Solvent Extraction of Zein from Dry‐Milled Corn

Batch extraction of zein from dry‐milled whole corn with ethanol was optimum with 70% ethanol in water, an extraction time of 30–40 min, and temperature of 50°C. High yields (60% of the zein in corn) and high zein contents in the extracted solids (50%) were obtained at a solvent‐to‐solids ratio of 8 mL of 70% ethanol/g of corn. However, zein concentration in the extract was higher at lower ratios. Multiple extraction of the same corn with fresh ethanol resulted in a yield of 85% after four extractions, whereas multiple extractions of fresh corn with the same ethanol resulted in high (15 g/L) zein concentration in the extract. Optimum conditions for batch extraction of zein were 45°C, with 68% ethanol at a solvent‐to‐solids ratio of 7.8 mL/g for an extraction time of 55 min. Column extractions were also best at 50°C and 70% ethanol; a solvent ratio of 1 mL/g resulted in high zein concentrations in the extract (17 g/L) but yields were low (20%).     

响应面优化花生叶可溶性蛋白提取工艺及抗氧化活性分析

为确定花生叶可溶性蛋白提取最佳工艺,本试验以花生叶为材料,利用碱溶酸沉法提取花生叶可溶性蛋白,分析浸提pH值、料液比及提取时间对蛋白提取率的影响;在单因素试验的基础上,采用Box-Behnken响应面分析法(RSM)优化花生叶可溶性蛋白提取条件,并对所得蛋白进行抗氧化活性分析。结果表明,各影响因素主次顺序为浸提pH值>提取时间>料液比,最佳提取条件为料液比1∶20(w/v)、提取时间40 min、浸提pH值 9.0,以此条件建立的响应面试验回归模型拟合性好(R²=0.992 7),花生叶可溶性蛋白理论提取率为52.8%,实际提取率为54.2%,纯度为63.8%。花生叶可溶性蛋白具有较强的DPPH自由基、超氧阴离子自由基清除能力,以及较好的还原能力。本研究结果为花生叶的开发利用及花生产业链的延长提供了一定的数据支持。     

Lunasin and Bowman-Birk protease inhibitor concentrations of protein extracts from enzyme-assisted aqueous extraction of soybeans

Lunasin and Bowman-Birk protease inhibitor (BBI) are two soybean peptides to which health-promoting properties have been attributed. Concentrations of these peptides were determined in skim fractions produced by enzyme-assisted aqueous extraction processing (EAEP) of extruded full-fat soybean flakes (an alternative to extracting oil from soybeans with hexane) and compared with similar extracts from hexane-defatted soybean meal. Oil and protein were extracted by using countercurrent two-stage EAEP of soybeans at 1:6 solids-to-liquid ratio, 50 °C, pH 9.0, and 120 rpm for 1 h. Protein-rich skim fractions were produced from extruded full-fat soybean flakes using different enzyme strategies in EAEP: 0.5% protease (wt/g extruded flakes) used in both extraction stages; 0.5% protease used only in the second extraction stage; no enzyme used in either extraction stage. Countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes was used as a control. Protein extraction yields increased from 66% to 89-96% when using countercurrent two-stage EAEP with extruded full-fat flakes compared to 85% when using countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes. Extruding full-fat soybean flakes reduced BBI activity. Enzymatic hydrolysis reduced BBI contents of EAEP skims. Lunasin, however, was more resistant to both enzymatic hydrolysis and heat denaturation. Although using enzymes in both EAEP extraction stages yielded the highest protein and oil extractions, reducing enzyme use to only the second stage preserved much of the BBI and Lunasin.     

