Effect of plasticizers on the moisture migration behavior of low-amylose starch films during drying
- Authors: Adhikari, Benu , Chaudhary, Deeptangshu , Clerfeuille, E
- Date: 2010
- Type: Text , Journal article
- Relation: Drying Technology Vol. 28, no. 4 (2010), p. 468-480
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- Description: We report the synergistic and competitive interactions between multiple plasticizers in plasticized low-amylose starch that result in either enhanced or reduced water migration fluxes and effective moisture diffusivities. The starch was plasticized using glycerol and xylitol either individually or in 1:1 combination. The water migration fluxes and moisture diffusivities were higher in xylitol plasticized films compared to the glycerol plasticized ones. For low plasticizer concentrations, the presence of both the plasticizers competitively reduced the effective moisture diffusivities and moisture migration fluxes due to antiplasticization. However, at higher plasticizer contents (at and above 15wt%), the presence of multiple plasticizers enhanced the moisture migration fluxes and effective moisture diffusivities due to synergistic plasticization. The moisture migration fluxes and effective moisture diffusivities exhibited both moisture and plasticizer concentration dependence and the former was found to be stronger than the latter. These findings can be used for designing and controlling the vapor barrier properties of starch-based bioplastics during drying and formulation phase.
- Description: 2003008138
Effect of cultivars and thermal processing with salt solutions on the textural attributes (hardness, chewiness and rate of softening) of potatoes (Solanum Tuberosum L.)
- Authors: Adhikari, Benu , Purcell, T. , Ristrom, A. , Chaudhary, Deeptangshu
- Date: 2010
- Type: Text , Journal article
- Relation: International Journal of Food Properties Vol. 13, no. 5 (2010), p. 1161-1177
- Full Text: false
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- Description: The change in textural attributes (hardness, chewiness and rate of softening) of three potato cultivars (Russet Burbank, Desiree and Sebago) was investigated. Uniform cylindrical samples (35-mm diameter and 3-mm thick) were prepared and exposed to different thermal processing regimes including; heating at 85°C, 95°C in water and steaming (100.2°C). The effect of salt on these textural attributes was also investigated using different salt concentrations (1.5%, 3% and 6% (w/w) NaCl). After thermal treatments the samples were subjected to texture profile analysis. The instrumental textural attributes were greatly affected by the cultivars and the thermal processing regimes. The change in textural attributes upon steaming was only marginally different compared to that at 95°C in water. Low concentrations of salt (1-3%) were found to accelerate the softening of the texture in these cultivars especially at lower temperatures. The textural attributes were modelled using a two-parameter reaction kinetics model. There was reasonable agreement by the model findings on the textural attributes prepared from all the thermal processing regimes and in presence and absence of (within average absolute error of 1.9-7%). Further, the model indicated that the order of reaction varied from 1.15-2.18 indicating that the changes in textural attributes in these thermal processing regimes followed higher reaction orders. [ABSTRACT FROM AUTHOR]
- Description: 2003008255
Effect of temperature and plasticizer molecular size on moisture diffusion of plasticized-starch biopolymer
- Authors: Chaudhary, Deeptangshu , Adhikari, Benu
- Date: 2010
- Type: Text , Journal article
- Relation: Starch Vol. 62, no. 7 (2010), p. 364-372
- Full Text: false
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- Description: Using starch pellets as precursor for traditional edible food packaging for making thermoformed products is an excellent idea. We report here the complex water migration behaviour of starch pellets as influenced by plasticizer type and concentration at various temperatures. The evidence for synergistic interaction between plasticizers and water within starch is shown by the reduced effective moisture diffusivities and moisture migration fluxes at different overall plasticizer concentrations. In addition, the effective moisture diffusivities showed stronger dependence on moisture concentration and the plasticizer molecular weight even though the moisture flux was comparable. The drying process was characterized by two effective diffusion coefficients (D 1, D2) and interestingly, the coefficients were an order of significance apart. Peleg model was investigated for predicting the drying behaviour and it is shown that the Peleg constants k1 and k 2 increase with temperature. k2, a material structure parameter, showed variation by addition of plasticizers, indicating that plasticizers were able to modify fundamental structure; and xylitol showed greater average k2 values than glycerol. Further, k1, a moisture diffusivity parameter, was affected by temperature and Arrhenius relationship was used for activation energy values for k1 of plasticized starch. It is shown that compared to starch and water, presence of plasticizer had many order of significance higher k1 and confirm the hypothesis that plasticizers can 'lock' in water within the new structure. Xylitol showed better stability in controlling moisture diffusivities and migration fluxes as compared to glycerol. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.
