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David Pearce - One of the best experts on this subject based on the ideXlab platform.
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Surface Composition of industrial spray-dried milk powders. 3. Changes in the Surface Composition during long-term storage
Journal of Food Engineering, 2009Co-Authors: Esther H.-J. Kim, David PearceAbstract:The changes in the Surface Composition of industrial spray-dried milk powders (skim milk powder, whole milk powder and cream powder) during long-term storage were investigated. The powders were stored in the conditions, which are more likely for commercial circumstances, for 6 months and the Surface Composition of the powders was analyzed before and after storage using electron spectroscopy for chemical analysis (ESCA). For the fat-containing powders (whole milk powder and cream powder), the various milk fat fractions (Surface free-fat, inner free-fat and encapsulated fat) were also extracted before and after storage, and analyzed for their fatty acid and triglyceride Compositions to evaluate whether there was a release of fat onto the powder Surface during storage and if this causes changes in the melting characteristics of the fat present on the powder Surface. The structure of the powders and the physical state of the lactose present in the powder were studied before and after storage by scanning electron microscopy (SEM) and X-ray diffractometer (XRD), respectively. The results showed that the lactose present in the powders remained in the amorphous state over the storage, and therefore no significant changes in structure and Surface Composition of the powders occurred. However, a release of encapsulated low-melting triglycerides towards the Surface of powder during storage was observed in the fat-containing powders, thereby the melting points of the Surface free-fat and the inner free-fat were lowered. This phenomenon was observed in both whole milk powder and cream powder, but more significant changes were observed in CP.
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Surface Composition of industrial spray-dried milk powders. 1. Development of Surface Composition during manufacture
Journal of Food Engineering, 2009Co-Authors: Esther H.-J. Kim, David PearceAbstract:Development of the Surface Composition of milk powders during manufacture was investigated in three industrial spray-dried milk powders (skim milk powder, whole milk powder and instant whole milk powder). Samples were obtained from commercial production plants and were collected at different manufacturing stages. As the powder properties of milk powder are defined in spray-drying and the subsequent manufacturing processes, the powder samples were collected at the exit of the spray drying chamber and the exit(s) of the fluidized bed(s), and the Surface Compositions of the powder samples collected were studied using electron spectroscopy for chemical analysis (ESCA). For all three industrial spray-dried milk powders, no significant differences in Surface Composition were observed between the samples collected at different manufacturing stages, except for a slight increase (3%) in the Surface fat coverage for whole milk powder after the fluidized bed drying process. These results indicate that the Surface Composition of milk powders is determined to a large extent during the spray drying process and that the subsequent fluidized bed drying and handling processes have no or little effect on the Surface Composition of milk powders, even though these processes affect the final powder quality (e.g. moisture content, particle size). For whole milk powder and instant whole milk powder, no fat appeared to leak out on to the powder Surface during the fluidized bed drying process; however, the fat present on the powder Surface after the spray-drying process appeared to flow over the particle Surfaces, resulting in a slight increase in the Surface fat coverage. After lecithin treatment (instantization), because a mixture of lecithin and anhydrous milk fat was sprayed on the powder, a slight increase in the thickness of the Surface fat layer was observed.
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effect of Surface Composition on the flowability of industrial spray dried dairy powders
Colloids and Surfaces B: Biointerfaces, 2005Co-Authors: Xiao Dong Chen, David PearceAbstract:The Surface Composition of four industrial spray-dried dairy powders (skim milk powder, whole milk powder, cream powder and whey protein concentrate) was estimated by electron spectroscopy for chemical analysis (ESCA), and its influence on powder flowability was studied. It was found that skim milk powder flows well compared to the other powders because the Surface is made of lactose and protein with a small amount of fat, whereas the high Surface fat Composition inhibits the flow of whole milk, cream and whey protein powders. However, the poor flowability of the powders with high Surface fat coverage was drastically improved by removal of fat present on the Surface through a brief wash with petroleum ether. The results obtained indicate that, although there are several parameters including particle size, which influence the flowability of powders, the flowability of powders is strongly influenced by the Surface Composition of powders, particularly for fat-containing powders.
