The effect of low molecular weight surfactants and proteins on surface stickiness of sucrose during powder formation through spray drying
- Adhikari, Benu, Howes, Tony, Wood, B. J., Bhandari, Bhesh
- Authors: Adhikari, Benu , Howes, Tony , Wood, B. J. , Bhandari, Bhesh
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Food Engineering Vol. 94, no. 2 (2009), p. 135 -143
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- Description: The effect of competitive surface migration of proteins and low molecular weight surfactants (LMS) on the powder recovery in spray drying of highly sticky sugar-rich food has been studied. Sucrose was chosen as a model sugar-rich food because it cannot be easily converted into a pure amorphous powder through spray drying. Sodium caseinate (Na-C) and hydrolyzed whey protein isolate (WPI) were used as model proteins. Polysorbate 80 (Tween-80) and sodium dodecyl sulfate (Na-DS) were used as model non-ionic and ionic LMS. A sucrose solution was spray dried without any additives to establish a base case. Following this, spray drying trials of sucrose-protein solutions were conducted. The sucrose: protein ratio was maintained at 99.5:0.5 and 99.0:1.0. Finally, 0.05% of Tween-80 and Na-DS, on a nominal feed basis, were individually added to the solutions and spray dried. The solid concentration of all of the feed solutions was set at 25% and the inlet and outlet temperatures were maintained at 170 °C and 70 °C, respectively. Powder recovery was determined using a standard procedure and taken as an indicator of the surface stickiness. Coverage of the particle surface by the proteins was determined through elemental surface analysis and a nitrogen balance. It was found that in the absence of LMS, the proteins covered up to 55% of the particle surface and increased the powder recovery to between 84% and 85%. Formation of a glassy protein-rich film acts to reduce the surface stickiness of sucrose droplets. However, when LMS was added to the sucrose-protein solutions, the recovery dropped to zero in the case of Tween-80. In the case of Na-DS the recoveries ranged to 39% and 68%. At these recoveries 83% and 59% of the protein, respectively, was displaced from the surface. This drastic effect of surfactant types on the powder recovery is explained using the Orogenic Displacement model. © 2009 Elsevier Ltd. All rights reserved.
- Authors: Adhikari, Benu , Howes, Tony , Wood, B. J. , Bhandari, Bhesh
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Food Engineering Vol. 94, no. 2 (2009), p. 135 -143
- Full Text:
- Reviewed:
- Description: The effect of competitive surface migration of proteins and low molecular weight surfactants (LMS) on the powder recovery in spray drying of highly sticky sugar-rich food has been studied. Sucrose was chosen as a model sugar-rich food because it cannot be easily converted into a pure amorphous powder through spray drying. Sodium caseinate (Na-C) and hydrolyzed whey protein isolate (WPI) were used as model proteins. Polysorbate 80 (Tween-80) and sodium dodecyl sulfate (Na-DS) were used as model non-ionic and ionic LMS. A sucrose solution was spray dried without any additives to establish a base case. Following this, spray drying trials of sucrose-protein solutions were conducted. The sucrose: protein ratio was maintained at 99.5:0.5 and 99.0:1.0. Finally, 0.05% of Tween-80 and Na-DS, on a nominal feed basis, were individually added to the solutions and spray dried. The solid concentration of all of the feed solutions was set at 25% and the inlet and outlet temperatures were maintained at 170 °C and 70 °C, respectively. Powder recovery was determined using a standard procedure and taken as an indicator of the surface stickiness. Coverage of the particle surface by the proteins was determined through elemental surface analysis and a nitrogen balance. It was found that in the absence of LMS, the proteins covered up to 55% of the particle surface and increased the powder recovery to between 84% and 85%. Formation of a glassy protein-rich film acts to reduce the surface stickiness of sucrose droplets. However, when LMS was added to the sucrose-protein solutions, the recovery dropped to zero in the case of Tween-80. In the case of Na-DS the recoveries ranged to 39% and 68%. At these recoveries 83% and 59% of the protein, respectively, was displaced from the surface. This drastic effect of surfactant types on the powder recovery is explained using the Orogenic Displacement model. © 2009 Elsevier Ltd. All rights reserved.
