Effect of spatial distribution of wax and PEG-isocyanate on the morphology and hydrophobicity of starch films
- Authors: Muscat, Delina , Adhikari, Raju , Tobin, Mark , McKnight, Stafford , Wakeling, Lara , Adhikari, Benu
- Date: 2014
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 111, no. (2014), p. 333-347
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- Description: This study proposes a novel method for improving surface hydrophobicity of glycerol plasticized high amylose (HAG) films. We used polyethylene glycol isocyanate (PEG-iso) crosslinker to link HAG and three natural waxes (beeswax, candelilla wax and carnauba wax) to produce HAG + wax + PEG-iso films. The spatial distributions of wax and PEG-iso across the thickness of these films were determined using Synchrotron-based Fourier transform infrared spectroscopy. The hydrophobicity and surface morphology of the films were determined using contact angle (CA) and scanning electron microscopic measurements, respectively. The distribution patterns of wax and the PEG-iso across the thickness of the film, and the nature of crystalline patterns formed on the surface of these films were found to be the key factors affecting surface hydrophobicity. The highest hydrophobicity (CA >90°) was created when the PEG-iso was primarily distributed in the interior of the films and a hierarchical circular pinnacle structure of solidified wax was formed on the surface. © 2014 Elsevier Ltd.
Understanding the distribution of natural wax in starch-wax films using synchrotron-based FTIR (S-FTIR)
- Authors: Muscat, Delina , Tobin, Mark , Guo, Qipeng , Adhikari, Benu
- Date: 2014
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 102, no. 1 (2014), p. 125-135
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- Description: High amylose starch–glycerol (HAG) films were produced incorporating beeswax, candelilla wax and carnauba wax in the presence and absence of Tween-80 in order to determine the distribution of wax in the films during the film formation process. The distribution of these waxes within the film was studied using Synchrotron based Fourier Transform Infrared Spectroscopy (S-FTIR) which provided 2D mapping along the thickness of the film. The incorporation of 5% and 10% wax in HAG films produced randomly distributed wax or wax-rich domains, respectively, within these films. Consequently, the addition of these waxes to HAG increased the surface roughness and hydrophobicity of these films. The addition of Tween-80 caused variations in wax-rich bands within the films. The HAG + carnauba wax + Tween-80 films exhibited domed wax-rich domains displayed with high integrated CH2 absorption value at the interior of the films, rougher surface and higher contact angle values than the other films. The S-FTIR 2D images indicated that the distribution of wax in starch–wax films correlated with the roughness and hydrophobicity of the starch–wax films.
Characterization of non-linear rheological behavior of SPI-FG dispersions using LAOS tests and FT rheology
- Authors: Bi, Chonghao , Li, Dong , Wang, Li-jun , Wang, Yong , Adhikari, Benu
- Date: 2013
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 92, no. 2 (2013), p. 1151-1158
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- Description: The effect of flaxseed gum (FG) on the rheological and nonlinear stress response behaviors of mixed soy protein isolate (SPI)-flaxseed gum (FG) dispersions were studied. Results showed that the viscosity of the SPI-FG mixed dispersions increased significantly with increase in the FG concentration. Both the shear stress and the apparent viscosity values as a function of shear rate were fitted well using Power law model as expected. The frequency dependence of G′, G′′ and tan δ of soy protein isolate decreased as the FG concentration increased. The large amplitude oscillatory shear (LAOS) test and Fourier transform (FT) rheology analysis showed that the addition of flaxseed gum strongly affected the structure of the SPI-FG mixed dispersion system as shown by deformation of the nonlinear stress response curve and significantly altered magnitude of higher harmonic curve. The addition of FG increased the instantaneous strain softening effect of the SPI-FG mixed dispersion system. © 2012 Elsevier Ltd.
- Description: 2003011034
Characterization of starch films containing starch nanoparticles Part 1: Physical and mechanical properties
- Authors: Shi, Aimin , Wang, Li-Jun , Li, Dong , Adhikari, Benu
- Date: 2013
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 96, no. 2 (2013), p. 593-601
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- Description: We report, for the first time, the preparation method and characteristics of starch films incorporating spray dried and vacuum freeze dried starch nanoparticles. Physical properties of these films such as morphology, crystallinity, water vapor permeability (WVP), opacity, and glass transition temperature (Tg) and mechanical properties (strain versus temperature, strain versus stress, Young's modulus and toughness) were measured. Addition of both starch nanoparticles in starch films increased roughness of surface, lowered degree of crystallinity by 23.5%, WVP by 44% and Tg by 4.3 °C, respectively compared to those of starch-only films. Drying method used in preparation of starch nanoparticles only affected opacity of films. The incorporation of nanoparticles in starch films resulted into denser films due to which the extent of variation of strain with temperature was much lower. The toughness and Young's modulus of films containing both types of starch nanoparticles were lower than those of control films especially at <100 °C. © 2012 Elsevier Ltd. All rights reserved.
