共查询到20条相似文献,搜索用时 15 毫秒
1.
Waltraud Vorwerg Jan Dijksterhuis Johannes Borghuis Sylvia Radosta Anja Krger 《Starch - St?rke》2004,56(7):297-306
The present study describes the preparation of low‐substituted hydroxypropyl (HP) starches and investigation of their suitability for the development of flexible, highly transparent cast films. Changes in molecular composition due to processing conditions were identified by determining molar mass distribution. Molecular characterisation was performed both by static light scattering (SLS) and size‐exclusion chromatography with multi‐angle laser light scattering (SEC‐MALLS) detection. The weight‐average molar mass, mean square radius of gyration, second virial coefficient, and molar mass distribution were determined. Rheological characterisation of concentrated aqueous solutions included a study of flow behaviour as a function of shear rate and oscillatory measurement of viscoelastic properties. Significant differences in rheological properties due to hydroxypropylation conditions were established. Mechanical testing was carried out by measuring tensile strength and elongation and determining the elastic modulus. The tensile strength of cast films based on hydroxypropyl starches was 40–50 MPa. Elongation values were dependent on the type of starch, use of plasticiser and storage conditions. 相似文献
2.
Acid hydrolysates of hydroxypropyl derivatives of wheat, maize, waxy maize and high amylose maize starches were separated using four HPLC procedures. An amine treated silica column gave best resolution of glucose and six nonglucose components. The proportions of these varied depending on the native starch and the acid used for hydrolysis. There was a linear relationship between molar substitution and ratio of nonglucose to glucose peak areas which varied between the native starches. 相似文献
3.
4.
Dr. Gerard Lammers Eize J. Stamhuis Prof. Dr. Antonie A. C. M. Beenackers 《Starch - St?rke》1993,45(7):227-232
A novel type of reactor for the chemical derivatization of starch pastes is presented. The design is based on the application of static mixers. The reactor shows excellent plug flow behaviour with a Peclet number of about 100. The viscosity behaviour of concentrated starch pastes in the static mixer reactor can be described by: ηapp = Ke[B mstarch +c/T-DW+(n-l)Inγ] where: K = 3.063.10−4 Pa-s., B = 12.03, C = 4.134.103 1/K., D = 2.83.10−23 kg dry starch/kJ and n = 0.494. mstarch is the mass fraction dry starch in the paste. The reactor was used for the production of hydroxypropyl starch with a molar substitution (MS) of up to 0.5. Propylene oxide conversions of 90% were reached within 9 min of reaction time which compares favourable with conventional production processes. The reactor was modelled as a non-isotherm plug flow reactor. Experimental results on propylene oxide conversion and MS of the derived starch are in good agreement with model calculations. Papp = Ke wobei: K = 3,063. 10-−4 pa.s., B=12,03. C= 4,134, C=4,134, 1-3I/K., D = 2.83.10−2kg trockene Stärke/kJ, und n = 0,494. mstarch ist die Massenfraktion trockener Stärke in dem Kleister. 相似文献
5.
以豌豆淀粉为原料,环氧丙烷、氢氧化钠分别为醚化剂和催化剂,对制备羟丙基淀粉的工艺和性质进行了研究。探讨了制备工艺中环氧丙烷、pH值、温度、时间对羟丙基取代度的影响;采用响应面法设计优化试验。得到最佳工艺条件为:环氧丙烷添加量12%、反应pH11.3、反应温度40℃、反应时间18h。结果表明:与原淀粉相比,制得的低取代度羟丙基淀粉糊化温度下降了11~18℃,峰值黏度增加了74%~109%;在34~90℃,溶胀度随取代度的增加而增加;同时,羟丙基化还降低了淀粉的消化性。 相似文献
6.
利用DHR-1流变仪,研究了氧化羟丙基木薯淀粉的静态流变和动态流变特性。结果表明,氧化羟丙基木薯淀粉糊为假塑性流体(n<1),符合Herschel-Bulkley模型(R2>0.98)。随着羧基含量和羟丙基摩尔取代度(molar substitution,MS)的增大,稠度系数k减小,非牛顿性减弱,趋近于牛顿流体。在整个振幅范围(1×10-4~1 rad),主要表现为黏性特性;随着振幅增加,样品的弹性模量(G’)和黏性模量(G”)变化不明显;随着羧基含量和羟丙基摩尔取代度(molar substitution,MS)的增大,G’和G”降低,损耗角正切(tanδ=G”/G’)增加。在频率范围(0.1~12.5 rad)内,随着频率增加,样品的G’和G”增加,tanδ变化不明显;随着羧基含量和MS的增大,G’和G”降低,tanδ增加。 相似文献
7.
