The dissolution efficiency for different stream liming methods

The dissolution efficiency for different stream liming methods is shown to depend upon the following parameters: Particle size distribution; Initial pH-value; Dose intensity; and Degree of wet slurrying. The particle size distribution and the degree of wet slurrying are the only free variables and when they are determined, the others are determined by the conditions at the dosing site. The way to influence the dissolution efficiency, and accordingly the cost of neutralization, will be to vary the particle size distribution of the powder used for dosing. This way the cost optimum may be located.     

Functional Properties of Submicron‐Scale Rice Flour Produced by Wet Media Grinding

The digestibility and hydration properties of wet‐ground submicron‐scale rice flour were compared with those of dry‐ground coarser microscale flours. The submicron flour (mean size 0.6 µm) was produced in a wet‐media mill with 0.3 mm zirconia beads by continuous 24 h pulverization. The solubility, water absorption index, and swelling power increased as the mean particle size decreased, reaching maximum values in the submicron flour. Starch damage was high in the submicron flour, with the absence of intact starch granules. The digestibility also increased as the particle size decreased, and it was highest in the submicron flour. These results show that wet‐ground submicron rice flour has different functional properties from dry‐ground coarser flour. The digestibility was more strongly influenced by starch damage and the water absorption index than by the mean particle size.     

Effect of Aflatoxin B1 on Dry‐Grind Ethanol Process

Aflatoxins, like all mycotoxins, are toxic fungal metabolites that can have adverse health effects on animals and human beings. Aflatoxins are a major concern for the dry‐grind corn processing industry as it is believed that aflatoxins affect yeast and reduce its efficacy in producing ethanol. In the present study, aflatoxin B1 (100, 200, 350, or 775 ppb) was added to mycotoxin‐free corn and laboratory‐scale fermentations were conducted. No effect of aflatoxin B1 was observed on the fermentation rates or final ethanol concentrations. Mean ethanol concentration in the fermenter was 14.01–14.51% (v/v) at 60 hr for all the treatments. In the dry‐grind ethanol process, 55% of aflatoxin B1 was detected in wet grains and 45% in thin stillage.     

Rapid screening method for aflatoxin M1 in milk

A rapid screening method for detecting aflatoxin M1 in milk has been developed, based on minicolumn chromatography and requiring 8-10 min for each test. The minicolumn is packed with dry Florisil (100-200 mesh) on the bottom, anhydrous Na2SO4 as the next layer, topped with neutral alumina (70-200 mesh) to which 8% water (wet basis) has been added. A blue fluorescent band at the Florisil-Na2SO4 interface indicates the presence of aflatoxin M1. The limit of detection is estimated to be about 0.2 microgram/kb. Because several items are disposable, both the time to maintain glassware and the cost per determination are reduced.     

Directional strength in aggregates as affected by aggregate volume and by a wet/dry cycle

Reduction of aggregate size in the upper, tilled soil layer as a result of one wet/dry cycle was observed for sandy soil and clay soils. Bulk density of aggregates tended to increase as their size diminished for the clay after the wet/dry cycle, whereas similar changes in bulk density for the loam were observed only for aggregates smaller than 5.6 cm. Slaking and water-drop impact seem to be the major factors in reducing the aggregate size of the sandy loam, while swelling and shrinkage affect clay aggregates of all size groups, but only aggregates smaller than 4.0 mm for the sandy loam. Tensile strength of the sandy loam aggregates was related to the axis along which the stresses were applied. A definite directional dependence of tensile strength was observed, e.g. the shorter the axis, the larger the tensile strength. The directional strength dependence was apparently not affected by one wet/dry cycle.     

Distribution of aflatoxin in pistachios. 6. Seller's and buyer's risk.

The seller's risk-the probability of a set of samples exceeding an agreed upon aflatoxin level when the lot mean does not-and the buyer's risk-the probability of a lot exceeding this level when a set of samples do not-have been computed using a parametrized experimental aflatoxin distribution and Monte Carlo simulation. The calculations are exemplified using the proposed EC standards (three 10 kg samples, 4 ng/g of total aflatoxin, basis kernels only) as well as for samples up to 250 kg and for varied lot aflatoxin levels. It is found that within this sample size range the seller's risk is as high as 42% at 10 kg and increases with increasing sample size to 80% at 250 kg. Only by reducing lot levels to 0.2 ng/g of total aflatoxin, basis kernels, can the risk be brought down to 2.5%, independent of sample size. The buyer's risk is as high as 58% at 10 kg but falls to 11% at 250 kg samples. The implications for both seller and buyer strategies are discussed.     

