碾轧对马铃薯淀粉的机械力化学效应

以马铃薯淀粉为原料,研究碾轧处理对淀粉结构和性质的影响。通过扫描电子显微镜、X射线衍射、差示扫描量热仪、傅里叶变换红外光谱仪、快速黏度分析仪、偏光显微镜等手段揭示碾轧对马铃薯淀粉的机械力化学效应。结果表明,碾轧处理对淀粉颗粒的无定形区、结晶区产生不同程度的机械力化学作用,导致马铃薯淀粉性质发生显著变化。由此推断淀粉颗粒内部依次发生了受力、聚集和团聚效应。     

高压均质对绿豆淀粉机械力化学效应的影响

以绿豆淀粉为原料,100 MPa分别均质处理1、3、5、7次,通过扫描电镜(SEM)、激光共聚焦显微镜(CLSM)、偏光显微镜(PLM)、X-射线衍射(XRD)、快速黏性分析仪(RVA)、差示扫描量热仪(DSC)等手段研究高压均质处理对绿豆淀粉微观结构及理化性质的影响,探究其相互关系并研究高压均质对绿豆淀粉机械力化学效应。结果表明,高压均质对淀粉颗粒无定形区、晶体结构产生了机械力化学作用,根据机械力化学相关理论可说明淀粉颗粒内部依次经过了受力阶段、聚集阶段、团聚阶段。     

高压均质对玉米淀粉机械力化学效应研究

以玉米淀粉为原料,通过扫描电镜(scanning electron microscope,SEM)、X-射线衍射(X-ray diffraction,XRD)、激光共聚焦显微镜(confocal laser scanning microscopy,CLSM)、快速黏度分析仪(rapid visco analyser,RVA)、差示扫描量热仪(differential scanning calorimetry,DSC)、偏光显微镜(polarizing microscope,PLM)等手段研究高压均质处理对玉米淀粉微观结构及理化性质的影响,揭示高压均质对玉米淀粉机械力化学效应。结果表明,高压均质对淀粉颗粒的无定形区、结晶区产生很强的机械力化学作用,推断淀粉颗粒内部依次发生了聚集和团聚效应。     

超声辅助制备辛烯基琥珀酸淀粉酯及其对品质的影响机制

超声波可显著提高变性淀粉的反应活性及品质，但其作用机制不清楚。本研究以木薯淀粉为原料，超声辅助制备低取代度辛烯基琥珀酸淀粉酯(OSAS)。通过研究不同超声功率处理对木薯原淀粉结构和理化性质的影响，借鉴机械力化学的理论分析超声处理对OSAS品质的影响机制。结果表明：超声波通过介质“水”可对淀粉颗粒内部产生很强的机械力作用，破坏了淀粉颗粒的结晶结构和颗粒形貌，使淀粉分子发生水化，从而使木薯淀粉的糊化温度和热稳定性降低，直链淀粉含量增加。超声对淀粉颗粒具有显著的机械力化学效应，所以超声辅助制备的OSAS的取代度和反应效率显著增加，其它质量（溶解度、膨胀度和黏度）也显著提高。     

高压微射流处理对马铃薯淀粉结构和糊特性的影响

为改善马铃薯淀粉的天然局限性,该文采用快速黏度分析仪（rapid visco analyser,RVA）研究高压微射流处理对马铃薯淀粉糊特性的影响。并利用激光共聚焦扫描显微镜（confocal laser scanning microscope,CLSM）、拉曼光谱研究马铃薯淀粉的微观结构和有序结构,结合粒径分布、直链淀粉表观含量分析高压微射流的处理对马铃薯淀粉糊特性的影响机制。结果表明：高压微射流处理可显著降低马铃薯淀粉糊黏度。80 MPa的处理导致马铃薯内部出现聚集现象,微观结构生长环变得清晰,淀粉分子变得有序,结晶度增大;在120 MPa～160 MPa较高压力下的高压微射流处理使得淀粉的颗粒破损严重,内部分子无序化严重,直链淀粉表观含量显著增加、拉曼峰值强度降低,峰值黏度降低至534.667。说明高压微射流产生的机械力深入到马铃薯颗粒内部,导致马铃薯淀粉的结构发生显著变化,从而影响其糊特性。     