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Surface characterization of four industrial spray dried dairy powders in relation to chemical Composition structure and wetting property
Colloids and Surfaces B: Biointerfaces, 2002Co-Authors: Esther H.-J. Kim, Dong X Chen, David PearceAbstract:The Surface Composition of powders is expected to play an important role during its end use. Understanding the mechanism of the powder Surface formation in terms of the Compositional aspect and the ability to control the Surface Composition will be highly useful in milk powder quality improvement and new product development. For a preliminary study, the Surface Compositions of four industrial spray-dried dairy powders (skim milk powder, whole milk powder, cream powder and whey protein concentrate) manufactured for consumer use, were studied by means of electron spectroscopy for chemical analysis (ESCA). It was found that all the powders have relatively high Surface fat coverage. In order to verify these results and to demonstrate the usefulness of ESCA in analysing the Surface Composition of dairy powders, fresh powders and fat extracted powders were subjected to the following experiments: measurement of powder Surface Composition, Surface structure studies, fat localization studies, wetting test and measurements of Surface oxygen uptake during storage. The results obtained indicate that the ESCA measurements are very reliable and the Surface Composition of the industrial spray-dried dairy powders estimated by ESCA is also expected to be reliable. In addition, the results showed fat globules encapsulated by protein or proteins are preferentially located underneath the Surface fat.
Esther H.-J. Kim - One of the best experts on this subject based on the ideXlab platform.
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Surface Composition of industrial spray-dried milk powders. 2. Effects of spray drying conditions on the Surface Composition.
Journal of Food Engineering, 2009Co-Authors: Esther H.-J. Kim, Xiao Dong Chen, David L. PearceAbstract:The effects of various spray drying conditions (feed solids content, drying temperature, degree of homogenization and initial droplet size) on the Surface Composition of industrial spray-dried milk powders (skim milk powder and whole milk powder) were investigated. Experiments were performed in a laboratory-scale spray drier and the Surface Compositions of the powders were measured using electron spectroscopy for chemical analysis (ESCA). For whole milk powder, the amount of Surface free-fat was also measured as a complement to the Surface Composition estimated using ESCA. For both skim milk powder and whole milk powder, the Surface Composition of the powders was found to be determined to a large extent by the spray drying conditions employed. At higher feed solids content or drying temperature, less fat and protein appeared on the Surface of the powders. Less redistribution of components seemed to occur within the drying droplet because of high viscosity and rapid crust formation. Increasing the number of homogenization passes reduced the fat globule size and consequently the amount of fat present on the powder Surface. The initial droplet size did not have a significant effect on the range of particle sizes studied in this work. Strong interaction effects between the spray drying conditions were also found. The results suggest that a combination of spray drying conditions is necessary to control the Surface Composition of milk powders. Possible mechanisms behind the formation of the Surface Composition of industrial spray-dried milk powders were proposed based on the findings in this work and theoretical considerations.
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Surface Composition of industrial spray-dried milk powders. 3. Changes in the Surface Composition during long-term storage
Journal of Food Engineering, 2009Co-Authors: Esther H.-J. Kim, David PearceAbstract:The changes in the Surface Composition of industrial spray-dried milk powders (skim milk powder, whole milk powder and cream powder) during long-term storage were investigated. The powders were stored in the conditions, which are more likely for commercial circumstances, for 6 months and the Surface Composition of the powders was analyzed before and after storage using electron spectroscopy for chemical analysis (ESCA). For the fat-containing powders (whole milk powder and cream powder), the various milk fat fractions (Surface free-fat, inner free-fat and encapsulated fat) were also extracted before and after storage, and analyzed for their fatty acid and triglyceride Compositions to evaluate whether there was a release of fat onto the powder Surface during storage and if this causes changes in the melting characteristics of the fat present on the powder Surface. The structure of the powders and the physical state of the lactose present in the powder were studied before and after storage by scanning electron microscopy (SEM) and X-ray diffractometer (XRD), respectively. The results showed that the lactose present in the powders remained in the amorphous state over the storage, and therefore no significant changes in structure and Surface Composition of the powders occurred. However, a release of encapsulated low-melting triglycerides towards the Surface of powder during storage was observed in the fat-containing powders, thereby the melting points of the Surface free-fat and the inner free-fat were lowered. This phenomenon was observed in both whole milk powder and cream powder, but more significant changes were observed in CP.
