酸热诱导大豆分离蛋白纳米颗粒形成及其荷载姜黄素的特性

以大豆分离蛋白(soy protein isolate,SPI)为原料,在特定pH值条件下(pH 7.0、5.9)静态加热处理(95℃、30 min)诱导SPI自组装形成纳米颗粒,分别记作HSPI及HSPI(pH 5.9)。进一步以姜黄素为模型疏水性活性物质,较系统地比较均质及超声处理对不同结构的蛋白颗粒荷载姜黄素的影响。荧光光谱结果表明,SPI、HSPI和HSPI(pH 5.9)均可与姜黄素发生疏水相互作用,使蛋白发生荧光猝灭并提高姜黄素的水分散性。热处理可显著提高蛋白颗粒的表面疏水性,其中HSPI(pH 5.9)的粒径分布更均一(多相分散系数0.2),且较SPI与姜黄素有更高的结合力。通过均质或超声处理,SPI、HSPI和HSPI(pH 5.9)可进一步通过疏水驱动作用荷载姜黄素形成富载姜黄素的纳米颗粒。与SPI及HSPI相比,HSPI(pH 5.9)的核-壳结构有利于蛋白与姜黄素在超声过程中发生共组装,形成形态均一且性质稳定的纳米颗粒,显著提高了姜黄素的水溶性及贮藏稳定性。     

超声预处理对大豆分离蛋白-儿茶素非共价/共价复合物结构及功能的影响

目的:探究超声预处理对大豆分离蛋白(soybean protein isolate,SPI)-儿茶素非共价/共价复合物结构及功能的影响.方法:对SPI进行超声处理后,在不同pH值(3.0、7.0、9.0、12.0)下与儿茶素通过非共价/共价结合方式制备复合物,并通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium do...     

罗非鱼-大豆共沉淀蛋白乳液稳定二十二碳六烯酸藻油的研究

为探究共沉淀蛋白乳液稳定二十二碳六烯酸(docosahexenoic acid, DHA)藻油的可行性,该研究以罗非鱼分离蛋白(tilapia protein isolate, TPI)、3种罗非鱼-大豆共沉淀蛋白(tilapia-soy protein co-precipitates, TSPC_2∶1、TSPC_1∶1和TSPC_1∶2)和大豆分离蛋白(soy protein isolate, SPI)为乳化剂,高压均质制备TPI、TSPC和SPI-DHA藻油乳液,比较5种乳液的物理稳定性和氧化稳定性。结果表明,与TPI乳液比较,随着原料中大豆比例的增加,TSPC-DHA藻油乳液的平均粒径和乳析指数减小(P<0.05),Zeta电位绝对值增大(P<0.05),乳液的物理稳定性增强。与SPI乳液比较,贮藏过程中TSPC-DHA藻油乳液的过氧化值和硫代巴比妥酸反应物值明显较小(P<0.05),乳液的氧化稳定性明显改善。TSPC_1∶1和TSPC_1∶2乳液在4℃贮藏28...     

pH值对罗非鱼蛋白-大豆蛋白混合热凝胶特性及体外消化性的影响

以罗非鱼和大豆为原料分别提取鱼分离蛋白(fish protein isolate,FPI)和大豆分离蛋白(soy protein isolate,SPI),制备罗非鱼蛋白-大豆蛋白(FPI∶SPI=1∶1,质量比)热诱导凝胶,探讨pH值(6.0、6.5、7.0、7.5)对混合蛋白热凝胶特性和体外消化性的影响。结果表明:pH 6.5时罗非鱼蛋白-大豆蛋白混合蛋白热凝胶储能模量G′值大于单一蛋白,凝胶特性最好,硬度和胶黏性相比FPI都得到提升。pH值会影响蛋白质与水分子的结合能力,混合蛋白热凝胶的持水性在pH 6.5时比其它pH值条件下强(P<0.05),达到最大值84.02%,与扫描电镜结果一致,网络结构致密且光滑平整。pH 6.5时,混合蛋白热凝胶的消化率达91.57%,高于其它pH值下的消化率(P<0.05)。因此,通过调节pH值可以改善FPI和SPI混合蛋白热凝胶的凝胶特性和消化性。     