双频超声协同强化提取黑米黑色素的试验研究

为进一步提高超声辅助提取黑米黑色素的效果,研究探讨了双频超声协同强化提取的方法。通过对pH值、提取时间、提取温度、液料比、乙醇浓度进行单因素试验,考察各因素对黑色素提取效果的影响,利用正交试验,优化其工艺条件。试验结果表明：各因素对黑米黑色素提取的影响大小依次为：pH＞乙醇浓度＞液料比＞温度＞时间。优化后的提取工艺条件为：pH值为2、超声时间为30?min、提取温度为50℃、液料比为30?mL/g、乙醇浓度为70%。在此条件下,得出平均提取率为6.85%。对比浸渍法、加热回流提取法,超声法提取黑米黑色素具有工艺简单、节省提取时间、溶剂用量少、提取效率高、减少黑色素损失的优点。     

Rapid Isolation of Sorghum and Other Cereal Starches Using Sonication

High‐intensity ultrasound (sonication) was investigated as a method to rapidly purify starch from sorghum and other cereal grains. To improve the process, buffers were optimized to solubilize sorghum proteins in combination with the sonication. Protein content and starch color were determined to evaluate the efficiency of the extraction process. Sonication times, SDS concentration, different types and concentrations of reducing agents (sodium metabisulfite, dithiothreitol, and β‐mercaptoethanol), and centrifugation speeds of the starch washing procedure were tested. Protein content of isolated sorghum starch was reduced to 0–0.14% (db) after 2 min of sonication (using any of the reducing agents tested). Sodium metabisulfite was chosen as the preferred reducing agent because of its lower toxicity and odor compared with other reducing agents tested. The optimum conditions for producing high‐purity sorghum starches (0.06% protein) were obtained using the following conditions: 2 min of sonication time with 12.5 mM sodium borate buffer, pH 10, containing 0.5% SDS (w/v) and 0.5% sodium metabisulfite (w/v) using 1,500 rpm centrifugation speed during starch washing. Starches separated by this method showed significantly less protein content and b values (yellowness) compared with starches separated by enzymatic methods or methods using NaCl solutions and protein extraction buffers with multiple washing steps, both of which take several hours to complete. Differential scanning calorimetry thermogram values for starches isolated by three different methods showed similar patterns, except that starches obtained with the enzymatic method had slightly higher values of T_o, T_p, and ΔH. Other cereal starches from whole wheat meal, wheat flour, corn, rice, and barley were also obtained rapidly using sonication.     

超声辅助提取辣椒籽蛋白工艺优化

以辣椒籽为原料,采用超声辅助法提取辣椒籽蛋白并利用响应面优化法提取工艺,在单因素试验的基础上,选取p H值,提取时间,超声功率,料液比4个因素进行响应面试验,根据所得试验结果确定最佳提取条件为:p H值11,提取时间13.31 min,超声功率336.21 W,料液比1∶35.85,在此条件下蛋白的预计提取量为5.90 g/(100 g)。利用Design expert软件对影响辣椒籽蛋白提取量的主要因素及其相互作用进行探讨,结果由大到小依次为:p H值料液比提取时间超声功率。与传统提取方法相比,超声辅助法使得蛋白提取量增加了0.81 g/(100 g)(占传统方法提取量的15.46%),蛋白纯度提高了5.47%。     

Optimization of DTPA and calcium chloride extractants for assessing extractable metal fraction in polluted soils

Abstract

Metal availability in soils is often assessed by means of extraction with chemical solutions, among others the chelating agent DTPA (diethylenetriaminepentaacetic acid) and the non‐buffered salt calcium chloride (CaCl₂). The same procedures are used for polluted soils that were originally created to assess the nutrient status of arable soils. We studied the influence of various parameters (type of shaker, shaking time, soil to solution ratio, and concentration of chemical extractant) and modify the DTPA and CaCl₂ extraction procedures to make them suitable for the study of polluted soils. The chosen extraction ratio and extractant concentration were the followings: 8 g/20 mL of 0.1 MCaCl₂ and 2 g/20 mL of 0.005 M DTPA. The optimized procedures were applied to nine soil samples affected by different sources of pollution (mine works, vehicle emissions, and various industries). Cadmium (Cd) showed the highest extractability with both extractants. Depending on the soil, copper (Cu) and zinc (Zn) (using DPTA) and Cu and manganese (Mn) (using CaCl₂) were the followings in the extractable amounts. Cadmium, Cu, and Zn were highly correlated in both extractions and with total contents.     