- Description: 2003008252
Understanding polymeric amylose retrogradation in presence of additives
- Authors: Chaudhary, Deeptangshu , Adhikari, Benu
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Applied Polymer Science Vol. 115, no. 5 (2009), p. 2703 - 2709
- Full Text: false
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- Description: Polymeric aging in starch is an important equilibrating process leading to long-chain amylose recrystallization and anisotropic properties of material made from starch. Investigations into a number of plasticizers and hydrocolloids showed that their water retention/binding capability influence the starch polymer’s crystallinity. Addition of up to 8 wt % glycerol and 3 wt % xylitol acted as an antiplasticizer and apparently increased the total crystalline phase, which reduced the degree of elongation of amylose matrix by 15%. Maltodextrin and xanthan gum also reduced matrix elongation capability but X-ray diffraction (XRD) analysis showed samples with varying crystallinity, and the extent of crystallinity did not correlate with respective tensile properties. Additives such as maltodextrin, with similar molecular structure as amylose, were ineffective in increasing degree of elongation even at 15 wt % addition rate, because of formation of pockets of crystalline region, as observed by XRD analysis. Both xylitol and xanthan gum samples showed similar tensile strength and elongation properties, but the water retention capability of xylitol-filled starch samples was about 27% lower than xanthan gum samples, at their respective higher concentrations. A dynamic structural unit is proposed to satisfy the isotropic increase in tensile strength and degree of elongation in oriented starch matrix. VVC 2009Wiley Periodicals, Inc. J Appl Polym Sci 000: 000–000, 2009
Glass-transition behaviour of plasticized starch biopolymer system - A modified Gordon-Taylor approach
- Authors: Chaudhary, Deeptangshu , Adhikari, Benu , Kasapis, Stefan
- Date: 2010
- Type: Text , Journal article
- Relation: Food Hydrocolloids Vol. 25, no. 1 (2010), p. 114-121
- Full Text: false
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- Description: Two plasticizers namely, glycerol and xylitol, based on their similar molecular size ( 6.3 Å) but different molecular weights (Glycerol-92; Xylitol-152) were selected for studying the glass-transition behaviour (rubber like behaviour) in multi-plasticized starch biopolymer with about 70% amylopectin structure. In the calorimetry measurements, glass-transition temperatures (onset temperature for bulk viscous flow) of plasticized samples were higher than non-plasticized samples at low water activities, thus showing typical antiplasticization behaviour. However, when plasticizer concentration was increased up to 15% and 20% wt, all plasticized samples showed significant reduction in glass-transition temperature. We used a modified Gordon-Taylor model to understand the competitive plasticization of glycerol and xylitol in presence of water, and suggest that competitive plasticization exists and occurs at a threshold amount of matrix free water content, due to strong three-way interactions: starch-plasticizer, plasticizer-plasticizer/water and starch-water. This competitive interaction is significant in determining the onset temperature for viscous flow behaviour; at higher matrix water content, the Gordon-Taylor constant was relatively unaffected by the plasticizer amount, and water was the dominant plasticizer. A new interaction parameter that separates the starch-plasticizer interaction in a starch-plasticizer-water system is also discussed. © 2010 Elsevier Ltd. All rights reserved.
- Description: 2003008289
Ultrasonic treatment and synthesis of sugar alcohol modified Na +-montmorillonite clay
- Authors: Chaudhary, Deeptangshu , Liu, Huihua
- Date: 2013
- Type: Text , Journal article
- Relation: Ultrasonics Sonochemistry Vol. 20, no. 1 (2013), p. 63-68
- Full Text: false
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- Description: Na +-montmorillonite clay (generally referred to as MMT) is very useful for reinforcing polymeric matrix at very low concentrations (typically, 2-5% wt). These clay particles are typically exfoliated before they can demonstrate the significant gains in heat deflection temperature, modulus, and elongation properties. In the case of hydrophilic biopolymer based matrices, such as carbohydrates and chitosan, exfoliating these nanoclay particles needs greater attention because the exfoliation is typically carried out using hydrophobic oligomers through ion-exchange. This study reports a new method of synthesizing completely hydrophilic MMT-assemblages using hydrophilic plasticizers for biopolymers. We used sugar alcohols (glycerol, xylitol with 3 and 5 hydroxyl groups) and polysaccharide maltodextrin to exfoliate the MMT. Sonication was conducted for MMT nanoclay and plasticizers at different weight ratios. It was confirmed that all plasticizer/modifier led to expansion of MMT gallery spacing (d-spacing) and the change in d-spacing could be related to the molecular structure of the plasticizer. Meanwhile, the extent of exfoliation was maximum with maltodextrin (fully exfoliation with 1:10 and 1:20 ratio of MMT:plasticizer) across all test samples and interestingly, glycerol and xylitol samples quickly established within the MMT galleries and exhibited minimal influence with further increase in relative concentrations. © 2012 Elsevier B.V. All rights reserved.
