Effect of Molar Substitution on Rheological Properties of Hydroxypropylated Rice Starch Pastes

The steady and dynamic shear rheological properties of hydroxypropylated rice starch pastes (5%, w/w) were evaluated at different molar substitution (MS, 0.030‐0.142). The swelling power (35.5‐52.8 g/g) and solubility (8.19‐10.7%) values of the hydroxyproylated rice starches were higher than those of native rice starch (26.6 g/g and 7.78%) and increased with an increase in MS. The hydroxypropylated starch pastes at 25°C showed a pronounced shear‐thinning behavior (n = 0.33‐0.40) with Casson yield stress (σ_oc = 15.9‐31.7 Pa). The consistency index (K) and yield stress (σ_oc) values of the hydroxypropylated starch pastes were lower than those of the native starch, and increased progressively with an increase in MS. The apparent viscosity (η_a,500) obeyed the Arrhenius temperature relationship over the temperature range of 10‐55°C; the activation energies (E_a) of the hydroxypropylated starch pastes were in the range of 14.8‐18.5 kJ/mol, i.e. higher than that (14.1 kJ/mol) of the native starch. Storage (G′) and loss moduli (G′′) of hydroxypropylated starch pastes increased with an increase in MS, while tan δ (G′′/G′) values decreased, indicating that G′ rose more strongly than G′′ with increased MS.     

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.     

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。     

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。     

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。     

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。     

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.     

梨果实蠕变基本流变特性研究

应用TA-XT2i质地分析仪对梨果实进行蠕变测试,结果表明,蠕变试验条件对蠕变变形量的影响是载荷大于蠕变时间,载荷越大,蠕变时间越长,蠕变变形量越大,越容易发生损伤.     

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。     

阴米淀粉糊的流变特性

考察两优培九、荆糯六号大米以及阴米淀粉糊在不同质量浓度和温度下的流变特性,结果表明：这两种大米和阴米淀粉糊都是典型的非牛顿型和剪切变稀流体,黏度随剪切速率的增加而降低;同时用幂律函数描述淀粉糊的流变特性,拟合精度较高。淀粉糊的动态流变行为表现为：在升温初期,储能模量(G′)和耗能模量(G″)的值先显著下降,进而平缓下降,在90℃时出现不同程度的升高,随后又下降。损耗因子(tanδ)随温度的升高呈现先下降后上升的趋势。原米淀粉糊的黏性大弹性小,而阴米淀粉糊的弹性大黏性小。     

超声波处理对玉米淀粉流变性质的影响

本文研究了不同功率超声波处理玉米淀粉的流变性质.结果表明,所有淀粉糊均呈现假塑性流体特征.随着超声功率的增大,其处理的淀粉糊触变性减弱.     

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.     

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.     

Octenylsuccinate Derivatives of Carboxymethyl Starch – Synthesis and Properties

Carboxymethyl starch (CMS, DS_CM 0.1) was modified with octenylsuccinic anhydride in various solvent systems. Using the dimethyl sulphoxide (DMSO)/p‐toluenesulphonic acid (p‐Ts‐OH) system, carboxymethyl starch octenylsuccinates (OS‐CMS) were obtained with degrees of substitution (DS) ranging from 0.03 to 0.53 at high reaction efficiency, and characterized with regard to their molecular structure, their rheological and surface active properties. The water‐soluble OS‐CMS derivatives showed a pseudoplastic behavior dependent on both the DS and polymer concentration (c_p). The thickening power displayed a maximum at DS 0.14 at higher c_p (2.5 and 5.0%). In spite of the only moderate surface‐tension decreasing effect of the OS‐CMS derivatives, most of them exhibited excellent emulsifying, foaming and antiredeposition effects. They represent novel polysaccharide‐based biosurfactants with a broad application potential.     

番茄浆料的流变特性研究

对不同浓度(15、18、20和24°Brix)的番茄浆料分别在30、40、50和60℃时的流变学性质进行了研究。结果显示,番茄浆料为假塑体系,屈服应力值的范围比较宽(40-140pa)。通过回归分析,发现数学模型,K=koexp(Ea/RT)和K=Aexp(BC),可以分别用来描述温度和浓度对番茄浆料稠度系数的影响。在实验条件下,实验值能够很好地拟合模型。并且推导出温度和浓度同时对番茄浆粘度影响的方程。利用这些方程,可以预测实际加工中不同温度和不同浓度下番茄浆料的粘度。     