Extraction of β‐Glucan from Oats for Soluble Dietary Fiber Quality Analysis

Extraction protocols for β‐glucan from oat flour were tested to determine optimal conditions for β‐glucan quality testing, which included extractability and molecular weight. We found mass yields of β‐glucan were constant at all temperatures, pH values, and flour‐to‐water ratios, as long as sufficient time and enough repeat extractions were performed and no hydrolytic enzymes were present. Extracts contained about 30–60% β‐glucan, with lower proportions associated with higher extraction temperatures in which more starch and protein were extracted. All commercial starch hydrolytic enzymes tested, even those that are considered homogenous, degraded β‐glucan apparent molecular weight as evaluated by size‐exclusion chromatography. Higher concentration β‐glucan solutions could be prepared by controlling the flour‐to‐water ratio in extractions. Eight grams of flour per 50 mL of water generated the highest native β‐glucan concentrations. Routine extractions contained 2 g of enzyme‐inactivated flour in 50 mL of water with 5mM sodium azide (as an antimicrobial), which were stirred overnight, centrifuged, and the supernatant boiled for 10 min. The polymer extracted had a molecular weight of about 2 million and was stable at room temperature for at least a month.     

Isolation of Hemicellulose from Corn Fiber by Alkaline Hydrogen Peroxide Extraction

For the first time, alkaline hydrogen peroxide (AHP) extraction conditions were used to isolate hemicellulose (arabinoxylan) from destarched corn fiber. Yields of the water-soluble hemicellulose B ranged from 35% (24 hr extraction at 25°C) to 42% (2 hr extraction at 60°C). The hemicellulose B resulting from the 2 hr extraction (pH 11.5) was off-white in color, and a very low proportion (1.7%) of water-insoluble hemicellulose A was extracted. AHP treatment caused delignification and facilitated the alkaline extraction of hemicellulose from the lignocellulosic fiber matrix. In the absence of H₂O₂, yields were reduced by more than one-third when using otherwise identical extraction conditions of time, temperature and pH. In the standard protocol, corn fiber, NaOH solution, and H₂O₂ were mixed in a 1:25:0.25 (w/v/w) ratio. Extractions were conducted at pH 11.5 at 25°C or 60°C. The pH was adjusted to 11.5 by addition of NaOH at ambient and elevated temperatures. The optimum hemicellulose yield (51.3%; dry, starch-free basis) was obtained when the pH was increased to 12.5 for the final one-half of the extraction period. Products obtained after extraction at pH values greater than 11.5 were tan in color, however, and the goal of the research has been to isolate white hemicellulose B and then evaluate its properties. Under most conditions, the yields ofhemicellulose B, potentially the most useful form for food and industrial applications, exceeded those of hemicellulose A by more than 10-fold. The hemicellulose B products were lighter in color than those obtained using traditional alkaline extraction conditions of refluxing with calcium or sodium hydroxide. Steps prior to extractions with alkaline H₂O₂, such as grinding to 20 mesh and extracting with azeotropic toluene-ethanol, were found to be unnecessary.     

Use of a Plackett-Burman experimental design to examine the impact of extraction parameters on yields and compositions of pectins extracted from chicory roots (Chicorium intybus L.)

Chicory root pectin was isolated by acid extraction followed by alcohol precipitation. Because the extraction conditions have important effects on the features of pectins, an experimental design was used to study the influence of 17 different extraction parameters on yield and composition of pectin: pH, temperature, time of extraction, solid/liquid ratio, and different pretreatments of the pulps before extraction. Twenty extractions were conducted and examined for their significance on yield and sugar content using the Plackett-Burman factorial design. The acid extraction of chicory roots resulted in an average yield of 11% containing 86% of sugars. It was found that extraction temperature, time, protease pretreatment, water purity, and water washing of pulps significantly affected yield and pectin composition with an increase of yield and purity of pectin in harsher extraction conditions.     