Effect of addition of proteins on the production of amorphous sucrose powder through spray drying
- Adhikari, Benu, Howes, Tony, Bhandari, Bhesh, Langrish, Tim
- Authors: Adhikari, Benu , Howes, Tony , Bhandari, Bhesh , Langrish, Tim
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Food Engineering Vol. 94, no. 2 (2009), p. 144 -153
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- Description: Spray drying trials were carried out to produce amorphous sucrose powder. Firstly, pure sucrose solutions were prepared and spray dried at inlet and outlet temperatures of 160 °C and 70 °C, respectively. No amorphous powder was obtained and only 18% of the feed solids were recovered in a crystalline form, with the remaining solids lost as wall deposits. Secondly, sodium caseinate (Na-C) and hydrolyzed whey protein isolate (WPI) were added in sucrose:protein solid ratios of (99.5:0.5) and (99.0:1.0) and drying trials were conducted maintaining the initial drying conditions. In both these cases, greater than 80% of the feed solids were recovered in an amorphous form. The increase in protein concentration from 0.5% to 1% on dry solid basis did not further improve the recovery. The remarkable increase in recovery from a small addition of protein is attributed to preferential migration of protein molecules to the droplet-air interface, and the subsequent transformation of the thin, protein-rich film into a non-sticky glassy state upon drying. This film overcomes both the particle-to-particle and particle-to-wall stickiness. The measured bulk glass rubber transition temperature (Tg-r) values of the bulk mixtures at various moisture contents were very close to the corresponding mean glass transition temperature (Tg) of the pure sucrose indicating that surface layer Tg rather than the bulk Tg is responsible for this. Electron spectroscopy for chemical analysis (ESCA) studies revealed that the particle surface was covered by 50-58% (by mass) proteins. The calculated glass transition temperature of the surface layer (Tg,surface layer), based on the surface elemental compositions, showed that the Tg,surface layer has increased to the extent that it remained within the safe drying envelope of spray drying. © 2009 Elsevier Ltd. All rights reserved.
- Authors: Adhikari, Benu , Howes, Tony , Bhandari, Bhesh , Langrish, Tim
- Date: 2009
- Type: Text , Journal article
- Relation: Journal of Food Engineering Vol. 94, no. 2 (2009), p. 144 -153
- Full Text:
- Reviewed:
- Description: Spray drying trials were carried out to produce amorphous sucrose powder. Firstly, pure sucrose solutions were prepared and spray dried at inlet and outlet temperatures of 160 °C and 70 °C, respectively. No amorphous powder was obtained and only 18% of the feed solids were recovered in a crystalline form, with the remaining solids lost as wall deposits. Secondly, sodium caseinate (Na-C) and hydrolyzed whey protein isolate (WPI) were added in sucrose:protein solid ratios of (99.5:0.5) and (99.0:1.0) and drying trials were conducted maintaining the initial drying conditions. In both these cases, greater than 80% of the feed solids were recovered in an amorphous form. The increase in protein concentration from 0.5% to 1% on dry solid basis did not further improve the recovery. The remarkable increase in recovery from a small addition of protein is attributed to preferential migration of protein molecules to the droplet-air interface, and the subsequent transformation of the thin, protein-rich film into a non-sticky glassy state upon drying. This film overcomes both the particle-to-particle and particle-to-wall stickiness. The measured bulk glass rubber transition temperature (Tg-r) values of the bulk mixtures at various moisture contents were very close to the corresponding mean glass transition temperature (Tg) of the pure sucrose indicating that surface layer Tg rather than the bulk Tg is responsible for this. Electron spectroscopy for chemical analysis (ESCA) studies revealed that the particle surface was covered by 50-58% (by mass) proteins. The calculated glass transition temperature of the surface layer (Tg,surface layer), based on the surface elemental compositions, showed that the Tg,surface layer has increased to the extent that it remained within the safe drying envelope of spray drying. © 2009 Elsevier Ltd. All rights reserved.
