Search

Carboxymethyl flaxseed gum (CMFG) is developed in our laboratory by modifying flaxseed gun through carboxymethylation. The aim of this study is to reveal the rheological properties of soy protein isolate – carboxymethyl flaxseed gum (SPI-CMFG) mixed dispersion in realistic processing conditions by conducting large amplitude oscillatory shear (LAOS) test, with consideration of concentration and degree of substitution (DS) of CMFG. Results showed that increasing CMFG concentration significantly increased storage moduli (Gʹ), loss moduli (Gʺ), and the apparent viscosity of all SPI-CMFG mixed dispersions. LAOS test illustrated that the dispersions experienced a transition from LAOS type IV to type III after increasing the concentration of CMFG, while the behavior converted from LAOS type I to type III by increasing DS. Fourier transform rheology (FTR) exhibited that increasing the concentration or DS of CMFG both induced a conversion from "soft sphere" to "hard sphere" behavior. The strain-stiffening ratio S and the shear-thickening ratio T demonstrated, that all SPI-CMFG dispersions experienced a similar conversion from strain stiffening to strain softening, and from shear thinning to shear thickening behaviors by increasing the concentration of CMFG. Nevertheless, the mixed dispersions presented shear thickening behaviors when DS was no more than 0.520 in the whole range of strain, while a conversion from shear thinning to shear thickening behavior occurred, when DS reached at 0.755 and 0.973. [ABSTRACT FROM AUTHOR]

Soy protein isolate (SPI) emulsion gel inks with polysaccharides of guar gum (GG) or xanthan gum (XG) for extrusion-based three-dimensional (3D) printing were investigated. The effects of the polysaccharide type and concentration on the printability, rheological properties, and microstructure of inks were discussed. Results indicated that the 3D printed products of SPI-GG 0.5 inks demonstrated low dimensional printing deviation with great self-supporting capability and smooth and slightly flawed surface texture, while SPI-XG 0.5 inks had the highest hardness and rough surface texture. The results of small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) test proved that SPI-XG 0.5 inks exhibited the maximal gel strength, providing its 3D printed products with highest hardness. Secondary loops of Lissajous plots wouldn't emerge in SPI-XG 0.5 inks, indicating decreased network flexibility and slightly larger dimensional printing deviation. The microstructure and fourier transform infrared (FTIR) analysis suggested the interaction of SPI with XG was stronger than that of GG due to hydrogen bonding and electrostatic interactions. When the XG concentration reached 0.5%, the network structure of the inks was changed, resulting in a rough surface texture of the 3D printed product. There are few studies on 3D printing of SPI emulsion gels, and this research offers more possibilities for the development of 3D printing inks. [Display omitted] • Adding polysaccharides to SPI emulsion gel was beneficial for printability and rheological properties. • The gel strength of SPI-XG inks was stronger than SPI-GG inks at same concentration. • SPI-GG 0.5 inks' 3D printed products had the lowest dimensional printing deviation. • The surface texture of SPI-GG 0.5 inks was smoother than that of SPI-XG 0.5 inks. • LAOS rheology confirmed high network strength with poor flexibility of SPI-XG 0.5 inks. [ABSTRACT FROM AUTHOR]

This research investigated the multi-scale characteristics of potato starch gel (PSG) with different addition ratios of xanthan gum (XG) and locust bean gum (LBG). These characteristics are closely related and had significant impacts on 3D printing performance. Both xanthan gum and locust bean gum were able to increase the apparent viscosity, storage modulus (G ′) and loss modulus (G ″) of the blended gel system to varying degrees. Large amplitude oscillation shear (LAOS) was used to detect slight rheological differences led by microstructure changes. The critical strain values of the blended gel system rose as the addition ratio of locust bean gum increased. At the same time, the elastic and viscous Lissajous curves could characterize the viscoelastic changes under large strains. Fourier transforms infrared spectroscopy (FT-IR) illustrated that locust bean gum could strengthen the hydrogen bonds so that the gel had stronger mechanical properties compared with the addition of xanthan gum. Scanning electron microscopy (SEM) could observe the changes in the microstructure of the blended gel systems with addition of different addition ratios of gums. From the perspectives of 3D printing results and data analysis, the appropriate amount of xanthan gum improved the fineness and fluidity of the gels by virtue of its lubricating and coating characteristics, while the locust bean gum enabled them to have stronger shape retention abilities and better performances of resisting compressed deformation. [Display omitted] • Different kinds of gums played different roles in the 3D printing processes of PSG. • Different compound ratios of gums had important influences on the properties of PSG. • LAOS rheology confirmed microstructure differences among blended gel systems. • Lissajous curves showed the changes in viscoelasticity within single blended gel system. • PSG with 0.8% LBG + 0.2% XG (w /w) performed a better printing performance. [ABSTRACT FROM AUTHOR]

