超高压辅助制备醋酸酯淀粉结构性质研究

以玉米淀粉为原料,乙酸酐为反应试剂,NaCl为反应介质,采用超高压辅助制备醋酸酯淀粉,利用光学显微、X-射线衍射、快速黏度分析技术对醋酸酯淀粉结构性质进行分析。研究表明,颗粒态醋酸酯淀粉结晶类型与原淀粉相同,当处理压力为600 MPa时淀粉糊化,颗粒结构被破坏,A型结晶向V型结晶转换,但糊化并不利于醋酸酯淀粉取代度的增加。适量NaCl的添加有利于超高压处理时淀粉颗粒态的维持,因而有效提高了醋酸酯淀粉的取代度。当NaCl溶液浓度为1.0%、乙酸酐添加量为2.0%、压力为400MPa时,所制备的醋酸酯淀粉取代度达到最大值(0.090),且表现出较高的峰值黏度(400.00cP)。     

超高压微射流对紫薯淀粉性质和结构的影响

以10%的紫薯淀粉溶液为原料,研究超高压微射流对紫薯淀粉的微观结构和性质的影响。结果表明,经超高压微射流处理后,紫薯淀粉吸水性、持油能力、冻融稳定性明显增强。与紫薯原淀粉RVA曲线相比,处理后的淀粉RVA曲线的走势和峰的数量基本不变,但是在峰顶值、谷底点以及曲线终点等关键点的粘度值有较大变化。随着超高压微射流处理压力的增大,紫薯淀粉糊化起始温度逐渐降低,且均低于原淀粉。在60MPa时,紫薯淀粉糊化峰值温度最高,为78.82℃。偏光显微显示紫薯淀粉颗粒的偏光十字随着处理压力的增加逐渐模糊,经100MPa处理后,多数淀粉颗粒偏光十字消失;红外吸收光谱和X射线衍射分析表明经超高压微射流处理后,紫薯淀粉结构发生一定程度的改变。     

湿热处理对马铃薯淀粉超高压糊化的影响

目的 研究湿热处理对马铃薯淀粉超高压糊化的影响。方法 将经过不同时间湿热处理的样品进行不同压力的超高压处理, 采用偏光显微、X射线衍射、差示扫描量热、快速粘度分析等技术对马铃薯淀粉样品颗粒形貌、结晶结构、糊化特性热特性进行研究。结果 湿热处理增加了马铃薯淀粉的相对结晶度及糊化焓值, 提升了糊化温度。同时通过改变淀粉颗粒内部结构, 引起淀粉分子吸水性降低, 进而导致淀粉膨胀性变差, 粘度降低, 粘度曲线由A型向D型转变。无论湿热与否, 淀粉在400~600 MPa超高压处理过程中, 其相对结晶度、糊化焓值均降低, 但与原淀粉相比, 湿热处理后淀粉在超高压处理过程中相对结晶度和糊化焓值降低程度减小。结论 马铃薯淀粉水分含量为30%(m:m)时, 90 ℃湿热处理5~15 h导致淀粉颗粒内部结构更为致密, 增加其压力抵抗性, 延缓了超高压糊化过程。     

微波对马铃薯淀粉特性影响的研究

采用DM2500P偏光显微镜、NDJ-5S黏度仪、RVA研究微波处理对马铃薯淀粉的特性的影响。结果表明:原淀粉颗粒呈椭圆形,而微波作用后的淀粉的颗粒结构被破坏,外形为不规则颗粒、纤维状;马铃薯原淀粉糊和微波淀粉的表观黏度随剪切速率的增大而降低,呈剪切稀化现象;微波淀粉的剪切应力和剪切速率的变化呈正相关;马铃薯原淀粉的糊化温度为64.5℃,峰值黏度是11491cp,保持黏度为3105cp,最终黏度是3653cp;微波马铃薯淀粉的RVA糊化黏度曲线中未出现明显的峰值黏度,微波淀粉保持黏度为232.00cp,最终黏度是578.00cp。     

韧化温度和时间对不同直链淀粉质量分数玉米淀粉物化性质的影响

为进一步探讨韧化处理对淀粉性质的作用机理,通过测定糊化性质、热特性、膨胀力、结晶特性及观察偏光十字现象和微观结构,研究了不同韧化温度和时间对不同直链淀粉质量分数玉米淀粉（普通玉米淀粉（normal corn starch,NCS）和蜡质玉米淀粉（waxy corn starch,WCS））物化性质的影响。结果表明,韧化处理主要作用于NCS和WCS淀粉颗粒的无定形区,对淀粉结晶类型没有影响;但韧化处理能够明显增强NCS和WCS的热稳定性和抗剪切能力,抑制淀粉老化和糊化,显著降低峰值黏度和膨胀力（P＜0.05）。韧化温度升高至60 ℃时韧化效果更加明显,糊化焓和相对结晶度明显降低,颗粒表面被明显破坏。但延长韧化时间对NCS和WCS老化的抑制效果和对糊化焓、膨胀力、颗粒形貌等的影响不明显。     

