Rheological Properties of Rice Starch Dispersions in Dimethyl Sulfoxide

The steady and dynamic shear rheological properties of rice starches dispersed in dimethyl sulfoxide (DMSO) solution (90% DMSO‐10% water) were evaluated at various concentrations (7, 8, 9 and 10%, w/w). Rice starch dispersions in DMSO solution at 25°C showed a shear‐thinning flow behavior (n=0.44–0.60) and their consistency index (K) and apparent viscosity (η_a,100) increased with the increase in concentration. The apparent viscosity over the temperature range of 25–70°C obeyed the Arrhenius temperature relationship, indicating that the magnitudes of activation energy (E_a) were in the range of 11.7–12.7 kJ/mol. The Carreau model provided better fit on the shear rate‐apparent viscosity data than the Cross model. Dynamic frequency sweep test showed that both storage modulus (G′) and loss modulus (G′′) of rice starch dispersions increased with the increase in concentration. G′′ showed a higher dependence on frequency (ω) compared to G′ due to the higher G′′ slopes. All rice starch dispersions showed the plateau of G′ at high frequencies. Intrinsic viscosity of rice starch dispersions in DMSO was 104.1 mL/g.     

Effect of Octenylsuccinylation on Rheological Properties of Corn Starch Pastes

Rheological properties of corn starch octenylsuccinate (OSA starch) pastes (5%, w/w), at different 1‐octenylsuccinic anhydride (OSA) contents (0, 1.0, 1.5, 2.0 and 2.5%, w/w) were evaluated in steady and dynamic shear. The OSA starch pastes had high shear‐thinning behaviors and their flow behaviors were described by power law, Casson, and Herschel‐Bulkley models. Magnitudes of consistency index (K, K_h) and yield stress (σ_oc, σ_h) increased with the increase in OSA content and the decrease in temperature. Over the temperature range of 10–50°C, the effect of temperature on apparent viscosity (η_a,100) was described by the Arrhenius equation. The activation energy values (E_a = 10.7–13.9 kJ/mol) of OSA starches were lower than that (E_a = 15.9 kJ/mol) of native starch. Dynamic frequency sweep test showed that both storage modulus (G′) and loss modulus (G′′) of OSA starch pastes increased with the increase in OSA content. Dynamic (η^*) and steady shear (η_a) viscosities of OSA starch pastes at various OSA contents did not follow the Cox‐Merz superposition rule.     

葛根淀粉糊流变学特性的研究

以葛根淀粉糊的动态及稳态流变特性为研究对象,以储存模量(G')、损耗模量(G")和表现黏度(η)为主要试验指标,利用旋转流变仪,研究淀粉浓度、氯化钠、蔗糖以及麦芽糊精对淀粉糊流变学特性的影响,旨在探究淀粉糊的弹性、黏性、表观黏度的变化,为葛根食品的工业生产提供一定理论依据。研究结果表明:葛根淀粉糊是典型的剪切变稀的非牛顿流体,其G'、G"及η均受这4种因素的影响。1)动态流变特性的研究结果显示,G'、G"与淀粉浓度呈正相关;随特定添加范围内的氯化钠、蔗糖以及麦芽糊精的添加量增加,G'、G"均有先升后降的趋势。2)稳态流变特性的研究结果显示,同一剪切速率下,η与淀粉浓度呈正相关,与麦芽糊精的添加量呈负相关;在特定添加范围内,氯化钠、蔗糖的添加量增加,η有先升后降的趋势。在工业生产中,葛根淀粉糊剪切稀化的行为有利于流动的淀粉糊充模成型,节省能耗。添加麦芽糊精会降低淀粉糊的弹性和黏性,而添加适量的氯化钠和蔗糖一定程度提高淀粉糊的弹性和黏性。     

高取代度羟丙基木薯淀粉流变特性研究(I)流变特征及羟丙基取代度的影响

研究了高取代度羟丙基木薯淀粉溶液（分子取代度ＭＳ＝１．６～４．５）的流变特性及羟丙基取代度对流变特性的影响规律。结果表明，高取代度羟丙基木薯淀粉呈现假塑性流体特征，符合幂定律τ＝Ｋγｍ。ｍ值在０．７～０．８范围，表明羟丙基化使木薯淀粉偏近牛顿流体。高取代度羟丙基木薯淀粉具有触变性和剪切稀化性质，并随溶液浓度升高而增大。羟丙基取代度对木薯淀粉流变特性有很大影响，当ＭＳ≤３．５时，溶液的表观粘度和剪切稀化现象随ＭＳ的增高而减小，当ＭＳ＞３．５时，溶液的表观粘度和剪切稀化现象随ＭＳ的增高而增大。这种变化规律符合羟丙基化反应机理。     

