高温水分散体系交联玉米淀粉的非晶化现象研究

研究了用三偏磷酸钠为交联剂制备高交联玉米淀粉的方法,采用偏光显微镜和广角X-射线衍射对交联玉米淀粉由多晶态向非晶态的渐变过程进行了详细报道,发现了随着温度的升高交联玉米淀粉逐渐非晶化现象,提出在高温条件下交联玉米淀粉存在着只含无定型结构的非晶颗粒态,并用扫描电镜对非晶颗粒态玉米淀粉的结构进行了详细研究.     

非晶颗粒态马铃薯淀粉的制备方法

报道了水分散体系高温溶胀、常温碱分散体系强碱溶胀作用非晶颗粒态马铃薯淀粉的制备方法 ,采用偏光显微镜对多晶态向非晶态的变化进行了确认 ,提出在一定条件下 ,高交联马铃薯淀粉 ,可以由原淀粉多晶颗粒态制备成只含无定形结构的非晶颗粒态淀粉     

高交联木薯淀粉的非糊化特性

以三氯氧磷为交联剂制备非糊化的高交联木薯淀粉,并测定了反应的取代度和布拉班德粘度曲线,研究了在沸水中受热后非糊化淀粉的颗粒形貌及粒度分布等特性．提出高交联非糊化木薯淀粉存在着不同于原淀粉颗粒的在沸水中只发生轻度有限溶胀的非糊化颗粒态     

非晶颗粒态木薯淀粉微生物降解特性

采用光学显微分析方法,以原木薯淀粉为参照,对非晶颗粒态木薯淀粉在微生物作用下的降解过程进行了观察和研究. 结果发现,在微生物作用下,从淀粉颗粒的爆裂孔开始,沿着淀粉颗粒爆裂孔逐步深入,直至最后将淀粉颗粒完全降解,而原淀粉颗粒具有致密的结晶结构,淀粉颗粒表面没有明显的孔洞,因此在同样条件下,生物降解性能要远远低于非晶颗粒态淀粉.     

三偏磷酸钠交联玉米淀粉颗粒膨胀历程及结构特征

利用淀粉与三偏磷酸钠的交联反应,通过控制交联反应程度,成功地控制了交联淀粉颗粒膨胀程度并使其停留在不同的溶胀阶段,详细研究了处在不同溶胀阶段交联淀粉颗粒的结构特征和变化趋势,揭示了三偏磷酸钠交联玉米淀粉颗粒的膨胀历程及结构特征,即随着淀粉颗粒交联程度的降低,颗粒的膨胀历程由中心脐点处爆裂膨胀方式转化为颗粒整体向外的均匀膨胀方式.     

醚化、交联对玉米淀粉功能性质的影响

本文研究了醚化和交联反应对玉米淀粉物理性质和结构的影响。实验结果表明:醚化明显地改善了淀粉糊的透明度和低温稳定性,降低了糊化温度;醚化淀粉再经交联后,可改善淀粉糊的粘度稳定性。醚化及交联反应主要在淀粉的非结晶区进行,反应并未破坏淀粉颗粒。醚化影响直链淀粉的构象并在颗粒表面形成空穴,交联则使淀粉颗粒在蒸煮后仍保持完整并抑制了直链淀粉的渗出。     

红豆淀粉的性质

对红豆淀粉的颗粒形貌、X-光衍射图样、相对分子质量分布及糊粘度等理化性质进行了研究,并与马铃薯淀粉和玉米淀粉进行了比较,为红豆淀粉的应用提供了一定的理论基础.     

乙酰化二淀粉磷酸酯性质的研究

本文研究了交联一酯化复合变性淀粉——乙酰化二淀粉磷酸酯的结构和物理化学特性。结果表明:由于乙酰基取代了淀粉分子的部分羟基而使淀粉与碘的结合能力下降,展现为直链淀粉含量降低,淀粉的溶解度和膨润力增加;淀粉糊的透明度和冻融稳定性有所改善,交联反应还提高了淀粉的耐热、耐酸稳定性。     

酯化交联淀粉反应及性质的研究

由三氯氧磷变性木薯淀粉所得的酯化交联淀粉,颗粒完整,形貌和偏光十字形态保持不变,反应主要发生在淀粉颗粒的无定形区内;经红外光谱等检测,发现产物分子中存在P—O—C和P＝O基团,表明淀粉分子中的羟基置换出三氯氧磷分子中的氯原子而发生酯化和交联;极小取代度的变性淀粉,其碘复合物的可见光吸收光谱与原淀粉相似,三氯氧磷最先和支淀粉作用.     

