黑麦草(Lolium mutliflorum)、水芹(Oenanthe javanica)和香根草(VetiveriaZizanioides)为植被模拟了不同基质人工湿地和无基质的浮床植物净化系统,研究了3种植物在4种净化系统内对生活污水N、P的吸收和去除作用.结果表明:3种植物在各净化系统中均能正常生长,总生物量干重在121.8～557.4g/m2之间,均以黑麦草最高.4种净化系统中,黑麦草、水芹和香根草的地上部N、P平均含量分别为26.33、3.33 mg/g,24.08、2.64 mg/g和12.39、1.41 mg,g;地下部N、P平均含量分别为8.92、1.52 mg/g,19.39、2.55 mg/g和10.85、1.33 mg/g.浮床系统因承受的N、P负荷较高且不存在基质,3种植物的地上部、地下部N、P平均含量几乎均高于各基质人工湿地.4种净化系统中,黑麦草对N、P的吸收能力均明显高于水芹和香根草,3种植物的N、P总吸收量分别为:(黑麦草)5.26～11.73、0.72～131g/m2,(水芹)1.88～8.08、0.18～1.83 g/m2,(香根草)0.86～2.44、0.07～0.79g/m2,各植物的N、P吸收量均以浮床系统最高.植物对N、P的吸收量主要取决于自身的生物量和N、P含量.黑麦草吸收的N、P量分别占4种净化系统N、P去除总量的39.3%～59.4%和88.9%～96.3%,其对N、P的吸收己成为各净化系统去除N、P的主要机制.水芹和香根草对N的吸收仅是各净化系统去N的一个途径,其贡献率分别为;10.2%～37.6%和4.8%～17.7%;水芹和香根草对P的吸收量占浮床系统去P总量的96.4%和83.2%,是系统除P的主要机制,但其对3种基质湿地的去P贡献则很小.     

Proteins Extracted by Water or Aqueous Ethanol During Refining of Developed Wheat Dough to Vital Wheat Gluten and Crude Starch as Determined by Capillary‐Zone Electrophoresis (CZE)

Fluids applied to large‐sale, technical separation of wheat starch and protein also extract soluble proteins. The degree and rate of extraction and the specific components extracted depend on the flour, the flour hydration and development, the starch‐displacing fluid composition, the temperature, and the mechanical processing method. This study sought to identify major extracted protein groups using high‐performance capillary zone electrophoresis (CZE) applied directly to fluids obtained during laboratory‐scale technical separations. A dough‐ball or compression separation method was applied using a Glutomatic system and a batter or dispersion method was applied using a a McDuffie mixer and Pharmasep vibratory separator. Process fluids were water at 22°C to model commercial practice and 70 vol% ethanol in water at ‐13°C to model the cold ethanol process being developed here. Data were referenced to use of 70 vol% ethanol in water at 22°C in the Glutomatic compression method. The dough processed by each method was developed by mixing to a separable state. When flooded with excess water, this dough immediately released starch and water‐soluble or albumin proteins. When flooded with excess cold aqueous ethanol, neither the albumin nor gliadin proteins appeared in significant amounts until the bulk of the starch had been displaced, regardless of the mechanical method. Even with extraction and manipulation well beyond that necessary for starch displacement, the net amount of gliadin proteins dissolved was only ≈10% of that available from wet developed dough using 70 vol% ethanol at 22°C. There was more gliadin protein in the fluids at earlier stages of processing when the batter dispersion method was applied using cold ethanol. The most common soluble proteins revealed in the electrophoresis patterns for the batter compression method using cold aqueous ethanol were initially albumins and later γ‐gliadins. Albumins not appearing as soluble in cold 70 vol% ethanol were found in the insoluble crude starch, suggesting their precipitation in the dough fluids during the change from free water to cold aqueous ethanol. These results establish that some protein is dissolved during starch displacement by cold aqueous ethanol, but that the amounts may be limited by control of the mechanical working of the dough in the presence of the displacing fluids.     