近年来,淀粉基水凝胶的研究备受关注,但是天然淀粉水凝胶存在高脆性、低拉伸性等缺陷,限制了它的应用。本研究旨在通过羟丙基改性木薯淀粉提高其凝胶特性,并将羟丙基木薯淀粉与玉米淀粉复配,探究复配淀粉水凝胶的性能。结果表明,木薯淀粉经羟丙基化改性后,焓值从14.885 J/g降低到7.780 J/g,结晶度由28.2%降低到22.1%,其构成的水凝胶拉伸应变从320%提高到550%。通过将羟丙基木薯淀粉与玉米淀粉复配,提高了复配淀粉凝胶的拉伸应变,能够拓展其在工业、农业、食品等领域的应用。 相似文献
8.
探讨氧化羟丙基淀粉浆料性能。利用氧化和羟丙基化复合变性制备了氧化羟丙基淀粉浆料,测试了黏度、取代度及pH值等因素对氧化羟丙基淀粉浆料及浆纱性能的影响。结果表明:氧化羟丙基淀粉浆料具有高浓低黏浆料特性,其黏度热稳定性和成膜性良好;在一定范围内,随着氧化剂用量的增加,黏度逐渐下降,浆膜断裂强度和断裂伸长率降低,耐磨性增加;随着取代度的增加,浆液黏度热稳定性提高,浆膜断裂强度和断裂伸长率都增加,水溶速度加快,浆液黏附力增大;取代度达到0.3的氧化羟丙基淀粉表现出良好的浆膜性能、黏附性能及对纯棉纱良好的浆纱效果。认为:取代度为0.3的氧化羟丙基淀粉具有较好的上浆性能。 相似文献
9.
羟丙基绿豆淀粉的制备及性能研究 总被引:2,自引:0,他引:2
以绿豆淀粉为原料,环氧丙烷为醚化剂,氢氧化钠为催化剂,无水硫酸钠为膨胀抑制剂,对羟丙基绿豆淀粉合成工艺及性能进行了研究.考察了环氧丙烷用量、反应时间、反应温度、氢氧化钠用量、无水硫酸钠用量对羟丙基绿豆淀粉取代度的影响.实验结果表明,环氧丙烷用量、反应时间、反应温度、氢氧化钠用量、无水硫酸钠用量对羟丙基绿豆淀粉取代度均有影响.采用分光光度法测定羟丙基绿豆淀粉取代度. 相似文献
10.
低粘度辛烯基琥珀酸淀粉酯的物化性质研究 总被引:2,自引:1,他引:2
以原淀粉为原料用湿法工艺制备的辛烯基琥珀酸淀粉酯,糊的粘度较高,采用洳淀粉酶进行水解得到低粘度的酶解产物,类似于纯胶的变性淀粉产品。本文采用X射线衍射、红外光谱、紫外-可见光谱、HPLC等方法,测定研究辛烯基琥珀酸淀粉酯酶解产物(OSA-SH)的结构、组成、DE值、粘度、表面张力、乳化性参数等理化特性。结果表明,试验的OSA-SH的DE值为3.06,无定形结构,分子中含有C=C、COOR官能团,具有较好的水溶性、高浓低粘性、表面活性和乳化性。 相似文献
11.
12.
羟丙基糯玉米淀粉合成工艺及性能研究 总被引:3,自引:2,他引:3
本文以糯玉米淀粉为原料,以环氧丙烷为醚化剂、氢氧化钠为催化剂、硫酸钠为抑制膨胀剂,对糯玉米羟丙基淀粉合成工艺及其性能进行了研究,探讨了糯玉米淀粉乳浓度、环氧丙烷用量、反应时间、反应温度、氢氧化钠用量及硫酸钠用量对糯玉米羟丙基淀粉取代度和反应效率的影响。实验结果表明,增加环氧丙烷用量、延长反应时间,可使羟丙基淀粉取代度增加。对糯玉米羟丙基淀粉的冻融稳定性、透明度及粘度进行研究表明,随着羟丙基糯玉米淀粉取代度的增加,其冻融稳定性和透明度增加,但粘度却降低。 相似文献
13.