壳聚糖铁(Ⅲ)配合物吸附动力学研究

采用非均相吸附法制备了壳聚糖铁(Ⅲ)配合物,用紫外光谱(UV)、红外光谱(IR)对配合物的结构进行了表征;研究了壳聚糖对Fe³⁺ 的吸附动力学特性。实验结果表明,壳聚糖与Fe³⁺之间发生了配位作用,壳聚糖分子中参与配位反应的主要是-NH_²、-OH及少量的-NHCOCH₃;壳聚糖对Fe³⁺的吸附行为可用Langmuir单分子层吸附机理解释,且求得吸附表观活化能为3.6476kJ/mol。     

pH和阿拉伯胶对大豆分离蛋白/大豆蛋白酶解产物乳化性质的影响

研究了pH和阿拉伯胶对大豆分离蛋白(soy protein isolate,SPI)或低限度酶解改性产物的乳化性质的影响。结果表明:SPI酶解改性处理后制备的乳液颗粒粒径和液滴间絮凝程度明显降低;添加阿拉伯胶促进了SPI或大豆蛋白酶解产物(soy protein hydrolysate,SPH)在油水界面的吸附,SPH-阿拉伯胶复合物制备的乳液在pH4的条件下室温放置14 d具有较好稳定性;添加阿拉伯胶前后,SPH制备的乳液黏度均低于SPI。     

羊毛/铁配合物非均相芬顿反应光催化剂的制备及其应用性能

为提升废旧羊毛的回收再利用价值,将具有不同直径和鳞片结构的3种羊毛分别与水溶液中Fe³⁺进行配位反应,得到3种羊毛/铁配合物,然后将其作为非均相芬顿反应光催化剂应用于活性红195的氧化降解反应中,研究了反应条件以及羊毛直径和鳞片层等对配合物的铁离子配合量和光催化性能的影响。结果表明:Fe³⁺浓度和配位反应温度的升高均能促进Fe³⁺和羊毛之间配位反应的进行,较薄鳞片层的羊毛更易与Fe³⁺反应,制备更高铁离子配合量的羊毛/铁配合物;可使用Lagergren准二级动力学模型方程对羊毛与Fe³⁺之间的配位反应进行描述,但较薄鳞片层羊毛的反应速度更慢;3种羊毛/铁配合物都可显著催化染料发生氧化降解反应,提高铁离子配合量和辐射光强度,均能增加其光催化性能,较细羊毛制备的配合物具有更强的催化作用和pH值适应性。     

响应面法优化花青素/Fe3O4纳米复合物的制备工艺及其体外消化研究

为了提高花青素的生物利用率，本研究采用共沉淀的方法制备花青素/Fe₃O₄纳米复合物。利用响应面法(Response Surface Method,RSM)优化花青素/Fe₃O₄纳米复合物的合成，并对花青素/Fe₃O₄纳米复合物进行粒径分析、Zeta电位测定、扫描电子显微镜、傅里叶变换红外光谱分析以及体外模拟消化实验。结果表明花青素/Fe₃O₄纳米复合物的最佳制备条件为花青素与Fe₃O₄的质量比为1:46，反应时间为19.6 h，反应温度为47℃，此工艺条件下花青素的包封率为87.51%。该纳米复合物粒径分布集中在100～1200 nm，且分布均匀，Zeta电位为-48.15 mV。通过扫描电子显微镜观察到花青素与Fe₃O₄纳米粒子间形成了表面光滑的球状颗粒。花青素/Fe₃O₄纳米复合...     