不同浸提条件对包膜控/缓释肥水中溶出率的影响

以几种不同包膜材料控／缓释肥为供试肥料,研究不同肥(养分)水比、浸提方式(连续浸提和更换浸提液)、温度和pH条件对控／缓释肥水中溶出率的影响。结果表明,浸提液中肥料浓度是影响养分释放的重要因素,加大肥水比、更换浸提液可以显著减小这种影响。升高温度,有机和无机材料包膜控／缓释肥水中溶出率均显著加快。肥料类型、肥水比对浸提液的pH都有显著影响,但在连续浸提和更换浸提液方式下,7d内浸提液的pH有着不同的变化趋势。控／缓释肥在pH.5的磷酸盐缓冲液中的溶出率显著高于在pH.7的磷酸盐缓冲液中的溶出率。因此,对于不同包膜材料控／缓释肥以一定pH值的微酸性缓冲溶液作为浸提剂,定期更换浸提液或采用动态流法,相同的氮(或磷、钾)水比,30℃左右的浸提条件是较为合理的。     

Association of cadmium,zinc, copper,and nickel with components in naturally heavy metal‐rich soils studied by parallel and sequential extractions

Abstract

In this study, a new parallel and sequential extraction procedure was proposed to investigate the solubility of metals [cadmium (Cd), zinc (Zn), copper (Cu), and nickel (Ni)] and their association with soil components in naturally metal‐rich soils of Norway. Two different soils, alum shale (clay loam) and moraine (loam), developed on alum shale minerals were used. Each soil had two pH levels. For parallel and successive extractions, H₂O, 0.1M NH₄OAc (soil pH), 0.3M NH₄OAc (soil pH), 1M NH₄OAc (soil pH), and 1M NH₄OAc (pH 5.0) were used. A significant amount of Cd was extracted by NH₄O Ac related to concentration of NH₄OAc in the extracting solution. The amounts of Zn, Cu, and Ni extracted by these reagents were almost negligible except with 1M NH₄OAc (pH 5.0). Thus these metals were strongly bound to soil components. A seven step sequential extraction procedure was applied to evaluate the association of metals with soil constituents. The extractions were performed sequentially by extracting the soil with reagents having an increasing dissolution strength: 1M NH₄OAc (soil pH), 1M NH₄OAc (pH 5.0), 1M NH₂OH.HCl (in 25% HOAc), 1M NH₂OH.HCl (in 0.1M HNO₃), 30% H₂O₂ (in 0.1M HNO₃), 30% H₂O₂ (1M HNO₃), and aqua regia. In both soils at both pH levels investigated, appreciable percentages of total Cd (20–50%) were found associated with the NH₄OAc extractable fraction (mobile fraction). For Zn, Cu, and Ni, the percentage of total metal extracted with NH₄OAc was low (<4%), but it increased significantly by introducing a reducing agent (NH₂OH.HCl). The NH₂OH.HCl‐extractable fraction was the greatest fraction (>60%) for all four metals examined. These results suggest that among the metals studied, only Cd was easily desorbed from soil and should be considered mobile and potentially bioavailable. Other metals (Zn, Cu, and Ni) were strongly associated with the soil components and should be considered less available to plants. Using the sequential fractionation technique as a measure of availability, mobility and potential bioavailability of these four metals in the alum shale soils were: Cd>Zn>Ni>Cu.     

Copper Availability in an Acidic and Limed Zeolite-Amended Soil

In acidic soils, copper (Cu) availability may be high because of Cu impurities of various agricultural additives. This research was aimed at assessing liming and zeolite application as availability reduction methods. In a soil with pH 3.8, lime was added at 6.6 Mg ha^?1, and zeolite was added at 3.3% and 10% in a 100-day pot trial with ryegrass. On day 50 zeolite was more effective in reducing Cu availability [as expressed by diethylenetriaminepentaacetic acid (DTPA) soil extractions and plant concentration measurements] than liming. On day 100, Cu levels were further reduced in both treatments, indicating the effectiveness of both zeolite and liming over the study period to retain Cu. Zeolite alone reduced Cu concentration in plants to 26%, liming alone reduced it by 21%, and the combination of the two reduced it by 43%. The orders in the DTPA extractions and the soil-to-plant Cu transfer coefficients were similar.     