14.
Aim of this work is to investigate the simultaneous effects of viscosity and temperature on the productivity of the alcohol fermentation of starch hydrolysate by Saccharomyces cerevisiae. Batch fermentations have been carried out at given pH, broth composition, inoculum, and agitation intensity, but at varying temperature (24<T<46 °C) or concentration of carboxymethyl cellulose (0.4<CCMC<2.0 g/L), chosen as viscosity-raising additive. The results of tests carried out at given viscosity demonstrate that the volumetric productivity increases with temperature up to an optimal value (32—36 °C). At higher temperatures a productivity drop occurs. In addition, a viscosity increase up to about 12 g m—1 s—1 (value determined at 30 °C) improves the fermentation kinetics, while the process is strongly negatively affected at viscosity values higher than this threshold. Both the Arrhenius and the so-called ”︁thermodynamic” models have then been used to estimate the related thermodynamic quantities referred to both fermentation and thermal deactivation. A comparison of the values of these quantities suggests that both cell growth repression provoked by mass transfer limitations due to viscosity rise and the reduction of product inhibition are possible simultaneous causes of the observed productivity enhancement at low CMC levels. 相似文献
15.
羟丙基马铃薯淀粉合成工艺及性能研究 总被引:9,自引:3,他引:9
本文以马铃薯淀粉为原料,环氧丙烷为醚化剂,氢氧化钠为催化剂对低取代度羟丙基淀粉的制备工艺进行了研究。考察了环氧丙烷用量、氢氧化钠用量、反应时间、反应温度对羟丙基淀粉取代度的影响。实验结果表明,提高环氧丙烷用量、氢氧化钠用量、反应时间和反应温度可提高羟丙基淀粉取代度,硫酸钠用量对羟丙基淀粉取代度有影响。采用分光光度法测定了羟丙基淀粉取代度。 相似文献
16.
17.
低取代度羟丙基木薯淀粉的制备 总被引:5,自引:0,他引:5
羟丙基木薯淀粉为优良的食品用变性淀粉。本文研究用环氧丙烷制备羟丙基木薯淀粉的最佳反应条件,着重研究了淀粉乳浓度、环氧丙烷用量、反应温度和时间对醚化程度和反应效率的影响规律。结果表明:增高淀粉乳浓度能提高醚化程度和反应效率;增加环氧丙烷用量能加速醚化反应,提高取代度,但使反应效率降低;一定范围内升高反应温度,延长反应时间,醚化程度和反应效率随之增高。 相似文献
18.
研究了微波作用下,淀粉乳质量分数、微波处理时间、微波的功率、环氧丙烷用量对羟丙基淀粉理化性质的影响,通过正交实验获得了制备羟丙基淀粉的最佳反应条件为:淀粉乳质量分数40%、环氧丙烷用量4.8%,微波作用时间90 s(每次作用10 s,间歇1 min)、微渡功率600 W,在该条件下制备的羟丙基淀粉的分子取代度为0.041,其冷水可溶性好、糊透明度高、热稳定性好、黏度大、冻融稳定性好.与常规方法相比,微波法制备羟丙基淀粉的反应时问大大缩短. 相似文献
19.
20.
以玉米淀粉为原料,利用乙醇溶剂法进行羟丙基醚化改性,再采用环氧氯丙烷交联剂和一氯乙酸进行处理而制得复合改性淀粉。采用傅里叶变换红外谱仪、X射线衍射仪和扫描电镜等对玉米原淀粉、羟丙基淀粉、交联羟丙基淀粉、羟丙基羧甲基淀粉和交联羟丙基羧甲基淀粉的微观结构进行了表征。红外分析表明改性淀粉在1287 cm-1处出现羟丙基的吸收峰,同时在1328~1603 cm-1处出现了-COO-吸收峰,说明原淀粉已接入了羟丙基和羧甲基基团。利用X-射线衍射分析改性淀粉仍属A型衍射图,证实了反应主要发生在无定形区。复合变性前后淀粉的表观形貌变化,证实了淀粉其反应不仅发生在淀粉颗粒表面,也发生在淀粉颗粒内部。讨论了改性淀粉的理化性质,结果表明交联羟丙基羧甲基淀粉具有良好的透明性、冻融稳定性、流变性。 相似文献