Rheology of Rice Starch‐Sucrose Composites

The effect of sucrose at different concentrations (0, 10, 20 and 30%) on rheological properties of rice starch pastes (5% w/w) was investigated in steady and dynamic shear. The steady shear properties of rice starch‐sucrose composites were determined from rheological parameters for power law and Casson flow models. At 25°C all the starch‐sucrose composites exhibited a shear‐thinning flow behavior (n=0.25–0.44). The presence of sucrose resulted in the decrease in consistency index (K), apparent viscosity (η_a,100) and yield stress (σ_oc). Dynamic frequency sweeps at 25°C indicated that starch‐sucrose composites exhibited weak gel‐like behavior with storage moduli (G′) higher than loss moduli (G′′). G′ and G′′ values decreased with the increase in sucrose concentration. The dynamic (η*) and steady‐shear (η_a) viscosities at various sucrose concentrations did not follow the Cox‐Merz superposition rule. G′ values as a function of aging time (10 h) at 4°C showed a pseudoplateau region at long aging times. In general, the values of G′ and G′′ in rice starch‐sucrose composites were reduced in the presence of sucrose and depended on sucrose concentration.     

Empirical Modeling of Starch Ester Synthesis from Octenylsuccinic Anhydride

In the present work, response surface methodology (RSM) was used to determine the mathematical relationship between octenylsuccinic anhydride (OSA) treated maize starch and the octenylsuccinylation reaction conditions. A second‐order polynomial model was chosen to approximate the relationship between the response variable (y, as the degree of substitution “DS” used to define the extent of the octenylsuccinylation) and the three regressors, x₁ as the temperature, x₂ as the time and x₃ as the pH. Analysis of variance (ANOVA) showed a high R² coefficient of 0.9905, thus ensuring a satisfactory adjustment of the selected model with the experimental data. Only temperature‐pH interaction was found to have a non‐significant effect. The positive sign for the regression coefficient of the temperature variable indicated that the y_DS increased with the increased levels of this factor from 25 to 45°C. The negative sign for the coefficient of time and also pH indicated that y_DS decreased as either the time or pH increased in the region of the tested range. The negative coefficients of the interaction between x₂ and x₃ indicated that a simultaneous increase in reaction time with decrease in pH of the esterification reaction led to an increase in y_DS. Maize starch octenylsuccinate synthesis on basis of its DS value was optimized for the three independent variables tested in this study. The predicted value for the DS was 0.02 where temperature, time and pH of the reaction were 28.0°C, 8.1 h, and pH 7.11, respectively. Results of some of the selected physicochemical properties of starch, tested in the present work were also discussed.     

甘薯淀粉粉团的流变行为研究

通过考察甘薯淀粉粉团在不同温度（20℃,30℃,40℃,50℃和60℃）、不同含水量（41%,44%,47%和50%）、不同淀粉糊含量（0%,12%,24%,36%和50%）、不同剪切速率（0.1s^-1,1 s^-1,10s^-1,100s^-1和500s^-1）和分别恒定剪切速率10 s^-1和100s^-1从20℃到70℃连续升温扫描的条件下的流变特性,得出含水量44%,含淀粉糊量24%的粉团在温度为50℃,剪切速率在10～100s^-1范围内最适合在甘薯粉丝生产中淀粉粉团的搅拌、输送和漏粉垂丝;同时用幂律方程、Cross方程来描述粉团的流变特性,发现Cross方程比幂律方程拟合精度更高,而Herschel-Bulkley方程则适于描述纯淀粉浆团的流变状态.在固定剪切速率下对甘薯淀粉粉团从20℃到70℃连续升温扫描的结果证明甘薯淀粉粉团对温度是敏感的,可以用Arrhenius方程来描述.在流变曲线图上,不同条件下分别呈现出不同滞后面积大小的具有屈服应力的开口型滞后回路,说明甘薯淀粉粉团是典型的触变性流体。     

Rheology of Okenia hypogaea Starch Dispersions in Aqueous Solution of DMSO

The aim of this work was to study the rheological behavior of Okenia hypogea starch dispersions (OSD) in aqueous solution (90/10, v/v) of dimethyl sulfoxide (DMSO). Okenia starch dispersions with 3 and 7 % (w/v) total solids were prepared at 20 °C and rheological tests were undertaken at 20, 40 and 60 °C, using a shear rate controlled rotational viscometer. The data fitted better the power law than the Casson model. Flow curves and flow behavior index indicated shear‐thinning behavior. All rheological parameters were affected by the solids concentration and the measurement temperature. As regards amylose and amylopectin content okenia starch is grouped among “ordinary” (non‐waxy) starches. Overall, OSD behaved similarly to potato starch dispersions and corn starch dispersions used as controls.