pH对魔芋胶复配体系凝胶特性及色泽的影响

考察pH对魔芋多糖、κ-卡拉胶与大豆分离蛋白混合凝胶强度、弹性、咀嚼性、黏度及色泽等的影响。结果表明:在强酸性条件下(pH4),凝胶特性较差,但此时色泽最好,较透明,易于上色;随着酸度的减小(pHpI),凝胶特性显著提高,此时凝胶特性较好,色泽呈乳白色;当到达蛋白质等电点时,表现出最高的凝胶强度和咀嚼性;当pH中性时,黏度最大,凝胶强度、弹性、咀嚼性均较高,色泽较好,呈乳白色;在碱性条件下,凝胶强度和咀嚼性有所提高,但是,当碱性超过一定值(pH8),凝胶强度反而下降,凝胶偏黄,色泽较差且有浓碱味。     

植物多糖胶流变性质的研究

胡芦巴、皂荚、野皂荚和塔拉多糖胶水溶液随着浓度的增加,溶液表现为假塑性流体．表现粘度随剪切速率增大而减小。通过Cross模型和实验数据计算得到1％多糖胶零剪切速率时表现粘度η0、无穷大剪切速率时表现粘度η∞和弹性松驰时间等重要流变参数。根据Arrhenius方程和实验数据计算得到1％浓度多糖胶的粘度流化能E和常数A,皂荚胶和塔拉胶的粘流活化能大。时间对多糖胶液粘度影响较大,新配制的多糖胶液随着水化时间的延长,胶液表观粘度增大,胶液放置时间超过24h后,表现粘度随时间的延长而降低。pH值、冻融处理和盐离子对多糖胶表现粘度的影响不太大。多糖胶与硼离子形成的冻胶．其粘度因多糖胶品种而异,其中胡芦巴冻胶粘度最高,是野皂荚冻胶粘度的165倍和瓜尔胶冻胶粘度的2．7倍。     

瓜尔胶与结冷胶复配协效作用规律及粘度流变性研究

瓜尔胶是一种天然高分子化合物,作为增稠剂、稳定剂被广泛使用。瓜尔胶可以与多种多糖胶复配,得到凝胶或高粘度溶液。结冷胶是一种优良的微生物多糖胶,具有极佳的稳定及悬浮效果,在含乳饮料及液态产品中应用广泛。由于其价格较高,溶胶受pH及阳离子浓度影响较大,结冷胶的应用常常受到限制。本文研究了结冷胶-瓜尔胶的配比、pH、离子种类和浓度对瓜尔胶-结冷胶复配体粘度的影响。研究结果表明:复配胶具有协同增粘效果;复配胶粘度在pH值7~11范围内随pH值升高而下降,在pH值为3~7范围内随pH值升高而上升;在盐离子达到一定浓度时,单独的结冷胶无法形成均一体系,而瓜尔胶-结冷胶复配体系能够形成稳定溶胶。     

一种新型生物聚合物Ss的流变学性质及成胶特性

本文对一种新型生物聚合物Ss的流变学性质及成胶特性进行了研究。该聚合物的流变学性质与黄原胶类似, 具有高粘性、假塑性及耐盐性。0.6％以上的Ss溶液加热(≥75℃)并冷却至室温可形成凝胶, 加入金属离子可以改变其成胶所需的最低聚合物浓度及所成凝胶的性质。利用质构分析(TPA)方法, 研究了不同聚合物浓度和钙离子浓度下凝胶的质构性质。钙离子的加入能促进凝胶的形成, 凝胶的硬度、弹性、内聚性随聚合物浓度及钙离子浓度的增加而增大, 但大于最适钙离子浓度时, 硬度、弹性及内聚性均有所下降。     

一种新型生物聚合物Ss的流变学性质及成胶特性

本文对一种新型生物聚合物ss的流变学性质及成胶特性进行了研究.该聚合物的流变学 性质与黄原胶类似,具有高粘性、假塑性及耐盐性.0.6%以上的Ss溶液加热(≥75℃)并冷却至室温可形成凝胶,加入金属离子可以改变其成胶所需的最低聚合物浓度及所成凝胶的性质.利用质构分析(TPA)方法,研究了不同聚合物浓度和钙离子浓度下凝胶的质构性质.钙离子的加入能促进凝胶的形成,凝胶的硬度、弹性、内聚性随聚合物浓度及钙离子浓度的增加而增大,但大于最适钙离子浓度时,硬度、弹性及内聚性均有所下降.     