碾轧对绿豆淀粉的机械力化学效应

以绿豆淀粉为原料,通过扫描电镜(SEM)、偏光显微镜(PLM)、激光扫描共聚焦显微镜(CLSM)、X-射线衍射(XRD)、差示扫描量热仪(DSC)、快速黏度分析仪(RVA)等手段研究碾轧处理对淀粉结构和性质影响,探究其相互关系并揭示碾轧对绿豆淀粉机械力化学效应。结果表明,碾轧处理3~6 h时,淀粉无定型区和部分结晶区发生破坏,水溶指数、膨胀度、透光率增大,热焓减小。碾轧处理9 h时,淀粉内部发生重结晶,颗粒表面形成球状凸起,脐点区域直链淀粉聚集导致膨胀度、透光率、峰值黏度下降,水溶指数、热焓值、糊化温度增大。碾轧处理12~24 h时,淀粉的结晶区域发生显著破坏,颗粒严重变形,从而使淀粉水溶指数、透光率增大,膨胀度、热焓值减小。根据机械力化学相关理论推断淀粉颗粒内部依次经过了受力阶段、聚集阶段、团聚阶段。     

碾轧处理对乙酰化淀粉品质的影响及作用机理

为研究碾轧处理对乙酰化淀粉品质的影响及其作用机理,本文以甘薯淀粉为原料,研究不同碾轧处理时间(0、2、5、7、18 h)对乙酰化甘薯淀粉的品质、结构和理化性质的影响,采用机械力化学相关理论分析碾轧处理对乙酰化甘薯淀粉品质影响的作用机理。结果表明:碾轧处理2和7 h后,乙酰化甘薯淀粉的反应效率分别增加到74.45%和75.40%,其它品质(溶解度、膨胀力和峰值黏度)也显著提高。甘薯淀粉在碾轧处理2 h后,与原淀粉相比,结晶度降低且位于17.8 °处的衍射峰消失,T₂值增大,糊化焓和峰值黏度减小,热稳定性减弱;碾轧处理5 h后,溶解度、膨胀力和峰值黏度都减小,但淀粉的热稳定性增大;与处理2 h后相比,结晶度变大,T_2,2值消失;碾轧处理7~18 h后,结晶度、糊化焓和热稳定性显著降低,T_2,1值增大,碾轧处理18 h后淀粉分子晶体区域的双螺旋结构呈短程有序方式排列。这些变化表明碾轧处理可对甘薯淀粉颗粒产生显著的机械力化学效应。随着碾轧处理时间的增加,淀粉颗粒内部依次经历了受力、聚集和团聚阶段。机械力化学对淀粉颗粒作用的三个阶段具有不同的影响机制,为今后研究制备高品质变性淀粉先进装备奠定一定的理论基础。     

挤压剪切活化对添加耐高温α-淀粉酶脱胚玉米淀粉结构和理化特性的影响

本研究通过偏光显微镜、扫描电子显微镜、热台显微镜、X射线衍射、差示扫描量热分析、傅里叶变换红 外光谱分析等手段,研究原脱胚玉米、挤压脱胚玉米和添加耐高温α-淀粉酶挤压脱胚玉米的淀粉结构及性质变化, 并探究其相互关系,揭示挤压剪切活化对脱胚玉米的淀粉颗粒机械力化学效应。研究表明：与原脱胚玉米和挤压脱 胚玉米相比较,挤压处理对添加耐高温α-淀粉酶脱胚玉米的淀粉结构及性质产生显著影响,酶解力和糊化度增大,碘 蓝值、直链淀粉含量减小。添加耐高温α-淀粉酶挤压脱胚玉米淀粉颗粒形貌破坏,偏光十字破坏,结晶度变小;升温糊 化过程中,焓变降低;挤压使淀粉颗粒的结晶结构破坏,淀粉颗粒发生聚集,破损淀粉颗粒易糊化和裂解。     

碾轧活化淀粉湿法制备阳离子淀粉及其性能研究

分别选取受力阶段(碾轧处理3 h)、聚集阶段(碾轧处理9 h)、团聚阶段(碾轧处理12 h和24 h)3种不同机械力化学阶段的玉米淀粉湿法制备阳离子淀粉。采用扫描电镜(scanning electron microscope,SEM)、偏光显微镜(polarized light microscopy,PLM)、X-射线衍射(X-ray diffraction,XRD)、傅立叶变换红外光谱仪(fourier transform infrared spectroscopy,FTIR)、快速黏性分析仪(rapid visco analyser,RVA)、热重分析仪(thermogravimetric analyzer,TGA)等手段对阳离子淀粉的形貌、晶体结构、糊特性和热稳定性进行了研究表征。通过分析不同机械力化学阶段碾轧预处理对阳离子淀粉的分子结构及性质的影响,从机械力化学的角度揭示碾轧对玉米淀粉活化机制。结果显示,碾轧可破坏淀粉颗粒有序的结晶区,有利于醚化剂渗入淀粉颗粒内部,故碾轧机械力显著提高淀粉的化学活性,并且碾轧预处理后的阳离子淀粉室温下即可糊化。其中,团聚阶段(碾轧处理12 h)变化最显著,制备的阳离子淀粉结晶度破坏最严重,取代度、反应效率、黏度特征值和透光率最大,淀粉分子化学活性最高。     

