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纸浆过程流中可能存在对香豆酸、磺基水杨酸、水杨酸、柠檬酸4种作为广义螯合剂的木素溶解物,采用电位法和吸光光度法测定该4种模型物对Al3+、Fe3+、cu2+、Mn2+、Mg2+、Ca2+金属离子的螯合平衡常数,并与传统螯合剂EDTA和DTPA进行比较,探讨纸浆过程流中螫合剂对金属离子的螯合竞争性和可能存在的螯合和脱螫合现象.结果表明,A13+和Fe3+与模型物的螯合平衡常数最大,螯合能力最强;具链式结构的柠檬酸螯合各种金属元素的能力较强,对香豆酸与会属元素的螯合能力较弱;金属离子与螯合剂螯合时的配位数越高,形成的配位物越稳定;根据纸浆过程流中金属离子的特征和木素溶出物的结构特点,选择性地采用不同的螯合剂去除浆料中的金属元素可达到理想效果. 相似文献
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二氧化硅(SiO2)含量的测定多用重量法,由于重量法的测定忽略了滤液中的微量SiO2,造成结果偏低.本研究用硅钼蓝分光光度法补测滤液中的微量SiO2含量,加和到重量法分析结果中去,以提高分析方法的准确度.氧化钙(CaO)和氧化镁(MgO)含量的测定采用沉淀--络合联合掩蔽法消除铁(Fe3+)、铝(Al3+)的干扰,使络合滴定法的应用更加广泛. 相似文献
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从螯合剂的络合稳定常数lgK和螯合容量两大指标性参数入手介绍氨基羧酸类、膦酸盐类、羟基羧酸类、氨基酸类和聚羧酸类五大有机螯合剂.重点评述取代因生态环保问题退出市场的NTA、EDTA、DTPA的有机膦酸盐类螯合剂,虽然在制造过程中涉及甲醛,但如经妥善处理,残留在纺织品上的甲醛将低于国内外有关法规的可控限量,且不会造成水体富营养化. 相似文献
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多糖铁配合物具有易吸收、无肠道刺激、定向吸收等优点。该研究通过对克雷伯氏菌胞外多糖螯合铁的制备工艺进行研究,以期实现微生物胞外多糖与铁的有效螯合,制得一种新型补铁剂。克雷伯氏菌胞外多糖和三氯化铁螯合后得到胞外多糖铁螯合物,采用单因素试验分别考察柠檬酸三钠、螯合温度、螯合时间和溶液pH值对多糖铁中铁含量的影响,再用正交试验确定最佳的螯合条件。通过单因素和正交试验发现,在克雷伯氏菌胞外多糖与柠檬酸三钠的质量比为3∶1、螯合时间为0.5 h、温度为60℃、溶液pH值为7的条件下,所得螯合物中含铁量最高达2.88%。 相似文献
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Performance of Nonmigratory Iron Chelating Active Packaging Materials in Viscous Model Food Systems
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Many packaged food products undergo quality deterioration due to iron promoted oxidative reactions. Recently, we have developed a nonmigratory iron chelating active packaging material that represents a novel approach to inhibit oxidation of foods while addressing consumer demands for “clean? labels. A challenge to the field of nonmigratory active packaging is ensuring that surface‐immobilized active agents retain activity in a true food system despite diffusional limitations. Yet, the relationship between food viscosity and nonmigratory active packaging activity retention has never been characterized. The objective of this study was to investigate the influence of food viscosity on iron chelation by a nonmigratory iron chelating active packaging material. Methyl cellulose was added to aqueous buffered iron solutions to yield model systems with viscosities ranging from ~1 to ~105 mPa·s, representing viscosities ranging from beverage to mayonnaise. Iron chelation was quantified by material‐bound iron content using colorimetry and inductively coupled plasma‐optical emission spectrometry (ICP‐OES). Maximum iron chelation was reached in solutions up to viscosity ~102 mPa·s. In more viscous solutions (up to ~104 mPa·s), there was a significant decrease in iron chelating capacity (P < 0.05). However, materials still retained at least 76% iron chelating capacity. Additionally, the influence of different food hydrocolloids on the performance of nonmigratory iron chelating active packaging was characterized. Methyl cellulose and carrageenan did not compete with the material for specific iron chelation (P > 0.05). Materials retained 32% to 45% chelating capacity when in contact with competitively chelating hydrocolloids guar gum, locust bean gum, and xanthan gum. This work demonstrates the potential application of nonmigratory iron chelating active packaging in liquid and semi‐liquid foods to allow for the removal of synthetic chelators, while maintaining food quality. 相似文献
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Generation,Fractionation, and Characterization of Iron‐Chelating Protein Hydrolysate from Palm Kernel Cake Proteins
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Mohammad Zarei Rahele Ghanbari Naser Tajabadi Azizah Abdul‐Hamid Fatimah Abu Bakar Nazamid Saari 《Journal of food science》2016,81(2):C341-C347
