Removal of hexavalent chromium from wastewater using a new composite chitosan biosorbent

A new composite chitosan biosorbent was prepared by coating chitosan, a glucosamine biopolymer, onto ceramic alumina. The composite bioadsorbent was characterized by high-temperature pyrolysis, porosimetry, scanning electron microscopy, and X-ray photoelectron spectroscopy. Batch isothermal equilibrium and continuous column adsorption experiments were conducted at 25 degrees C to evaluate the biosorbent for the removal of hexavalent chromium from synthetic as well as field samples obtained from chrome plating facilities. The effect of pH, sulfate, and chloride ion on adsorption was also investigated. The biosorbent loaded with Cr(VI) was regenerated using 0.1 M sodium hydroxide solution. A comparison of the results of the present investigation with those reported in the literature showed that chitosan coated on alumina exhibits greater adsorption capacity for chromium(VI). Further, experimental equilibrium data were fitted to Langmuir and Freundlich adsorption isotherms, and values of the parameters of the isotherms are reported. The ultimate capacity obtained from the Langmuir model is 153.85 mg/g chitosan.     

麦麸中植酸的脱除工艺

植酸是麦麸中的主要抗营养因子,为提高麦麸中蛋白质和膳食纤维的利用率,文中以植酸脱除率为目标,对麦麸中植酸的脱除工艺进行了分析和优化。结果显示,植酸脱除的最佳工艺是：以0.5 mol/L盐酸溶液为植酸提取溶剂,料液比为1:10 (g/mL),20 ℃下提取2 h,植酸脱除率可达到73.54%。结果表明,升高提取温度不利于植酸提取,提取时间过长或料液比过高都不利于植酸的脱除。经上述工艺处理后,麦麸中植酸和灰分含量有显著降低,蛋白质含量略有降低;淀粉含量和粗纤维含量均有明显提高,分别提高了16.70%和30.10%,其总体营养价值有明显改善,更有利于麸皮中营养组分的加工利用。     

冬小麦抗冻蛋白制备及其在汤圆中的应用研究

研究了冬小麦麸皮抗冻蛋白的制备方法及其在速冻汤圆中的应用。研究确定冬小麦麸皮抗冻蛋白的提取工艺为:pH8.0,提取时间3h,液料比5:1,该条件下小麦麸皮水溶性蛋白质提取率达到38%,其中含抗冻蛋白1.6%。抗冻蛋白粗品在汤圆中的应用实验结果显示,2.5%的蛋白添加量对汤圆的品质有明显的改善效果。      

小麦麸皮结构层中抗氧化物质的研究

采用酶法与化学法,分别对麦麸的外皮层、中间层及糊粉层进行水解,对提取物中酚酸的种类和含量进行了测定。对比了酶解与碱解所得提取物中总酚的含量和清除自由基的能力。结果表明：碱解处理后,外皮层申阿魏酸脱氢聚体含量最高,达4．34mg／g,而糊粉层中阿魏酸单体的含量最高,达5．90mg/g;酶解后,外皮层、中间层和糊粉层的水解液中阿魏酸脱氢聚体含量分别为碱解释放量的71．0％、52．6％和51．1％,而阿魏酸单体的释放量为碱解释放量的46．9％、51．0％和56．3％。同时,碱解和酶解提取物中的总酚含量和抗氧化能力与酚酸含量直接相关。     

Removal of hexavalent chromium by biosorption process in rotating packed bed

Removal of hexavalent chromium ions from an aqueous solution by crude tamarind (Tamarindus indica) fruit shell was examined in a rotating packed bed contactor by continuously recirculating a given volume of solution through the bed. Reduction of Cr(VI) to Cr(III) within the biosorbent appeared to be the removal mechanism. Depletion rate of Cr(VI) from, and release of reduced Cr(III) ions into the aqueous phase, was influenced by mass transfer resistance besides pH and packing depth. A mathematical model considering the reduction reaction to be irreversible and incorporating intraparticle and external phase mass transfer resistances represented the experimental data adequately. The study indicated that the limitations of fixed bed contactor operating under terrestrial gravity in intensifying mass transfer rates for this system can be overcome with rotating packed bed due to liquid flow under centrifugal acceleration.     

复合风味蛋白酶酶解麦麸蛋白制备麦麸抗氧化肽的研究

以麦麸蛋白为原料,复合风味蛋白酶为水解酶,探讨麦麸蛋白水解度(DH)与麦麸肽抗氧化能力的关系,并以超氧阴离子自由基(O2-·)清除率为指标,采用正交试验设计优化制备麦麸抗氧化肽的工艺条件.试验结果表明,制备麦麸抗氧化肽的最佳酶解条件为pH 5.0,加酶量为6000U/g麦麸蛋白,底物浓度5%,温度55℃,酶解7.5h,在该条件下制得的麦麸抗氧化肽清除超氧阴离子自由基的清除率可达53.70%.     

