云南本地黄牛盐溶蛋白热诱导凝胶功能特性的研究

以云南本地黄牛的背最长肌和股二头肌为材料,采用L9(34)正交设计研究了不同提取条件对背最长肌和股二头肌的盐溶蛋白热诱导凝胶保水性、蛋白组分及凝胶超微结构的影响。结果表明,云南本地黄牛背最长肌和股二头肌的盐溶蛋白最佳提取条件均为NaCl 浓度0.6mol/L、温度70℃、pH7.0,凝胶的保水性分别是96.21%、96.35%。SDS-PAGE 电泳和扫描电镜显示,背最长肌和股二头肌在保水性最佳的条件下,其肌球蛋白含量较高,同时凝胶的网络比较均匀、细致。而保水性较差,其肌球蛋白含量比较低,凝胶网络结构粗糙、疏松、不均匀。     

牛肉盐溶蛋白质热诱导凝胶特性研究

实验以牛背最长肌为材料,采用L9（3^4）正交设计研究了MgCl2、NaCl和pH值对盐溶蛋白质热诱导凝胶特性的影响。研究表明,在0．01mol／LMgCh．0．6mol／LNaCl．pH值7．0条件下牛背最长肌盐溶蛋白质热诱导凝胶保水性最好,为92．25％,破断应力最高,为14．00kPa。NaCl浓度和pH值对凝胶保水性和凝胶强度均有显著影响（p〈0．01）。MgCl12仅对凝胶破断应力影响较大。凝胶的超微结构分析表明,保水性高的凝胶的网络结构比较致密,大量的微细孔洞均匀分布。保水性低的凝胶的网络结构中线条多呈束状、结构粗糙、不均匀。     

猪肉盐溶蛋白质热诱导凝胶功能特性的研究

以猪背最长肌为材料,采用L9(34)正交设计及混料回归分析研究了猪背最长肌盐溶蛋白质热诱导凝胶保水性和凝胶超微结构。结果表明,猪背最长肌最佳提取条件为MgCl2浓度0.01mol/L、NaCl浓度0.6mol/L、提取液pH7.0,其凝胶的保水性为69.26%。扫描电镜研究结果显示,保水性不同的凝胶,其超微结构表现出很大的差异, 保水性为69.26%,其凝胶的网络比较均匀、细致,蛋白束平滑;保水性为37.81%,其凝胶的网状结构粗糙、疏松、不均匀。     

鹅肉盐溶蛋白提取条件对其凝胶特性的影响

探讨鹅肉盐溶蛋白质的提取条件对其凝胶特性的影响。通过单因素试验确定NaCl浓度、提取液pH、热变温度3个因素的取值范围,再用响应面设计法确定其最佳提取条件。结果表明:NaCl浓度、pH和热变温度显著影响盐溶蛋白凝胶的硬度和保水性,最佳提取条件为NaCl浓度0.75 mol/L,pH 6.80,热变温度77℃,此时硬度和保水性达到极大值。此条件下凝胶硬度和保水性的预测值分别为81.89 g、96.64%,验证值分别为79.87 g、94.66%,与模型预测值基本相符。     

猪肉盐溶性蛋白热诱导凝胶特性的研究

盐溶性蛋白是影响猪肉制品的保水性及凝胶特性的一类最主要蛋白质,其中对蛋白质热凝胶起决定作用的是肌球蛋白.本试验以猪肉为原料,首先通过单因素试验研究贮藏时间、离子强度、磷酸盐等因素的影响,再通过正交试验得出猪背最长肌(P1d)盐溶蛋白最合适的提取条件:MgCl2浓度0.01 mol/L、NaCl浓度0.5 mol/L、焦磷酸钠及多聚磷酸钠的比例均为0.4%.     

