西米羟丙基淀粉的理化性质研究

利用环氧丙烷为醚化剂制备西米羟丙基淀粉,并对其理化性质进行研究。结果表明:醚化后淀粉的颗粒形貌没有发生变化;糊化起始温度(T_o),峰值温度(T_p),终止温度(T_c)以及热焓值(ΔH)均高于原西米淀粉;透明度提高,远高于西米原淀粉;凝沉性增强,冷糊和热糊稳定性提高,表观黏度降低,流动性增加。     

西米交联淀粉的理化性质

以三偏磷酸钠为交联剂,采用水分散法制备西米交联淀粉,利用扫描电镜、聚焦光束发射测量仪、Bra-bender快速黏度计和紫外分光光度计对其性质进行测定和分析,并与西米原淀粉进行比较。结果表明:西米交联淀粉发生了中等程度的交联;西米交联淀粉保持了西米原淀粉绝大多数颗粒完整、呈椭圆形、存在断切面和断切面处有凹坑的形貌特征,但其表面比较粗糙,有凹痕,且断切面处凹坑更加明显;西米交联淀粉颗粒粒径分布图呈单峰,在水相中的平均粒径为30.1μm,比西米原淀粉颗粒小;西米交联淀粉比西米原淀粉难于糊化,其热稳定性和冷糊稳定性均优于西米原淀粉,有很高的最终黏度;西米交联淀粉的透光率为5.1%,小于西米原淀粉,其透明度较差。     

西米辛烯基琥珀酸淀粉酯的结构表征及性质研究

采用现代仪器分析方法对西米辛烯基琥珀酸淀粉酯的结构特征、颗粒形貌、粒径分布、乳化性、糊粘度等性质进行了测定和研究,并以西米原淀粉作为参照。结果表明,西米淀粉经辛烯基琥珀酸酐处理后,产品的红外光谱在1570cm-1和1714cm-1处出现新的吸收峰,608cm-1处吸收峰加强;颗粒表面受到损害,形状发生不规则变化;颗粒粒径分布不均,平均粒径大于西米原淀粉;乳化能力和乳化稳定性有显著提高;糊粘度明显增大,热糊稳定性高,凝沉性较弱。为进一步研究西米辛烯基琥珀酸淀粉酯的开发应用提供了一定理论依据。     

西米柠檬酸酯淀粉物化性质研究

利用扫描电子显微镜、红外光谱仪、聚焦光束反射测量仪、X射线衍射仪和布拉班德粘度计对西米柠檬酸酯淀粉性质进行测定和分析,并与西米原淀粉进行比较。结果表明,西米淀粉经柠檬酸酯化后,其表面被侵蚀,甚至有颗粒已破碎;酯化后淀粉颗粒平均粒径从30.8μm减至27.1μm;柠檬酸酰基引入会破坏淀粉颗粒结晶,淀粉相对结晶度从24.5%显著降至11.6%;通过对淀粉糊粘度分析发现,西米淀粉与柠檬酸在酯化作用下发生交联,其浆液在粘度测定过程中不发生糊化和胶凝。     

化学糊化法研究乙酰化马铃薯淀粉的性质

室温下用4mol/L CaCl2溶液对乙酰化马铃薯淀粉颗粒外围进行化学糊化,去除外围糊化物后得到残存颗粒。对乙酰化马铃薯淀粉原颗粒和残存颗粒的粒径、取代度、结晶性质以及热性质进行分析比较,结果表明：用乙酸酐制备的乙酰化马铃薯淀粉的取代度与淀粉颗粒的大小相关,颗粒越小,取代度越大。乙酰基团在颗粒中分布不均匀,大多分布在淀粉颗粒的外围。残存颗粒与原颗粒晶型相同,均为B-型;淀粉颗粒糊化程度越高,所得残存颗粒的相对结晶度和糊化峰值温度越大。     