麦麸膳食纤维软糖的制备

探讨了麦麸膳食纤维软糖的制备工艺,由实验得知软糖的最佳工艺参数为麦麸膳食纤维为5%、卡拉胶为2.5%、甜味料为85%(蔗糖与淀粉糖浆比为1.51∶)。     

热稳定米糠粕和米糠低温浸出粕制备米糠蛋白的对比研究

为探讨热稳定米糠粕和米糠低温浸出粕制备米糠蛋白的差异,测定了两种原料所得米糠蛋白的乳化性、乳化稳定性、起泡性和泡沫稳定性,分析了热稳定米糠粕制得的米糠蛋白和米糠低温浸出粕制得的米糠蛋白的溶解性能差异和氨基酸组成变化,并利用差示扫描量热仪(DSC)研究了其蛋白质结构的差异。结果表明:两种原料制得的米糠蛋白的功能特性差别不大,但以热稳定米糠粕为原料制得的米糠蛋白的蛋白质含量低于以米糠低温浸出粕为原料制得的米糠蛋白的;热稳定米糠粕制得的米糠蛋白的溶解性比米糠低温浸出粕制得的米糠蛋白的溶解性差,胱氨酸含量的提高和蛋白质结构的变化可能是热稳定米糠粕溶解性相对较差的原因。     

麸皮生料制醋曲

传统醋曲微生物多、酶系广,代谢产物丰富,产品质量好,但出醋率低。纯种麸曲糖化力强,出醋率高,成品质量不如传统曲醋,提出麸皮生料接入多种优良菌株制曲,保存了麸皮中丰富的酶系,发挥优良菌株群体协同作用,提高成曲生化性能,产生较多的代谢产物,增加营养和风味成分。     

米糠多糖的脱蛋白研究

采用Sevag法、三氯乙酸法和酶法对米糠多糖进行脱蛋白研究.结果表明,酶法脱除蛋白的效果最好,Sevag法的多糖损失较小,结合酶法和Serag法脱蛋白可大大提高蛋白脱除率,具体操作条件为:0.0055mg/mL木瓜蛋白酶、pH6.0、60℃水浴,再加入总体积为1/2的氯仿-正丁醇(2:1)溶液进行脱蛋白,重复操作4次,此时蛋白脱除率为71.23%.多糖损失率为17.38%.     

Bioactive xylo-oligosaccharides from wheat bran soluble polysaccharides

Soluble polysaccharides (SP, 35 g) isolated from wheat bran (100 g) consisted mainly of arabinose and xylose with minor quantities of rhamnose, mannose, galactose and glucose. Wheat bran SP was subjected to purified endoxylanase (from 96 h ragi malt) treatment to obtain xylo-oligosaccharides (0.3 g/1 g wheat bran). The oligosaccharide mixture was purified on Biogel P-2 column into four major peaks designated as WO-1, WO-2, WO-3 and WO-4. Individual oligosaccharide purity was ascertained by HPLC and their composition was determined by GLC. The purified oligosaccharides were characterized by ESI-MS and ¹H NMR analysis. WO-1 and WO-2 were identified as arabinose containing xylotetraose and xylotriose, respectively, whereas WO-3 and WO-4 were identified as unsubstituted xylotriose and xylobiose, respectively. In vitro studies carried out using Bifidobacterium spp and Lactobacillus spp suggested the prebiotic nature of the crude as well as purified xylo-oligosaccharides as revealed by growth characteristics such as high O.D. of the culture broth, decrease in its pH, increase in cell mass and the resultant fermentation products. β-xylanase, β-xylosidase, α-arabinofuranosidase, α/β-galactosidases and acetyl esterase activities were determined in 24 h old culture broth and xylanase activity (440-830 μU/ml) was found to be the most preponderant among all of them.     

麦麸中抗氧化性物质的提取技术

利用木瓜蛋白酶对小麦麦麸进行酶解,在单因素实验的基础上,利用响应曲面法优化出最佳的工艺参数:提取温度50.7℃、提取时间84.8min、料液比1∶12.03时,麦麸酶解液对羟自由基的清除率可达到最大值58.16%,扫描图谱中最大吸收峰为204nm和264nm。     

小麦麸皮阿魏酰低聚糖的分离与结构分析

利用色谱技术对小麦麸皮中阿魏酰低聚糖(FOs)进行了分离与结构分析研究.结果表明,FOs由酯化的阿魏酸、阿拉伯糖和木糖所组成.紫外光谱分析表明,FOs的MOPS缓冲液在325nm处有最大吸收值.证明了阿魏酸的存在.红外光谱分析表明,FOs在990cm-1处有一低强度的肩峰.表明阿拉伯糖基的存在,并且与吡喃型木糖O-3位相连;在1731cm-1处有酯键的特征吸收峰.电喷雾电离质谱分析表明,分子质量为722和854的两种化合物是FOs的主要成分.     