鸡胸肉盐溶蛋白质热诱导凝胶保水性的研究

试验利用正交试验Lq(34)研究了NaCl浓度、MgCl2浓度和提取液的pH值对鸡胸肉盐溶蛋白质热诱导凝胶特性的影响。结果表明,提取液pH对凝胶保水性和超微结构的影响最大;NaCl的影响次之,MgCl2的影响较小。不同提取方法对盐溶蛋白热诱导凝胶特性的影响差异显著,当提取液pH为7.0、NaCl浓度为0.6M、MgCl2浓度为0.1M时,盐溶蛋白质热诱导凝胶的蛋白含量为34.54mg／m,保水性高达96.92％,其特性好于提取液pH 6.0、NaCl浓度为0.4M、MgCl2浓度为0.1M时制备的凝胶(p<0.01),从SINS-PAGE可知,肌球蛋白是影响凝胶形成的一种重要蛋白质。     

提取条件对鲨鱼肉盐溶蛋白热诱导凝胶特性的影响

以鲨鱼肉为材料,研究NaCl 浓度、pH 值、静置提取时间及加热时间对鱼肉盐溶蛋白热诱导凝胶保水性和质构特性的影响。结果表明：鲨鱼肉盐溶蛋白凝胶的保水性、硬度、弹性和黏聚性与NaCl 溶液浓度呈正相关;在NaCl 溶液浓度0.8mol/L、pH6.5～7.0、静置提取时间24h、40℃加热40～60min 时形成的凝胶保水性及其质构指标较理想;40℃加热盐溶蛋白,有利于形成凝胶结构,但随着加热时间的延长,盐溶蛋白凝胶硬度增加,保水性降低。     

响应面法优化猪肉盐溶蛋白热诱导凝胶工艺的研究

研究pH值、NaCl、MgCl2和复合磷酸盐(MP)对猪后腿肉盐溶蛋白(SSP)提取率及热诱导凝胶的保水性(WHC)和凝胶强度(BS)的影响。通过数学模型的建立和响应面分析,确定制备热诱导凝胶的最佳工艺条件。结果表明,在pH6.7、NaCl 0.7mol/L、MgCl2 0.006mol/L、MP 2.5g/kg处理条件下,盐溶蛋白提取率为9.41%、凝胶保水性为86.13%、凝胶强度为86.50g。MgCl2与MP的交互作用显著增加盐溶蛋白的溶出率。各因素间的协同作用对热诱导凝胶的品质有显著影响。     

影响鸭肉肌原纤维蛋白凝胶保水性的因素研究

以鸭胸肉为材料,提取鸭肉中的肌原纤维蛋白,研究溶液环境(蛋白浓度、NaCl浓度、pH)和加热方法(加热温度、加热时间、加热速率),对肌原纤维蛋白热诱导凝胶保水性的影响。研究结果表明:在一定范围内,鸭肉肌原纤维蛋白凝胶的保水性与蛋白溶解度呈正相关;随着蛋白浓度越大,NaCl浓度升高,凝胶保水性也相应提高;pH偏离蛋白的等电点越远,保水性越好;加热温度为70℃,加热时间为20 min,加热速率0.2℃/min～0.5℃/min,凝胶保水性最好。     

离子强度和pH值对肌原纤维蛋白热诱导凝胶特性的影响

以肌原纤维热诱导凝胶的保水性和质构特性,包括硬度、弹性、内聚性、胶黏性、回复性为指标,考察离子强度和pH值对猪背最长肌肌原纤维热诱导凝胶特性的影响.结果表明,离子强度和pH对凝胶不同特性的影响存在差异,综合各种指标,离子强度为0.5,pH值在6.5和7.0之间有利于形成较好的凝胶.不同条件下凝胶形成的机制可能存在差异.凝胶的硬度与弹性、胶黏性和保水性相关性显著(P＜0.05),可以作为重点考察的指标.     

