Freeze drying and vacuum impregnating characteristics of Nostoc sphaeroides Kützing

ABSTRACT

Nostoc sphaeroides Kützing (N. sphaeroides) is a kind of edible algae widely growing in China. The paper is aimed at developing a novel snack food of N. sphaeroides using vacuum impregnation. The samples from freeze drying (FD) have large volume and loose structure, which were found suitable for processing. With nuclear magnetic resonance and imaging, the water signal of N. sphaeroides was measured in FD, and different drying-stage raw N. sphaeroides were selected to impregnate by different solutions, when the products’ impregnated mass, water activity, and flavor difference were analyzed. Results indicate that the water distribution in FD was uniform. Sucrose impregnated product was stable with large impregnated mass and low water activity, whereas trehalose impregnated product was easy to separate from the solution with low sweetness. For the products with the raw N. sphaeroides dried for 9 and 12?h, no obvious difference was found in water activity and flavor. Result shows that N. sphaeroides dehydrated for 9?h in FD is suitable for vacuum impregnation, and different impregnated products are acceptable from the point of view of flavor and storage stability.     

地皮菜添加量对鸡胸肉糜凝胶特性的影响

以新鲜鸡胸肉为实验对象,探究地皮菜添加量对鸡胸肉糜蒸煮得率、保水性、色泽、质构、凝胶强度、流变特性和微观结构等的影响。结果表明：随着地皮菜添加量的增加,鸡胸肉糜的蒸煮得率和保水性呈先上升后下降的趋势,添加量在1.2%时最大,分别为95.71%和95.33%;鸡胸肉糜的L*值、a*值、b*值均显著降低（P＜0.05）;硬度、弹性、内聚性和咀嚼性均持续上升,添加量为1.2%和1.5%时,硬度和弹性变化差异不显著（P＞0.05）。升温过程中,20 ℃和80 ℃的储能模量G’随地皮菜添加量的增加而升高;动态频率扫描过程中,同一频率振荡下,G’随地皮菜添加量的增加先升高后降低,添加量为1.2%时,G’最高。扫描电镜结果显示,与对照组相比,添加地皮菜的鸡胸肉糜凝胶微观结构更加致密、均匀。综上所述,添加适量的地皮菜可以明显改善鸡胸肉糜的凝胶品质,该研究为地皮菜在肉类凝胶制品中的应用提供了一定的理论基础和技术支撑。     

反复冻融法在葛仙米破壁技术上的应用

葛仙米营养价值较高，但传统的加工方法使人体不易吸收其营养成分，为了能使人体更有效的利用其营养成分，本文以葛仙米为原料，采用反复冻融法进行破壁处理，并以葛仙米中蛋白质的溶出率作为破壁指标。实验结果表明，反复冻融法可以一定程度的破坏细胞壁，其最佳破壁条件为：将葛仙米粉在0℃保持30min，取出研磨，如此反复3次，并且于30℃，pH7时进行提取，做壁效果最好，蛋白质的溶出率最高。     

Monitoring cell substrate interactions in exopolysaccharide-based films reinforced with chitin whiskers and starch nanoparticles used as cell substrates

Exopolysaccharides (EPS) extracted from Nostoc commune cyanobacteria were used to prepare low-adhesion cell substrates for tumor-selective cell growth. The substrates were reinforced with chitin whiskers and starch nanoparticles and characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and tensile tests. Two anchorage independent cells, green fluorescent protein-modified HeLa and THP-1 cells were seeded on the samples to assess their interaction with the composites. The results confirmed the cell–surface interaction of EPS-based composites. The mechanical properties of these films can be tailored by controlling the type and concentration of the reinforcement, which can be used in the design of different types of biomaterials.     

念珠藻Fe-SOD基因的克隆及在大肠杆菌中的表达

根据低等物种Fe-SOD核酸序列设计简并引物，以念珠藻基因组为模板，扩增获得了念珠藻Fe-SOD基因.将此基因重组至原核表达载体pET22b（＋），构建成工程菌pET-SOD，并转化至大肠杆菌宿主.异丙基-β-D-硫代半乳糖苷(IPTG)诱导表达获得Fe-SOD蛋白分子量约为28 kD，占全菌蛋白的78％，并以包涵体形式表达.经Ni2＋亲和层析柱纯化后，目的蛋白的SOD比活力达1 100 U/mg，在紫外可见光谱中表现出金属Fe的特征峰.肿瘤细胞共培养试验表明，此Fe-SOD具有一定的抗SPC-A-1肺腺癌细胞增殖的能力.     