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Surface Composition of industrial spray-dried milk powders. 1. Development of Surface Composition during manufacture
Journal of Food Engineering, 2009Co-Authors: Esther H.-J. Kim, David PearceAbstract:Development of the Surface Composition of milk powders during manufacture was investigated in three industrial spray-dried milk powders (skim milk powder, whole milk powder and instant whole milk powder). Samples were obtained from commercial production plants and were collected at different manufacturing stages. As the powder properties of milk powder are defined in spray-drying and the subsequent manufacturing processes, the powder samples were collected at the exit of the spray drying chamber and the exit(s) of the fluidized bed(s), and the Surface Compositions of the powder samples collected were studied using electron spectroscopy for chemical analysis (ESCA). For all three industrial spray-dried milk powders, no significant differences in Surface Composition were observed between the samples collected at different manufacturing stages, except for a slight increase (3%) in the Surface fat coverage for whole milk powder after the fluidized bed drying process. These results indicate that the Surface Composition of milk powders is determined to a large extent during the spray drying process and that the subsequent fluidized bed drying and handling processes have no or little effect on the Surface Composition of milk powders, even though these processes affect the final powder quality (e.g. moisture content, particle size). For whole milk powder and instant whole milk powder, no fat appeared to leak out on to the powder Surface during the fluidized bed drying process; however, the fat present on the powder Surface after the spray-drying process appeared to flow over the particle Surfaces, resulting in a slight increase in the Surface fat coverage. After lecithin treatment (instantization), because a mixture of lecithin and anhydrous milk fat was sprayed on the powder, a slight increase in the thickness of the Surface fat layer was observed.
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Surface characterization of four industrial spray dried dairy powders in relation to chemical Composition structure and wetting property
Colloids and Surfaces B: Biointerfaces, 2002Co-Authors: Esther H.-J. Kim, Dong X Chen, David PearceAbstract:The Surface Composition of powders is expected to play an important role during its end use. Understanding the mechanism of the powder Surface formation in terms of the Compositional aspect and the ability to control the Surface Composition will be highly useful in milk powder quality improvement and new product development. For a preliminary study, the Surface Compositions of four industrial spray-dried dairy powders (skim milk powder, whole milk powder, cream powder and whey protein concentrate) manufactured for consumer use, were studied by means of electron spectroscopy for chemical analysis (ESCA). It was found that all the powders have relatively high Surface fat coverage. In order to verify these results and to demonstrate the usefulness of ESCA in analysing the Surface Composition of dairy powders, fresh powders and fat extracted powders were subjected to the following experiments: measurement of powder Surface Composition, Surface structure studies, fat localization studies, wetting test and measurements of Surface oxygen uptake during storage. The results obtained indicate that the ESCA measurements are very reliable and the Surface Composition of the industrial spray-dried dairy powders estimated by ESCA is also expected to be reliable. In addition, the results showed fat globules encapsulated by protein or proteins are preferentially located underneath the Surface fat.
Björn Bergenståhl - One of the best experts on this subject based on the ideXlab platform.
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Surface Composition of spray dried milk protein stabilised emulsions in relation to pre heat treatment of proteins
Colloids and Surfaces B: Biointerfaces, 2001Co-Authors: Anna Millqvistfureby, Ulla M Elofsson, Björn BergenståhlAbstract:Abstract Several important technical properties of spray-dried food powders depend on particle–liquid interactions (e.g. wettability, dispersability) and particle–particle interactions (e.g. flowability). It can be assumed that the chemical Composition of the Surface layer of the particles to a large extent determine these properties. The present study has been aimed to investigate the relation between the Surface Composition of spray-dried milk protein-stabilised emulsions and pre-heat treatment of the proteins. Solutions of WPC were heat-treated at low (60–90°C) and high (140°C) temperature and the degree of denaturation was determined, prior to the preparation of emulsions with rapeseed oil. The Surface Composition of the dry powders were established by using ESCA (electron spectroscopy of chemical analysis). The emulsions were characterised by droplet size distribution before spray drying and after dissolution of the powders. Also free fat extractions and estimations of wettability (dissolution rates) were performed. The powder Surface coverage of protein decreased with increasing degree of protein denaturation before the emulsification, whereas the emulsion droplet size increased both before spray drying and after reconstitution of powders. The free fat extraction as well as the dissolution rate, whereof the latter decreased with increasing Surface fat coverage, correlated well with the fat coverage of the powder Surface.