Removal of arsenic from high ionic strength solutions: effects of ionic strength, pH, and preformed versus in situ formed HFO

Arsenic sorption to hydrous ferric oxide (HFO) is an effective treatment method for removing dissolved arsenic from fresh drinking water sources. However, detailed information is limited regarding arsenic removal from solutions of high ionic strength such as brackish groundwater, seawater, or high-pressure membrane process residuals. Bench-scale treatment experiments were conducted exploring arsenic removal from simple solutions with ionic strengths ranging from 0.008 to 1.5 M by addition of ferric chloride followed by solid/liquid separation (microfiltration or ultrafiltration). Arsenic removal from these solutions during in situ iron precipitation was approximately 90% at Fe:As molar ratios of 10 to 15 and > 95% for Fe:As molar ratios greater than 20. Arsenic removal at iron doses of 10(-6) to 10(-4) mol-Fe/L improved when pH was lowered from 8 to less than 6.5 at ionic strength 0.2 M; this improvement was not as significant at ionic strength 0.7 M. Arsenic removal diminished when alkalinity was increased from 400 to 1,400 mg/L as calcium carbonate; however, arsenic removal at the higher alkalinity improved when pH was lowered from approximately 8 to less than 7. Arsenic removal with preformed HFO solids and subsequent microfiltration was significantly less than that observed with in situ HFO precipitation. Increased removal by in situ precipitation compared to that of preformed solids is explained by an increased number of adsorption sites due to uptake during iron oxy-hydroxide polymerization as well as an increase in surface area resulting in diminished surface charge effects. Model simulations of arsenic uptake by in situ precipitation adequately captured these effect by changing the model parameters used to model arsenic uptake by preformed HFO, specificallythe total number of surface sites and surface area.     

离子液体中酶的活性、稳定性及选择性研究进展

考察了离子液体中酶催化反应的酯交换、酯化、糖苷化、氧化以及手性分子的动力学拆分等反应类型里关于酶在离子液体及有机溶剂中的催化活性、稳定性、对映选择性等问题的研究,结果表明,许多酶在离子液体或其形成的两相体系或单相体系中保持较高的催化活性、对映选择性和稳定性,并且离子液体中的酶催化反应具有高反应收率、产物易分离、酶和离子液体可重复使用等优点．开发价格低、性能好的离子液体将是今后该领域的研究方向．     

Measurement of ionic calcium, pH, and soluble divalent cations in milk at high temperature

Dialysis and ultrafiltration were investigated as methods for measuring pH and ionic calcium and partitioning of divalent cations of milk at high temperatures. It was found that ionic calcium, pH, and total soluble divalent cations decreased as temperature increased between 20 and 80°C in both dialysates and ultrafiltration permeates. Between 90 and 110°C, ionic calcium and pH in dialysates continued to decrease as temperature increased, and the relationship between ionic calcium and temperature was linear. The permeabilities of hydrogen and calcium ions through the dialysis tubing were not changed after the tubing was sterilized for 1 h at 120°C. There were no significant differences in pH and ionic calcium between dialysates from raw milk and those from a range of heat-treated milks. The effects of calcium chloride addition on pH and ionic calcium were measured in milk at 20°C and in dialysates collected at 110°C. Heat coagulation at 110°C occurred with addition of calcium chloride at 5.4 mM, where pH and ionic calcium of the dialysate were 6.00 and 0.43 mM, respectively. Corresponding values at 20°C were pH 6.66 and 2.10 mM.     

离子液体的安全性研究进展

作为环境友好的“绿色溶剂”, 离子液体发展迅猛, 取得了令人瞩目的成果。作为新物质的离子液体, 其毒性、降解性、环境相容性等安全性问题已日趋成为人们必须高度重视解决的问题。受传统思想的影响, 有关离子液体安全性研究还是滞后于其应用研究。为此, 对离子液体的安全性进行综述就显得格外必要。本文对离子液体的细胞毒性、微生物毒性、高等动植物毒性和影响其毒性的离子液体本身的构效特性, 离子液体对环境作用性以及其降解性等安全性问题进行了简要综述, 并对离子液体安全性研究趋势作了展望。     

离子液体催化合成酯类化合物的研究进展

酯化反应是重要的有机合成反应之一,在药物、材料、食品、香料、溶剂和增塑剂等生产中有广泛的应用.传统方法合成酯类化合物具有反应时间长、产率低、污染大、副反应多及后处理困难等缺点,离子液体区别于传统的溶剂和催化剂主要在于可通过改变其阴阳离子的结构进行调节,是可设计的绿色催化剂和溶剂,具有无腐蚀性、无毒、不挥发、不易氧化、液态范围宽、稳定性好、催化活性高等一系列独特性质,已被广泛应用于化学合成、分离工程和纳米材料制备等领域.离子液体催化酯化反应合成酯类化合物具有反应快、高效、产物易分离和安全等优点.本文综述了离子液体催化酯化反应合成脂肪酸酯类和芳香酯类的研究进展,并展望了该方法在酯类合成中的发展前景.     

