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Unexpected high pressure effects on the structural properties of condensed whey protein systems

- Dissanayake, Muditha, Kasapis, Stefan, Chaudhary, Vinita, Adhikari, Benu, Palmer, Martin, Meurer, Barbara

  • Authors: Dissanayake, Muditha , Kasapis, Stefan , Chaudhary, Vinita , Adhikari, Benu , Palmer, Martin , Meurer, Barbara
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Biopolymers Vol. 97, no. 12 (2012), p. 963-973
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  • Description: We show that application of high hydrostatic pressure (600 MPa for 15 min) on condensed whey protein (WP) systems (e.g., 80% w/w solids content) results in unexpected structure-function behavior when compared with conventional thermal treatment. Unraveling the relaxation properties in first-order thermodynamic transitions, the manifestation of glass transition phenomena and the preservation of native conformation in condensed preparations were recorded using small-deformation dynamic oscillation in shear, modulated differential scanning calorimetry, and infrared spectroscopy. Informed temperature application results in the formation of continuous networks at the denaturation temperature, which undergo vitrification at subzero temperatures. In contrast, high-pressure-treated WPs resist physicochemical denaturation, hence preserving the native conformation of secondary and tertiary structures. This was rationalized on the basis of a critical concentration threshold where transfer of water molecules to nonpolar residues in the protein interior is minimized because of low moisture content and restricted molecular mobility. The physical state and morphology of these high-solid preparations were further examined by the combined framework of reduced variables and Williams, Landel, and Ferry equation/free volume theory. Theoretical treatment of experimental observations unveils the dynamic range of the mechanical manifestation of the glass transition region in samples subjected to heat or pressure. In addition to preserving native conformation, WPs subjected to high pressure form glassy systems at parity with the structural functionality of the thermally treated counterparts. © 2012 Wiley Periodicals, Inc.

Comparative study of film forming behaviour of low and high amylose starches using glycerol and xylitol as plasticizers

- Muscat, Delina, Adhikari, Benu, Adhikari, Raju, Chaudhary, Deeptangshu

  • 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 gum Arabic on stability of oil-in-water emulsion stabilized by flaxseed and soybean protein

- Wang, Bo, Wang, Li, Li, Dong, Adhikari, Benu, Shi, John

  • Authors: Wang, Bo , Wang, Li , Li, Dong , Adhikari, Benu , Shi, John
  • Date: 2011
  • Type: Text , Journal article
  • Relation: Carbohydrate Polymers Vol. 86, no. 1 (2011), p. 343-351
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  • Description: The effects of gum Arabic (GA) addition (0-4%, w/w) on stability of oil-in-water emulsion stabilized by flaxseed protein concentrate (FPC) and soybean protein concentrate (SPC) were studied. The result shows that emulsions stabilized by both proteins in the presence of the 2% gum Arabic (w/w) have better stability than its absence, by increasing the emulsion viscosity of the FPC stabilized emulsion and causing competitive adsorption between the GA and SPC layer to give a steric repulsion for the SPC stabilized emulsion, respectively. Then, the influences of ionic strength (0-200 mM NaCl) and temperature (25-95 °C for 20 min) on these emulsions in presence of GA were determined. The GA adsorbed at SPC-stabilized oil-water interface provided stability against NaCl concentration. In presence of GA, the SPC-stabilized emulsions also showed better stability at higher temperatures compared to the FPC-stabilized emulsions due to the denaturation of SPC and competitive adsorption between GA and SPC at higher temperatures. © 2011 Elsevier Ltd All rights reserved.

Effects of high-pressure homogenization on the properties of starch-plasticizer dispersions and their films

- Fu, Z. Q., Wang, Li J., Li, Dong, Wei, Q., Adhikari, Benu

  • Authors: Fu, Z. Q. , Wang, Li J. , Li, Dong , Wei, Q. , Adhikari, Benu
  • Date: 2011
  • Type: Text , Journal article
  • Relation: Carbohydrate Polymers Vol. 86, no. 1 (2011), p. 202-207
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  • Description: The properties of starch-plasticizer (glycerol:xylitol = 1:1) dispersions obtained with and without high-pressure homogenization and their corresponding films were investigated. The fully gelatinized dispersions with or without homogenization were subsequently converted into films using solution casting. The apparent viscosity of the dispersions with or without homogenization was determined. The water vapor permeability, opacity, crystalline/amorphous nature, and mechanical properties of these starch-based films were determined. The high-pressure homogenization greatly reduced the apparent viscosity of the dispersions and altered the flow behavior from shear-thinning into Newtonian one. The films obtained from high-pressure homogenized dispersions had better moisture barrier property, better film transparency and higher tensile strength but lower elongation. © 2011 Elsevier Ltd All rights reserved.