高取代度羟丙基木薯淀粉流变特性研究(I)不同因素对流变特性的影响

研究了浓度、温度和ｐＨ值对高取代度羟丙基木薯淀粉溶液流变特性的影响。结果表明，高取代度羟丙基木薯淀粉溶液在浓度为５％～３０％，温度为２０～４０℃，ｐＨ为３～１１的范围内，均呈现假塑性流体特征，符合幂定律τ＝Ｋγｍ。浓度和温度因素对高取代度羟丙基木薯淀粉的表观粘度有显著影响，浓度越高，粘度越大，温度越低，粘度越小，它们之间的关系可用η＝ＡＣＢ和η＝ＤＴＥ表示。ｐＨ值对高取代度羟丙基木薯淀粉的流变特性没有明显影响，木薯淀粉经高度羟丙基化后具有良好的耐酸耐碱稳定性。     

莲子淀粉糊流变特性的研究

为探讨莲子淀粉糊及莲子淀粉-胶体体系的流变特性,使用流变仪研究了不同莲子淀粉乳浓度和添加不同亲水性胶体的莲子淀粉糊的流变特性。静态流变特性研究结果表明,莲子淀粉糊和添加胶体的莲子淀粉糊均为典型的非牛顿、时间依赖剪切变稀和触变性的流体,其流变特性曲线可用Herschel–Bulkley方程进行较好的拟合。随淀粉乳浓度和瓜尔豆胶(guar)、黄原胶(xan)添加量的增大,莲子淀粉糊的屈服应力τ0增大,而添加羧甲基纤维素(CMC)、卡拉胶(car)和海藻酸钠(alg)可使淀粉糊的流动性增强。动态流变特性研究结果表明,莲子淀粉糊储能模量(G')、损耗模量(G″)随莲子淀粉乳浓度增大而增大,且G'大于G″。添加CMC、alg能提高莲子淀粉糊的黏弹性,而添加guar和低浓度的xan、car则降低莲子淀粉糊的黏弹性。     

Effects of High Hydrostatic Pressure on Rheological Properties of Rice Starch

The effect of high hydrostatic pressure-750 on rheological properties of rice starch-water system was examined. The starch dispersions (20% w/v) were pressurized at 120, 240, 360, 480, and 600 MPa for 30 min. The storage modulus and loss modulus increased with the pressure increase. A yield stress was generated at a low shear rate. The high hydrostatic pressure-treated starch gels performed shear thinning and the apparent viscosity dropped sharply at 480 MPa. Hysteresis loop area increased with the pressure increased and reached the maximum at 600 MPa. High hydrostatic pressure-treated starch gels were found to be weak gels and thixotropic.     

Dynamic Rheological and Thermal Properties of Acetylated Sweet Potato Starch

Dynamic rheological and thermal properties of acetylated sweet potato starch (SPS) pastes (5%, w/w) were evaluated as a function of the degree of substitution (DS). The transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinization (ΔH) of acetylated SPS, which were determined using differential scanning calorimetry, were lower than those of native starch, and significantly decreased with an increase in DS. Magnitudes of storage modulus (G′), loss modulus (G′′) and complex viscosity (η*) of acetylated SPS pastes were determined using a small‐deformation oscillatory rheometer. Dynamic moduli (G′, G′′ and η*) values of acetylated SPS pastes except for 0.123 DS were higher than those of native starch, and they also decreased with an increase in DS. The tan δ (ratio of G′′/G′) values (0.37–0.39) of acetylated SPS samples were lower than that (0.44) of native starch and no significant differences were found among acetylated SPS samples, indicating that the elastic properties of SPS pastes were affected by acetylation but did not depend on DS. The G′ values of acetylated SPS during aging at 4°C for 10 h were much lower than those of native starch, showing that the addition of acetyl groups produced a pronounced effect on the retrogradation properties of SPS.     

大米淀粉及其不同取代度磷酸酯淀粉的糊化和流变特性

粳米淀粉与磷酸二氢钠发生酯化反应,通过改变反应温度得到取代度分别为0.028、0.049、0.073和0.14的磷酸酯淀粉。使用快速黏度分析仪和流变仪对比测定粳米淀粉及具有不同取代度的磷酸酯淀粉的糊化和流变特性。快速黏度分析仪测定的糊化特性显示PO43-与淀粉的结合降低了淀粉的糊化温度,升高了淀粉的峰值黏度,与粳米淀粉相比,磷酸酯淀粉更不易回生。流变仪测定的流变特性显示高取代度的磷酸酯淀粉抗剪切,随着取代度的增加,凝胶硬度降低,凝胶黏性增强。     