Capture of dioxins by ionic liquids

Dioxins are highly toxic compounds that mainly originate from incineration and combustion sources. In this work, a new, simple, and efficient approach for the absorption of dioxins from gaseous streams using thermally stable ionic liquids is proposed. The absorption process of nonchlorinated and chlorinated dibenzo-p-dioxin compounds was studied in the temperature range 100-200 degrees C. Imidazolium-, ammonium-, and guanidinium-based ionic liquids were designed for this specific purpose. It was observed that imidazolium cations having long alkyl side chains exhibit the highest absorption capacities, whereas the anion dicyanoamide [DCA] possesses higher absorption capacity than other anions studied. In a typical experiment, it was found that the ionic liquid 1-n-octyl-3-methyl imidazolium dicyanoamide [C8mim][DCA] can absorb more than 14% by weight of dibenzo-p-dioxin, 2-chlorodibenzo-p-dioxin, and 1,2,3,4-tetrachlorodibenzo-p-dioxin from a gaseous stream. A process for desorption of dioxins from the ionic liquid was tested, revealing that complete desorption can be achieved under a high vacuum. Additionally, the feasibility ofthe process was examined by carrying out experiments under real operating conditions of incineration and combustion processes. The success of the method heavily relies upon the design and selection of specific ionic liquids having enhanced affinity for the aromatic compound functionality present in dioxins and, simultaneously, possessing extremely low volatility and high chemical and thermal stability.     

Measurement of ionic calcium in milk

There are many reports in the literature regarding the effects of ionic calcium on reactions related to casein micelle stability, such as heat stability, ethanol stability and susceptibility to gelation, sediment formation and fouling. However, experimental evidence supporting these assertions is much less readily available.
This paper evaluates three selective ion electrode systems for measuring ionic calcium directly in milk as well as looking at the effects on pH reduction and addition of calcium chloride.
The best electrode system was the Ciba Corning 634 system, which was designed for blood but has been modified for milk. This was found to be reproducible and stable when calibrated daily and allowed direct measurements to be taken on milk in 70 s. This has been found to perform well now for 3 years. The other systems were not so useful, as they took longer to stabilize, but may be useful for higher ionic calcium concentrations, which are found in acidified milk products.
Reducing the pH increased ionic calcium and reduced ethanol stability. Calcium chloride addition reduced pH, increased ionic calcium and reduced the ethanol stability. Readjusting the pH to its value before calcium addition reduced the ionic calcium, but not back to its original value. Milks from individual cows showed wide variations in their ionic calcium concentrations.
This establishes the methodology for a more detailed investigation on measurement of ionic calcium in milks from individual cows and from bulk milks, to allow a better understanding of its role in casein micelle stability.     

离子液体及聚离子液体在基于固相萃取技术的食品安全分析中的应用

由于食品样品多样性和复杂性,样品前处理成为食品安全分析的关键。固相萃取技术是食品安全分析中富集痕量组分、分离干扰物质的重要前处理方法。将具有特殊物理化学性质的离子液体及聚离子液体,应用于固相微萃取、基质固相分散萃取、分子印迹固相萃取、整体柱固相萃取等固相萃取技术中,改善了固相吸附剂性能,提高了固相萃取效率,实现了对食品样本中重金属离子、农兽药残留、违规或超标添加剂等的高效富集、分离,合并其他分离分析方法,达到了准确测定这些物质的含量的目的。离子液体及聚离子液体在食品分析的前处理中的应用将越来越广泛。