羟丙基直链扩增,蜡性和正常玉米淀粉功能性质的研究注

本文对ＳｔａｒｃｈＡｕｓｔａｌａｓｉａ公司提供的直链扩增玉米淀粉，蜡性玉米淀粉进行痉丙基化反应，并对其功能性质和酶解率进行研究。     

醋酸直链扩增（ae）,蜡性（wx）和正常玉米淀粉功能性质的研究

对StarchAustralasia公司提供的直链扩增玉米淀粉（Hi－Maize，直链淀粉含量66％，GELOSE50，直链淀粉含量47％），蜡性玉米淀粉（MAZACA3401X，直链淀粉含量3．3％），和正常玉米淀粉（直链淀粉含量22．4％）进行乙酰化反应，并对其功能性质和酶解率进行研究，乙酰化反应降低所有淀粉的糊化温度，同时增加淀粉的粘度。所有乙酰化淀粉与未改性淀粉相比均有较低的To，Tp，Tc和ΔH，但乙酰化反应增加淀粉的膨胀率和溶解率。乙酰化后，除wx淀粉的粘度增加外，所有淀粉的硬度和粘度均下降。除wx淀粉透光率下降外，乙酰化反应增加所有淀粉的透光率和酶解率。     

不同直链淀粉含量对羟丙基氧化玉米淀粉性质的影响

本文采用蜡质玉米、普通玉米和高直链玉米淀粉为原料,改变有效氯添加量,制备羟丙基氧化淀粉,通过XRD、DSC、Brabender粘度仪等测定手段,研究不同直链淀粉含量对羟丙基氧化淀粉理化性质的影响。实验表明,直链淀粉含量对羟丙基化和氧化程度影响显著,其中直链淀粉含量高有利于羟丙基化,而不利于氧化;X-射线衍射分析发现,改性淀粉没有改变晶型,随氧化程度增加,淀粉分子结晶度下降,直链淀粉含量越高,下降趋势越缓;DSC测试和Brabender粘度分析表明,直链淀粉含量直接影响到羟丙基氧化淀粉糊化特性,糊化温度:高直链普通蜡质,糊粘度:蜡质普通高直链,糊化焓:蜡质普通高直链;通过观察淀粉的偏光特性和颗粒表面形态,发现直链淀粉含量越高,羟丙基氧化淀粉的偏光十字越弱,颗粒越不易破碎。     

热处理对直链淀粉扩增,蜡性及正常玉米淀粉物理性质和酶解率的影响

对直链淀粉扩增（ａｅ），蜡性（ＷＸ）及正常玉米淀粉经热处理（ａｕｔｏｃｌａｖｉｎｇ）后，其物理性质和酶解率的变化进行研究。淀粉经热处理后，除蜡性淀粉其峰值粘度增加外，所有淀粉的峰值粘度降低，且糊化温度提高，热处理增加扩增淀粉的热焓，但降低蜡性淀粉的ΔＨ；同时对正常玉米淀粉的ΔＨ几乎无影响。热处理使蜡性和正常玉米淀粉的硬度和粘结力增加，但使扩增淀粉的硬度和粘结力降低；同时使所有淀粉的弹性降低。热处理     

普通玉米杂交种间原淀粉与羟丙基淀粉糊化性质关系的研究

本文采用湿法在实验室的条件下提取了17种普通玉米杂交种淀粉，并制取了羟丙基淀粉。采用快速粘度测定仪（RVA）测定了所有淀粉的糊化性质参数。结果表明：羟丙基淀粉提高了所有原淀粉的峰值和破损值；降低了所有原淀粉的谷值、终粘度、回生值、出峰时间和成糊温度；原淀粉和羟丙基淀粉的糊化性质参数在普通玉米杂交种间均达到了极显著相关水平，表明了羟丙基淀粉并没有改变原淀粉在普通玉米杂交种间的糊化性质差异性。羟丙基淀粉的糊化性质参数间的相关性显著水平发生了明显的变化，表明了不同的普通玉米杂交种的羟丙基淀粉的糊化性质参数的变化幅度是不同的。但是，羟丙基和原淀粉的相同糊化性质参数间的相关性都达到极显著的正相关水平，说明了羟丙基淀粉与原淀粉的糊化性质参数间存在密切关系，二者的糊化性质又存在着一致性。     

交联羟丙基玉米淀粉性质研究

本试验以玉米淀粉为原料，分别以环氧丙烷为醚化剂、三偏磷酸钠为交联剂制备了不同取代度和交联度的交联羟丙基玉米淀粉，并对其透明度、冻融稳定性、抗酸性、高温稳定性及流变学特性进行了分析，同时对其加入面条后对面条特性的影响进行了研究。结果显示，黏液的透明度、冻融稳定性、抗酸性、耐高温性及耐剪切性方面都有显著的提高，加入面条后对面条的最佳烹煮时间和烹煮损失方面有较大改善。     