Optimization of twin-screw extrusion process to produce okara-maize snack foods using response surface methodology

- Shi, Cong, Wang, Li-jun, Wu, Min, Adhikari, Benu, Li, Li-te

  • Authors: Shi, Cong , Wang, Li-jun , Wu, Min , Adhikari, Benu , Li, Li-te
  • Date: 2011
  • Type: Text , Journal article
  • Relation: International Journal of Food Engineering Vol. 7, no. 2 (2011), p.
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  • Description: Okara-maize flour blends were extruded in a co-rotating twin-screw extruder in order to assess their suitability as snack foods. Response surface methodology (RSM) using a central composite design was used to evaluate the effects of process variables (extrusion temperature (120-180 degrees C), screw speed (100-180 rpm) and feed composition (20-40 percent ww) and moisture content (14-22 percent ww)). Multiple regression equations were developed to describe the effects of each variable on product responses. The product characteristics such as bulk density, expansion index, appearance (colour, porosity), flavor (aroma, grittiness and off-odor), texture (hardness, crispness and brittleness) and overall acceptability were determined through experiments and sensory analyses. Through superimposed RSM contour map, it was found that the feed composition with 30 percent okara content, 14.5-19.3 percent moisture content and the extrusion temperature 120.0-171.2 degrees C and screw speed of 140 rpm, respectively to be the optimum extrusion conditions. The sensory tests showed that the products extruded at the optimized condition had the best appearance, taste, texture and overall acceptability. These results show that the okara-maize blends can be extruded into acceptable snack foods.

Physicochemical and functional properties of lentil protein isolates prepared by different drying methods

- Joshi, Matina, Adhikari, Benu, Aldred, Peter, Panozzo, Joe, Kasapis, Stefan

  • Authors: Joshi, Matina , Adhikari, Benu , Aldred, Peter , Panozzo, Joe , Kasapis, Stefan
  • Date: 2011
  • Type: Text , Journal article
  • Relation: Food Chemistry Vol. 129, no. 4 (2011), p. 1513-1522
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  • Description: Lentil protein isolate (LPI) extract was converted into powder by freeze drying, spray drying and vacuum drying. Differences in particle size distribution, protein subunit composition and colour and surface morphology were observed amongst the three drying methods. Spray and freeze-dried LPI powders exhibited higher solubility (81% and 78%, respectively) compared to vacuum dried powders (50%). The spray dried powders showed a low water absorption capacity (0.43 ± 0.02 g/g) compared to freeze (0.48 ± 0.02 g/g) and vacuum-dried (0.47 ± 0.01 g/g) LPI powders. Spray and freeze-dried powders displayed better gelation ability and higher gel strength, compared to vacuum-dried powder. Both spray and freeze-dried gels showed typical viscoelastic gel characteristics, with G′ dominating over G″ and very low loss tangent. The holding time required for gelation of vacuum dried powder at 90 °C was significantly longer, compared to spray and freeze dried powders. Hence, drying methods used for preparation of lentil protein isolate powders can affect physicochemical and associated functional properties. © 2011 Elsevier Ltd. All rights reserved.