食品成分对淀粉糊性能的影响

用Ｂｒａｂｅｎｄｅｒ淀粉粘度仪研究分析了一些食品成分如食盐、蔗糖、柠檬酸以及琼脂等对玉米淀粉和玉米淀粉磷酸酯糊的粘度性质的影响，结果表明：柠檬酸、食盐、蔗糖、琼脂对玉米淀粉和玉米淀粉磷酸酯的粘度、老化都有影响。玉米淀粉经磷酸脂化后，老化速率减慢。食盐（浓度＜１％）、柠檬酸可减缓玉米淀粉的老化，却使酯化淀粉更易于老化。琼脂可以减缓玉米淀粉和玉米淀粉磷酸脂的老化，蔗糖却加速了这两种淀粉的老化。     

内源脂类对抗性淀粉RSⅢ形成的影响

以普通玉米淀粉为试验材料 ,先制备出低脂淀粉和无脂淀粉 ,经高温压热处理后 ,分别测定它们的抗性淀粉含量 ,发现内源脂类对抗性淀粉RSⅢ的形成有显著影响 .多量脂类的存在不利于抗性淀粉的形成 ,少量脂类的存在提高了抗性淀粉产率 ,甚至略高于无脂淀粉的产率 .故对淀粉适当脱脂有利于抗性淀粉的形成 .     

Coagulation effects of a recently developed hydroxyethyl starch (HES 130/0.4) compared to hydroxyethyl starches with higher molecular weight

BACKGROUND: Hydroxyethyl starches (HES) are known to interfere with blood coagulation according to molecular weight, the degree of substitution and the C2/C6 ratio. A recently developed low molecular hydroxyethyl starch (HES 130/0.4) was designed to reduce the blood compromising potency. METHODS: In this study, effects of a 30% in vitro haemodilution with the new HES preparation (HES 130/0.4) in comparison to HES 200/0.5, HES 450/0.7 and sodium chloride solution were investigated using intrinsic and extrinsic activated thrombelastography (TEG) and plasmatic coagulation tests. RESULTS: Whereas plasmatic tests revealed no prolongation of coagulation by HES in comparison to sodium chloride, the TEG variables clotting time, clot formation time and maximal clot firmness showed a significant (P<0.05) inhibition by all the HES preparations. The inhibition was most pronounced in HES 450 (P<0.05 vs HES 130) while HES 130 did not show a statistically significant difference in extrinsic activated maximal clot firmness when compared to sodium chloride. CONCLUSION: These in vitro results demonstrate that hydroxythyl starches especially compromise clot polymerisation. The new preparation HES 130/0.4 seems to inhibit platelet function to a lesser extent than hydroxyethyl starch preparations with a higher molecular weight and degree of substitution.     

Voluven, a new colloid solution

Hydroxyethyl starch (HES) 130/0.4 (Voluven, Fresenius/Hospira, Germany) is indicated for the treatment and prophylaxis of hypovolemia. As the Voluven molecule is smaller than those of other available hydroxyethyl starch products, it is associated with less plasma accumulation and can be safely used in patients with renal impairment. Previous studies have demonstrated that Voluven has comparable effects on volume expansion and hemodynamics as other available HES products. Voluven is also associated with fewer effects on coagulation and may be an acceptable alternative to albumin for volume expansion in situations in which other starches are contraindicated secondary to risk of coagulopathy.     

Pharmacology of plasma expanders

Plasma expanders are used to restore the circulating volume of a hypovolaemic patient. Typically, colloids are used to expand the plasma volume, although combinations of hypertonic crystalloid and colloid have recently been used. The currently available colloids vary in their physicochemical, pharmacodynamics and pharmacokinetic properties. In particular, they differ in molecular weight, which partly determines their duration of action, and in their ability to expand the plasma volume. Dextran, hydroxyethyl starch and hypertonic colloid solutions improve oxygen flux within the microcirculation. Despite their benefits, the use of dextran and high-molecular-weight starches is limited by their negative impact on coagulation. In addition, these macro-molecules may also induce acute renal failure in susceptible patients. Current research focuses on the development of artificial oxygen carriers as plasma expanders. These substances, which include modified stromal-free haemoglobin and perfluorocarbon emulsions, are undergoing clinical trials.     