高压均质预处理对玉米淀粉阳离子化、结构和性能的影响

为探究高压均质机械力作用对淀粉化学活性的影响,本研究采用处于3 种不同机械力作用阶段的玉米淀粉 为原料,湿法制备了阳离子淀粉。通过扫描电子显微镜、激光共聚焦显微镜、偏光显微镜、X射线衍射分析、快速 黏度分析、差示扫描量热分析等手段研究了高压均质预处理对阳离子淀粉结构及性能的影响。结果表明：高压均质 预处理可破坏淀粉晶体结构,能提高淀粉化学活性。聚集阶段变化最为显著,该阶段阳离子淀粉峰值黏度、透光 率、化学活性最高,取代度和反应效率增幅分别达43.80%、43.86%。     

超声波处理对马铃薯全粉理化性质和消化特性的影响

以马铃薯全粉为原料,研究超声处理对马铃薯全粉理化性质和消化特性的影响。结果表明:超声处理使得马铃薯全粉的结晶度增大,晶体结构明显改变,溶解度、膨胀度、吸油性、崩解值、糊化温度和消化特性显著降低。随着超声波处理时间的延长,马铃薯全粉的结晶度、峰值黏度、谷值黏度和最终黏度先升高后降低。随着超声波处理时间的延长,快消化淀粉(RDS)含量降低,慢消化淀粉(SDS)和抗性淀粉(RS)含量升高。研究表明,超声处理显著影响马铃薯全粉的理化性质和消化特性(P0.05)。     

流化床气流超微粉碎对马铃薯淀粉结构及性质的影响

为研究流化床气流超微粉碎对淀粉结构及性质的影响,以马铃薯淀粉为原料,采用激光粒度分析仪、扫描电子显微镜、光电子能谱仪、同步热分析仪、流变仪等多种仪器及分析手段,考察气流粉碎对马铃薯淀粉颗粒大小及形貌、表面基团、热稳定性、流变特性、溶解度、膨胀度及透明度等结构及性质的影响。结果表明:马铃薯原淀粉经气流粉碎微细化处理后,平均粒径（D₅₀）减小至13.59±0.04 μm;X射线光电子能谱（XPS）的谱图中没有出现新元素峰位,淀粉颗粒表面没有引入新元素;直链淀粉含量增加,支链淀粉分子链变短,溶解度、膨胀度和淀粉糊透明度增加;粘性阻力减小,表观粘度降低;淀粉分子氢键及分子链均发生断裂,凝沉性下降,该研究为马铃薯淀粉的深度加工与应用提供了理论依据及技术支撑。     

Effects of pulsed electric fields (PEF) treatment on physicochemical properties of potato starch

Potato starch–water suspensions (8.0%, w/w) were subjected to pulsed electric fields (PEF) treatment at 30 kV·cm^− 1, 40 kV·cm^− 1 and 50 kV·cm^− 1, respectively. The physicochemical properties of PEF-treated potato starch samples were investigated using scanning electron microscopy (SEM), laser scattering technique, X-ray diffractometry (XRD), differential scanning calorimetry (DSC), and the Brabender rheological method, with native potato starch as reference. It has been concluded from SEM analysis that dissociation and damage of PEF-treated potato starch granules appeared. Some granules aggregated with each other and showed gel-like structures. It was revealed from particle size analysis that there was an obvious increase of the granule size after PEF treatment. This has been attributed to the aggregation among granules. It was also demonstrated from other analysis that relative crystallinity, gelatinization temperatures, gelatinization enthalpy, peak viscosity as well as breakdown viscosity of modified samples all decreased with increasing electric field strength.