采样深度和计算方法影响保护性耕作土壤碳氮储量的评估结果

为探讨不同年限耕作措施下土壤有机碳（SOC）和全氮（TN）在土壤剖面中的分布和累积特征,了解采样深度和计算方法对SOC和TN储量评估结果的影响,基于山东桓台（5a）和河北栾城（17a）耕作定位试验,设置翻耕（CT）、旋耕（RT）和免耕（NT）三个处理（秸秆均还田）,分析土壤剖面中（桓台60cm;栾城50cm）土壤容重（b）、SOC和TN浓度的分布特征,并比较不同土层深度下“固定深度法（FD）”和“等效重量法（ESM）”所计算SOC和TN储量的差异。结果表明,连续多年保护性耕作后,NT处理较CT促进了SOC和TN储量在表层积累,增加了SOC和TN浓度的层化比率（SR）值。在山东桓台试验点,NT处理较CT显著增加了0−5cm土层SOC和TN储量（P＜0.05）,增幅分别为29%和30%,而整个土壤剖面（0−60cm）的碳氮储量分别降低8%和10%。河北栾城试验点,0−10cm土层NT和RT处理较CT分别增加SOC储量10%和14%,但在≥20cm剖面中不同耕作处理之间的碳氮储量无显著差异。由于各处理之间b的差异,传统FD法高估了山东桓台免耕处理SOC和TN储量,但低估了河北栾城碳氮储量。因此,为准确评估不同耕作措施下土壤碳氮固持效应,推荐在“深层采样”（≥30cm）策略基础上,利用ESM法计算其储量。保护性耕作对改善土壤质量有积极作用,但其通过土壤碳截留以缓解气候变化的潜力不应该被高估。     

Nitrogen Fertilizer Replacement Value of the Liquid Fraction of Separated Livestock Slurries Applied to Potatoes and Silage Maize

Separation of livestock slurries followed by reverse osmosis yields mineral concentrates (MCs) in which almost all nitrogen (N) is ammonium (NH₄)-N. The ability of MCs to substitute calcium ammonium nitrate (CAN), a common conventional mineral N fertilizer, was tested in two trials on a silty loam soil (ware potatoes, 2009 and 2010) and four trials on sandy soils (starch potatoes, 2009 and 2010; silage maize in 2010 and 2011). The N fertilizer replacement value (NFRV) of spring-injected MCs ranged from 72 to 84%, slightly less than their share of ammonium-N (90–100%). The fate of N that was apparently unavailable to crops was not fully disclosed, but there were indications that ammonia loss may have played a role.     

水土保持生态效益评价方法探讨

水土保持生态效益的计算与评价是水土保持科学研究的重要内容。根据水土保持项目实施后可能引起的区域生态要素变化的实际,探讨了土壤理化性质、水质、林草植被覆盖度和小气候变化的计算方法与评价方法。     

Evaluation of Modified Mehlich and Sikora Buffer Methods as an Alternative to Modified Woodruff Buffer in Determining Lime Requirement for Missouri Soils

The modified Woodruff buffer (MWB) test is used to determine lime requirement (LR) for Missouri soils. Though this method is proven to work for Missouri soils, it uses p-nitrophenol, which is a hazardous substance. Soil-testing laboratories are under increasing pressure to reduce hazardous wastes, which must be collected and disposed of following U.S. Environmental Protection Agency protocols. The goal of this study was to evaluate the modified Mehlich buffer (MMB) and the Sikora buffer (SB) as alternatives to the MWB in determining the LR for Missouri soils. Thirty soils were collected from major agricultural areas in Missouri, treated with calcium carbonate (CaCO₃), and incubated for 90 days. Soil pH_s [0.01 M calcium chloride (CaCl₂) 1:1] was regressed against CaCO₃ rate, and the actual LR was estimated for each soil to raise the soil pH_s to target levels of 5.8, 6.3, and 6.8. The MWB, MMB, and SB pHs were regressed against the actual LR for all 30 soils to evaluate the effectiveness of each test for estimating the LR. The MMB and SBs were found to be as good as or better than MWB in predicting LR in Missouri soils. Both buffers (MMB and SB) were found to be equally effective in generating accurate estimates of the LR to raise soils to pH_S 5.8, 6.3, and 6.8 (for pH values 5.8: R² = 0.76, 0.82, 0.81; for pH values 6.3: R² = 0.80, 0.88, 0.86; and pH values 6.8: R² = 0.77, 0.89, 0.87 for MWB, MMB, and SB, respectively). A test to evaluate the stability of the buffers over time indicated that MMB had the shortest bench life (about 21 days) when compared to the MWB and SB, thus making it less feasible for use by soil test laboratories. Based on performance and stability, SB is a better alternative than MWB for Missouri soils.     