Surface protein coverage and its implications on spray-drying of model sugar-rich foods: Solubility, powder production and characterisation

- Jayasundera, Mithila, Adhikari, Benu, Howes, Tony, Aldred, Peter

  • Authors: Jayasundera, Mithila , Adhikari, Benu , Howes, Tony , Aldred, Peter
  • Date: 2011
  • Type: Text , Journal article
  • Relation: Food Chemistry Vol. 128, no. 4 (2011), p. 1003-1016
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  • Description: We have investigated the amount of protein required to produce amorphous sugar powders through spray-drying. Pea protein isolate was used as a model plant protein and sodium caseinate was used as a model dairy protein. Powder recovery in a laboratory spray dryer was used as a measure of the ease of spray drying for a given formulation. More than 80% of amorphous sucrose and fructose was produced with the addition of sodium caseinate, while the pea protein isolate was able to produce only recoveries of less than 50% of amorphous sucrose. Sensitivity of low molecular weight surfactants has been demonstrated using both ionic (sodium stearoyl lactylate) and non-ionic (polysorbate-80) surfactants. Spray-dried powders were subjected to physico-chemical characterisation and dissolution experiments. The maximum solubility of all powders was obtained after 5 min of dissolution. The solubility of the sodium caseinate increased by 6-7% in the presence of fructose and low molecular weight surfactants. The solubility of the amorphous powders of sucrose-pea protein isolate was found to be lower than amorphous powders of sucrose-sodium caseinate and fructose-sodium caseinate. The addition of sucrose in water increased the solubility of the pea protein isolate from 16.84% to more than 83%. The non-ionic surfactant (Tween-80) has reduced the solubility of sucrose-pea protein isolate-Tween-80 powders significantly (p < 0.05) compared to those of sucrose-pea protein isolate-sodium stearoyl lactylate powders. The solubility of sucrose-sodium caseinate powders was comparable to that of pure sodium caseinate, indicating that addition of sucrose into 0.13% sodium caseinate does not have any significant effect on the solubility of this protein at this concentration. © 2011 Elsevier Ltd. All rights reserved.

The effect of addition of flaxseed gum on the emulsion properties of soybean protein isolate (SPI)

- Wang, Yong, Li, Dong, Wang, Li Ming, Adhikari, Benu

  • Authors: Wang, Yong , Li, Dong , Wang, Li Ming , Adhikari, Benu
  • Date: 2011
  • Type: Text , Journal article
  • Relation: Journal of Food Engineering Vol. 104, no. 1 (2011), p. 56-62
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  • Description: The effect of addition of flaxseed gum on the emulsion properties of soybean protein isolate (SPI) were investigated in this study. Flaxseed gum with 0.05-0.5% (w/v) concentration was used together with 1% (w/v) SPI to emulsify 10% (v/v) soybean oil. The emulsion was analyzed for emulsion activity (turbidity), stability, particle size, surface charge, and rheological properties. The turbidity and absolute zeta-potential values decreased initially by the addition of flaxseed gum and subsequently increased with further increase in the gum concentration to reach their peak around 0.35% (w/v) gum. The particle size of the emulsion decreased and reached a minimum value at 0.1% (w/v) gum concentration. Any increase in gum concentration beyond this value resulted into increase in the particle size. This study would help to widen the application of SPI and flaxseed gum mixture, and also contribute to the understanding of protein-gum interaction in emulsion. © 2010 Elsevier Ltd. All rights reserved.

The effects of proteins and low molecular weight surfactants on spray drying of model sugar-rich foods: Powder production and characterisation

