Influence of ultrasound pretreatment on the subsequent glycation of dietary proteins

The influence of ultrasound treatment on the subsequent glycation process of proteins is controversial. Glycation behaviors of bovine serum albumin (BSA), β-lactoglobulin (β-Lg) and β-casein (β-CN) after ultrasound pretreatment (UP) were compared by both evaluating glycation kinetics and analyzing structural changes of proteins. UP resulted in both unfolding and aggregation behavior in protein samples, which altered the accessibility of the Lys and Arg. Five cycles of UP up-regulated the glycation degree of BSA and β-Lg, possibly due to the unfolding behavior induced by UP, which exposed additional glycation sites. In contrast, 30 cycles of UP induced a dramatic increase (by 97.9 nm) in particle size of BSA, thus burying portions of glycation sites and suppressing the glycation process. Notably, UP had minimal influence on glycation kinetics of β-CN, due to its intrinsic disordered structure. Based on proteomics analysis, the preference of Lys and Arg during glycation was found to be changed by UP in BSA and β-Lg. Four, 3 and 3 unique carboxyethylated lysine residues were identified in glycated BSA after 0, 5 and 30 cycles of UP, respectively. This study suggests that the protein glycation can be affected by UP, depending on the ultrasonication duration and native structure of the protein.     

顺序注射-样品预处理模块系统-电热原子吸收法测定海水中痕量铜

将样品预处理模块与自动化顺序注射系统相结合,建立了未经稀释的海水中痕量铜的分离富集方法。铜-PDC螯合物在样品预处理模块中被吸附在聚四氟乙烯微珠填充柱上,用少量甲醇洗脱后,将洗脱液引入电热原子吸收中测定。进样体积为1.0mL时,富集倍率为20,检出限为0.015μg/L,采样频率为26次/h,线性范围为0.05~1.00μg/L,相对标准偏差(RSD)为1.8%(0.50μg/L)。利用本方法分离富集并测定了标准海水样品NASS-5及近海水样中的铜含量,并进行了加标回收实验。     

光谱预处理对近红外光谱预测木材纤维素结晶度的影响

木材纤维素结晶度是木质材料的一个重要性质,它与树木的生长特性、结构与化学组成均有密切关系,并对木材的杨氏模量、尺寸稳定性、密度和硬度等具有重要的影响,文章研究了利用近红外光谱结合多变量数据分析技术对人工林木材纤维素的结晶度进行预测的能力。本研究从人工林湿地松木粉试样的表面采集近红外漫反射光谱,并利用X射线衍射法测定了木材纤维素的结晶度。研究表明,采用一阶导数和二阶导数光谱预处理没有提高近红外模型的预测效果,而采用原始光谱的预测效果最好,预测值与X射线衍射测定值的相关系数r可以达到0.950,各项预测误差值较低, 说明采用近红外光谱结合多变量数据分析方法建立的结晶度预测模型具有理想的预测能力。     

金银花中绿原酸的微波预处理提取及检测

采用微波预处理法对金银花中绿原酸的提取进行优化,用三波长法测定了绿原酸的含量.设计正交试验,以绿原酸的含量为指标,考察乙醇用量、乙醇浓度和微波处理时间对金银花中绿原酸提取工艺的影响.三波长法检测波长为λ1=280 nm,λ2=325 nm,λ3=380 nm,其回归方程为ΔA=0.0426C 0.0017,相关系数为R=0.998.结果表明在气化剂用量20 mL,乙醇浓度为70(,微波辐射70 s时绿原酸得率最高.与常用的提取和测定方法相比,此方法对设备要求不高,具有更高的准确性与精密度.     

Fungal Proteins from Sargassum spp. Using Solid-State Fermentation as a Green Bioprocess Strategy

The development of green technologies and bioprocesses such as solid-state fermentation (SSF) is important for the processing of macroalgae biomass and to reduce the negative effect of Sargassum spp. on marine ecosystems, as well as the production of compounds with high added value such as fungal proteins. In the present study, Sargassum spp. biomass was subjected to hydrothermal pretreatments at different operating temperatures (150, 170, and 190 °C) and pressures (3.75, 6.91, and 11.54 bar) for 50 min, obtaining a glucan-rich substrate (17.99, 23.86, and 25.38 g/100 g d.w., respectively). The results indicate that Sargassum pretreated at a pretreatment temperature of 170 °C was suitable for fungal growth. SSF was performed in packed-bed bioreactors, obtaining the highest protein content at 96 h (6.6%) and the lowest content at 72 h (4.6%). In contrast, it was observed that the production of fungal proteins is related to the concentration of sugars. Furthermore, fermentation results in a reduction in antinutritional elements, such as heavy metals (As, Cd, Pb, Hg, and Sn), and there is a decrease in ash content during fermentation kinetics. Finally, this work shows that Aspergillus oryzae can assimilate nutrients found in the pretreated Sargassum spp. to produce fungal proteins as a strategy for the food industry.     