超声波均质法制备糖基化蛋白-茶油纳米乳液及其稳定性的研究

以超声波均质作为技术手段，乳清分离蛋白(whey protein isolate, WPI)和乳糖(D-lactose, Lac)的糖基化反应产物(WPI-Lac)为水相，茶油为油相，通过超声波均质法制备由糖基化反应产物稳定的茶油纳米乳液，优化了pH、油相质量分数、超声波功率、超声波时间，研究了温度和pH对乳液储藏稳定性和氧化稳定性的影响。结果表明，在水相pH为7.0,油相分数为10%,超声波功率为450 W,超声波处理时间为10 min时可制备出粒径为(206.2±1.572) nm和多分散性指数为(0.136±0.109)的均匀纳米乳液。为期15 d的贮存中，超声波处理糖基化蛋白(ultrasonic whey protein isolate glycosylated, UWPIL)-茶油纳米乳液的过氧化值及次级氧化产物的浓度显著低于超声波处理蛋白(ultrasonic whey protein isolate, UWPI)稳定的茶油纳米乳液，并维持在低水平，基于超声波均质处理，使用乳糖改性后的WPI为乳化剂，使包裹的乳液更稳定，并有效减缓了茶油的氧化。     

美拉德产物-果胶负载CoQ10纳米颗粒的制备及研究

采用大豆分离蛋白-燕麦β-葡聚糖美拉德产物(SPI-OG)和果胶(PEC)通过复凝聚反应制备出三元复合物作为壁材,以CoQ₁₀为芯材利用超声-乙醇注入法制备CoQ₁₀纳米颗粒。探究制备壁材及CoQ₁₀纳米颗粒的工艺条件,并对样品进行结构表征及稳定性和功能性质研究。结果表明,pH 3.8、总质量浓度5 mg/mL、SPI-OG与PEC的质量比1∶1时制备的壁材是最为稳定的;芯壁质量比1∶7.5是制备纳米颗粒的最佳比例,包埋率和负载量分别为70.58%和8.61%。结构表征方面,红外光谱、X-射线衍射、差示扫描量热的结果均可证实CoQ₁₀被包埋在壁材中。储存稳定性研究表明低温以及避光可以很好地储存CoQ₁₀纳米颗粒。功能性质方面,CoQ₁₀包埋后其DPPH清除自由基的能力没有太大变化,胃肠道模拟发现CoQ₁₀纳米颗粒的溶出度明显高于CoQ₁₀的溶出度,说明CoQ₁₀纳米颗粒的制备基本上没有破坏C...     

Treatment of hexavalent chromium in chromite ore processing solid waste using a mixed reductant solution of ferrous sulfate and sodium dithionite

We investigated a method for delivering ferrous iron into the subsurface to enhance chemical reduction of Cr(VI) in chromite ore processing solid waste (COPSW) derived from the production of ferrochrome alloy. The COPSW is characterized by high pH (8.5-11.5) and high Cr(VI) concentrations in the solid phase (up to 550 mg kg(-1)) and dissolved phase (3-57 mg L(-1)). The dominant solid-phase minerals are forsterite (Mg2SiO4), brucite (Mg-(OH)2), and hydrocalumite [Ca4(Al, Fe)2(OH)12X x 6H2O), X = (OH)2(2-), SO4(2-), CrO4(2-)]. The method utilizes FeSO4 in combination with Na2S2O4 to inhibit oxidation and precipitation of the ferrous iron, thereby preventing well and formation clogging. Laboratory batch tests using a 0.05 M FeSO4 + 0.05 M Na2S2O4 solution indicated effective treatment of both dissolved and solid-phase Cr(VI). Contrary to treatments with FeSO4 and FeCl2 alone, the combination resulted in both complete removal of Cr(VI) from solution and sustained Fe(ll) concentrations in solution after a 24 h period. A field test involving injection of 5700 L of a 0.07 M FeSO4 + 0.07 M Na2S2O4 solution into a COPSW saturated zone (pH 11.5) indicated no well and formation clogging during injection. Examination of a core collected 0.46 m from the injection well following injection indicated effective treatment of the solid phase Cr(VI) based on analysis of water, phosphate solution, and high temperature alkaline extracts. The combined reductant solution also imparted a residual treatment capacity to the COPSW allowing for subsequent treatment of dissolved phase Cr(VI); however, dissemination of the iron in the highly alkaline environment appeared to be impeded by the inability to sufficiently lower the pH with distance from the injection well to avoid precipitation of Fe(OH)2 and likely also FeCO3. Injection of a 0.2 M FeSO4 + 0.2 M Na2S2O4 solution into another COPSW saturated zone (pH 9) indicated much more effective dissemination of the injected iron.     