- Jayasundera, Mithila, Adhikari, Benu, Adhikari, Raju, Aldred, Peter

  • Authors: Jayasundera, Mithila , Adhikari, Benu , Adhikari, Raju , Aldred, Peter
  • Date: 2011
  • Type: Text , Journal article
  • Relation: Journal of Food Engineering Vol. 104, no. 2 (2011), p. 259-271
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  • Description: The effects of proteins and low molecular weight surfactants (LMS) on spray drying and powder characteristics of model sugar-rich foods have been studied. Fructose and sucrose were selected as model sugar-rich foods and sodium caseinate (NaCas) was selected as a model protein. Sodium stearoyl lactylate (SSL) and Polysorbate 80 (Tween-80) were chosen as model ionic and non-ionic low molecular weight surfactants. The feed solutions for spray drying had 25% solid concentration in all. To achieve identical powder recoveries of the order of 80% much higher NaCas:fructose ratio (30:70) was required compared to NaCas:sucrose ratio (0.5:99.5) which corresponded to 7.89% and 0.13% of sodium caseinate (initial bulk concentration), respectively. There was no change in powder recovery when the SSL concentration was increased from 0.01% to 0.05% in fructose-NaCas-SSL solution and also addition of 0.01% Tween-80 into fructose-NaCas solution did not affect the powder recovery (76.7 ± 2.3%), however, it was slightly affected with the increase of Tween-80 to 0.05% (69.0 ± 1.9%). At NaCas concentration above critical micelle concentration of NaCas (3% w/w), the presence of up to 0.05% low molecular weight surfactants had either no effect or minimal effect on the surface coverage of the droplets/particles and also on the powder recovery depending on the nature of the low molecular weight surfactants. The surface protein coverage and the recovery of the powder in sucrose-protein systems were very sensitive in the presence of low molecular weight surfactants due to being below the critical micelle concentration of NaCas. SSL displaced 2.0% and 29.3% of proteins from the droplet surface of sucrose-NaCas-SSL, respectively, when its concentration was varied from 0.01% to 0.05% thereby reducing the powder recovery from 75.5% to 30%. The addition of 0.01% Tween-80 in sucrose-NaCas solution resulted in a 48.2 ± 1.5% reduction in powder recovery and at 0.05% concentration, it displaced a substantial amount of NaCas from the droplet surface and no powder was recovered. These phenomena are explained on the basis of surface-glass transition temperature, dynamic surface tension, nature of surfactants and glass transition temperature of sugars used. X-ray diffraction and scanning electron microscopy results showed that the powders of sucrose-NaCas, sucrose-NaCas with 0.01% SSL and all powders of fructose were amorphous. © 2010 Elsevier Ltd. All rights reserved.

Ability of flaxseed and soybean protein concentrates to stabilize oil-in-water emulsions

- Wang, Bo, Li, Dong, Wang, Li J., Adhikari, Benu, Shi, John

  • Authors: Wang, Bo , Li, Dong , Wang, Li J. , Adhikari, Benu , Shi, John
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Journal of Food Engineering Vol. 100, no. 3 (2010), p. 417-426
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  • Description: The ability of flaxseed protein concentrate (FPC) to stabilize soybean oil-in-water emulsion was compared with that of soybean protein concentrate (SPC). The stability of emulsions increased with increase in protein concentration. The FPC-stabilized emulsions had smaller droplet size and higher surface charge, but worse stability at the same protein concentration compared to SPC-stabilized emulsions. Oil-in-water emulsions stabilized by both proteins were diluted and compared at different pH values (3-7), ionic strength (0-200 mM NaCl) and thermal treatment regimes (25-95 °C for 20 min). Considerable emulsion droplet flocculation occurred around iso-electric point of both proteins: FPC (pH 4.2) and SPC (pH 4.5). FPC and SPC-stabilized emulsions remained relatively stable against droplet aggregation and creaming at NaCl concentration below 100 and 50 mM, respectively. The emulsions stabilized by both proteins were fairly stable within these thermal processing regimes. FPC appears to be less effective as an emulsifier compared to SPC due to its lower emulsion viscosity. Hence, FPC could be more effective in emulsions that are fairly viscous. © 2010 Elsevier Ltd. All rights reserved.
  • Description: 2003008230

Effect of cultivars and thermal processing with salt solutions on the textural attributes (hardness, chewiness and rate of softening) of potatoes (Solanum Tuberosum L.)

- Adhikari, Benu, Purcell, T., Ristrom, A., Chaudhary, Deeptangshu

  • 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

- Adhikari, Benu, Chaudhary, Deeptangshu, Clerfeuille, E

  • 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

- Chaudhary, Deeptangshu, Adhikari, Benu

  • 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

Effects of drying methods on the functional properties of flaxseed gum powders

- Wang, Yong, Li, Dong, Wang, Li J., Li, Shu Juan, Adhikari, Benu

  • Authors: Wang, Yong , Li, Dong , Wang, Li J. , Li, Shu Juan , Adhikari, Benu
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Carbohydrate Polymers Vol. 81, no. 1 (2010), p. 128-133
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  • Description: The effects of different drying methods (spray drying, freeze drying, vacuum drying, oven drying at 80 and 105 °C, and ethanol precipitation) on the color and functional properties such as zeta potential, foaming, gelling, and emulsion properties of flaxseed gum were studied. Spray dried powders had the lightest color among all the powders. The powder obtained from ethanol precipitation had the lowest zeta potential and the resultant emulsion was in the most stable state. The ethanol precipitated powders had the best emulsion capacity and stability, better than even the untreated samples. The oven dried (105 °C) powders had the best foaming capacity and the foam stability, while the 80 °C oven dried powder had highest gel strength among all the dried samples. These results will be helpful in selecting suitable drying method depending on the functional properties of the flaxseed gum powders. © 2010 Elsevier Ltd. All rights reserved.