酸预处理对酶法骨明胶功能性质和分子质量分布的影响

本文以牛骨粉为原料,采用酶解法制备明胶,考察了骨粉预处理试剂——盐酸的浓度对明胶产品的冻力、粘度、分子量分布和等电点的影响.研究表明,随着骨粉预处理用的盐酸浓度的增大,明胶产率降低.骨粉经过盐酸预处理后,明胶产品的冻力大于300 bloom g,高于原料未经盐酸处理得到的明胶产品.与传统的碱法工艺明胶相比,酶法明胶具有高冻力、高等电点和相对较低的粘度等特点.采用聚丙烯酰胺凝胶电泳表征明胶的分子质量分布,酶法明胶不但具有传统碱法明胶具有的96 KDa、97 KDa、193 KDa和289 KDa组分,而且具有165 KDa和120 KDa组分.酶法明胶的等电点在碱性范围内,随着预处理用盐酸浓度的增大,明胶产品的等电点升高.骨料的预处理工艺对明胶的产率、冻力、粘度、等电点和分子质量分布有重要的影响,在明胶制备过程中,通过调控骨料预处理酸浓度可以调控明胶的技术指标.     

RF预处理对ZnO/Si生长的影响

氧化锌是一种Ⅱ-Ⅵ族直接带隙的宽禁带半导体材料,其室温下的禁带宽度3.36eV,由于其具有紫外发光的特性,近来受到研究者的广泛关注.由于ZnO在高效率光散发设备和其它光学方面有应用前景,所以要进行高质量的ZnO薄膜制备的研究.由于晶格失配,ZnO/Si的异质结质量不高,现在主要应用过渡层或表面处理的方法进行改善.本文用MOCVD设备生长ZnO/Si薄膜,所用载气为N2,反应源为CO2和DEZ,衬底为Si(111)单晶外延片.除了对衬底进行常规的化学清洗以外,在生长前进行Ar RF的预处理,是氩离子对硅表面进行一定的破坏,处理能量从0～110W进行了梯度变化,再以同样的生长条件进行原位生长.对于样品我们分别作了XRD、PL、AFM测量,发现Ar RF预处理对薄膜结晶有很大影响,未作处理的样品一般呈多晶态,而处理后的样品在一定能量范围内晶格取向有显著提高,但随预处理能量达到一定限值后取向性被破坏,XRD测试图如1、2、3.预处理对于发光也有很大的影响,在一定能量范围内发光强度只随处理能量加大缓慢衰减,但在高能量状态下,发光明显减弱,峰位也随之变化.可见氩离子轰击硅表面形成了缺陷,这些缺陷在生长中顺延在ZnO部分,并且这些缺陷是发光淬灭中心,随能量的增加而增加.PL测试图如4.通过AFM分析样品的粗糙度,发现预处理对表面粗糙度有减低的作用,随着处理能量的增加,表面粗糙度下降.     

噪声对近红外光谱分析的影响及相应的数学处理方法

以玉米籽粒的粉末样品为例,对噪声较高近红外光谱分析仪进行近红外分析的可行性进行了分析。结果表明,采用四次平均光谱,不采取其他数据处理,使用PLS算法,自编软件CAU-NIR可以得到很好的预测模型。通过与其他噪声较低近红外分析仪预测结果的对比,噪声较高的光栅型近红外光谱分析仪预测样品的相关系数高达98%,变异系数为6.2%。因此当近红外光谱分析仪器的信噪比低于105时,借助一定的软件技术,仍然可以用于定量分析。     

预处理方法对钛硅沸石催化性能的影响

 采用不同的介质（HCl－H2O2,NH4F－H2O2,HNO3－H2O2,H2SO4－H2O2）对钛硅沸石TS－1进行预处理,并用IR,XRD,UV－Vis,XRF和27AlMASNMR对样品进行了表征;以丙烯环氧化为探针反应,考察了样品的催化性能．结果表明,经预处理后,TS－1中的TiO2均被脱除约20％,而Al几乎未被脱除;所脱除的TiO2为非骨架钛;环氧丙烷的选择性降低,但H2O2的有效利用率明显升高．特别是采用NH4F－H2O2预处理时,H2O2的转化率和有效利用率均提高10％．     

Ethanol production from lignocellulosic byproducts of olive oil extraction

The recent implementation of a new two-step centrifugation process for extracting olive oil in Spain has substantially reduced water consumption, thereby eliminating oil mill wastewater. However, a new high sugar content residue is still generated. In this work the two fractions present in the residue (olive pulp and fragm ented stones) were assayed as substrate for ethanol production by the simultaneous saccharification and fermentation (SSF) process. Pretreatment of fragmented olive stones by sulfuric acid-catalyzed steam explosion was the most effective treatment for increasing enzymatic digestibility; however, a pretreatment step was not necessary to bioconvert the olive pulp into ethanol. Theolive pulp and fragmented olive stones were tested by the SSF process using a fed-batch procedure. By adding the pulp three times at 24-h intervals, 76% of the theoretical SSF yield was obtained. Experiments with fed-batch pretreated olive stones provided SSF yields significantly lower than those obtained at standard SSF procedure. The preferred SSF conditions to obtain ethanol from olives stones (61% of theoretical yield) were 10% substrate and addition of cellulases at 15 filter paper units/g of substrate.