水土保持对可持续发展贡献的评估方法与应用研究

在简评国内外相关研究成果的基础上,通过剖析水土保持与可持续发展间的相依关系,确立了水土保持对可持续发展贡献的评估内容和评估准则;从土地承载力、粮食安全、水安全、降低贫困和减灾5个方面,较为系统地剖析了水土保持对可持续发展的贡献机理,构建了测算、评估其贡献率的相应指标和模型方法。该套评估方法体系具有较强的创新性和可操作性,可供区(流)域水土保持贡献评估或相关研究参考借鉴。     

Methods to investigate fertilization as a means to improve growth and sugar yield of sugar maple

Abstract

In a randomized block experiment, NPKCa fertilizers were applied annually for 5 years to a mature sugar maple (Acer saccharum Marsh.) woodlot in southern Ontario. Trees selected from 3 crown classes were fitted with dendrometer bands, tapped for sap and analyzed for foliar starch and nutrients and sap nutrients. Crown classes responded differently to the fertilizers. Trees which responded significantly in diameter growth did not respond the most in sugar yield. Effects of the fertilizer treatments on sugar yield were shown to be significant when the area of crown overlap of competing trees was subtracted from the crown area of crop trees. Foliar analysis and DRIS showed which nutrients were in demand after fertilizer applications. Sap analysis showed significant relations between sap nutrients and between sap nutrients and diameter growth. Starch analysis showed significantly higher foliar starch concentrations after potassium fertilization than after other fertilizer treatments.     

Atmospheric Deposition of Nitrogen to a Caribbean Coastal Zone (Cayo Coco,Cuba): Temporal Trends and Relative Importance as a Nitrogen Source

Nitrogen (N) deposition to the ocean is thought to be increasing worldwide, but the amount of coastal and open ocean measurements is very limited. In this paper, we assess N deposition in the coastal zone of Cayo Coco, in central Cuba, during a multi-annual period (2005–2007). Wet and dry N depositions were estimated based on the NH₄⁺ and NO_x^– concentrations in the rain. Cold fronts and troughs, coming from the west, contributed most to rain (41%) and to N deposition, followed by tropical waves and storms coming from the east, which caused 31% of the rain. Average concentrations of NH₄⁺ and NO_x^– in the rain were 8.8 and 8.3 μM. NO_x^– presented a clearly decreasing trend (0.26 μM per month), decreasing by half during 2005–2007. Total N deposition averaged 3.23 kg N ha⁻¹ year⁻¹, similar to that found in Virgin Islands and Puerto Rico, but lower than previously measured in Cuba and in nearby areas of the USA and than model predictions for the oceanic region around Cuba. These low values and the decreasing trend found are attributed to drastic reduction of fossil fuel and fertilizer use in Cuba since 1990. Because land input has decreased even more drastically, deposition seems to be nowadays the most important N source to the coastal zone of Cayo Coco. The δ¹⁵N range of seagrass (Thalassia testudinum) and macroalgae (Penicillus dumetosus) in the area (−1.83‰ to 3.02‰ and +1.02‰ to +4.17‰, respectively) sustain that atmospheric sources (deposition and N₂ fixation) comprise 70–90% of the N budget.     

Culture-Dependent and Culture-Independent Methods in Evaluation of Emission of Enterobacteriaceae from Sewage to the Air and Surface Water