毛胶薯蓣多糖胶与常用植物胶的流变性比较研究

用毛胶薯蓣提取分离毛胶薯蓣多糖胶(DSP)。将DSP与其他四种胶(瓜尔胶、魔芋胶、白芨胶、海藻酸钠)的粘度与浓度、温度、pH、降解时间、冻融变化及耐盐性的关系,以及起泡性能进行了比较研究。结果表明:DSP溶液的浓度与粘度正相关;温度在0~40℃间具有良好的热稳定性,40~90℃间其粘度随温度的升高而降低,且符合阿累尼乌斯动力学曲线;pH的改变、冻融变化和加入氯化钠、氯化钙对DSP粘度的影响甚微;同时DSP还具有优良的起泡性。     

添加剂对金针菇挂面加工工艺的影响研究

4种增稠剂（瓜尔胶、CNS-Na、CMC-Na、魔芋精粉）和面粉混合后,其味觉阈值各有不同,当瓜尔胶添加量超过1%,或当魔芋精粉添加量大于4.5%,均有明显异味。羧甲基淀粉钠和羧甲基纤维素钠的添加,对于金针菇挂面的味道基本无影响。在合适的添加范围内,CMC-Na对最大拉伸力和最大剪切力的影响最大,CMC-Na与质构特性之间均呈现正相关;瓜尔胶和魔芋精粉对咀嚼度的相对较大。金针菇挂面中复合磷酸盐和大豆软磷脂的加入都可以改变金针菇挂面的质构特性,从而改良金针菇挂面的品质。金针菇挂面的最佳配方为：9.17%金针菇粉、4%CMC-Na、复合磷酸盐0.2%、大豆卵磷脂1.5%。     

营养型葛仙米果冻的制作工艺研究

研究营养型葛仙米果冻的制作工艺,为武陵山区葛仙米特色资源的开发提供新途径。将烫漂护色后的葛仙米打浆制得葛仙米汁,以葛仙米汁为主要原料,卡拉胶、魔芋胶为胶体基材,进行营养型葛仙米果冻生产工艺的研究。利用单因素试验和正交试验,通过感官评价和质构指标的综合分析,得到葛仙米果冻的最佳配方为:复合胶含量1%(m卡拉胶∶m魔芋胶=6∶4),柠檬酸含量0.3%,葛仙米汁含量30%,白糖含量14%和β-环糊精含量2%~4%。在此条件下制作的葛仙米果冻口感爽滑,绿色天然、酸甜适口、质地均匀,具有一定的保健功能。     

改善吞咽功能食品增稠剂的研究

为了提供一种适合老年吞咽障碍患者使用的增稠剂,以黄原胶和罗望子胶及麦芽糊精为原料,粘度及溶解时间为指标,采用单因素实验和正交实验相结合的方法确定胶体最适的复配比例。结果表明:复配后的胶体粘度均大于单一胶体的粘度,且三种胶体复配后的溶解速度得到了显著地提高。黄原胶、罗望子胶和麦芽糊精的最适复配比例为3∶1∶30,粘度为611mPa·s,溶解时间为3min。随后通过流变仪对复配溶液的流变特性及粘度进行分析验证。最后将最适配方的增稠剂与市面上具有代表性的国内外增稠剂进行对比,表明该配方的增稠剂不仅具有成本低及速溶的优势,还能应用于医学钡餐造影。     

phbC基因敲除对土壤杆菌产可得然胶的影响

本文构建了phbC基因无痕敲除菌株ΔphbC,分析了ΔphbC菌株生长代谢情况和产生的可得然胶在产量、凝胶性质和红外结构的变化。结果显示,ΔphbC菌株在发酵过程中氨基氮消耗情况与野生型菌株一致,在蔗糖消耗方面,ΔphbC菌株与野生型菌株在18 h之后出现显著差异,蔗糖消耗比野生型菌株明显降低。ΔphbC菌株可得然胶产量约24 g/L,相对于野生型菌株降低了45%;胶凝胶强度为812.521 g/cm^2,相对于野生型菌株降低了21%;红外结构与野生型菌株一致,无明显差异。phbC基因不影响菌体生长,不影响可得然胶结构,但是影响可得然胶的合成。     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.