Soil processes and productivity in relation to climatic cycles in Kazakhstan

The amount of precipitation in a number of boreal zone regions changes greatly from year to year. The precipitation fluctuation curves are in conformity with those of the solar activity having 11-year or secular (80–90 years) periodicity.Observations carried out in the lower reaches of the Syr-Darya River have shown that the river discharge fluctuations are subject to the same relationships. In wet years severe floods occur, with soils being swamped in depressions and the salinization process intensified on the highlands. In dry years the swamped soils dry up and turn into meadow-boggy soils, and the salinization process ceases due to the lowering of the ground water. In the alluvial-meadow soils of the Syr-Darya levees the soils become salinized in dry years, whereas in wet years the accumulated salts are washed away by floods. The hydrologic regime affects the irrigated paddies as well; in spring prior to flooding in wet years the groundwater table is higher than it is in dry years.In drought years the moisture storage in the soils of the North Kazakhstan experimental stations is negligible and not enough for a good grass yield, whereas in wet years the yield is satisfactory. The natural addition of plant residues to the soil is also of a rhythmical nature, depending upon the moistening rhythm. In dry years biochemical processes in the soil are much less intensive than they are in wet years, and the composition of the resultant products is different. For example, nitrogen compounds in chestnut soils of the Tien Shan foothills in wet years are mainly represented by ammonia forms and in dry years by nitrate forms. Knowing these relationships would be of great scientific and practical value in forecasting agricultural production and taking preventive measures in due time against drought and other hazards. These relationships have not been well investigated yet and need further study.     

Release kinetics of volatile organic compounds from roasted and ground coffee: online measurements by PTR-MS and mathematical modeling

The present work shows the possibilities and limitations in modeling release kinetics of volatile organic compounds (VOCs) from roasted and ground coffee by applying physical and empirical models such as the diffusion and Weibull models. The release kinetics of VOCs were measured online by proton transfer reaction-mass spectrometry (PTR-MS). Compounds were identified by GC-MS, and the contribution of the individual compounds to different mass fragments was elucidated by GC/PTR-MS. Coffee samples roasted to different roasting degrees and ground to different particle sizes were studied under dry and wet stripping conditions. To investigate the accuracy of modeling the VOC release kinetics recorded using PTR-MS, online kinetics were compared with kinetics reconstituted from purge and trap samplings. Results showed that uncertainties in ion intensities due to the presence of isobaric species may prevent the development of a robust mathematical model. Of the 20 identified compounds, 5 were affected to a lower extent as their contribution to specific m/z intensity varied by <15% over the stripping time. The kinetics of these compounds were fitted using physical and statistical models, respectively, the diffusion and Weibull models, which helped to identify the underlying release mechanisms. For dry stripping, the diffusion model allowed a good representation of the release kinetics, whereas for wet stripping conditions, release patterns were very complex and almost specific for each compound analyzed. In the case of prewetted coffee, varying particle size (approximately 400-1200 microm) had no significant effect on the VOC release rate, whereas for dry coffee, the release was faster for smaller particles. The absence of particle size effect in wet coffee was attributed to the increase of opened porosity and compound diffusivity by solubilization and matrix relaxation. To conclude, the accurate modeling of VOC release kinetics from coffee allowed small variations in compound release to be discriminated. Furthermore, it evidenced the different aroma compositions that may be obtained depending on the time when VOCs are recovered.     

Influence of lipids with and without other cottonseed reserve materials on aflatoxin B(1) production by Aspergillus flavus

Cottonseed storage lipids (primarily triglycerides), in either crude or refined form, were found to support growth and aflatoxin B(1) production by Aspergillus flavus. When lipids were removed from ground whole cottonseed by petroleum ether extraction, aflatoxin production dropped by more than 800-fold. Reconstitution of the lipid-extracted ground whole seed with a crude preparation of cottonseed lipids restored aflatoxin production to the previous levels. Fungal utilization of the three major cottonseed reserve materials, raffinose, triglycerides (refined cottonseed oil), and cottonseed storage protein, was monitored in vitro over a 7 day fermentation period. The fermentation medium contained the reserve compounds in proportions approximating those found in mature cottonseed. A. flavus rapidly converted raffinose to fructose and melibiose, presumably by action of invertase, and then hydrolyzed the melibiose. These simple sugars apparently supported initial growth and aflatoxin B(1) production. Raffinose and the resulting melibiose were nearly exhausted by day 2. Fungal hydrolysis of triglycerides began as exhaustion of carbohydrate approached. After day 2, rapid catabolism of the released fatty acids began and coincided with glucose regeneration through gluconeogenesis, which peaked on day 6. The fungus did not preferentially utilize specific fatty acids. A. flavus also produced a number of storage metabolites, including arabitol, erythritol, mannitol, and trehalose. Mannitol was produced in much higher concentrations than the other storage metabolites. Selective use of simple carbohydrates by A. flavus to drive aflatoxin production may suggest strategies for reducing vulnerability of cottonseed to aflatoxin contamination.     