交联羟丙基玉米淀粉性质研究

本试验以玉米淀粉为原料,分别以环氧丙烷为醚化剂、三偏磷酸钠为交联剂制备了不同取代度和交联度的交联羟丙基玉米淀粉,并对其透明度、冻融稳定性、抗酸性、高温稳定性及流变学特性进行了分析,同时对其加入面条后对面条特性的影响进行了研究。结果显示,黏液的透明度、冻融稳定性、抗酸性、耐高温性及耐剪切性方面都有显著的提高,加入面条后对面条的最佳烹煮时间和烹煮损失方面有较大改善。     

微乳化法合成羟丙基高直链淀粉研究

系统地研究以玉米高直链淀粉、环氧丙烷为主要原料,采用微乳化法合成羟丙基高直链淀粉工艺,通过实验探讨各影响因素对产品取代度的影响;并用X射线衍射仪、电子扫描仪等对产品性能进行分析。     

羟丙基氧化高直链玉米淀粉的制备、表征及性能研究

以高直链玉米淀粉为原料,次氯酸钠为氧化剂,环氧丙烷为醚化剂,氢氧化钠为催化剂,对羟丙基氧化高直链玉米淀粉的制备、表征及性能进行了研究。考察了环氧丙烷用量、羟丙基化时间、羟丙基化温度、氢氧化钠用量和无水硫酸钠用量对羟丙基氧化高直链玉米淀粉取代度的影响。结果表明,制备氧化高直链玉米淀粉的较佳工艺条件为:羟丙基化时间18h、羟丙基化温度40℃、无水硫酸钠用量10%、氢氧化钠用量1.2%。高直链玉米淀粉经氧化后,在波数1 735cm-1处出现CO的伸缩振动峰;羟丙基化、氧化改变了高直链玉米淀粉热稳定性。氧化、羟丙基化能提高高直链玉米淀粉的冻融稳定性和膨胀能力,氧化使高直链玉米淀粉蓝值降低,羟丙基化基本不改变高直链玉米淀粉的蓝值。     

高直链玉米淀粉/羟丙基甲基纤维素可食性膜的制备及性能研究

以高直链玉米淀粉(HACS)和羟丙基甲基纤维素(HPMC)为主要成膜基材,采用溶液流延法制备了HACS/HPMC可食性膜。研究了不同配比的HACS与HPMC对可食性膜的结晶性能、力学性能、亲水性能和水蒸气阻隔性能等的影响。结果表明,随着HPMC比例的增大,HACS与HPMC之间的氢键作用减弱,复合膜的水溶性增大,连续相由HACS转变为HPMC,但HACS与HPMC的相容性变差。HPMC可有效降低可食性膜的结晶程度并抑制其在储藏过程中的老化。在复合膜中,当HACS与HPMC比例为8∶2时,可食性膜具有最大抗拉强度(7.5 MPa)、断裂伸长率(14.7%)、水接触角(84.33°)和最低水蒸气透过系数(2.17×10~(-10 )g·m·m~(-2)·s~(-1)·Pa~(-1))。纯HACS膜和纯HPMC膜的透光性能均优于HACS/HPMC复合膜。     

不同原淀粉及其羟丙基淀粉性质的研究

本实验对糯米淀粉、糯玉米淀粉、马铃薯淀粉、普通玉米淀粉及其羟丙基淀粉的基本性质进行了研究比较.结果表明,四种淀粉及其羟丙基淀粉的黏度、透明度、冷藏稳定性、冻融稳定性、碘显色反应以及白度都有明显差异.研究还发现,羟丙基化不仅可以降低各种淀粉的糊化起始温度及碘显色反应,还可改善淀粉的透明度、冷藏稳定性及冻融稳定性.     

Physicochemical and Gelatinization Properties of Starches Separated from Various Rice Cultivars

Morphological, viscoelastic, hydration, pasting, and thermal properties of starches separated from 10 different rice cultivars were investigated. Upon gelatinization, the G′ values of the rice starch pastes ranged from 37.4 to 2057 Pa at 25 °C, and remarkably, the magnitude depended on the starch varieties. The rheological behavior during gelatinization upon heating brought out differences in onset in G′ and degree of steepness. The cultivar with high amylose content (Goami) showed the lowest critical strain (γ_c), whereas the cultivars with low amylose content (Boseokchal and Shinseonchal) possessed the highest γ_c. The amylose content in rice starches affected their pasting properties; the sample possessing the highest amylose content showed the highest final viscosity and setback value, whereas waxy starch samples displayed low final viscosity and setback value. The onset gelatinization temperatures of the starches from 10 rice cultivars ranged between 57.9 and 64.4 °C. The amylose content was fairly correlated to hydration and pasting properties of rice starches but did not correlate well with viscoelastic and thermal characteristics. The combined analysis of hydration, pasting, viscoelastic, and thermal data of the rice starches is useful in fully understanding their behavior and in addressing the processability for food applications.     