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spray dried whey protein lactose soybean oil emulsions 1 Surface Composition and particle structure
Food Hydrocolloids, 1996Co-Authors: Pia Fäldt, Björn BergenståhlAbstract:Abstract Emulsions made of whey protein, lactose and soybean oil were spray-dried and the chemical Surface Composition of the dried powders estimated by electron spectroscopy for chemical analysis. In particular, the ability of whey protein to encapsulate fat was highlighted. Additionally, the structure of the spray-dried powder particles was studied by scanning electron microscopy. The powders were examined after storage in both dry and humid atmospheres (relative humidity 75%, 4 days). It was found that the ability of whey protein to encapsulate soybean oil is rather low compared with sodium caseinate, with a large part of the powder Surface covered by fat after spray-drying. After storage in humid atmosphere there is a release of encapsulated oil onto the powder Surface in most cases, and an increase in fat coverage. The release offat onto the powder Surfaces causes the particle structure to change dramatically for powders containing a critical amount of lactose. Such powders agglomerate and lose structure completely. In comparison, powders containing no lactose storage under humid conditions also cause a release of fat onto the powder; however, in this case particle structure remains intact. Powders containing only a small amount of lactose, up to ~25% of emulsion dry weight, do not exhibit the release of fat onto the powder Surfaces after storage under humid conditions and the structure of these powder particles does not change. The presence of lactose in whey protein-stabilized emulsions, however, does not increase fat encapsulation by whey protein, as reported earlier for sodium caseinate-stabilized emulsions that were spray-dried. During spray-drying of whey protein/lactose solutions there is a strong overrepresentation of Surface-active whey protein on the powder Surface. Whey protein coverage increases even further when the powders are stored under humid conditions, also making them lose structure.
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changes in Surface Composition of spray dried food powders due to lactose crystallization
Lwt - Food Science and Technology, 1996Co-Authors: Pia Fäldt, Björn BergenståhlAbstract:Abstract The Surface Composition of spray-dried lactose-containing powders was estimated by electron spectroscopy for chemical analysis (ESCA), and particle structure was studied by scanning electron microscopy before and after storage in a humid atmosphere. The Surface Composition of dry powders made from lactose/sodium caseinate solutions was nearly identical to that of powders stored at 75% relative humidity for 4 d. Protein started to dominate the powder Surface even when it was present at only low solution concentrations. The particle structure after storage in a humid atmosphere was completely changed even though the Surface Composition remained relatively unchanged. When soybean oil emulsions with sodium caseinate and lactose were spray-dried, protein was over-represented on the powder Surface. If the protein concentration was sufficiently high, the fat was almost completely encapsulated. In the case of the powders with high lactose content almost total release of encapsulated fat on the powder Surface was observed after storage in a humid atmosphere. When the lactose concentration was lower, release of fat on the powder Surface was less pronounced. The structure of fat-containing powders was studied by scanning electron microscopy. Before storage in a humid atmosphere, particles were discrete with smooth Surfaces. As the fat was released onto the powder Surface, the powder became highly agglomerated and attained a smooth structure.
Xiao Dong Chen - One of the best experts on this subject based on the ideXlab platform.