Enzyme-linked immunosorbent assay for screening aflatoxin B1 in cottonseed products and mixed feed: collaborative study

A joint AOAC/IUPAC (International Union of Pure and Applied Chemistry) interlaboratory study of an enzyme-linked immunosorbent screening assay (ELISA) for aflatoxins was conducted in laboratories in Canada, France, Japan, South Africa, Switzerland, The Netherlands, Tunisia, and the United States. Twenty-eight samples of raw and roasted peanuts, corn, whole cottonseed, cottonseed meal, ammoniated cottonseed meal, and poultry feed containing various quantities of natural aflatoxins and supplemented when appropriate with aflatoxin B1 were distributed to participating laboratories for testing. The assay is based on conjugation of pure aflatoxin B1 to an enzyme and the competition between this conjugate and (free) aflatoxins in the product for aflatoxin-specific antibodies coated onto microtiter well walls. After a wash step to remove all unbound aflatoxins, a substrate, added to each well, is catalyzed from a colorless to a green solution by any bound enzyme-conjugated aflatoxin B1 present. The intensity of the color decreases as the amount of free aflatoxin B1 in the product increases. Overall correlation was good between ELISA and thin-layer chromatographic (TLC) results for cottonseed products and mixed feed. Variable results were reported for corn and peanut product samples. Although some positive samples (greater than 15 ng/g) of cottonseed products and mixed feed were reported to contain less than 15 ng/g by visual determination, a review of data for absorbance measurements showed that the contamination level was close to the greater than or equal to 15 ng/g standard and would not have been reported as negative under routine screening.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ethanol Production from Modified and Conventional Dry‐Grind Processes Using Different Corn Types

Different corn types were used to compare ethanol production from the conventional dry‐grind process to wet or dry fractionation processes. High oil, dent corn with high starch extractability, dent corn with low starch extractability and waxy corn were selected. In the conventional process, corn was ground using a hammer mill; water was added to produce slurry which was fermented. In the wet fractionation process, corn was soaked in water; germ and pericarp fiber were removed before fermentation. In the dry fractionation process, corn was tempered, degerminated, and passed through a roller mill. Germ and pericarp fiber were separated from the endosperm. Due to removal of germ and pericarp fiber in the fractionation methods, more corn was used in the wet (10%) and dry (15%) fractionation processes than in the conventional process. Water was added to endosperm and the resulting slurry was fermented. Oil, protein, and residual starch in germ were analyzed. Pericarp fiber was analyzed for residual starch and neutral detergent fiber (NDF) content. Analysis of variance and Fisher's least significant difference test were used to compare means of final ethanol concentrations as well as germ and pericarp fiber yields. The wet fractionation process had the highest final ethanol concentrations (15.7% v/v) compared with dry fractionation (15.0% v/v) and conventional process (14.1% v/v). Higher ethanol concentrations were observed in fractionation processes compared to the conventional process due to higher fermentable substrate per batch available as a result of germ and pericarp fiber removal. Germ and pericarp yields were 7.47 and 6.03% for the wet fractionation process and 7.19 and 6.22% for the dry fractionation process, respectively. Germ obtained from the wet fractionation process had higher oil content (34% db) compared with the dry fractionation method (11% db). Residual starch content in the germ fraction was 16% for wet fractionation and 44% for dry fractionation. Residual starch in the pericarp fiber fraction was lower for the wet fractionation process (19.9%) compared with dry fractionation (23.7%).     

Rapid high pressure liquid chromatographic determination of aflatoxin M1 in milk and nonfat dry milk

A modification of the current revised AOAC method, 26.A10-26.A15, is described for the rapid analysis of aflatoxin M1 in milk and nonfat dry milk. The method incorporates chloroform extraction and eliminates the need for column chromatography by using liquid-liquid partition for sample extract cleanup. Quantitation is carried out by using fluorescence detection combined with high pressure liquid chromatography (HPLC) of aflatoxin M1 which has been converted to aflatoxin M2a with trifluoroacetic acid. The method has a detection limit of 0.014 micrograms/L (2 X signal/noise) for whole milk. For 6 samples of naturally contaminated nonfat dry and freeze-dried milk, the modified method gave an average result of 0.698 micrograms/L; the AOAC method gave an average result of 0.386 micrograms/L.     

