Rheological properties of cereal starch gels and Mesona Blumes gum mixtures

The effect of Mesona Blumes gum (MBG) was examined on steady and dynamic shear of MBG/rice starch and MBG/wheat starch gels. In addition, stress relaxation and creep tests were performed for two types of cereal starch gels. The flow curves of both MBG/starch gels exhibited pseudoplastic behavior at shear rates between 0.01 and 10 s⁻¹, and the data were fitted into the power law model (R² = 0.91–0.98). Dynamic mechanical spectrum showed that all gels were strong gels in frequency between 0.1 and 10 Hz. Stress relaxation data at different strains indicated a strain‐softening phenomenon for both gels. Data were fitted into Maxwell model (R² = 0.91–0.98). Creep curves were conducted at the shear stress 6.4 Pa within linear viscoelastic region of both MBG/starch gels. Data were fitted into Burgers model (R² = 0.91–0.98). Apparent viscosity η, storage moduli G′, equilibrium stress relaxation modulus G_e and zero apparent viscosity η₀ of MBG/rice starch gels decreased in the following order: 6/0>6/0.5>6/0.35>6/0.1 (starch/gum w/w). Whereas η, G′, G_e, and η₀ of MBG/wheat starch gels increased gradually along side the increase of MBG contents. The stress relaxation time λ of MBG/rice starch gels increased in the following order: 6/0<6/0.5<6/0.35<6/0.1 (starch/gum w/w) while λ of MBG/wheat starch gels decreased gradually with the increase of MBG level. The influence of MBG on two examined cereal starch is totally opposite.     

鸡骨明胶的流变性研究

研究从鸡骨中提取的明胶的流变性质。结果表明：质量分数为0．5％的鸡骨明胶溶液为塑性流体，其流动需要克服一定的屈服应力，屈服应力的大小受温度影响，温度越高，屈服应力越小；当剪切应力大于屈服应力时，粘度基本不随剪切速率变化，表现出牛顿流体的流动特征；温度越高，鸡骨明胶溶液粘度越小，温度对其的影响符合Arrhenius模型，流动活化能为19．58kJ／mol；鸡骨明胶的粘度随质量分数的增加呈指数递增；鸡骨明胶的粘度受pH值影响，在等电点9附近，鸡骨明胶溶液的粘度最小，偏离pI则粘度增大；鸡骨明胶的粘弹性强烈受温度的影响，质量分数为3％的鸡骨明胶从粘性为主的溶胶体系变成以弹性为主的凝胶体系的转变温度(胶凝点)为23．6℃，而凝胶转变成溶液的转变温度(溶点)为33．6℃。适当质量分数及在室温条件下，鸡骨明胶主要表现为弹性体。     

Rheology and microstructure of cross-linked waxy maize starch/whey protein suspensions

The objective of the present work was to investigate the effect of the heating process on the structural and rheological properties of whey protein isolate/cross-linked waxy maize starch (WPI/CWMS) blends depending upon the concentration and the starch/whey protein ratio. Starch concentration ranged from 3 to 4% (w/w) and the protein content was of 0.5, 1 and 1.5% (w/w). The blend (pH 7, 100 mM ionic strength) was heated using a jacketed vessel at two pasting temperatures: 90 and 110 °C. The particle size distribution of the WPI suspension (1.5%) displayed three distinct classes of aggregates (0.3, 65 and 220 μm), whereas the size of swollen starch granules varied from 48 to 56 μm according to the pasting temperature. When the two components were mixed together, the peak attributed to swollen starch granules was attenuated and broadened towards higher values (up to 88 μm) due to protein aggregates (260–410 μm). This effect was more pronounced as the protein concentration increased. When compared to starch alone, the rheology of the mixed system was dramatically modified for the flow behaviour as well as for the viscoelastic properties which changed from a solid-like (3–4% starch) to a liquid-like behaviour (3–4% starch/1.5% protein). Microscopic observations showed aggregated proteins located in the continuous phase and swollen starch granules as the dispersed phase. Protein aggregates were of different sizes, part of them appeared adsorbed onto swollen starch granules while another part was unevenly distributed in the continuous phase, yielding discontinuous network which could explain the peculiar viscoelastic behaviour of such suspensions.     