- Description: C1
Effect of montmorillonite on morphology, glass transition and crystallinity of the xylitol-plasticized bionanocomposites
- Authors: Liu, Huihua , Chaudhary, Deeptangshu
- Date: 2013
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 98, no. 1 (2013), p. 391-396
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- Description: High amylose based nanocomposites plasticized by xylitol were prepared via twin-screw extrusion. The synergistic interaction in the xylitol-plasticized nanocomposite was studied via various characterization methods and the unique behavior of the xylitol-plasticized nanocomposite had been discussed. As revealed in the XRD and TEM results, good intercalated/exfoliated morphology had been achieved in all the nanocomposites. Furthermore, the expansion of nanoclay basal spacing was related to the xylitol/nanoclay ratio. DSC analysis clearly proved the unique crystallization process of xylitol-plasticized samples. Moreover, in the crystallization domain results, two domains sized at approximately 93.7. Å and 346. Å were found. This observation points to a two-level complex effect from two aggregate domains; one, the re-aggregation of certain number of silicate layers into domains which trap some of the amylose polymer chains, and two, the bulk drying process which combines smaller amylose crystalline domains within a larger amorphous high amylose matrix. © 2013.
- Description: 2003011127
Optimization of production yield and functional properties of pectin extracted from sugar beet pulp
- Authors: Lv, Cheng , Wang, Yong , Wang, Li-jun , Li, Dong , Adhikari, Benu
- Date: 2013
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 95, no. 1 (2013), p. 233-240
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- Description: A central composite design was employed to determine the optimum extraction condition to obtain higher yield, better color attribute as well as better rheological and emulsifying properties in pectin extracted from sugar beet pulp (SBP). A second-order polynomial model was developed for predicting the yield of sugar beet pulp pectin (SBPP) based on the composite design. Response surface methodology (RSM) was used to quantify the integral effect of three processing parameters (extraction temperature, time and pH) on yield, yield stress, color attribute (tint value) and emulsifying activity index (EAI). Through the frequency analysis it was found that the optimal temperature, time and pH value of the extraction were 93.7 °C, 3 h, and 1.21, respectively. The yield, yield stress and tint value of the SBPP extracted at the optimal condition were 24.45%, above 0.1 Pa and -6.0, respectively. © 2013 Elsevier Ltd.
- Description: 2003011020
Physicochemical and functional characteristics of lentil starch
- Authors: Joshi, Matina , Aldred, Peter , McKnight, Stafford , Panozzo, Joe , Kasapis, Stefan , Adhikari, Raju , Adhikari, Benu
- Date: 2013
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 92, no. 2 (2013), p. 1484-1496
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- Description: The physicochemical properties of lentil starch were measured and linked up with its functional properties and compared with those of corn and potato starches. The amylose content of lentil starch was the highest among these starches. The crystallinity and gelatinization enthalpy of lentil starch were the lowest among these starches. The high amylose: amylopectin ratio in lentil starch resulted into low crystallinity and gelatinization enthalpy. Gelatinization and pasting temperatures of lentil starch were in between those of corn and potato starches. Lentil starch gels showed the highest storage modulus, gel strength and pasting viscosity than corn and potato starch gels. Peleg's model was able to predict the stress relaxation data of these starches well (R2 > 0.98). The elastic modulus of lentil starch gel was less frequency dependent and higher in magnitude at high temperature (60 °C) than at lower temperature (10 °C). Lentil starch is suitable where higher gel strengthened pasting viscosity are desired. © 2012 Elsevier Ltd.