This article focused on the freeze-thaw stability and rheological properties of soy protein isolate (SPI) emulsion gels induced by NaCl. The freeze-thaw stability was characterized by particle size, ζ-potential, and differential scanning calorimetry (DSC) measurements. The salt concentration (200–400 mM) could promote protein aggregation and improve freeze-thaw stability. The study of both linear and nonlinear rheology properties proved that SPI emulsion gels exhibited the maximal gel strength at 300 mM NaCl that could resist structure disruption and oil droplet migration. The nonlinear responses were further analyzed using Lissajous plots. Initial SPI emulsion gels had higher peak stress values at 300 mM NaCl, indicating more resistance to deformation and increased elastic-dominant behavior as well as improved freeze-thaw stability. While the area of the elastic and viscous Lissajous plots narrowed as the salt concentration exceeded 300 mM, suggesting the viscosity and elasticity decreased. Scanning electron microscopy (SEM) images further confirmed that the SPI emulsion gels had smaller pores and denser structures at 300 mM NaCl, resulting in good freeze-thaw stability. Besides, the maximum gel strength emerged in 300 mM NaCl and 100 mM NaCl before and after freeze-thaw cycles, respectively, which was due to moderate dehydration and a small amount of oil leakage from the network. These findings provide valuable information for the relationships between freeze-thaw stability and rheology property of emulsion gels. [Display omitted] • The presence of NaCl remarkably improved freeze-thaw stability and strength of emulsion gels. • At 200–400 mM NaCl, no coalescence was observed after freeze-thaw cycles. • SPI emulsion gels had the maximal peak stress and gel strength at 300 mM NaCl. • The gel strength changed after freeze-thaw cycles due to dehydration. • LAOS rheology confirmed microstructure changes of SPI emulsion gels after freeze-thaw cycles. [ABSTRACT FROM AUTHOR]

In this work, carboxylated nanocellulose had been prepared by using TEMPO-periodate oxidized reaction, in which the level of carboxylation was controlled by adjusting sodium hypochlorite (NaClO) concentration. The effects of the level of carboxylation on the rheological behavior and microstructure for the carboxylated nanocellulose dispersion had been investigated. It indicated that the nanocellulose dispersion exhibited sol state with low storage (G′) and loss (G″) modulus when NaClO concentration controlled to 2 mmol/g. But nanocellulose dispersion presented a form of gel at high NaClO concentration (6–12 mmol/g) and a critical state (similar values of G′ and G″) was obtained with the NaClO concentration of 4 mmol/g. In addition, both the G′ and G″ of nanocellulose dispersion were increased and then decreased with the increase of NaClO concentration. The highest modulus obtained when NaClO concentration controlled to 8 mmol/g, and a high fractal dimension (D f) was also obtained at this concentration, indicating a compact network structure. The large amplitude oscillation shear (LAOS) suggested that nanocellulose dispersion exhibited Ⅰ behavior (strain thinning) but had a trend of III behavior (weak strain overshoot). The Fourier transform rheology, Chebyshev coefficient, and Lissajous curves were used to analyze the nonlinear behavior, implying a correlation between the nonlinear behavior and the network structure of the nanocellulose dispersion. This work would provide some guidance for regulating the properties of nanocellulose dispersion. [Display omitted] • Sol-gel transition of nanocellulose dispersion closely related to the level of carboxylation. • Nanocellulose dispersion with high NaClO concentration exhibited compact structure. • Highest modulus and fractal dimension obtained at NaClO concentration of 8 mmol/g. • LAOS rheology confirmed microstructure changes of nanocellulose dispersion by NaClO. [ABSTRACT FROM AUTHOR]

Highland barley gels were subjected to hydrothermal treatment, and the rheological properties of both small and large strain amplitude oscillation shear (SAOS/LAOS) were investigated in this study. The results showed that untreated highland barley gels formed a wider linear viscoelastic region (LVE) than hydrothermal-treated gels, and the storage moduli (G′) & loss moduli (G″) decrease as the hydrothermal treatment time increased. In particular, the LAOS behavior of highland barley gels in strain sweep was changed from Type Ⅳ strong strain overshoot to Type Ⅰ strain thinning by hydrothermal treatment. The frequency dependence of the viscoelastic moduli (G'∝ω 0.41−0.74 and G''∝·ω 0.41−0.77) for hydrothermal gels was classified as an entangled network. The creep behavior fitted well with a four-element Burgers model (R 2 >0.93). Moreover, after 10 min treatment, hydrothermal treatment had changed the gels from elastic-dominated to viscous-dominated, and the strain-stiffening/shear-thinning properties of highland barley gels also increased. • The behavior of barley gels in strain sweep was changed from Type Ⅳ to Type Ⅰ. • Hydrothermal treatment resulted in the decrease of dependence on frequency. • Hydrothermal treatment changed the gels be viscous-dominated in nonlinear analysis. • Strain-stiffening and shear-thinning were increased in nonlinear analysis. [ABSTRACT FROM AUTHOR]