酶法制备阿魏酰低聚糖的研究

利用B．subtilis木聚糖酶对小麦麸皮中阿魏酰低聚糖（FOs）的制备进行研究,并对试验条件进行优化,得到最佳制备条件：反应温度42℃,pH5．2,反应时间35h,酶量4．8g／L,底物浓度120g／L,在此条件下,产物中FOs的浓度达到1．546mmol／L。     

酶解麦麸产品抗氧化活性研究

采用黑曲霉发酵制备阿魏酸酯酶和阿拉伯木聚糖酶混合酶制剂，利用该酶制剂降解麦麸获得麦麸酶解产物（E—HWB）；通过测定它的DPPH清除能力、还原能力和对亚油酸过氧化的抑制作用，探讨了其抗氧化能力。结果表明，EHWB的抗氧化活性强于Vc及阿魏酸，是一种天然、无毒、高效的天然抗氧化剂。     

Extraction of protein and solids from wheat bran

The influence of pH, time, temperature, cellulase treatment and washing conditions on the recovery of solids and protein from Australian wheat bran was investigated. Highest yields (83% of available protein, 72% of total solids) were achieved by extracting at pH 12 and washing with water at pH 7. However, acceptable yields could be obtained under near neutral conditions by extracting at pH 6.5 for 16 h followed by three washes at pH7. Under these conditions 72% of the protein and 55% of the total solids were extracted and greater stability of the vitamins thiamin, riboflavin and pyridoxine was expected. The use of cellulase in an attempt to disrupt the aleurone cell walls did not improve the recoveries of either protein or solids.     

Antioxidant activity of feruloylated oligosaccharides from wheat bran

Ferulic acid, the main phenolic acid in wheat bran, is esterified to arabinose residues in the cell wall arabinoxylan. Treatment of wheat bran insoluble dietary fibre with xylanases from Bacillus subtilis released feruloylated oligosaccharides, which were purified with Amberlite XAD-2. The antioxidant activity of such oligosaccharides was evaluated using the assay system for erythrocyte hemolysis mediated by peroxyl free radicals generated from 2,2^′-azobis-2-amidinopropane dihydrochloride (AAPH) under in vitro conditions. The feruloylated oligosaccharides inhibited hemolysis of erythrocytes in a dose-dependent manner with 91.7% inhibition of erythrocyte hemolysis at 4 mg/ml.     

Reduction of hexavalent chromium with the brown seaweed Ecklonia biomass

A new type of biomass, protonated brown seaweed Ecklonia sp., was used for the removal of Cr(VI). When synthetic wastewater containing Cr(VI) was placed in contact with the biomass, the Cr(VI) was completely reduced to Cr(III). The converted Cr(III) appeared in the solution phase or was partly bound to the biomass. The Cr(VI) removal efficiency was always 100% in the pH range of this study (pH 1 to approximately 5). Furthermore, the Cr(VI) reduction was independent of the Cr(III) concentration, the reaction product, suggesting that the reaction was an irreversible process under our conditions. Proton ions were consumed in the ratio of 1.15 +/- 0.02 mol of protons/mol of Cr(VI), and the rate of Cr(VI) reduction increased with decreasing the pH. An optimum pH existed for the removal efficiency of total chromium (Cr(VI) plus Cr(III)), but this increased with contact time, eventually reaching approximately pH 4 when the reaction was complete. The electrons required for the Cr(VI) reduction also caused the oxidation of the organic compounds in the biomass. One gram of the biomass could reduce 4.49 +/- 0.12 mmol of Cr(VI). From a practical viewpoint, the abundant and inexpensive Ecklonia biomass could be used for the conversion of toxic Cr(VI) into less toxic or nontoxic Cr(III).     

Thermogravimetric analysis of water release from wheat flour and wheat bran suspensions

Bran is hygroscopic and competes actively for water with other key components in baked cereal products like starch and gluten. Thermogravimetric analysis (TGA) of flour–water mixtures enriched with bran at different incorporation levels was performed to characterise the release of compartmentalised water. TGA investigations showed that the presence of bran increased compartmentalised water, with the measurement of an increase of total water loss from 58.30 ± 1.93% for flour only systems to 71.80 ± 0.37% in formulations comprising 25% w/w bran. Deconvolution of TGA profiles showed an alteration of the distribution of free and bound water, and its interaction with starch and gluten, within the formulations. TGA profiles showed that water release from bran-enriched flour is a prolonged event with respect to the release from non-enriched flour, which suggests the possibility that bran may interrupt the normal characteristic processes of texture formation that occur in non-enriched products.