Palm kernel cake protein was hydrolyzed with different proteases namely papain, bromelain, subtilisin, flavourzyme, trypsin, chymotrypsin, and pepsin to generate different protein hydrolysates. Peptide content and iron‐chelating activity of each hydrolysate were evaluated using O‐phthaldialdehyde‐based spectrophotometric method and ferrozine‐based colorimetric assay, respectively. The results revealed a positive correlation between peptide contents and iron‐chelating activities of the protein hydrolysates. Protein hydrolysate generated by papain exhibited the highest peptide content of 10.5 mM and highest iron‐chelating activity of 64.8% compared with the other hydrolysates. Profiling of the papain‐generated hydrolysate by reverse phase high performance liquid chromatography fractionation indicated a direct association between peptide content and iron‐chelating activity in most of the fractions. Further fractionation using isoelectric focusing also revealed that protein hydrolysate with basic and neutral isoelectric point (pI) had the highest iron‐chelating activity, although a few fractions in the acidic range also exhibited good metal chelating potential. After identification and synthesis of papain‐generated peptides, GGIF and YLLLK showed among the highest iron‐chelating activities of 56% and 53%, whereas their IC50 were 1.4 and 0.2 μM, respectively. 相似文献
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从络合滴定法的角度探究硫酸盐法制浆白液中硫酸盐的测定,结果表明,与重量法测定相比较,络合滴定法步骤简单、用时较短,适合于制浆造纸工艺生产控制的过程分析。 相似文献
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大豆蛋白水解物的酶法修饰及其亚铁和钙离子的螯合能力 总被引:1,自引:0,他引:1
利用碱性蛋白酶水解大豆分离蛋白制备出水解度为14.1%的水解物,并在醇-水介质中对其进行类蛋白反应修饰。固定底物质量分数30%,反应时间4 h,利用响应面分析法对类蛋白反应条件进行优化,得到最优条件为:酶添加量5.26 kU/g蛋白质,乙醇体积分数56.8%,温度33.1℃。在乙醇-水或甲醇-水介质中制备反应程度不同的修饰产物,并评价其对亚铁和钙离子的螯合能力。结果表明,亚铁离子螯合能力由39.8%提升至59.3%,钙离子螯合能力由62.1%提升至76.6%。大豆分离蛋白的酶解以及类蛋白反应修饰,是一个提高金属离子鳌合能力大豆蛋白螯合肽的新技术。 相似文献
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从有机微量元素的螯合率对于衡量产品的品质、调节工艺条件、研究作用机理3 个方面,阐述了测定螯合率的重要意义;综述了螯合率测定的方法,对凝胶过滤色谱法和有机溶剂萃取法进行比较,指出有机溶剂萃取法测定螯合率可能具有比较好的适用性。 相似文献
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采用响应面法优化猪血复合微量元素补铁剂的螯合工艺。在单因素试验的基础上,选择pH值、多肽溶液质量分数、多肽溶液与1.0 mol/L FeCl2溶液的体积比为影响因素,以Fe2+螯合率为指标,进行3因素3水平的Box-Behnken试验设计,采用响应面法分析3 个因素对响应值的影响。结果表明:响应面法优化猪血复合微量元素补铁剂的最佳螯合工艺条件为pH值5.40、多肽溶液质量分数2.27%、多肽溶液与1.0 mol/L FeCl2溶液的体积比2.16∶1;在此条件下,猪血多肽Fe2+螯合率的预测值为79.37%,实测值为79.41%。 相似文献
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研究了四乙撑五胺(TEPA)在猪油和豆油中的抗氧化效果,发现一般抗氧化剂在猪油中均有明显的抗氧化作用,但比TEPA要低得多,TEPA在豆油也有很强的抗氧化作用,菲醌的抗氮化作用也曾明显,但酚型抗氧化剂和紫草的石油醚提取物(LE-pet)未显示明显抗氧化作用,2mg/kgFe^3+对0.04%TEPA的抗氧化活性只有很微小的抑制作用,10mg/kgFe^3+对其有很强的抑制作用,用20mg/kgFe 相似文献
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本研究以废弃物山杏核壳为原料,采用单因素及响应面试验法优化黑色素的提取工艺参数并对得到的黑色素进行了紫外-可见吸收光谱、红外吸收光谱及扫描电镜等结构鉴定,之后以提取的黑色素与Fe3+、Cu2+、Zn2+三种金属离子的螯合效果为指标,采用单因素实验优化了黑色素与三种金属离子的螯合工艺,并对得到的螯合物进行了紫外-可见吸收光谱、红外吸收光谱、扫描电镜及能谱扫描等结构鉴定,以期为其作为功能食品的进一步开发利用提供理论依据。结果表明:实验选取的各因素对山杏核壳黑色素得率的影响大小顺序为:超声提取时间、碱浓度、pH、料液比。响应面得到提取的最佳工艺为:料液比1:10 g/mL,氢氧化钠浓度1.5 mol/L,酸沉pH为1,超声时间35 min,此条件下得率为4.78%±0.23%。黑色素铁螯合物的最佳螯合工艺为铁离子浓度5 mmol/L,pH5.5,反应8 h;黑色素铜螯合物的最佳螯合工艺为铜离子浓度4 mmol/L,pH7.5,反应6 h;黑色素锌螯合物的最佳螯合工艺为锌离子浓度3 mmol/L,pH7.5,反应4 h。相同条件下,黑色素铁螯合物的螯合率最大,达63.86%。紫外和红外结果表明黑色素主要通过氨基、羰基或羧基与金属离子螯合,扫描电镜及能谱结果表明了三种金属螯合物的成功制备。本研究为开发功能食品添加剂及金属元素补充剂提供了理论依据,具有广泛的实用价值和市场前景。 相似文献
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工业生产和控制中钙镁测定多采用EDTA络合滴定分析,在实际测定中,发现当p H值大于12.5时,加入糊精、三乙醇胺、氢氧化钾及钙羧酸指示剂,用EDTA络合滴定Ca,以及在p H值为10时,加入盐酸羟胺、三乙醇胺、氨性缓冲溶液及酸性铬兰K-萘酚绿B指示剂,用EDTA络合滴定Mg具有广泛的适用性,实验在p H值大于12.5时,只加入三乙醇胺、氢氧化钾及钙羧酸指示剂,用EDTA络合滴定Ca做了初步的实验分析。 相似文献