Plasma volume substitution

Blood loss up to 10–15% of the total blood volume can be substituted by mere crystalloids. A quicker and more stable volume replacement can be accomplished with colloid solutions. Combination of artificial colloids (e.g., dextran 60, dextran 70 or hydroxyethyl starches with high degree of hydroxyethylation) with crystalloids (isotonic balanced solutions) produces a long lasting volume effect. Due to dose limitation recommendations for the artificial colloids, volume substitution may be continued, at a later stage, by albumin.     

The effects of hydroxyethyl starch solutions on thromboelastography in preoperative male patients

BACKGROUND: Hydroxyethyl starches (HES) have been shown to decrease clot strength and to increase coagulation times assessed by thromboelastography (TEG). HES with minimal anticoagulant side-effects is beneficial for plasma volume expansion in the perioperative setting. A comparison of the in vivo effects of high, middle and low molecular weight HES solutions on TEG variables has not been performed so far. METHODS: Blood was obtained before and after intravenous infusion (10 ml kg-1) of either saline, HES 70/0.5/4 (molecular weight in kDa/degree of substitution/C2:C6 ratio), HES 130/0.4/9, HES 200/0.6/9.4, or HES 450/0.7/4.6 in 50 otherwise healthy patients. Thromboelastography was performed in 360 micro l of 1% celite activated citrated whole blood after recalcification. RESULTS: HES 450/0.7/4.6 prolonged reaction time indicating impairment of the plasmatic coagulation system. TEG parameters indicative for platelet function, including angle alpha, maximum amplitude and coagulation time, deteriorated after infusion of HES 450/0.7/4.6 and HES 70/0.5/4. HES 200/0.6/9.4 and HES 130/0.4/9 impaired platelet contribution to hemostasis only partially, decreasing two or one TEG platelet parameters, respectively. CONCLUSION: Infusion of HES 450/0.7/4.6 compromises TEG parameters more than the other solutions tested, whereas HES 130/0.4/9 has the smallest effect. Further outcome-related studies are needed in order to assess the clinical relevance of our findings.     

食盐对普通玉米杂交种淀粉糊化性质的影响

采用快速粘度分析仪（RVA）研究了食盐对18种普通玉米杂交种淀粉糊化性质的影响。结果表明：食盐显著降低了所有普通玉米杂交种淀粉的峰值、破损值和回生值;提高了谷值、终粘度、出峰时间和成糊温度。但对不同的普通玉米杂交种淀粉的糊化性质的影响程度有显著差别。随着食盐溶液质量分数的增加,普通玉米杂交种淀粉的谷值、终粘度、出峰时间和成糊温度也逐渐增加,破损值和回生值则显著降低,峰值受食盐溶液质量分数的影响很小。     

玉米淀粉的挤压研究——淀粉在挤压过程中降解机理的研究(Ⅱ_a)

采用SephadexG-50葡聚糖凝胶层析、酶法分析、红外光谱以及统计分析等方法对挤压淀粉进行了研究。研究表明,玉米淀粉在挤压过程中降解处于力化学降解初期,经过挤压支链淀粉级分中的a链和b链,在G-50色谱中的分布未发生显著性变化,挤压导致支链淀粉级分的支点发生裂解。     

玉米淀粉的挤出研究(Ⅰ)—淀粉聚合物的降解及其表征

用Creusot-Loire BC-45型同向旋转双螺杆挤出机加工玉米淀粉。通过特性粘度,Sepharose CL-2B琼脂糖凝胶过滤层析,铁氰化钾数测定等方法,对挤出产物进行了研究。结果表明,经过挤压,玉米淀粉被降解,其平均分子大小降低,支链淀粉级分显著减小,淀粉聚合物中的部分糖苷键被裂解,应力是淀粉聚合物降解的主要原因。