Green rust and iron oxide formation influences metolachlor dechlorination during zerovalent iron treatment

Electron transfer from zerovalent iron (Fe0) to targeted contaminants is affected by initial Fe0 composition, the oxides formed during corrosion, and surrounding electrolytes. We previously observed enhanced metolachlor destruction by Fe0 when iron or aluminum salts were present in the aqueous matrix and Eh/pH conditions favored formation of green rusts. To understand these enhanced destruction rates, we characterized changes in Fe0 composition during treatment of metolachlor with and without iron and aluminum salts. Raman microspectroscopy and X-ray diffraction (XRD) indicated that the iron source was initially coated with a thin layer of magnetite (Fe3O4), maghemite (gamma-Fe2O3), and wüstite (FeO). Time-resolved analysis indicated that akaganeite (beta-FeOOH) was the dominant oxide formed during Fe0 treatment of metolachlor. Goethite (alpha-FeOOH) and some lepidocrocite (gamma-FeOOH) formed when Al2(SO4)3 was present, while goethite and magnetite (Fe3O4) were identified in Fe0 treatments containing FeSO4. Although conditions favoring formation of sulfate green rust (GR(II); Fe6(OH)12SO4) facilitated Fe0-mediated dechlorination of metolachlor, only adsorption was observed when GR(II) was synthesized (without Fe0) in the presence of metolachlor and Eh/pH changed to favor Fe(III)oxyhydroxide or magnetite formation. In contrast, dechlorination occurred when magnetite or natural goethite was amended with Fe(II) (as FeSO4) at pH 8 and continued as long as additional Fe(II) was provided. While metolachlor was not dechlorinated by GR(II) itself during a 48-h incubation, the GR(II) provided a source of Fe(II) and produced magnetite (and other oxide surfaces) that coordinated Fe(II), which then facilitated dechlorination.     

Selenite reduction by mackinawite, magnetite and siderite: XAS characterization of nanosized redox products

Suboxic soils and sediments often contain the Fe(II)-bearing minerals mackinawite (FeS), siderite (FeCO3) or magnetite (FesO4), which should be able to reduce aqueous selenite, thereby forming solids of low solubility. While the reduction of selenate or selenite to Se(O) by green rust, pyrite and by Fe2+ sorbed to montmorillonite is a slow (weeks), kinetically limited redox reaction as demonstrated earlier, we show here that selenite is rapidly reduced within one day by nanoparticulate mackinawite and magnetite, while only one third of selenite is reduced by micrometer-sized siderite. Depending on Fe(II)-bearing phase and pH, we observed four different reaction products, red and gray elemental Se, and two iron selenides with structures similar to Fe7Se8 and FeSe. The thermodynamically most stable iron selenide, ferroselite (FeSe2), was not observed. The local structures of the reaction products suggest formation of nanoscale clusters, which may be prone to colloid-facilitated transport, and may have a higher than expected solubility.     