- Description: 2003011035
Suspensions of vacuum-freeze dried starch nanoparticles : Influence of NaCl on their rheological properties
- Authors: Shi, Aimin , Wang, Li-jun , Li, Dong , Adhikari, Benu
- Date: 2013
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 94, no. 2 (2013), p. 782-790
- Full Text: false
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- Description: The effect of addition of NaCl on rheological properties of suspensions containing vacuum freeze dried starch nanoparticles was studied. These starch nanoparticles were produced through high pressure homogenization and emulsion cross-linking technique. Rheological properties such as continuous shear viscosity, storage and loss moduli and creep-recovery were measured. The presence of NaCl at concentration (5-15%, w/v) increased viscosity marginally (p > 0.05) while at 20% (w/v) it significantly (p < 0.05) increased viscosity. The presence of NaCl enhanced heat stability and weakened gelling capacity of suspensions. NaCl concentration below 15% (w/v) marginally (p > 0.05) increased the storage and loss moduli of suspensions. At 20% (w/v), NaCl increased both moduli significantly (p < 0.05) within frequency range tested (0.1-10 rad/s). Creep-recovery behavior was affected by NaCl and recovery rate was the highest (98.6%) at 20% (w/v) NaCl. The Cross, Power Law and Burgers' models followed experimental shear viscosity, storage and loss moduli and creep-recovery data reasonably well ((R
- Description: 2003010855
Effects of partial gelatinization on structure and thermal properties of corn starch after spray drying
- Authors: Fu, Zong-qiang , Wang, Li-jun , Li, Dong , Adhikari, Benu
- Date: 2012
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 88, no. 4 (2012), p. 1319-1325
- Full Text: false
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- Description: Partially gelatinized starch was prepared by gelatinizing corn starch at 64-72°C followed by spray drying (inlet temperature, feed flow rate, air flow rate of 200°C, 7.2 ml/min and 0.375 m 3/h, respectively). The morphology, granule size, crystalline fraction, swelling power and gelatinizing properties of partially gelatinized starch were investigated and compared with those of native starch. The surface morphology of partially gelatinized starch granules was shriveled with multiple surface folds. The granule size of partially gelatinized starch was smaller than that of native corn starch. There was either complete absence of crystalline fraction in partially gelatinized starch or the extent of crystalline fraction was greatly reduced. The swelling power of partially gelatinized starch was higher than that of the native starch below 60°C, while it was lower than that of native starch above 60°C. There was an increase in gelatinization temperature and a decrease in gelatinization enthalpy in partially gelatinized starch compared to that of native starch. © 2012 Elsevier Ltd. All rights reserved.
The effect of annealing and cryoprotectants on the properties of vacuum-freeze dried starch nanoparticles
- Authors: Shi, Aimin , Wang, Li-Jun , Li, Dong , Adhikari, Benu
- Date: 2012
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 88, no. 4 (2012), p. 1334-1341
- Full Text: false
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- Description: Starch nanoparticles prepared through high pressure homogenization and mini-emulsion cross-linking technology were successfully vacuum-freeze dried. Annealing process was introduced in the drying process and the cryoprotectants (lactose and mannitol) were used in the sample matrix. The effect of the annealing and cryoprotectants on the moisture content, glass transition temperature (T-g), amorphous/crystalline nature, particle size, morphology and the redispersibility of these nanoparticles was investigated. The residual moisture content of the nanoparticles was 4-9% (w/w) and it was lower in samples which were unannealed and contained cryoprotectants. Mannitol as cryprotectant resulted into starch nanoparticles with uniform spherical shape. The T-g of these nanoparticles varied from 52 degrees C to 57 degrees C and the difference was due to annealing and cryoprotectants. The annealing process and the presence of cryoprotectant did not hugely affect the X-ray diffraction pattern and FT-IR spectra which revealed the fully cross-linked and amorphous glassy state of starch nanoparticles. (C) 2012 Elsevier Ltd. All rights reserved.
The interaction in sorbitol-plasticized starch bionanocomposites via positron annihilation lifetime spectroscopy and small angle X-ray scattering
- Authors: Liu, Huihua , Chaudhary, Deeptangshu , Roberts, Jason , Weed, Ryan , Sullivan, James , Buckman, Stephen
- Date: 2012
- Type: Text , Journal article
- Relation: Carbohydrate Polymers Vol. 88, no. 4 (2012), p. 1172-1176
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- Description: We investigated the free volume variations (size and distribution) within sorbitol plasticized high amylose bionanocomposites of different formula where the interactions among sorbitol, amylose and hydrophilic montmorillonite nanoclay (MMT) modified the crystallinity and therefore, the free volume of the matrix. Positron Annihilation Lifetime Spectroscopy (PALS) is a useful technique to monitor the changes of free volume within the polymer matrix - due to polymer-plasticizer or polymer-polymer interactions. In a recent investigation (Liu et al.; Carbohydrate Polymer, 2011, 85(1), 97-104), we demonstrated that there exists a threshold plasticizer concentration - above which the matrix crystallinity and moisture content can be significantly altered. By investigating the relationship between the changes of free volume and the development of crystalline morphology, we presented evidence that, at the molecular level, the free volume changes due to amylose-MMT interactions were affected by the concentration of the sorbitol plasticizer. The free volume analysis revealed that when the concentration of sorbitol was low (5 wt%), the bionanocomposite showed a bimodal distribution for free volume pore-size. As the sorbitol concentration increased, these free volume pores coalesced. Further, due to sorbitol's hydrophilic nature, this study also presented the evidence of moisture 'lock-in' within the bionanocomposites matrix; only one pore size - was confirmed in the high moisture content samples; meaning that sorbitol was able to have binary interactions with the amylose and with the water molecules so that the free volume pore-size was relatively more uniform. © 2012 Elsevier Ltd. All rights reserved.