Glass-transition behaviour of plasticized starch biopolymer system - A modified Gordon-Taylor approach

- Chaudhary, Deeptangshu, Adhikari, Benu, Kasapis, Stefan

  • 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

Preparation of gelatin microparticles using water-in-water (w/w) emulsification technique

- Kong, Yin. Q., Li, Dong, Wang, Li. J., Adhikari, Benu

  • Authors: Kong, Yin. Q. , Li, Dong , Wang, Li. J. , Adhikari, Benu
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Journal of Food Engineering Vol. 103, no. 1 (2010), p. 9-13
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  • Description: Gelatin microparticles were prepared using water-in-water (w/w) emulsification technique, in which aqueous solutions of gelatin and polypropylene glycol (PEG) were employed as dispersed phase and continuous phase, respectively. The effect of gelatin and PEG concentrations on the size of gelatin microparticles were evaluated. The size of the gelatin microparticles decreased with the increase in PEG concentration and increased with the increase in gelatin concentration. The gelatin microparticles obtained through this process were nearly perfect spheres with smooth surface. The gelatin microparticles, both un-crosslinked and crosslinked, were found to be fully amorphous in nature. The un-crosslinked gelatin microparticles were found to swell instantaneously (within 10 s) whereas the crosslinked ones were quite resistant to water uptake. © 2010 Elsevier Ltd. All rights reserved.

Preparation of starch-based nanoparticles through high-pressure homogenization and miniemulsion cross-linking: Influence of various process parameters on particle size and stability

- Shi, Aimin, Li, Dong, Wang, Li Ming, Li, Bingzheng, Adhikari, Benu

  • Authors: Shi, Aimin , Li, Dong , Wang, Li Ming , Li, Bingzheng , Adhikari, Benu
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Carbohydrate Polymers Vol. 83, no. 4 (2010), p. 1604-1610
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  • Description: A new and convenient synthetic route using high-pressure homogenization combined with water-in-oil (w/o) miniemulsion cross-linking technique was used to prepare sodium trimetaphosphate (STMP)-cross-linked starch nanoparticles. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) revealed that starch nanoparticles had narrow size distribution, good dispersibility and spherical shape. Effect of process parameters (surfactant content, water/oil ratio, starch concentration, homogenization pressure and cycles) on the starch nanoparticle size in miniemulsion was evaluated. We show that there is an optimal surfactant concentration giving rise to smaller starch nanoparticles and better stability. Apart from the water/oil ratio and starch concentration, the homogenization pressure and cycles (passes) also significantly affect the size of starch nanoparticles (p < 0.05). The stability analysis of starch nanoparticles in water for 2 h to 2 days and in temperature ranges of 25-45 °C showed firm structure and good stability. These nanoparticles are expected to be exploited as drug carriers. © 2010 Elsevier Ltd. All rights reserved.
  • Description: 2003008433

The effect of food-grade low-molecular-weight surfactants and sodium caseinate on spray drying of sugar-rich foods