Iron(VI) and iron(V) oxidation of copper(I) cyanide

Copper(Il) cyanide (Cu(CN)4(3-)) in the gold mine industry presentsthe biggest concern in cyanide management because it is much more stable than free cyanide. Cu(CN)4(3-) is highlytoxic to aquatic life; therefore, environmentally friendly techniques are required for the removal of Cu(CN)4(3-) from gold mine effluent. The oxidation of Cu(CN)4(3-) by iron-(VI) (FeVIO4(2-), Fe(VI)) and iron(V) (FeVO4(3-), Fe(V)) was studied using stopped-flow and premix pulse radiolysis techniques. The stoichiometry with Fe(VI) was determined to be 5HFeO(4-) + Cu(CN)4(3-) + 8H2O - > 5Fe(OH)3 + Cu2+ + 4CNO- +3/202 + 6OH-. The rate law for the oxidation of Cu(CN)4(3-) by Fe(VI) was found to be first-order with each reactant. The rates decreased with increasing pH and were mostly related to a decrease in concentration of reactive protonated Fe(VI) species, HFeO4-. A mechanism is proposed that agrees with the observed reaction stoichiometry and rate law. The rate constant for the oxidation of Cu(CN)4(3-) by Fe(V) was determined at pH 12.0 as 1.35 +/- 0.02 x 10(7) M(-1) s(-1), which is approximately 3 orders of magnitude larger than Fe(VI). Results indicate that Fe(VI) is highly efficient for removal of cyanides in gold mill effluent.     

Iron optimization for Fenton-driven oxidation of MTBE-spent granular activated carbon

Fenton-driven chemical oxidation of methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was accomplished through the addition of iron (Fe) and hydrogen peroxide (H2O2) (15.9 g/L; pH 3). The Fe concentration in GAC was incrementally varied (1020-25 660 mg/kg) by the addition of increasing concentrations of Fe solution (FeSO4-7H2O). MTBE degradation in Fe-amended GAC increased by an order of magnitude over Fe-unamended GAC and H2O2 reaction was predominantly (99%) attributed to GAC-bound Fe within the porous structure of the GAC. Imaging and microanalysis of GAC particles indicated limited penetration of Fe into GAC. The optimal Fe concentration was 6710 mg/kg (1020 mg/kg background; 5690 mg/kg amended Fe) and resulted in the greatest MTBE removal and maximum Fe loading oxidation efficiency (MTBE oxidized (microg)/ Fe loaded to GAC (mg/Kg)). At lower Fe concentrations, the H2O2 reaction was Fe limited. At higher Fe concentrations, the H2O2 reaction was not entirely Fe limited, and reductions in GAC surface area, GAC pore volume, MTBE adsorption, and Fe loading oxidation efficiency were measured. Results are consistent with nonuniform distribution of Fe, pore blockage in H2O2 transport, unavailable Fe, and limitations in H2O2 diffusive transport, and emphasize the importance of optimal Fe loading.     

食品营养强化剂甘氨酸亚铁螯合物的合成工艺

以硫酸亚铁和L 甘氨酸为原料 ,对食品营养强化剂甘氨酸亚铁螯合物的合成进行了研究。重点研究了反应摩尔比 [甘氨酸 :硫酸亚铁 (Gly :Fe) ]和 pH值对螯合反应的影响 ,确定合适的螯合反应的条件为甘氨酸与硫酸亚铁摩尔比 =1∶1 ,温度 40℃ ,pH =4,产品螯合率 65 43 %。     

Fenton/电-Fenton降解造纸废水中2,4-二氯苯酚的研究

探讨了Fenton/电-Fenton氧化法降解2,4-二氯苯酚影响因素及降解效果。结果显示:Fenton法的最佳工艺条件是pH值为2,3%H2O2投加量为2mL,FeSO4.7H2O投加量为0.30g,去除效率在80%-85%;电-Fenton法的最佳工艺条件是1mol/LNa2SO450mL,电压为5V,pH为4时处理效果最好,去除效率在90%-93%。对比分析研究的结果是Fenton法比电-Fenton法反应速率快、消耗的药品量大、产生的Fe(OH)3沉淀多、去除效果差,但是电耗低。     