马铃薯淀粉和豌豆淀粉复配体系的流变与凝胶特性研究

以马铃薯淀粉和豌豆淀粉按照一定的比例进行复配,采用动态流变仪和质构仪测定复配体系的糊化、流变特性及凝胶强度。结果表明:复配体系的糊化温度随着马铃薯淀粉比例的增大而有所下降,由70.1℃降低到64.6℃;在淀粉质量分数为6%的体系中,马铃薯淀粉和豌豆淀粉的比例为1∶5和1∶11时复配体系的弹性模量G′较大(分别为810.1 Pa和814.7 Pa),而在比例为1∶3或1∶5时复配体系的粘性模量G″较大(分别为41.0 Pa和41.6 Pa);马铃薯淀粉和豌豆淀粉的比例为1∶5和1∶11时复配体系的Tanδ较小,此配比的两个复配体系具有较好的凝胶形成能力,且凝胶强度较大(98.5~100.1 g)。      

Rheological and thermal effects of galactomannan addition to acorn starch paste

Effect of galactomannans (guar gum and locust bean gum) at different concentrations on rheological and thermal properties of acorn starch pastes was examined. Steady and dynamic shear rheological tests indicated that the magnitudes of consistency index (K), apparent viscosity (η_a,100), Casson yield stress (σ_oc), dynamic moduli (G′, G″), and complex viscosity (η∗) of acorn starch-galactomannan mixtures were much higher than those of the control (0 g/100 g gum concentration), and that these values also increased with an increase in gum concentration. At temperatures ranging from 25 to 70 °C, the effect of temperature on η_a,100 was well described by the Arrhenius equation. In addition, DSC studies showed that the presence of galactomannans resulted in an increase in the transition temperatures (T_o, T_p, and T_c) and a decrease of the gelatinization enthalpy (ΔH). In general, these results suggest that the presence of galactomannans in acorn starch modifies the rheological and thermal properties, but that these modifications are dependent on the gum type and gum concentration.     

Rheological and physical characterization of film-forming solutions and edible films from tapioca starch/decolorized hsian-tsao leaf gum

Rheological properties of the film-forming solutions of tapioca starch/decolorized hsian-tsao leaf gum (dHG) as well as the structural properties and viscoelasticity of the resulting films were characterized as a function of dHG and glycerol concentrations. As compared to film-forming solutions with tapioca starch alone, the apparent viscosity, storage modulus and loss modulus of starch/dHG film-forming solutions increased, and tan δ decreased with increasing dHG. After casting of the film-forming solutions, all starch/dHG films showed relatively low opacity values. SEM and X-ray diffraction analysis revealed that all starch/dHG films exhibited homogeneous and highly amorphous structure. The extensional creep compliance of starch/dHG films increased with increasing glycerol concentration, implying weaker mechanical strength and higher mobility of polymer chains by the plasticizing effect of glycerol. However, addition of dHG pronouncedly increased the mechanical and elastic properties of tapioca starch films as evidenced by a decrease in extensional creep compliance and retardation time. Such results implied that dHG may possibly modify the network structure of tapioca starch film.     

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。     

Physicochemical,Rheological, and Thermal Properties of Six Types of Honey from Various Floral Origins in Tunisia

The present study was undertaken to determine the physicochemical, rheological, and thermal properties of six types of Tunisian honey samples from various floral origins (eucalyptus, orange, thyme, mint, rosemary, and horehound). All the honey samples exhibited non-Newtonian behavior at a shear rate ranging between 0.01 and 500 s^–1, with the highest levels of viscosity (µ) being observed for thyme, followed by eucalyptus, rosemary, mint, orange, and horehound honeys, respectively. The effect of temperature on the dynamic viscosity of the samples followed an Arrhenius-like pattern, with activation energy values ranging from 21.23 to 34.91 kJ/mol. The results from oscillatory rheology analysis also revealed that the loss modulus predominated over the storage one in the whole frequency range. As determined by differential scanning calorimetry, the glass transition (T_g) and melting temperatures of the Tunisian honey samples varied between –41.55 and –47.06 °C and between 197.9 and 221.1°C depending on their sugar compositions, respectively.     

Spectral analysis and physical properties of benzylated starch

A‐ and B‐wheat starch (in native or acetylated form) and potato starch (slightly acetylated) were subjected to benzylation with benzylchloride in various reaction conditions and at various reaction times (40–100°C, 1–90 h). Modified and original starches were characterized by elemental analysis and spectroscopic methods (FT‐IR and 1H NMR). The semicrystalline or amorphous character was indicated by X‐ray powder (XRD) patterns. Rheological properties of benzyl starch of DS ∼ 1 were measured by small amplitude oscillation shear rheology (SAOS) using the rheometer Haake Rheostress RS 80. The results indicated predominantly elastic behavior because the storage modulus was higher than the loss modulus over the whole frequency range; it corresponded to a true gel. The storage and loss moduli increased with increasing frequency while the tangent of phase did not change and was approximately δ = 40°.     