西米淀粉的物化性质研究

研究了西米淀粉的组成、颗粒形貌及糊化、透明度、老化方面的性质,并与木薯和马铃薯进行了比较。结果表明,西米淀粉的蛋白质含量为0.21%,直链淀粉含量为28%,颗粒为椭圆形,西米淀粉的起糊温度为70.3℃,热糊稳定性高,凝沉性比薯类淀粉弱,西米淀粉的透明度为57.5%,比薯类淀粉易老化。为进一步了解西米淀粉的特性及应用开发提供了一定的理论依据。     

西米柠檬酸酯淀粉颗粒结构与性质研究

利用光学显微镜、扫描电子显微镜、紫外分光光度计和布拉班德黏度计对西米柠檬酸酯淀粉的性质进行测定和分析,并与西米原淀粉进行比较。结果表明:西米淀粉经柠檬酸酯化作用后,其表面被侵蚀,甚至有的颗粒已破碎,偏光十字变弱,结晶度降低;西米柠檬酸酯淀粉的溶胀度和透明度都远远小于原淀粉;通过淀粉糊黏度分析发现,西米淀粉与柠檬酸在酯化作用下发生交联,其浆液在黏度测定过程中不发生糊化和胶凝。     

不同原料微波辐射制备醋酸酯淀粉及性质的研究

分别以马铃薯、小麦、玉米淀粉为原料,以醋酸酐为乙酰化试剂,利用微波辐射技术时醋酸酯淀粉的合成工艺和性能进行了研究.结果表明,由不同原料合成的醋酸酯淀粉取代度不同,其中马铃薯淀粉合成的醋酸酯淀粉取代度最高,小麦最低.并且对三种醋酸酯淀粉的凝沉性和透明度进行了测定分析.     

机械活化辛烯基琥珀酸西米淀粉酯的制备及其乳化性能分析

采用自制搅拌式球磨机对西米淀粉进行机械活化预处理,以辛烯基琥珀酸酐为酯化剂制备辛烯基琥珀酸西米淀粉酯。探讨活化时间、反应时间、辛烯基琥珀酸酐添加量、反应温度和pH等因素对辛烯基琥珀酸西米淀粉酯取代度的影响。结果表明,机械活化对西米淀粉辛烯基琥珀酸酐酯化反应有明显的增强作用;在相同反应条件下,活化淀粉的取代度和反应效率显著上升;通过正交试验确定了活化1.0 h西米淀粉酯的最佳工艺条件：反应时间为2.0 h,辛烯基琥珀酸酐用量为3%,pH为8.0,反应温度为35℃;在此条件下酯化得到的淀粉酯取代度为0.02294,反应效率为98.01%。FTIR、XRD、SEM测试结果表明,西米淀粉经过辛烯基琥珀酸酐处理后,产品的红外光谱在1570 cm^-1和1712 cm^-1处出现了新的吸收峰,淀粉结晶度下降,淀粉颗粒表面受到破坏,颗粒中间出现较大孔洞,进一步证实西米淀粉发生了酯化反应。取代度为0.02294的辛烯基琥珀酸西米淀粉酯的乳化性为26.43%,乳化稳定性为24.10%,均优于原西米淀粉酯。     

西米淀粉糊流变特性研究

利用Brookfield旋转粘度计研究西米淀粉糊流变性、抗剪切能力、触变性以及温度、浓度和剪切速率对表观粘度的影响,为西米淀粉在食品行业的应用提供理论上的依据。结果表明:西米淀粉糊属于非牛顿流体。温度、浓度、剪切速率对流变性质均有影响,在同一浓度和剪切速率下,表观粘度随温度的增加而减小;在同一温度和剪切速率下,表观粘度随浓度的增加而增加;在同一温度和浓度条件下,淀粉糊的表观粘度随剪切速率的增加而减小。西米淀粉糊属于剪切稀化体系,抗剪切能力优于马铃薯淀粉糊和木薯淀粉糊;淀粉糊粘度随剪切速率增大的上行线与随剪切速率减小的下行线之间存在滞后圈,说明西米淀粉糊具有触变性。     