湿热处理对大米淀粉流变特性的影响

本文通过测定湿热处理前后大米淀粉的流变学特性,旨在研究湿热处理对大米淀粉稳态流变、动态流变及温度流变学行为的变化。结果表明,湿热处理后大米淀粉均呈现剪切稀化的现象,且湿热处理增强了大米淀粉的凝胶强度;在动态流变测定中发现,所有大米淀粉样品的弹性模量（G'）都大于黏性模量（G″）,且湿热处理后大米淀粉的弹性模量（G'）和黏性模量（G″）均增加,损耗角正切值tan δ降低,表明大米淀粉的凝胶强度增强;在温度流变测定中发现,湿热处理大米淀粉的糊化温度升高,弹性模量（G'）的峰值温度增加,表明湿热处理增强了淀粉分子链之间的相互作用,从而使大米淀粉凝胶具有较强的凝胶强度。     

经丙烯酸共聚物改性的淀粉糊的流变性能的研究

采用溶液聚合法合成了三元丙烯酸酯共聚物（MA／BA／AA）。红外光谱和X－射线衍射分析了共聚物的组成,并探讨了该共聚物与淀粉反应的过程。结果表明,该共聚物在淀粉颗粒上进行自由基接枝共聚反应,反应主要发生在淀粉颗粒的无定形区,改性后的淀粉能够保持原淀粉颗粒的完整结构。     

超高压处理对莲子淀粉糊流变特性的影响

为了解超高压处理对莲子淀粉糊流变特性的影响,采用500 MPa高压处理莲子淀粉10~60min,使用流变仪研究了经不同超高压时间处理后莲子淀粉糊的流变特性。静态流变特性研究结果表明,莲子原淀粉及经不同超高压时间处理后的淀粉糊均为非牛顿流体,具有假塑性流体特征,其流变特性曲线可用Herschel-Bulkley方程进行较好的拟合。在相同处理条件下,莲子淀粉糊的表观黏度随着剪切速率的增大而减小,超高压处理前后的淀粉糊均存在剪切稀化现象,具有明显的触变性;动态流变特性研究结果表明,莲子淀粉糊的储能模量(G')与损耗模量(G″)均随着处理时间的增加呈先上升后下降的趋势,在60 min处理条件下达到最小值。剪切结构恢复力试验结果表明,淀粉糊在经历低—高—低速剪切后较难恢复到原始结构。本研究结果可为超高压处理后的莲子淀粉的应用提供理论依据。     

Characterization of the Pasting,Flow and Rheological Properties of Native and Phosphorylated Rice Starches

Phosphorylation of rice starch and its effects on the physiochemical properties of the starch were investigated. Phosphorylation was conducted using the oven heating method by heating mixtures of rice starch and monosodium dihydrogenphosphate at 120‐150°C for 0.5‐2 h, and the pasting, flow and rheological properties of the resulting starch phosphates were analyzed. Phosphorylation with substitution degrees of up to 0.12 was achieved by raising the reaction temperature to 140°C, but further increase in the temperature to 150°C caused a marked reduction in the degree of substitution. Phosphorylation resulted in significant declines in pasting temperature and setback, but increases in peak viscosity and breakdown. Suspensions of rice native starch and starch phosphates were shown to be non‐Newtonian, pseudoplastic fluids, exhibiting typical shear thinning. They also exhibited yield stress, the magnitude of which increased with the degree of phosphate substitution. Dynamic testing showed that phosphorylation resulted in a decrease in the temperature at which storage and loss moduli (G′ and G″) reached a peak during heating and a reduction in G′ during cooling. These results appeared to indicate that phosphorylation improved the shear stability of rice starch pastes and enhanced swelling of starch granules, but impeded starch retrogradation.     

自然发酵工艺对米粉流变学性质的影响

本文通过对自然发酵米粉的理化性质和流变性的研究,探讨传统自然发酵对米粉感官性质的作用机理。研究发现发酵过程中总淀粉及直链淀粉含量变化不显著,蛋白、脂肪和灰分含量减少,而游离脂肪酸的含量上升。流变学测定发现,发酵法生产的米粉相对于对照样品最大破断应力减小而最大应变增加。快速黏度分析仪(RVA)测定表明发酵样品的RVA粘度减小、糊化温度降低。感官评定结果表明发酵法生产的米粉柔韧筋道,品质更好。     

羟丙基化对木薯淀粉糊性质的影响

羟丙基化对改善木薯淀粉糊的性质具有重要作用。作者用不同醚化程度的羟丙基木薯淀粉进行试验，测定其Ｂｒａｂｅｎｄｅｒ粘度性质、冻融稳定性和糊透明度。结果表明，羟丙基化能大大提高淀粉糊的热粘、冷粘稳定性和抗剪切性能，使糊的透明度和冻融稳定性增加，当分子取代度大于０．１时，冻融稳定性高达３５次以上。作者还发现，深度羟丙基化木薯淀粉具有特殊的絮凝性质，能溶于冷水，当水溶液加热到一定温度时，溶液发生浑浊，进而絮凝成为胶状物质。胶状物质可从热水中取出，并复溶于冷水，在热水中再絮凝成胶，重复多次。     