求解理想的住宅——“建筑师走廊”给出的答案

本文通过对“亚洲建筑师走廊”中建筑的环境、空间、材料、色彩的评论,探讨对理想的个性化居住建筑的理解。     

Pieces of the Past: Early Photomontage and the Voice of History

A key dimension of photomontage is the way that its formal features – and consequent debates about the probity of making a photograph out of multiple sources – illuminate some of the fundamental problems of representation in the late nineteenth century. Among these was the question of whether an account of the past was properly presented as an unmediated transmission of fact, or demonstrably fashioned by an author: whether the tools of representation were to be submerged or emphasised. This article examines the parallels between the strategies of authorial visibility in early photomontage and the rhetorical approaches adopted by historians to modulate their presence in their texts. In particular, this study investigates the convergences of historiography and photomontage around the collapse of the Second Empire, a moment that witnessed powerful shifts in the conception of the voice of the historian as well as the production of photomontages that grappled with – and even thematised – the problem of their constructedness. An important but little-known group of photomontages by Eugène Appert, depicting the Imperial family in exile as well as the emerging Third Republic from which they fled, registers these conjunctions in their full complexity.     

基于主成分与聚类分析的甘肃地区产地木耳品质综合评价

为优化评价地木耳品质的指标,采用主成分和聚类分析,对甘肃8个地区产地木耳的粗蛋白、总灰分、磷、总糖、脂类、总脂、水溶性灰分、水不溶性灰分以及Ca、Na、K、Mg、Fe、Zn、Mn、Cu、Pb、Ni和Cd 19个品质指标进行分析。结果表明,不同地区来源的地木耳品质指标中,总脂、脂类、总糖以及Mn、Na、Zn变异系数较大,均超过30%,其他指标的变异系数相对较小,在3%左右。主成分分析表明19个反映不同地区产地木耳品质的指标可以用5个主成分（累计贡献率达到92.71%）表示。根据聚类分析得到总糖、水溶性灰分、脂类、Fe、Ca和磷6 个品质指标可以用来衡量地木耳品质的优劣。甘肃8 个地区产地木耳中,山丹的品质最好,其次是天祝,甘州区地木耳的品质最差。     

发状念珠藻藻蓝蛋白分离纯化及性质研究

采用冻融法破碎发状念珠藻细胞,经过磷酸缓冲液提取、硫酸铵分步沉淀、离子交换层析和凝胶层析分离纯化发状念珠藻藻蓝蛋白,其纯度(A615/A280)达到5.321,纯化因子为7.623。纯化的藻蓝蛋白最大吸收峰为615 nm,其室温荧光发射峰为646 nm,SDS-PAGE电泳显示其α和β亚基的分子质量在14.4～18.4 ku。稳定性实验表明,低温、避光、pH 6～8以及低浓度的蔗糖等条件下发状念珠藻藻蓝蛋白是稳定的。实验结果将为开发利用发状念珠藻藻蓝蛋白提供参考。     

液体悬浮培养发状念珠蓝细菌生物量测定方法的条件确定及比较

干重法、比浊法和叶绿素a含量换算法是测定液体悬浮培养发状念珠蓝细菌常用的3种方法.该研究对这3种常用测定方法的条件进行了确定,并对适用性进行比较.结果显示,干重法烘干条件确定为80℃,6.5h～9.5h;比浊法用波长为750nm;叶绿素a含量换算法测定波长为675nm.测定培养初期的发状念珠蓝细菌,比浊法测定数值略高于干重法和叶绿素a含量换算法所测数值,且具有更高的敏感性;培养中期3种方法所测数值较接近,且重复性好;培养末期,细胞内叶绿素含量降低,用叶绿素a含量换算法测定结果低于干重法及比浊法.