Drying kinetics and survival studies of dairy fermentation bacteria in convective air drying environment using single droplet drying
- Ghandi, Amir, Powell, Ian, Chen, Xiao Dong, Adhikari, Benu
- Authors: Ghandi, Amir , Powell, Ian , Chen, Xiao Dong , Adhikari, Benu
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Food Engineering Vol. 110, no. 3 (2012), p. 405-417
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- Description: The drying and survival kinetics of Lactococcus lactis ssp. cremoris in a convective air drying environment were measured using single droplet drying experiments. Tests were carried out at five different drying temperatures (45-95°C) at a constant air velocity (0.5 m/s) and within 2.4-11% relative humidity. The effect of protective agents (10% w/w) of lactose, sodium caseinate and lactose:sodium caseinate (3:1) was also evaluated. The thermal inactivation kinetics parameters in convective air drying and isothermal water bath heating were determined and compared. The results showed that the final temperature attained by the droplet affected the survival of the bacteria significantly, however, most of the bacterial death occurred in early stage of drying while evaporative cooling kept the drop temperature relatively low. At higher droplet temperatures (≥65°C) the bacterial cultures were inactivated by both dehydration and thermal stresses. At lower droplet temperatures (≤55°C) the rate of change in droplet moisture content had much stronger effect on the bacterial survival. Lactose and sodium caseinate, as protective agents, enhanced the survival of bacterial cells significantly at all the test conditions. The lactose:sodium caseinate (3:1) mixture synergistically enhanced the survival of the bacterial cultures. The death of these bacteria followed first-order kinetics during convective single droplet drying as well as during isothermal water-bath heating. However, the inactivation energy in convective single droplet drying (181.3 kJ/mol) was much higher than the inactivation energy in isothermal water bath heating (16.8 kJ/mol) within the medium temperature of 45-95°C. © 2012 Elsevier Ltd. All rights reserved.
- Authors: Ghandi, Amir , Powell, Ian , Chen, Xiao Dong , Adhikari, Benu
- Date: 2012
- Type: Text , Journal article
- Relation: Journal of Food Engineering Vol. 110, no. 3 (2012), p. 405-417
- Full Text:
- Reviewed:
- Description: The drying and survival kinetics of Lactococcus lactis ssp. cremoris in a convective air drying environment were measured using single droplet drying experiments. Tests were carried out at five different drying temperatures (45-95°C) at a constant air velocity (0.5 m/s) and within 2.4-11% relative humidity. The effect of protective agents (10% w/w) of lactose, sodium caseinate and lactose:sodium caseinate (3:1) was also evaluated. The thermal inactivation kinetics parameters in convective air drying and isothermal water bath heating were determined and compared. The results showed that the final temperature attained by the droplet affected the survival of the bacteria significantly, however, most of the bacterial death occurred in early stage of drying while evaporative cooling kept the drop temperature relatively low. At higher droplet temperatures (≥65°C) the bacterial cultures were inactivated by both dehydration and thermal stresses. At lower droplet temperatures (≤55°C) the rate of change in droplet moisture content had much stronger effect on the bacterial survival. Lactose and sodium caseinate, as protective agents, enhanced the survival of bacterial cells significantly at all the test conditions. The lactose:sodium caseinate (3:1) mixture synergistically enhanced the survival of the bacterial cultures. The death of these bacteria followed first-order kinetics during convective single droplet drying as well as during isothermal water-bath heating. However, the inactivation energy in convective single droplet drying (181.3 kJ/mol) was much higher than the inactivation energy in isothermal water bath heating (16.8 kJ/mol) within the medium temperature of 45-95°C. © 2012 Elsevier Ltd. All rights reserved.
- 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.
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