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
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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.
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
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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 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 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
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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
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
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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
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
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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