Influence of gluten on the viscoelastic properties of starch pastes and gels

Viscoelastic properties of dispersions (60–300 g kg⁻¹) of gluten (G) and wheat starch (S) blends (0 < G/S < 0·20) and wheat flour have been studied during heating and cooling. In both cases, the moduli followed power law relationships with concentration. The temperature at which the transient network development began, caused by granule–granule interactions, decreased as the concentration increased and increased with an increase in the proportion of gluten. Moreover, gluten weakened the strength of both starch pastes and gels, as shown by the lower values of the moduli. The viscoelastic behaviour of flour samples reflected the role played by internal lipids. A structural model is proposed in order to explain the influence of gluten on the rheological behaviour of starch pastes and gels. © 1998 Society of Chemical Industry.     

冷榨亚麻籽油的流变特性研究

通过低温压榨亚麻籽获得冷榨亚麻籽油（cold—pressed flaxseed oil,CFO）,并分析其主要理化指标,着重研究CFO的静态、动态流变特性,同时分别采用Casson、Herschel-Bulkley和Bingham模型对其流体行为进行拟合,并采用Arrhenius方程分析其粘度热动力学参数。研究结果表明：在剪切速率为0．1～200s“下,CFO由非牛顿流体逐渐转化为牛顿流体;当剪切速率大于10s^-1时,CFO呈牛顿流体;同时分析得出CFO的粘度活化能为3095．4cal／mol;CFO的粘度、剪切应力、损耗模量、塑性稠度系数、高剪切极限粘度和稠度系数随着温度升高而降低,但是温度变化对CFO的贮能模量影响不显著;另外通过比较3个流变模型得出Bingham模型适用于CFO。     

不同添加物质对羟丙基木薯淀粉流变特性的影响

淀粉糊流变特性是影响淀粉类食品加工品质的主要因素。本文利用C-LTD80 RheolabQC流变仪测定了不同添加物质对羟丙基木薯淀粉流变特性的影响,结果表明：添加不同的物质均未改变羟丙基木薯淀粉糊的流体类型,各流变参数经Herschel-Bulkley模型进行拟合,拟合系数接近1。单甘酯、食盐、柠檬酸使羟丙基木薯淀粉糊的剪切应力不同程度降低,黏稠系数K减小,流变特性指数n增加;蔗糖酯、酪朊酸钠、黄原胶、CMC、瓜尔豆胶、蔗糖使羟丙基木薯淀粉糊的剪切应力明显提高,黏稠系数K增加,流变特性指数n减小。该结果对羟丙基木薯淀粉类食品深加工开发具有较大的指导意义。     

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。     

Influence of prior acid treatment on physicochemical and structural properties of acetylated sorghum starch

Influence of prior acid treatment on acetylation of starch isolated from an Indian sorghum cultivar was investigated. The starch was acid thinned (AT) using 0.1, 0.5, and 1 M HCl for 1.5 h and then acetylated (Ac) with acetic anhydride (8% w/w). The acid thinning and subsequent acetylation appeared to reduce the percentage acetylation as indicated by degree of substitution. Ac‐AT starches exhibited significantly different physicochemical, thermal, pasting, and gel textural properties from those of AT and Ac starches. Starches after dual modification showed higher solubility, lower AM content, gelatinization temperatures, retrogradation, peak viscosity, and gel hardness than native starch. Enthalpy and range of gelatinization were observed to be higher in dual modified starches than native starch. However, no significant changes in granule morphology or crystalline pattern of Ac‐AT starches were observed compared with native starch.     

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.     

Rheological/textural properties of starch and crude hsian‐tsao leaf gum mixed systems

The Effects of hsian‐tsao leaf gum (HG) on the rheological/textural properties of non‐waxy starches were studied. Pronounced interactions between starch and HG were observed. The rheological properties, including pseudo‐gel viscosity in the rapid visco‐analyser test, storage and loss moduli in the dynamic rheological test, as well as firmness in the texture analyser test, of the mixed gels generally improved with increasing gum concentration to a certain level, then deteriorated with further increase in gum concentration. The critical gum concentration for the development of optimal rheological properties depended on the starch type and concentration. Within the concentration range studied, mixed systems with wheat starch could generally reach the highest pseudo‐gel viscosity, firmness, and storage modulus if the starch/HG ratio was appropriate, followed by those with corn and tapioca starch. Copyright © 2003 Society of Chemical Industry     

电解质对淀粉浆料粘着性能的影响

NaCl等电解质的存在对淀粉浆料粘着性能有害，减少浆料中电解质的种类和含量有助于提高淀粉浆液的粘着性能。