超高压处理对发芽糙米淀粉凝胶特性的影响

糙米发芽过程中,淀粉理化特性发生改变,该研究采用超高压技术处理发芽糙米淀粉,考察处理压力,保压时间及pH值对发芽糙米淀粉凝胶质构特性、糊化特性及冻融稳定性的影响。结果表明,不同压力、保压时间、pH处理对淀粉凝胶的弹性、黏着性、胶黏性、回弹性、咀嚼性有不同程度的改善。RVA结果显示,当保压时间为20 min时,峰值黏度由404.83 m Pa·s增至595.75 m Pa·s,同时热糊黏度、最终黏度、回生值、衰减值也呈现上升趋势,出峰时间减小,糊化温度降低;超高压处理压力和pH对淀粉的糊化特性的影响较小,说明超高压处理的淀粉对压力和pH有较好的稳定性。超高压处理后淀粉的冻融稳定性显著提高,在200 MPa时达到最大;随保压时间延长,淀粉糊析水率呈先下降后上升趋势,保压时间为10 min时,淀粉糊的析水率达到最小值;当pH为5或8时析水率与对照相比没有显著变化(p0.05)。     

微波处理对大米RVA谱特征值和微观结构的影响

本研究采用不同的微波功率和时间处理包装大米,并进行品质测定和电镜扫描,系统分析处理后大米的糊化特性和微观结构的变化,从微观结构的角度探讨RVA谱特征值的改变规律及机理。结果表明:微波处理降低了大米蒸煮RVA谱峰值黏度、热浆黏度、最终黏度和回生值,糊化温度和衰减值均随微波功率和处理时间的增加而升高。微波功率(400、640 W)和处理时间(60、90 s)对RVA特征值都有显著影响(p0.05),800 W的微波功率及120 s的微波时间影响均为极显著(p0.01);微波处理对淀粉颗粒的结构和形态有修饰作用,使淀粉颗粒间空隙变大,大米在蒸煮时可渗入更多水分,蒸煮品质得到改善。微波处理可以优化大米的糊化性质,改变大米淀粉颗粒形态和结构,提高大米的食味品质。     

用RVA仪分析玉米淀粉的糊化特性

以玉米淀粉为原料,利用RVA(快速黏度分析仪),研究了不同浓度玉米淀粉以及在同一浓度下氯化钠、蔗糖以及转速对淀粉糊化特性的影响,并且在此基础上将RVA糊化程序改为多重RVA程序,然后观察对淀粉的特性的影响。结果表明:随着玉米淀粉溶液浓度的增加,起始成糊温度降低,淀粉糊的热稳定性降低,凝胶性增强。随氯化钠浓度增大,起始成糊温度逐渐升高,到达峰值时间有所延长,热稳定性明显提高,但凝胶性降低。当蔗糖浓度增加时,淀粉成糊温度、峰值黏度、最低黏度和最终黏度都随之增加,热稳定性增强,冷却过程中淀粉糊形成凝胶的能力减弱。玉米淀粉在多重RVA程序中,淀粉胶体反复形成并且溶解。添加油脂后的玉米淀粉的黏度曲线的变化是复杂的,由淀粉和油脂之间的相互作用引起,油脂的水溶性以及淀粉颗粒与蛋白质的关系影响着它们的相互反应。     

超高压对马铃薯淀粉糊化作用的研究

采用偏光显微镜对超高压处理后的马铃薯淀粉偏光十字进行了观察,结果表明5%的马铃薯淀粉乳液在300、400、500 MPa下处理5 min后,马铃薯淀粉的偏光十字没有消失,在600 MPa下,少数淀粉颗粒的偏光十字开始消失,在700 MPa的超高压下处理5 min后,偏光十字全部消失,说明马铃薯淀粉糊化压力在600～700 MPa.     