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。     

Physicochemical Properties of Waxy and Normal Maize Starches Irradiated at Various pH and Salt Concentrations

Waxy and normal maize starches of various pH values and salt contents were prepared, irradiated with gamma rays (5–20 kGy) and their molecular structure, pasting viscosity and rheological properties determined. Average molar mass and size of both waxy and normal maize starches decreased considerably by irradiation from >338.0×10⁶ to <39.4×10⁶ g/mol and from >237.5 to <125.2 nm, respectively. Adjustments of pH had little influence on the average molar mass and size of irradiated starch, whereas incorporation of salt greatly reduced the molar mass and size of irradiated waxy and normal maize starches. As the pH increased from 4 to 8, the pasting viscosity of the irradiated starches decreased from 1032 to 279 mPa s in waxy and from 699 to 381 mPa s in normal starches. Pasting viscosity of both irradiated waxy and normal starch decreased from 689 to 358 mPa s and from 327 to 184 mPa s as the salt concentration increased from 1 to 5%. The G′ of gels, determined during cooling from 90 to 10°C or storage for 8 h, decreased in irradiated waxy and normal starches by pre‐conditioning at pH 8 and in irradiated waxy starches by pre‐conditioning at 5% NaCl. With 5% NaCl, G′ of irradiated normal maize starch during cooling increased up to the irradiation level of 10 kGy, and increased during storage for 8 h at all levels of irradiation. Incorporated salt prior to irradiation appears to induce incremental modifications in the molecular structure, rheological and retrogradation properties of starch by boosting the degradation of molecules.     

小米淀粉与玉米淀粉糊性质比较研究

对小米淀粉和玉米淀粉糊性质进行较详细比较研究,包括透明度、冻融稳定性、凝沉性、膨胀力、酸解、酶解,和介质对糊粘度性质影响。结果表明,小米淀粉与玉米淀粉相比,糊的凝胶稳定性好、持水力强、膨胀力高、糊化温度高、热焓变值大、但透明度较差、冻融稳定性不佳、热稳定性差;且氯化钠及糖溶液对小米淀粉糊粘度性质影响较大。     

羟丙基糯米淀粉微观形态及其淀粉糊性质的研究

对羟丙基糯米淀粉微观形态及其淀粉糊性质进行了研究。通过电镜扫描和RVA分析,发现羟丙基糯米淀粉的颗粒表面出现了凹槽状和浅褶皱等被腐蚀的痕迹,且羟丙基糯米淀粉的起始糊化温度和峰值黏度都明显降低。研究还发现,羟丙基糯米淀粉的表观黏度随糖浓度的增大增加,随盐浓度、酸碱浓度和转子转速增大而降低;其透明度随淀粉乳浓度、糖浓度和pH值增大而提高,随氯化钠浓度的增大,则是先下降再增高,但总体变化不大;同时羟丙基化还可以显著提高淀粉的冻融稳定性。     

In vitro Digestibility of Hydroxypropylated and Cross-linked Waxy and Non-waxy Rice Starches

In vitro digestibility of hydroxypropylated and cross-linked waxy and non-waxy rice starches was investigated to find the proper resistant starch (RS) assaying method for chemically modified starches. RS and total dietary fiber (TDF) content of hydroxypropylated and cross-linked waxy and non-waxy rice starches were measured using the approved AOAC RS assay procedure (AOAC method 2002.02) and the AOAC TDF assay procedure (AOAC method 985.29). Hydroxypropylation did not alter the RS content of waxy and non-waxy rice starches (less than 1% of RS). Cross-linking also did not change the RS content of waxy and non-waxy rice starches (less than 1% of RS). It is interesting to note that non-RS content decreased with increasing hydroxypropylation (97-80%) and cross-linking (99-95%) in both waxy and non-waxy rice starches. This indicates that some fraction of RS in hydroxypropylated and cross-linked waxy and non-waxy rice starches cannot be measured using approved AOAC RS and TDF assay procedures. Therefore, the RS and TDF assay procedures performed in this study are not appropriate to determine the RS content of chemically modified starch. Further investigation is needed to develop a method to determine the RS content of chemically modified starch.