Extraction,Quantification, and Characterization of Phenolics Extracted with the Aid of Sonication from Rice Bran

Phenolics are phytochemicals extensively distributed among plants that have been receiving great deal of attention for their functionality. Rice bran is a good source of phenolics, especially hydroxycinnamates. Although chemicals are commonly employed to isolate phenolics, the use of physical treatments such as sonication is still limited. This study was conducted to optimize a procedure to isolate phenolics from rice bran using sonication as a preextraction treatment. Sonication was optimized by varying output, time, and temperature. Extraction was optimized by varying solvent, extraction time, temperature, and sample-to-solvent ratio. After an optimum procedure was established, HPLC analyses were conducted to identify and quantify the major individual phenolic acids extracted. The optimum conditions for extracting phenolics from rice bran were sonication with water (1:100 sample-to-solvent ratio) for 1 min; output intensity of 10; holding at ambient temperature; and autoclave treatment for 20 min at 121°C. This procedure extracted 8.85 ± 0.18 mg of phenolics/g of dried rice bran. Benzoic, p-coumaric, and trans-ferulic acids were the major phenolics identified in the extract. The proposed procedure will be valuable in obtaining phenolics for increasing product functionality such as lipid oxidation inhibitors in food systems.     

An acidic method of zein extraction from DDGS

Zein with a higher intrinsic viscosity and phosphorus content, similar protein content, lower yellowness, and at potentially much lower cost than commercially available zein was obtained from distillers dried grains with solubles (DDGS). A novel extraction method using acidic conditions in the presence of a reducing agent has been used to obtain about 10% aqueous ethanol soluble zein from DDGS. The optimum pH, time, temperature, and amount of reducing agent that can produce zein with high quality and yield have been developed. In addition to the zein, about 17% oil based on the dry weight of DDGS has also been obtained during zein extraction. The zein obtained from this research is expected to be suitable for use as fibers, films, and binders and in paints.     

Comparison of 0.1N sodium hydroxide with 0.1M sodium pyrophosphate in the extraction of soil organic matter from various soil horizons

Abstract

Soil samples representing the O, A, B, and C soil horizons from soil organic matter (SOM) studies were selected to study the relative effectiveness of 0.1N sodium hydroxide (NaOH) and 0.1M sodium pyrophosphate (NaPyr) in extracting organic carbon (OC). Replicate samples were extracted with each extractant in a ratio of about 1:144 and successive extractions were performed for each soil. Results indicated the importance of successive extractions for more complete removal of extractable OC. A single extraction removed an average of only 68%, 78%, 86%, and 60% of the OC extracted with four successive extractions for the O, A, B, and C horizons, respectively. The C horizons were lowest in OC and the slowest to release OC in the extraction process. Organic C was solubilized from the B horizons most quickly with an average of 95% of the successively extractable OC removed with only two extractions. The extractability of the soil TOC was highest in the Bhs and then the Bw, C, A, and O horizons at 92% and 42%, 46%, 38%, and 3 6%, respectively. The NaOH and NaPyr were nearly equal in extracting OC from the Bhs horizons. The NaOH extracted more OC than the NaPyr at 53%, 55%, 29%, and 47% more in the O, A, Bw, and C horizon samples, respectively. These results stress the importance of considering the soil horizon type and the use of NaOH in successive extraction for maximum removal of OC in soil studies.     

Comparison of soil solution extraction procedures: Effect on solute chemistry

Abstract

A study was undertaken to evaluate the effect of five methods of soil solution extraction on solute chemistry. The methods evaluated were high speed centrifugation, immiscible displacement, column equilibration/vacuum extraction, and 1:1 and 2:1 solution:soil water extractions. Solutions were analyzed for pH, major cations and anions, silicon, and dissolved inorganic and organic carbon. Solute concentrations followed a general trend of centrifugation > immiscible displacement > column equilibration ≈2:1 extract ≈1:1 extract. Solution pH varied up to 3 units depending on the method employed. A significant soil type times method interaction also occurred indicating that the extraction methods differ with soil type. The coefficients of variation averaged over all solutes for each method ranged between 0.079 and 0.130. This study shows that the method of choice for a given experimental design must be carefully evaluated for each soil.     