The number of Enterobacteriaceae, with particular attention given to the presence of Escherichia coli and Klebsiella pneumoniae, was determined in hospital effluents and municipal wastewater after various stages of purification. The emission of these microorganisms to the ambient air near wastewater treatment plant (WWTP) facilities and to the river water, which is a receiver of the WWTP effluent, was also studied using fluorescence in situ hybridization (FISH) and cultivation methods. The number of Enterobacteriaceae determined by cultivation and fluorescence methods in different kinds of sewage sample ranged from 0.5?×?10(3) to 2.9?×?10(6)?CFU/ml and from 2.2?×?10(5) to 1.3?×?10(8) cells/ml, respectively. Their removal rates during treatment processes were close to 99?%, but the number of these bacteria in the WWTP outflow was quite high and ranged from 5.9?×?10(3) to 3.5?×?10(4)?CFU/ml and from 1.1?×?10(5) to 6.1?×?10(5) cells/ml, respectively. In the river water and the air samples, the number of Enterobacteriaceae was also high and ranged from 4.1?×?10(3) to 7.9?×?10(3)?CFU/ml and from 3 to 458?CFU/m(3), respectively. The numbers of these microorganisms obtained from fluorescence and cultivation methods were statistically and significantly correlated; however, the analysis of the studied samples indicated that the FISH method gave values up to 10(3)-fold times greater than those obtained by the cultivation method. From a sanitary point of view, this means that the number of viable fecal bacteria is systematically underestimated by traditional culture-based methods. Thus, the FISH proves to be a method that could be used to estimate bacterial load, particularly in air samples and less contaminated river water.     

Nitrogen fixation by red clover as related to the supply of Cobalt and Molybdenum from some Norwegian soils

A field trial, a pot experiment and a survey of organically farmed leys were undertaken to investigate whether N fixation in red clover pastures in Norway was limited by a low supply of cobalt and/or molybdenum. Fertilization with Mo did not result in any higher production or N fixation, whereas the N yield both from established clover leys and red clover grown in pots increased slightly after application of Co to many of the investigated soils. In the organically farmed leys there was a significant and positive correlation between Co content and the N content of the red clover. As many of the investigated clover-soil systems were of those previously known to be very low in Co and Mo, and the gain in N yield obtained by extra Co supply was marginal, it is unlikely that deficiency of these trace elements is a problem of great concern in legume based forage production systems in Norway.     

Evaluation of Ceres-Rice,Aquacrop and Oryza2000 Models in Simulation of Rice Yield Response to Different Irrigation and Nitrogen Management Strategies

This study evaluated CERES-Rice, AquaCrop, and ORYZA2000 models performance in simulation of biological and grain yield of rice in response to different irrigation intervals and nitrogen levels. These models were calibrated and validated by using three years (2005 to 2007) field experiments. Three levels of irrigation interval included pond treatment, five days interval, and eight days interval, and consisted of four levels of nitrogen. The study results showed that there were significant differences among study crop models in simulation of grain and biological yield in response to different irrigation intervals. As results showed, study models performed more accurate in estimation of rice yield under irrigation intervals than nitrogen levels. All models illustrated high performance in estimation of rice yield under different irrigation intervals. CERES-Rice and AquaCrop models showed highest accuracy in simulation of grain and biological yield of rice under different levels of nitrogen, respectively. In addition, CERES-Rice model indicated highest performance in simulation of grain yield (rRMSE = 16). However, AquaCrop model estimated biological yield more accurate compared to other models (rRMSE = 15). ORYZA2000 showed less accurate in simulating grain (rRMSE = 23) and biological (rRMSE = 21) yield of rice in comparison with other models.     

Nitrogen isotopes as a screening tool to determine the growing regimen of some organic and nonorganic supermarket produce from New Zealand

An isotopic study was performed on nine varieties of organically and conventionally grown vegetables from an organic food market and a chain supermarket in New Zealand. The main aim of the study was to assess the applicability of stable nitrogen isotopes as a screening tool to differentiate between organic and conventional growing conditions of various vegetable types sampled directly off supermarket shelves. This could be further used as the basis of a simple authentication tool to detect noncompliant organic farming practices and false labeling of organic produce. In this study, nitrogen isotopes are found to be an excellent way of identifying faster growing organic vegetables (maturity time to harvest of <80 days), as these vegetables tend to be significantly more enriched in (15)N than conventionally grown vegetables and natural soil N. For slower growing organic produce (maturity time to harvest of >80 days), more information would be required to understand isotopic variations and fractionation effects between vegetables and soil over time as the technique does not discriminate organic from conventional regimens for these vegetables with as much certainty.     

Different Response of Grain Yield to Soil Organic Carbon,Nitrogen, and Phosphorus in Red Soil as Based on the Long-Term Fertilization Experiment

Eurasian Soil Science - Soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) are essential nutrients for plant growth. Thus, soil amendments that increase the amounts of these...