西米淀粉结构及消化特性

以马铃薯淀粉和红薯淀粉作为参照,用Englyst法测定西米淀粉的消化特性,并研究其成糊特性、直链淀粉含量、分子链长分布以及脂肪含量与消化特性的关系。结果表明：与马铃薯淀粉和红薯淀粉相比,西米淀粉具有较高含量的快消化淀粉（90.32%）和较低的抗消化淀粉含量（3.27%）。西米淀粉样品较低的脂肪含量（0.11%）、较高的短链含量（聚合度10～30,83.57%）、较低的长链含量（聚合度＞55,0.80%）,较高的直链淀粉含量（29.3%）和较低的终值黏度（1 096.67 mPa·s）。对消化特性起主要影响作用的因素有链长分布、直链淀粉含量和脂肪含量。     

Physicochemical Properties of Carboxy-methylated Sago (Metroxylon sagu) Starch

ABSTRACT: Carboxymethyl starch (CMS) with degree of substitution (DS) ranging from 0.1 to 0.32 was prepared from sago ( Metroxylon sagu ) starch in non-aqueous medium using isopropanol as a solvent. The physico-chemical, rheological, and thermal properties of the starches were investigated. At room temperature (25 °C), CMS hydrated readily, resulting in higher swelling power compared with native (unmodified) starch. Light microscopy revealed that CMS granules imbibed more water than native starch at room temperature and thus caused a larger increase in granule size. Some of the CMS granules lost their integrity. Scanning electron microscopic observation revealed fine fissures on the surface of CMS (DS 0.32) granules compared with a relatively smooth surface of native starch granules. Carboxymethylated sago starch exhibited excellent dispersibility and cold water solubility as judged by the absence of peak viscosity in the pasting profile (determined by Rapid ViscoAnalyzer). Pasting profile of CMS was qualitatively similar to pregelatinized starch. Despite exhibiting greater swelling power, CMS showed significantly lower pasting viscosity compared with the native starch. Intrinsic viscosity was also greatly reduced by carboxymethylation. Studies using differential scanning calorimetry (DSC) showed that transition temperatures and enthalpies decreased with an increase of degree of substitution. CMS at higher substitution levels (DS 0.27 and 0.32) showed significantly lower retrogradation tendency, as indicated by lower setback, absence of DSC endotherm upon storage at 4 °C and lower syneresis upon repeated freeze-thaw cycles. The results suggested that retrogradation might be effectively retarded by the presence of the bulky carboxymethyl group.     

西米淀粉颗粒结构与性质的研究

利用光学显微镜、扫描电子显微镜、X-射线衍射仪、聚焦光束发射测量仪、差式量热扫描仪和紫外分光光度计对西米淀粉的性质进行测定和分析,并与马铃薯淀粉和木薯淀粉进行比较。结果表明:西米淀粉颗粒为椭球体,颗粒表面光滑;偏光十字明显;颗粒在水相中的平均粒径为27.3μm;晶体结构为C型,结晶度为25%;DSC测得To、Tp、Tc分别为68.51、72.79、82.29℃,ΔH为12.00J/g;透明度较好。     

Sago starch and its utilisation

The importance and development of industrial biotechnology processing has led to the utilisation of microbial enzymes in various applications. One of the important enzymes is amylase, which hydrolyses starch to glucose. In Malaysia, the use of sago starch has been increasing, and it is presently being used for the production of glucose. Sago starch represents an alternative cheap carbon source for fermentation processes that is attractive out of both economic and geographical considerations. Production of fermentable sugars from the hydrolysis of starches is normally carried out by an enzymatic processes that involves two reaction steps, liquefaction and saccharification, each of which has different temperature and pH optima with respect to the maximum reaction rate. This method of starch hydrolysis requires the use of an expensive temperature control system and a complex mixing device. Our laboratory has investigated the possibility of using amylolytic enzyme-producing microorganisms in the continuous single-step biological hydrolysis of sago flour for the production of a generic fermentation medium. The ability of a novel DNA-recombinated yeast, Saccharomyces cerevisiae strain YKU 107 (expressing alpha-amylase production) to hydrolyse gelatinised sago starch production has been studied with the aim of further utilizing sago starch to obtain value-added products.     