Deposition of heavy elements on Belgian agricultural soils

A network of 19 rain gauges was set up over Belgium in agricultural zones. Determination of heavy metals content of water samples collected during a 1 yr meteorological cycle allowed to estimate wet plus dry deposition rate of many toxic metals over the country. It appears that soils contamination by deposition exceeds contamination through the use of chemical fertilizers.     

Substrate suitability of different genotypes of sorghum in relation to Aspergillus infection and aflatoxin production

Grain sorghum is often damaged by rain in the field and severely infected by grain mold, which includes Aspergillus infection and aflatoxin production. The objective of the study is to investigate the extent of aflatoxin production with Aspergillus infection in vitro in different sorghum genotypes with different pericarps, red, yellow, and white, the physical and chemical characteristics of grain during infection, and the changes in grain polyphenols and phytic acid in comparison to maize and groundnut. The physical characters and biochemical composition of sorghum grain contribute to make it less susceptible to Aspergillus infection and aflatoxin contamination compared to maize and groundnut. The lowest amounts of aflatoxin and ergosterol were observed in genotypes with red pericarp, whereas higher amounts of aflatoxin and ergosterol were found in white genotypes followed by maize and groundnut. All of the red genotypes differ in polyphenol composition and aflatoxin produced, showing resistance to mold damage. Another indication of resistance in red genotypes was the delayed peaking of aflatoxin production (9 days after infection). In red sorghum genotypes there was a significant, positive correlation existing between polyphenol content and aflatoxin produced at 3 and 6 days after infection, the r values being 0.589 and 0.513, respectively. The starch content decreased whereas the protein content in all sorghum genotypes increased during infection. Maximum phytic acid was observed in white sorghum genotypes. Phytic acid in yellow genotypes was found to have a significant negative correlation (r = -0.569) with aflatoxin produced.     

Redoxpotentialmessungen mit dauerhaft installierten Platinelektroden unter reduzierenden Bedingungen

Redox potential measurements with permanently placed platinum electrodes under reducing conditions It was the aim of this investigation to find out whether it is possible to measure the redox potential under wet and reducing conditions with permanently installed selfmade Pt-electrodes or whether mechanical breakdown and/or electrode contamination restrict a permanent use of the electrode in general. Redox measurements were obtained for a Go horizon characterized by changing redox conditions (-180 to 700 mV; pH 7,2) and for a Gr horizon with constantly reducing conditions (-200 to 150 mV; pH 7,3) indicated by the presence of sulfide. After fixed time intervalls, electrodes were removed to compare their potential in distilled water with the potential of a similar electrode which had not been installed in soil. Changing redox potentials in the Go horizon were closely linked to variation of the ground water table and temporary redox processes of Mn and Fe. Even after 20 months of use, soil aeration when induced for a short period of time was indicated soon. After removal from soil, the test electrodes did not show any visible coat on the surface. Independent of depth and time of installation no systematic differences were observed among the electrodes, although the potentials for the electrodes used in soil were generally somewhat lower (11 to 33 mV) compared to the potential of a non-installed electrode. The results show that the electrodes were not subjected to mechanical breakdown and contamination, which would restrict the qualitative interpretation of redox potentials. Therefore, it is recommended to measure the redox potential of saturated or frequently saturated soils by permanently installed electrodes.     

Development and application of solvent-free extraction for the detection of aflatoxin M1 in dairy products by enzyme immunoassay

The official methods for the quantification of aflatoxin M1 in dairy products (cheese and yogurt) include extraction into dichloromethane or chloroform, evaporation of the solvent, partitioning of the reconstituted residue with hexane, and subsequent analysis. To secure a rapid and inexpensive screen for aflatoxin M1 contamination, a sensitive competitive ELISA, using a rabbit polyclonal antibody, was developed for measuring aflatoxin M1 in milk and used in a comparative study for measuring the extraction efficiency of aflatoxin M1 in aqueous or organic solvent buffers using yogurt samples. An aqueous sodium citrate solution was found to be suitable for extracting aflatoxin M1, thus eliminating the need for organic solvents. The citrate extraction proved to be efficient (recovery ranged from 70 to 124%) in fortified samples of very different kinds of dairy products, including yogurt and six types of cheese. Fourteen yogurt and cheese samples were extracted with citrate solution and analyzed by ELISA. A good correlation was observed (y=0.95x-0.59, r2=0.98) when the data were compared with those obtained through the official method, across a wide range of aflatoxin M1 contaminations (10-200 ng/kg).     