Effect of Plasticizers on Mechanical and Barrier Properties of Rice Starch Film

The effect of plasticizers, glycerol, sorbitol and poly(ethylene glycol) 400 (PEG 400), on mechanical and barrier properties of rice starch film has been investigated. Sorbitol‐ and glycerol‐plasticized starch films appeared homogeneous, clear, smooth, and contained less insoluble particles compared to unplasticized rice starch films. PEG 400 did not form plasticized films of suitable characteristics. The softness and stickiness of films improved with increasing concentrations of glycerol and sorbitol. In general, films plasticized with glycerol and sorbitol displayed a better solubility in water than unplasticized films, i.e. 35% (w/w) glycerol and 45% w/w (sorbitol) (optimum solubility). The tensile strength of films decreased especially in the high concentration regime of plasticizers, between 20–45% (w/w) of plasticizer/rice starch film. Through the entire concentration regime, the tensile strength of glycerol‐plasticized films was significantly lower than that of sorbitol‐plasticized films, but their elongation was larger. The water vapor transmission rate (WVTR) through plasticized films and the oxygen transmission rate (OTR) increased with glycerol and sorbitol concentrations, however, glycerol was revealed to be significantly more effective in reducing the tensile strength as well as increasing the WVTR and the OTR compared to sorbitol. With the higher tensile strength and the smaller OTR and WVTR, the 30% sorbitol‐plasticized film reveals an improved coating performance in terms of a reduction of coating failures.     

4种马铃薯淀粉糊流变特性的研究

对4种不同加工方式获得的马铃薯淀粉糊流变特性进行了探讨。静态流变特性测定结果表明,4种淀粉糊的流变模型为幂率模型,均为假塑性流体,每种淀粉糊以相同方式流动需要施加的力不同。在相同流动方式下,淀粉4粘度最大,其次为淀粉2,淀粉1和淀粉3的粘度近似相同。动态流变特性测定结果表明:随着温度的增加,淀粉1、2、4的弹性模量、粘性模量刚开始基本不发生变化,到60℃后,两模量急剧增加到最大值,然后降低到某恒定值。淀粉3的两模量随温度升高逐渐增加到最大值,然后逐渐降低到某恒定值。粘性模量达到最大后,淀粉2的粘性模量最大,其次为淀粉4、淀粉1,淀粉3的最低。弹性模量达到最大后,淀粉4的弹性模量最大,其次为淀粉2、淀粉1,淀粉3最低。     

Steady and Dynamic Shear Rheology of Rice Starch‐Galactomannan Mixtures

Rheological properties of rice starch‐galactomannan mixtures (5%, w/w) at different concentrations (0, 0.2, 0.4, 0.6 and 0.8%, w/w) of guar gum and locust bean gum (LBG) were investigated in steady and dynamic shear. Rice starch‐galactomannan mixtures showed high shear‐thinning flow behaviors with high Casson yield stress. Consistency index (K), apparent viscosity (η_a,100) and yield stress (σ_oc) increased with the increase in gum concentration. Over the temperature range of 20–65°C, the effect of temperature on apparent viscosity (η_a,100) was described by the Arrhenius equation. The activation energy values (E_a = 4.82–9.48 kJ/mol) of rice starch‐galactomannan mixtures (0.2–0.8% gum concentration) were much lower than that (E_a = 12.8 kJ/mol) of rice starch dispersion with no added gum. E_a values of rice starch‐LBG mixtures were lower in comparison to rice starch‐guar gum mixtures. Storage (G′) and loss (G′′) moduli of rice starch‐galactomannan mixtures increased with the increase in frequency (ω), while complex viscosity (η*) decreased. The magnitudes of G′ and G′′ increased with the increase in gum concentration. Dynamic rheological data of ln (G′, G′′) versus ln frequency (ω) of rice starch‐galactomannan mixtures have positive slopes with G′ greater than G′′ over most of the frequency range, indicating that their dynamic rheological behavior seems to be a weak gel‐like behavior.     

低取代度乙酰化大米淀粉的性质研究

以大米淀粉为原料,乙酸酐为酯化剂,制备了5种取代度分别为0.056、0.079、0.091、0.098和0.124的乙酰化淀粉。结果表明乙酰化大米淀粉的透明度随着取代度的增大而增加。大米淀粉经酯化后,凝沉性明显减弱,不易回生。乙酰化大米淀粉的溶解度和膨润力随温度的升高而增加,且明显高于原大米淀粉;糊化温度显著降低,衰减值也降低。乙酰化大米淀粉凝胶的硬度比原淀粉明显降低,弹性和内聚性变化不大。通过乙酰化处理,大米淀粉的功能性质得到明显改善。     

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。