菜籽蛋白加工废液中多酚和多糖同步提取工艺优化

为开发利用菜籽蛋白加工废液中的生理活性物质,该研究在单因素试验基础上,采用Box-Behnken响应面试验设计法,对菜籽蛋白加工废液中多酚和多糖提取工艺条件进行优化,同时探究两种物质的体外抗氧化活性。结果表明,影响菜籽蛋白加工废液中多酚和多糖得率的因素大小顺序为:乙醇体积分数浸提温度浸提时间,最佳提取工艺为:浸提温度60℃、乙醇体积分数65%、浸提时间31 min,在此条件下多酚得率为2.19%,多糖得率为8.14%;多酚提取物对DPPH·具有较强清除能力,其半抑制质量浓度为0.20 mg/mL,多糖提取物对DPPH·和·OH均具有较强的清除能力,其半抑制质量浓度分别为1.45、2.38 mg/mL;高效液相色谱法初步检测表明,菜籽蛋白加工废液中含有香豆酸、丁香酸、对香豆酸、芥子酸和苯甲酸。研究结果为菜籽蛋白加工废液的再利用提供参考。     

中国黑土上腐殖酸和腐殖物质的提取及其描述

Twenty-three progressive extractions were performed to study individual humic acids (HAs) and humin fractions from a typical black soil (Mollisol) in Heilongjiang Province, China using elemental analysis and spectroscopic techniques. After 23 HA extractions the residue was separated into high and low organic carbon humin fractions. HA yield was the highest for the first extraction and then gradually decreased with further extractions. Organic carbon (OC) of the humin fractions accounted for 58% of total OC even after 23 successive HA extractions. In addition, the atomic C/H ratio decreased during the course of extraction while C/O increased; the E4/E6 ratio from the UV analysis decreased with further extraction while E~/E3 increased; the band assigned to aliphatic carbon (2 930 cm-1) in the diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) spectra gradually increased with progressive extraction; the calculated ratio of the sum of aromatic carbon peak heights to that of aliphatic carbon peak heights from DRIFTS spectra declined with extractions; and nuclear magnetic resonance (NMR) data suggested that HA aliphatic carbons increased with extractions while aromatic carbons decreased. Thus, hydrophobicity and aliphaticity of HAs increased with extractions while polarity and aromaticity decreased. These data showed substantial chemical, structural, and molecular differences among the 23 HAs and two humin fractions. Therefore, these results may help explain why soil and sediment humin fractions have high sorption capacity for organic contaminants.     

Extraction kinetics of copper,zinc, iron,and manganese from contaminated sediment using Disodium Ethylenediaminetetraacetate

One technique for cleansing heavy metal contaminated soils is to wash the excavated soil with an extraction solution of a chelating agent. The rate of extraction is an important parameter when considering the length of time needed for soil clean-up and the amount and concentration of wash solution required. The extraction kinetics of copper, zinc, iron and manganese from a contaminated sediment of the Clark Fork River in western Montana, U.S.A., with Disodiun Ethylenediaminetetraacetate (Na₂EDTA) as the extraction agent, were investigated. The results showed the extraction process consisted of rapid extraction in the first minutes followed by much slower extraction for the remainder of the experiment. The rate of extraction, particularly in the rapid phase, demonstrated clear pH dependence: the lower the pH, the faster the extraction rate. In the EDTA concentration range of 0.01 M to 0.05 M, the effect of the EDTA concentration on the extraction rate was not important compared with that of the solution pH. Extraction kinetics for different size particles were similar, although in the first few minutes, EDTA extracted more metals from clay and silt than sand. The two reaction, diffusion, and two-constant kinetic models were compared to experimental results. The two reaction model did not fit any of the data well, and only iron extraction could be described with a simple diffusion model. In general the extraction rates can be well described by the two-constant model, C=A t ^B, up to 600 minutes and under different conditions such as solution pH, EDTA concentration, and different sediment particle size.