Effect of pH on aqueous Se(IV) reduction by pyrite

Interaction of aqueous Se(IV) with pyrite was investigated using persistently stirred batch reactors under O2-free (<1 ppm) conditions at pH ranging from 4.5 to 6.6. Thermodynamic calculations, an increase in pH during the experiments, and spectroscopic observation indicate that the reduction of aqueous Se(IV) by pyrite is dominated by the following reaction: FeS2+3.5HSeO3?+1.5H+=2SO4(2?)+Fe2++3.5Se(0)+2.5H2O. The released Fe(II) was partitioned between the bulk solution and pyrite surface at pH≈4.5 and 4.8, with the Fe2+ density at pyrite-solution interface about 4 orders of magnitude higher than that in the bulk solution, while iron oxyhydroxide precipitated at pH≈6.6, resulting in the decrease of dissolved iron. In the Se(IV) concentration range of the experiments, aqueous Se(IV) reduction rate follows the pseudofirst order which is in the form of ln mSe(IV)=?k′t+ln mSe(IV)0, where k′ is apparent rate constant combining the rate constant k and pyrite surface area to mass of solution ratio (A/M). And the aqueous Se(IV) reduction rate constant for a standard system (k) with 1 m2 pyrite surface area per 1 kg solution was obtained to be 1.65×10(?4) h(?1), 3.28×10(?4) h(?1), and 4.76×10(?4) h(?1) at pH around 4.5, 4.8, and 5.1, respectively. The positive correlation between reaction rate and pH disagrees with the theories that protons are consumed when HSeO3? is reduced to Se0, and negative charge density on pyrite surface increases as pH increases. Thus, a ferrous iron mediated electron transfer mechanism is proposed to operate during the reduction of aqueous Se(IV) by pyrite. pH and iron concentration affect significantly on Se(IV) reaction rate and reaction product.     

A polymer membrane containing Fe(0) as a contaminant barrier

A poly(vinyl alcohol) (PVA) membrane containing iron (Fe(0)) particles was developed and tested as a model barrier for contaminant containment. Carbon tetrachloride, copper (Cu2+), nitrobenzene, 4-nitroacetophenone, and chromate (Cr04(2-)) were selected as model contaminants. Compared with a pure PVA membrane, the Fe(0)/PVA membrane can increase the breakthrough lag time for Cu2+ and carbon tetrachloride by more than 100-fold. The increase in the lag time was smaller for nitrobenzene and 4-nitroacetophenone, which stoichiometrically require more iron and for which the PVA membrane has a higher permeability. The effect of Fe(0) was even smaller for CrO4(2-) because of its slow reaction. Forty-five percent of the iron, based on the content in the dry membrane prior to hydration, was consumed by reaction with Cu2+ and 15% by reaction with carbon tetrachloride. Similarly, 25%, 17%, and 6% of the iron was consumed by nitrobenzene, 4-nitroacetophenone, and CrO4(2-), respectively. These percentages approximately double when the loss of iron during membrane hydration is considered. The permeability of the Fe(0)/PVA membrane after breakthrough was within a factor of 3 for that of pure PVA, consistent with theory. These results suggest that polymer membranes with embedded Fe(0) have potential as practical contaminant barriers.     

Study of the effect of different iron salts used to fortify infant formulas on the bioavailability of trace elements using ICP-OES

Five different iron salts—sulphate, lactate, diphosphate, encapsulated sulphate, and EDTA-Fe(III)—were used to fortify an infant formula to study possible differences in iron bioavailability. The effect of iron fortification at two levels (0.5 mg Fe 100 kcal⁻¹ and 1.5 mg Fe 100 kcal⁻¹) on the bioavailability of other important trace elements such as copper and zinc were also evaluated. An in vitro method based on element dialysability (i.e., the fraction available by absorption) to simulate newborn digestion was applied to study iron, copper and zinc bioavailability. Enzyme treatment was carried out in two stages involving pepsin at pH 5.0 followed by pancreatin at pH 7.0. The incubation times were short to mimic the transit of meal in an infant's gastrointestinal tract. Iron, copper and zinc were determined using inductively coupled plasma atomic emission spectrometry using an axially configured device. The percentages of Fe, Cu and Zn dialysable at both iron fortification levels are discussed. From these results, EDTA-Fe (III) appears to be the most adequate salt for iron fortification of infant formulas.