The thermal, linear and non-linear rheological as well as microstructural properties of casein/κ-carrageenan mixtures were investigated. The results showed that the addition of κ-carrageenan greatly affected the rheological behavior of casein. The storage (G′) and loss (G″) moduli, and apparent viscosity (η) values were positively associated with κ-carrageenan concentration. Casein/κ-carrageenan mixtures showed the typical type Ⅳ (strong strain overshoot) network behavior in the large amplitude oscillatory shear tests. Lissajous plots of casein/κ-carrageenan mixtures appeared stronger nonlinear behavior by adding of κ-carrageenan. The existence of κ-carrageenan also increased the thermal denaturation temperature of casein in the mixture and produced a significant microstructural change within the network entanglements of casein. These changes of casein/κ-carrageenan mixed systems were due to associative interaction between casein and κ-carrageenan caused by electrostatic forces and hydrogen bonding. Image 1 • κ-Carrageenan significantly improves the linear and non-linear rheological, thermal and microstructural properties of casein. • Casein/κ-carrageenan mixtures showed typical strong strain overshoot network behavior in LAOS test. • Electrostatic interaction and hydrogen bonding occurred between casein and κ-carrageenan. [ABSTRACT FROM AUTHOR]

The interactions between sodium caseinate and polysaccharide were investigated by choosing both neutral (locust bean gum) and anionic polysaccharides (κ-carrageenan). The linear and non-linear rheological properties, ζ-potential and structures of the sodium caseinate/gum mixtures were evaluated. The mixtures all displayed shear-thinning phenomenon, and the increase of either locust bean gum or κ-carrageenan content led to the increase of storage (G′) and loss (G″) moduli. The large amplitude oscillation shear (LAOS) test and Fourier-transform have been successfully used to detect the slight rheological differences caused by microstructure changes. Increasing levels of κ-carrageenan led to critical strain decreased of the mixture, but not for locust bean gum. The sodium caseinate/locust bean gum mixtures behaved as "hard gel", while the sodium caseinate/κ-carrageenan mixtures behaved as "soft gel" in Fourier-transform rheology. Changes in viscoelasticity under large strain were illustrated using elastic and viscous Lissajous curves, which were correlated to the microstructural change within the network of the mixtures. The zeta-potential values were significantly decreased in the presence of κ-carrageenan, while the addition of locust bean gum had no significant influence. Phase separation was found more dominant to change the structure than the protein network formation in the sodium caseinate/locust bean gum mixtures. However, protein network formation was the factor to dominate the structure forming of sodium caseinate/κ-carrageenan mixtures with electrostatic forces and hydrogen bonding. Image 1 • LAOS rheology verified differences in sodium caseinate/gum mixtures microstructure. • The caseinate/locust bean gum behaved as "hard gel" in Fourier-transform rheology. • The caseinate/κ-carrageenan behaved as "soft gel". • Phase separation dominated the structure in caseinate/LBG mixtures. • Protein network formation dominated the caseinate/κ-carrageenan mixtures' structure. [ABSTRACT FROM AUTHOR]

The linear and nonlinear rheological properties of konjac glucomannan solutions as affected by its concentration and the addition of sodium chloride were investigated by both small and large amplitude oscillatory shear tests (SAOS/LAOS). This study has identified that the apparent viscosity, storage modulus, and loss modulus of konjac glucomannan solutions increased significantly by increasing its concentration but reduced dramatically by adding sodium chloride. Shear thinning was observed in all konjac glucomannan concentrations with or without sodium chloride. Besides, sodium chloride delayed the critical shear rate at which shear thinning appeared and reduced the viscosity dependency. Notably, both the conversion from "soft gel" to "hard gel" and the appearance of secondary loops (Lissajous curves) were captured by increasing konjac glucomannan concentration. Chebyshev coefficients illustrated that all konjac glucomannan solutions transformed from shear thickening to shear thinning behavior. Thick konjac glucomannan solutions (0.8%, 1.0%) exhibited strain stiffening, while thin solutions (<0.8%) experienced strain softening under large deformations. The findings of this research provide insights for the diversified nonlinear rheological behaviors of konjac glucomannan solutions induced by its concentration and sodium chloride, which will prove useful in expanding our understanding of konjac glucomannan for its further application. • Apparent viscosity, G′ and G″ reduced by increasing NaCl concentration. • NaCl increased the frequency dependence and the critical strain of KGM solution. • Lissajous curves showed secondary loops after KGM concentration reaching to 0.6%. • Conversion from "soft gel" to "hard gel" appeared by increasing KGM concentration. • All KGM solutions converted from shear thickening to shear thinning behavior. [ABSTRACT FROM AUTHOR]