Aggregate strength and mechanical behaviour of a sandy loam soil under long-term fertilization treatments

Current concern for soil quality has stimulated research on soil biological and chemical properties. In contrast, the mechanical behaviour of soil is somewhat neglected. We have examined the effects on soil mechanical properties of more than 100 years of contrasting fertilization employing three treatments from the Askov long‐term experiment: UNF (unfertilized), NPK (mineral fertilized) and AM (animal manured). We have measured tensile strength of aggregates when air‐dry and when adjusted to ?10, ?30 and ?100 kPa pressure potential. Four aggregate size classes were investigated (1–2, 2–4, 4–8 and 8–16 mm diameter). Soil fragmentation was characterized in the field using a drop‐shatter test. Bulk soil strength was determined in the field using a shear vane and a torsional shear box. Soil texture, pH, cation exchange capacity and microbial biomass were measured. The unfertilized soil has little soil organic matter and microbial biomass and is dense. Its aggregates were strong when dry and weak when wet. In contrast, the manured soil had strong aggregates when wet and rather weak ones when dry. The NPK soil generally had intermediate properties. The differences between the soils when dry seem to be related to differences in dispersible clay content, whereas the differences when wet are related to differences in the amount of organic binding and bonding material. The optimal water content for tillage as well as the tolerable range in water content was largest in the manured soil and smallest in the unfertilized soil. Our results indicate that soil mechanical properties should be measured over a range of water regimes to determine the effects of various long‐term fertilization treatments.     

Wet‐Milling and Dry‐Milling Properties of Dent Corn with Addition of Amylase Corn

A transgenic corn (amylase corn) has been developed that produces an endogenous α‐amylase that is activated in the presence of water and elevated temperature (>70°C). Wet‐ and dry‐milling characteristics of amylase corn were evaluated using laboratory wet‐ and dry‐milling procedures. Different amounts of amylase corn (0.1–10%) were added to dent corn (with the same genetic background as the amylase corn) as treatments. Samples were evaluated for wet‐ and dry‐milling fraction yields using 1‐kg laboratory procedures. Milling yields for all amylase corn treatments were compared with the control treatment (0% amylase corn or 100% dent corn). No significant differences were observed in wet‐ and dry‐milling yields between the control and the 0.1, 1, and 10% amylase corn treatments. Most of the amylase activity (77%) in wet‐milling fractions was detected in the protein fraction. In dry‐milling, amylase activity (68.8%) was detected in endosperm fractions (fines, small grits, and large grits).     

基于SWAT模型的内蒙古锡林河流域降水-径流特征及不同水文年径流模拟研究

以我国北方寒旱区草原中典型流域——锡林河流域为研究对象,结合我国北方寒旱区草原型河流流域的气候特点、下垫面条件及水文过程的特殊性,通过分析锡林河流域近30 a的降水—径流变化特征,利用锡林河水文站的年径流频率曲线,采用一定保证率条件下的年径流量作为划分流域丰平枯水年的标准,对锡林河流域历史水文年进行划分。基于此基础,以ARCSWAT2012为操作平台,应用地理统计分析方法,对模型建立过程中所需的各数据库进行基础数据整备与参数化,分析影响模型径流模拟精度的主要参数,进行模型的参数率定与结果精度评价,分别对锡林河流域各丰、平、枯水年进行径流模拟,并对其结果进行了检验。结果表明:SWAT模型对细化流域降水—径流分配的径流模拟具有不同的精度,即平水年 > 偏丰水年 > 丰水年 > 偏枯水年 > 枯水年,体现出SWAT模型在中国北方寒旱区丰水年和平水年具有较好的可操作性。     

Earthworm biomass: Influence of gut content and formaldehyde preservation on live-to-dry weight ratios of three common species of pasture lumbricidae

Allolobophora caliginosa (Savigny), A. trapezoides (Duges) and Lumbricus rubellus Hoffmeister were reared on enriched sandy soil. Live and dry weights, and weights after preservation in 5% formaldehyde were determined for worms with and without gut contents. Quadratic regressions of the log transformed weights gave a significantly better fit than linear regressions for the relationships between live weight including gut contents, and either dry weight with an empty gut or dry weight with gut contents. Intermediate size worms had the highest proportion of gut contents. The dry weight of gut contents as a proportion of live weight could be more easily and accurately calculated from the difference between dry weights with and without gut contents averaged over size classes defined by the log of the weights of live worms.Dry weight minus gut contents, the best standard for biomass can be determined from field samples perserved in formaldehyde by combining linear regressions predicting live weight from formaldehyde weight which are independent of gut contents, with linear regressions predicting dry weight minus gut contents from live weight with gut contents. Because the density of the gut contents affects the latter regression it should be determined from a subsample of worms of each species on each sampling occasion.