Industrial relevance

In this study, the effect of PEF treatment (up to 50 kV·cm^− 1) on physicochemical properties of potato starch has been investigated. The results from SEM images showed that dissociation, denaturation and damage of potato starch granules had been induced by the PEF treatments. Some of granule fragments showed gel-like structures, and congregated with each other or with other starch granules. Laser scattering measurements of particle size revealed that an obvious increase of granule size under electric field strength of 50 kV·cm^− 1, which was attributed to the aggregation of the starch granules. The X-ray diffraction pattern showed an obvious loss of crystalline structure after the PEF treatment at 50 kV·cm^− 1, which induced a trend of transformation from crystal to non-crystal in potato starch granules. DSC analysis showed a decrease in gelatinization temperatures (T_o and T_p) and gelatinization enthalpy (ΔH_gel) with increasing electric field strength. Brabender rheological method has been used to show that the peak viscosity and breakdown viscosity decrease with increasing electric field strength of PEF treatment. All the results reveal that the PEF treatment can lead to an intragranular molecular rearrangement of potato starch granules, which induces changes of various physicochemical properties of the treated starch thus may endow it some new characteristics and functions. This phenomena may warrant further more detailed study.     

Ultrasound-treated starch: SEM and TEM imaging,and functional behaviour

Potato, wheat, corn and rice starch granules were suspended in water or ethanol and sonicated at frequency of 20 KHz and power 170 W for 30 min. The effect of ultrasonic treatment on starch structure was assessed on the basis of blue value (BV), A₆₈₀/A₅₄₅ ratio and λ_max determinations. The results showed that modification of starches in both solvents led to the reduction of all parameters connected with the starch–iodine complex. However, depolymerization of starch was higher when it was sonicated in water than in ethanol (e.g. BVs for potato starch: native and sonicated in water and ethanol were equal, respectively, 0.306, 0.275, and 0.279). Starch granules were also observed under scanning and transmission electron microscopes. The main effects of ultrasonic action were cracks and depressions on the surface of granules, which were especially well seen in the case of potato and wheat starches. Ultrasonic treatment, especially in water, influenced functional properties of starch causing an increase of fat and water absorption, least gelling concentration (except potato starch), solubility and swelling power, and a decrease of starch paste viscosity. Effect of ultrasounds on clarity of pastes was rather small, except potato starch for which its value increased from 70.3 to 82.5% after sonication in water.     

Comparative susceptibilities of sago,potato and corn starches to alkali treatment

The effects of steeping starch (sago, corn, and potato), in 0.025 M of sodium hydroxide for 0, 15, and 30 days at 30 °C, on its granular structure and other physicochemical properties were investigated. Changes in the morphology of starch granules indicated that the alkaline solution affected the granular structure of the starch. Pasting studies showed that the peak viscosity, breakdown, and setback of sago and potato starch decreased significantly, whereas that of corn starch increased significantly, when steeping time was prolonged. Swelling power increased significantly for treated potato and corn starches, but it decreased for sago starch. The amylose content of all alkali-treated starches also decreased significantly after treatment. Onset and peak temperatures of gelatinization (as analyzed with a differential scanning calorimeter) increased significantly, but the enthalpy decreased, for both gelatinization and retrogradation. The results showed that the physicochemical properties of starch of various botanical origins were affected to variable degrees when it was treated with alkaline solution.     

冻融处理对淀粉膜结构、热稳定性、机械性能及物理性质的影响

本实验分别以天然马铃薯淀粉（potato starch,PS）、改性马铃薯淀粉（包括羟丙基二淀粉磷酸酯（hydroxypropyl distarch phosphate,HDP）、醋酸淀粉（acetate starch,AS）和氧化淀粉（oxidized starch,OS））为基材,通过流延法制备可食用淀粉膜,考察冻融处理对膜物理性质、机械性能、阻隔性能、微观结构和热稳定性的影响。X射线衍射结果表明,马铃薯来源的淀粉颗粒具有典型的B型晶体结构,在成膜过程中淀粉结晶度降低,冻融处理后淀粉膜晶体峰强度明显减弱。扫描电子显微镜观察结果显示,冻融处理破坏了淀粉膜的微观结构,其中PS膜上出现明显裂纹,AS膜上出现蜂窝和层状结构,而HDP和OS淀粉膜具有更完整的形态。热重分析结果表明,随着温度的升高,淀粉膜的热重曲线出现4 个质量损失阶段,分别对应水分散失、甘油挥发、淀粉解聚及淀粉分解,而冻融处理对膜热稳定性影响较小。常温条件下,PS膜具有最佳的机械性能,其拉伸强度为2.29 MPa,断裂伸长率为68.82%。在3 个冻融循环后,淀粉膜的拉伸强度至少增加了2 倍,断裂伸长率普遍降低,而溶解度和水蒸气透过率仅有轻微变化。综合考虑不同淀粉膜微观结构、机械性能、水蒸气透过率及水溶性,HDP膜表现出更好的冻融稳定性,可应用于冷冻低水分食品的保藏。