- Jayasundera, Mithila, Adhikari, Benu, Adhikari, Raju, Aldred, Peter

  • Authors: Jayasundera, Mithila , Adhikari, Benu , Adhikari, Raju , Aldred, Peter
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Food Biophysics Vol. 5, no. 2 (2010), p. 128-137
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  • Description: The effect of low-molecular-weight surfactants (LMS) and sodium caseinate (NaCas) on spray drying of sugar-rich foods has been studied. Sucrose and NaCas were selected as a model sugar-rich food and protein, respectively. Sodium stearoyl lactylate (SSL) and Polysorbate 80 (Tween 80) were chosen as model ionic and nonionic LMS. Sucrose-NaCas solutions with the solids ratio of 99.5:0.5 in the absence and presence (0.01% and 0.05%) of SSL and Tween 80 were prepared. The feed solutions had 25% solid concentration in all cases. The dynamic surface tension (DST) values of the solutions were measured for 100 s and the solutions were subsequently spray dried at inlet and outlet temperatures of 165 and 65 °C, respectively. The glass-rubber temperature (Tg-r), the surface elemental composition and amorphous-crystalline nature of the powders were also determined. At these concentrations and experimental time frame, it was found that the proteins preferentially migrated to the air-water interface reasonably swiftly. The addition of LMS resulted in partial or complete displacement of the proteins from the air-water interface. For spray-drying trials with the yield of 82.0%, it was found that 52.0% of the powder particle surface was covered with proteins. The powder recovery was greatly reduced by the LMS concentration and type. At 0.05% on dry solid basis, in the case of nonionic surfactant (Tween 80), the displacement of protein from the surface was such that no powder was recovered. The ionic surfactant (SSL) displaced 2.0% and 29.3% proteins from the droplet surface at concentrations of 0.01% and 0.05%, respectively, resulting in 75.5 ± 1.8% and 30.1 ± 1.4% powder yield. The Tg-r results revealed that the amount of protein required for successful spray drying of the sucrose-protein solution depends on the amount of proteins present in the droplet surface but not in the bulk. X-ray diffraction and scanning electron microscopy results confirmed that the powders of both sucrose-NaCas and sucrose-NaCas with 0.01% SSL were mostly amorphous, while those with sucrose-NaCas-Tween 80 (0.01%) and sucrose-NaCas-SSL (0.05%) were crystalline. © 2010 Springer Science+Business Media, LLC.

Water uptake and its impact on the texture of lentils (Lens culinaris)

- Joshi, Matina, Adhikari, Benu, Panozzo, Joe, Aldred, Peter

  • Authors: Joshi, Matina , Adhikari, Benu , Panozzo, Joe , Aldred, Peter
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Journal of Food Engineering Vol. 100, no. 1 (2010), p. 61-69
  • Full Text: false
  • Reviewed:
  • Description: Water uptake behavior of three cultivars of lentils (Boomer, French-green and Nugget) was studied at three different hydration temperature regimes (room temperature, 50 °C and 85 °C). Boomer had the highest amount of water uptake capacity (74.60 g water/100 g of seeds) at room temperature (20 °C) which can be linked with its pore properties. French-green lentils imbibed the largest amount of water at elevated soaking temperatures (50 °C and 85 °C) and can be attributed to its higher seed surface area to volume ratio, high protein content and relatively thinner seed coat. Water uptake at elevated temperatures (50 °C and 85 °C) were predicted by a two parameter Mitscherlich model (R2 > 0.99,
  • Description: 2003008231

A composite reaction engineering approach to drying of aqueous droplets containing sucrose, maltodextrin (DE6) and their mixtures

- Patel, Kamlesh, Chen, Xiao Dong, Lin, Sean, Adhikari, Benu

  • Authors: Patel, Kamlesh , Chen, Xiao Dong , Lin, Sean , Adhikari, Benu
  • Date: 2009
  • Type: Text , Journal article
  • Relation: AIChE Journal Vol. 55, no. 1 (2009), p. 217-231
  • Full Text: false
  • Description: Recently, several studies have been published on the spray drying of sucrose and other low-molecular-weight sugars which are typically sticky materials. Sticky materials can not be processed under normal drying conditions and may require addition of high-molecular-weight carbohydrates such as maltodextrin. Predicting appropriate drying conditions are however difficult due to the unavailability of drying kinetics. In this article, we have formulated the drying kinetics model using the reaction engineering approach (REA) for the drying of aqueous sucrose and aqueous maltodextrin (DE6) droplets. The relative activation energy was empirically obtained based on experimental measurements. To model the drying of droplets containing both solutes (sucrose and maltodextrin), a new "composite" REA has been established and presented here for the first time. Results demonstrated that the composite REA forms a reliable framework to model the drying of aqueous solutions of pure carbohydrates and their mixtures. © 2008 American Institute of Chemical Engineers.