重复韧化对普通玉米淀粉消化、理化性质和结构特性的影响

通过体外消化、快速黏度分析、X射线衍射、傅里叶红外光谱、扫描电子显微镜观察等方法,探究重复韧化处理（55 ℃,24 h）1~3次对普通玉米淀粉消化、糊化性质及淀粉颗粒结构等的影响。结果表明,重复韧化3次可以降低普通玉米淀粉的膨胀力、快速消化淀粉和慢速消化淀粉含量,降低衰减值和回生值,提高抗性淀粉含量和凝胶硬度,相对结晶度增加4.1%,糊化温度升高2.3 ℃,淀粉颗粒微观表面的孔洞和缝隙增多,但没有破坏结晶结构。重复韧化处理通过促进淀粉分子链间的相互作用,使淀粉易于形成完美晶体结构,提高淀粉颗粒的热稳定性。     

Effects of Annealing on ultra-high pressure induced gelatinization of corn starch

Ultra-high pressure (UHP) can induce starch gelatinization at the room temperature, while the change of starch architecture could affect the gelatinization process. This work evaluated the effects of annealing on UHP induced starch gelatinization. Native and annealed corn starches were subjected to UHP treatment (300–600 MPa) for 15 min at room temperature. The scanning electron microscopy, confocal laser scanning microscopy, differential scanning calorimetry and X-ray diffraction analysis showed that UHP treatment partially disrupted the ordered structures of native and annealed starches, which made starch gelatinized gradually and a transformation in crystal type from type A to type B. However, compared with native starch, annealing (C3 and C24) delayed the internal and external structure destruction of starch granules, as well as induced a slower decrease in ΔH and relative crystallinity as increasing pressure. Therefore, the suitable UHP treatment can increase the pressure resistance of starch, or delay the UHP gelatinization process.     

Characterization of amorphous granular starches prepared by high hydrostatic pressure (HHP)

Amorphous granular starches (AGS) and non-granular amorphous starches (non-AGS) of corn, tapioca and rice were prepared using high hydrostatic pressure (HHP) treatment with ethanol and water washing, respectively and their physicochemical properties were investigated. Water holding capacity and apparent viscosity of AGS and non-AGS were higher than those of native one in all starches. In RVA pasting properties, AGS and non-AGS showed higher pasting temperature and lower peak viscosity than those of native one. Furthermore, non-AGS showed distinctively lower peak viscosity compared to that of AGS possibly due to its non-granular structure. Apparent viscosity of non-AGS revealed relatively lower than commercial pre-gelatinized starch because of heat and pressure-induced gelatinization. Maintaining granular structure in HHP treated pre-gelatinized starch provide a distinctive physicochemical characteristics compared to native starch and preparation of gelatinized starch with different gelatinization and washing methods could cause big differences in their physicochemical properties.     

Gelatinization of waxy starches under high pressure as influenced by pH and osmolarity: Gelatinization kinetics, final structure and pasting properties

We investigated the influence of pH and osmolarity on the high-pressure-induced gelatinization of waxy corn and waxy rice starches in salt solutions, and the properties of the resulting gels. Gelatinization kinetics, the gel swelling power of starches, their structure and their rheological properties were studied for starch suspensions treated at 500 MPa. Gelatinization took place mostly in the first 15 min of the pressure treatment and both the gelatinization speed and the maximal level of gelatinized starch decreased with increasing osmolarity. pH had a minor influence on gelatinization kinetics differing from one starch to another. The resulting gels appeared as a mix of a gel and starch granules with a higher proportion of native granules with increasing osmolarity. Gel strength and swelling were positively correlated to their proportion of gelatinized starch. Thus, gels with different structures and gelatinization levels can be obtained under pressure depending on pH and osmolarity.     

Effect of High Hydrostatic Pressure on Physicochemical and Structural Properties of Rice Starch

Rice starch–water suspension (20%) were subjected to high hydrostatic pressure (HHP) treatment at 120, 240, 360, 480, and 600 MPa for 30 min. Polarizing light microscope, scanning electron microscopy (SEM), rapid visco analyzer (RVA), differential scanning calorimeter (DSC), and X-ray diffraction were used to investigate the physicochemical and structural changes of starch. Microscopy studies showed that the treatment of starch with HHP under 600 MPa for 30 min resulted in a complete loss of birefringence and a gel-like appearance. The treatment of starch suspension with HHP at 600 MPa resulted in a significant increase in swelling power and solubility at low temperature (50–60 °C), but opposite trends were found at high temperature (70–90 °C). The DSC analysis showed a decrease in gelatinization temperatures and gelatinization enthalpy with increase of pressure levels. RVA viscograms of starches exhibited an increase in peak, trough, and final viscosities, peak time, and pasting temperature but decrease of breakdown, setback viscosities, and pasting temperature when pressure was increased. X-ray diffraction studies showed that the HHP treatment converted rice starch that displayed the A-type X-ray patterns to the B-type-like pattern. These results showed that the treatment of rice starch in 20% starch/water suspension at a pressure of 600 MPa for 30 min led to a complete gelatinization of starch granules.     