Effects of cationization on DSC thermal profiles,pasting and emulsifying properties of sago starch

Cationic sago starches were prepared using an aqueous alkaline process with different levels of cationic reagent 3‐chloro‐2‐hydroxypropyltrimethylammonium chloride (0.01–0.10 M ), sodium hydroxide (0.03–0.86 M ) and reaction temperature (30–62 °C). The degree of substitution (DS), reaction efficiency, thermal and pasting properties of cationic sago starches were analysed. Emulsifying and fat binding properties of native sago starch, cationized sago starch and commercial chitosan were compared at two different pH values (4 and 7). Degree of substitution increased with an increase in concentration of cationic reagent or NaOH, or reaction temperature. The reaction efficiency was proportional to the concentration of NaOH and reaction temperature but inversely proportional to the cationic reagent concentration. The highest DS and reaction efficiency achieved was 0.06 and 79%, respectively. The pasting temperature and gelatinization enthalpy of cationic starch (DS 0.06) were lower compared with native sago starch. Cationization increased the peak viscosity and breakdown of the starch paste but decreased the setback. The presence of cationic groups significantly increased emulsion stability, emulsion viscosity and fat binding capacity of sago starch. However, the cationic sago starch was still inferior to chitosan, which showed the highest emulsion stability, emulsion viscosity and fat binding capacity. There was no significant difference between the surface tension values of native and cationic sago starch and chitosan. The influence of pH on emulsifying properties was not significant. The emulsion stability of the cationic sago starch improved due to an increase in viscosity and fat binding capacity but not its surface active property. Copyright © 2004 Society of Chemical Industry     

60Co-γ辐射对马铃薯淀粉特性的影响

采用60Co-γ射线对马铃薯淀粉进行辐照处理,辐照剂量分别为4、8、10、12、16kGy和20kGy,测定淀粉的颗粒特性及淀粉糊的透明度、热稳定性及冷稳定性。结果表明：辐照后的马铃薯淀粉颗粒形貌未发生明显变化、平均粒径变小;淀粉糊的透明度升高,峰值黏度减小,热稳定性及冷稳定性均显著提高。辐照剂量高于10kGy时,淀粉糊的峰值黏度与冷、热稳定性变化趋于平缓。     

Rheological and textural studies of fresh and freeze-thawed native sago starch–sugar gels. II. Comparisons with other starch sources and reheating effects

The viscoelastic and textural properties of freshly prepared and freeze-thawed sago starch–sugar gels were studied in comparison with other native starches from corn, wheat, tapioca, and potato. The gelatinisation and retrogradation properties of starches were studied using a DSC while the pasting properties of starch–sugar mixtures during the cooking period were studied using a starch pasting cell. The freeze-thaw stability of gels was evaluated by gravimetric measurements of the water of syneresis. The different starches gave properties which varied following to their botanical sources. High-amylose cereal starches (wheat and corn) produced harder gels, while low-amylose root starch (tapioca) produced softer gels. Sago and potato gels showed close similarities in their viscoelastic and textural characteristics. Although the freeze-thaw cycle greatly increased the viscoelasticity and hardness of these two gels, reheating at high temperature significantly reduced these negative effects and resulted in partial recovery of the gel structures. Sago starch produced gels with very low syneresis and high cohesiveness, implying its potential use as a gelling agent in the frozen food industries.