- Description: 2003010397
Microstructure changes of on the extruded high-amylose bionanocomposites as affected by moisture content via synchrotron radiation studies
- Authors: Liu, Huihua , Chaudhary, Deeptangshu
- Date: 2014
- Type: Text , Journal article
- Relation: Solid State Communications Vol. 192, no. (August 2014 2014), p. 10-14
- Full Text: false
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- Description: The crystalline domain changes and lamellar structure observations of sorbitol-plasticized starch nanocomposite had been investigated via synchrotron. Strong interactions were found between amylose-sorbitol, resulting in reduced inter-helix spacing of the starch polymer. Achievable dspacing of nanoclay was confirmed to be correlated to the moisture content (mc) within the nanocomposites. SAXS diffraction patterns changed from circular (high mc samples) to elliptical (low mc samples), indicating the formation of long periodic structure and increased heterogeneities of the electron density within the samples. Two different domains sized at around 90 Ã… and 350 Ã… were found for the low mc samples. However, only the ~90 Ã… domain was observed in high mc samples. Formation of the 380 Ã… domain is attributed to the retrogradation behaviour in the absence of water molecules. Meanwhile, the nucleation effect of nanoclay is another factor leading to the emergence of the larger crystalline domain.
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
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.
Investigations into the free-volume changes within starch/plasticizer/nanoclay systems using Positron Annihilation Lifetime Spectroscopy
- Authors: Liu, Huihua , Chaudhary, Deeptangshu , Campbell, Colin , Roberts, Jason , Buckman, Stephen , Sullivan, James
- Date: 2014
- Type: Text , Journal article
- Relation: Materials Chemistry and Physics Vol. 148, no. 1-2 (2014), p. 349-355
- Full Text: false
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- Description: The free-volume of a matrix is a fundamental parameter that relates to its molecular and bulk characteristics, such as crystalline change and glass transition behavior. In starch-based bionanocomposite, we investigated the effect of the addition of montmorillonite nanoclay (MMT) and food plasticizers (glycerol and sorbitol) on changes of molecular pore size (including pore volume and pore distribution) using the Positron Annihilation Lifetime Spectroscopy (PALS) method. The results demonstrated counter-intuitive impact of MMT on the total free-volume where the total free-volume increased within the polymeric matrix. When compared to the pure matrix free-volume, the addition of MMT also resulted in the appearance of a broader distribution of the void sizes. The plasticizers, on the other hand, apparently occupied the void spaces, and therefore decreased the free-volume of the matrix. Further, together with the small angle X-ray scattering (SAXS) analysis, we concluded that this is a result of interplay between the plasticizer-plasticizer interactions and the polymer-plasticizer interactions. For example, in the starch/glycerol/MMT system, the pore radii slightly decrease upon the increasing of glycerol amount (OG210 = O.27 nm and OG220 = 0.26 nm), but the relative weight did increase with the increasing glycerol concentration. However, increasing the sorbitol amount increased the pore size from 0.23 nm(OS210) to 0.28 nm(OS220). Furthermore, the addition MMT in the OS010 system, promote the emergence of a new dateable pore radius(0.90 nm), and the total weight significantly increased from 13.70 (OS010) to 19.5% (OS210). We suggest that the pore variation (size and distribution) due to the MMT and plasticizers are reflected in the polymer glass transition and crystallinity because ultimately, the, total free-volume is a reflection of level of interactions existing within the bulk of these nanocomposites.
Comparative study of film forming behaviour of low and high amylose starches using glycerol and xylitol as plasticizers
- Authors: Muscat, Delina , Adhikari, Benu , Adhikari, Raju , Chaudhary, Deeptangshu
- Date: 2011
- Type: Text , Journal article
- Relation: Journal of Food Engineering Vol.109, no.2 (2011), p.189-201
- Full Text: false
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- Description: In this study, the film forming behaviour of low amylose (LA) and high amylose (HA) starches was studied. The starch-alone and a blend of plasticizer (polyol)-starch films were developed by gelatinising at various temperatures and casting at 25 °C. The starch-plasticizer films contained glycerol and xylitol either individually or in 1:1 combination. The concentration of plasticizer used was 15%, 20% and 30% for LA films while it was 20%, 30% and 40% for HA films on dry solid basis. The HA-glycerol films retained the highest moisture content among all the films. The HA films exhibited higher glass transition temperature, higher tensile strength, higher modulus of elasticity and lower elongation at break than those obtained from LA starch. The tensile strength and modulus of elasticity decreased and the elongation increased with increasing plasticizer concentrations above 15% on dry solid basis regardless the starch type. Low water vapour permeability was evident in LA and HA films plasticized by combined plasticizers at 20% plasticizer concentration. Rheological measurements showed that most of the suspensions exhibited Herschel-Bulkley behaviour and some of the HA suspensions exhibited Bingham plastic behaviour. At 15% (on dry solid basis) plasticizer concentration, the films obtained from both the starches were brittle due to the anti-plasticization behaviour. © 2011 Elsevier Ltd. All rights reserved.