高静压处理对红薯淀粉颗粒结构的影响

淀粉颗粒结构研究是进行淀粉改性及拓宽其应用范围的基础。采用高静压对红薯淀粉进行改性处理,并 通过扫描电子显微镜观察、X射线衍射分析、傅里叶变换红外光谱分析、差示扫描量热分析及快速黏度分析探究不 同压力对淀粉颗粒结构的影响。结果显示,200～500 MPa高静压处理的红薯淀粉颗粒形貌无明显变化。600 MPa 处理后,淀粉颗粒开始塌陷并与周围颗粒凝聚,失去双折射现象;峰值黏度、谷值黏度和最终黏度分别显著升高 9.15%、27.18%和20.21%（P＜0.05）;糊化温度升高1.9 ℃,峰值时间延长1.16 min,但糊化焓和崩解值分别显著 降低46.18%和66.46%（P＜0.05）。此外,高静压处理后红薯淀粉分子基团和晶体类型保持不变。     

湿热处理对玉米淀粉性质的影响

研究了湿热处理对不同直链淀粉含量的普通玉米淀粉?高直链玉米淀粉和蜡质玉米淀粉性质的影响。试验证明,经湿热处理后,三种玉米淀粉的颗粒形状都没有发生明显的变化,偏光十字也没有消失,但表面出现一些裂纹;湿热处理不会改变三种玉米淀粉的晶型,但经湿热处理后玉米淀粉的晶体结构变强,糊化温度提高,糊黏度降低。     

超高压处理对槟榔芋淀粉理化性质的影响

以槟榔芋淀粉为原料,采用超高压技术对淀粉进行改性处理,研究不同压力处理对其理化性质的影响.结果表明:随着压力的增大,槟榔芋淀粉的溶解度、膨胀度呈先减小后增大的趋势,但是均显著低于原淀粉;超高压处理可以显著增大槟榔芋淀粉的透光率;经200 MPa压力处理后,其冻融稳定性有明显改善.经300 MPa压力处理后,槟榔芋淀粉凝胶的硬度、咀嚼性和胶黏性都显著增加,但弹性和凝聚性变化不显著.RVA测定结果表明:淀粉糊的峰值黏度随处理压力的增大而显著增大;改性后槟榔芋淀粉的崩解值略高于原淀粉,而回生值变化不显著;200 MPa压力处理可降低槟榔芋淀粉的糊化温度.研究表明,一定程度的高压处理可以达到改善槟榔芋淀粉理化性质的目的.     

Effect of High-Pressure Homogenization on the Structure of Cassava Starch

Cassava starch suspension was homogenized at different pressures (0, 20, 40, 60, 80, and 100 MPa) with a high-pressure homogenizer. To investigate the effect of high-pressure homogenization on the structure of cassava starch, the samples were characterized using microscopy, laser scattering, and X-ray diffraction techniques, with native and heat gelatinized cassava starches as controlled samples. The temperature of starch suspension increased linearly with applied pressure at a rate of 0.187°C/MPa. Microscopy studies showed that cassava starch was partly gelatinized after high-pressure homogenization, and the degree of gelatinization increased with homogenizing pressure. Results of laser scattering measurements suggested a considerable increase in particle size after homogenization at 100 MPa as a result of granule swelling. The X-ray diffraction pattern showed that there was no evident change after homogenization suggesting that the crystalline structure of starch granules was resistant to high-pressure homogenization.     

Effect of high hydrostatic pressure on physicochemical, thermal and morphological properties of mung bean (Vigna radiata L.) starch

Mung bean starch-water suspension was subjected to high pressure treatment at 120, 240, 360, 480 and 600 MPa for 30 min, and changes in the structure, morphology and some physicochemical properties were investigated. Light transmittance, swelling power and solubility decreased after the high hydrostatic pressure treatment. A significant increase in the peak viscosity, trough viscosity, final viscosity, pasting temperature and setback, and decrease in breakdown viscosity with increase in pressure treatment was observed. The differential scanning calorimeter (DSC) analysis showed a decrease in gelatinization temperatures and gelatinization enthalpy upon high pressure treatments. The X-ray analysis showed that high hydrostatic pressure (HHP) treatment converted starch that displayed the C-type X-ray pattern to the B-type-like pattern. The HHP treatments altered the shape of starch granules and changed their surface appearance according to SEM analysis. HHP treatment (600 MPa, 30 min) caused a completely gelatinize of mung bean starch.