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a continuum approach modeling of Surface Composition and ternary component distribution inside low fat milk emulsions during single droplet drying
Aiche Journal, 2017Co-Authors: Aditya Putranto, Martin Foerster, Cordelia Selomulya, Xiao Dong ChenAbstract:Surface Composition of dairy powders plays an important role in determining the functionality. However, the Surface Composition may be different from the bulk Composition because of component migration during drying. In this study, a comprehensive mathematical model has been developed to describe the phenomena. To the best of our knowledge, it is the first mathematical model which predicts the dynamics of Surface Composition during drying. The model consists of a set of equations of conservation of mass of water, lactose, protein and fat as well as conservation of heat and momentum in which the effects of diffusion induced material migration (DIMM) and Surface activity are incorporated. This model is applicable to describe the kinetics of Surface Composition of dairy droplets during drying. It suggests that both diffusion and protein Surface activity govern the component segregation during drying. The study indicates that the model implementing the measured initial Surface Composition as the initial conditions generates more realistic profiles than the one using the bulk Composition. The modeling confirms that the difference between the Surface and bulk Composition that occurs prior to drying is not primarily governed by diffusion, but the emulsion's atomization behaviour seems to play an essential role in the overrepresentation of fat. This article is protected by copyright. All rights reserved.
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Surface Composition of industrial spray-dried milk powders. 2. Effects of spray drying conditions on the Surface Composition.
Journal of Food Engineering, 2009Co-Authors: Esther H.-J. Kim, Xiao Dong Chen, David L. PearceAbstract:The effects of various spray drying conditions (feed solids content, drying temperature, degree of homogenization and initial droplet size) on the Surface Composition of industrial spray-dried milk powders (skim milk powder and whole milk powder) were investigated. Experiments were performed in a laboratory-scale spray drier and the Surface Compositions of the powders were measured using electron spectroscopy for chemical analysis (ESCA). For whole milk powder, the amount of Surface free-fat was also measured as a complement to the Surface Composition estimated using ESCA. For both skim milk powder and whole milk powder, the Surface Composition of the powders was found to be determined to a large extent by the spray drying conditions employed. At higher feed solids content or drying temperature, less fat and protein appeared on the Surface of the powders. Less redistribution of components seemed to occur within the drying droplet because of high viscosity and rapid crust formation. Increasing the number of homogenization passes reduced the fat globule size and consequently the amount of fat present on the powder Surface. The initial droplet size did not have a significant effect on the range of particle sizes studied in this work. Strong interaction effects between the spray drying conditions were also found. The results suggest that a combination of spray drying conditions is necessary to control the Surface Composition of milk powders. Possible mechanisms behind the formation of the Surface Composition of industrial spray-dried milk powders were proposed based on the findings in this work and theoretical considerations.
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effect of Surface Composition on the flowability of industrial spray dried dairy powders
Colloids and Surfaces B: Biointerfaces, 2005Co-Authors: Xiao Dong Chen, David PearceAbstract:The Surface Composition of four industrial spray-dried dairy powders (skim milk powder, whole milk powder, cream powder and whey protein concentrate) was estimated by electron spectroscopy for chemical analysis (ESCA), and its influence on powder flowability was studied. It was found that skim milk powder flows well compared to the other powders because the Surface is made of lactose and protein with a small amount of fat, whereas the high Surface fat Composition inhibits the flow of whole milk, cream and whey protein powders. However, the poor flowability of the powders with high Surface fat coverage was drastically improved by removal of fat present on the Surface through a brief wash with petroleum ether. The results obtained indicate that, although there are several parameters including particle size, which influence the flowability of powders, the flowability of powders is strongly influenced by the Surface Composition of powders, particularly for fat-containing powders.
Mingshu Chen - One of the best experts on this subject based on the ideXlab platform.
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disclosure of the Surface Composition of tio2 supported gold palladium bimetallic catalysts by high sensitivity low energy ion scattering spectroscopy
ACS Catalysis, 2018Co-Authors: Yangyang Li, Yanping Zheng, Jun Hu, Mingshu ChenAbstract:It is well-known that there is a critical relationship between the Surface Composition and activity for a bimetallic catalyst. However, the Surface is normally reconstructed under different conditions, which makes the Surface more complicated. In this work, TiO2-supported colloidal PdxAuy-NPs with different atomic ratios were prepared and treated under oxidation, reduction, and actual catalytic reaction conditions. The Surface Composition and structure were measured using X-ray photoelectron spectroscopy (XPS) and high-sensitivity low-energy ion scattering spectroscopy (HS-LEIS). Phase diagrams of the Surface Compositions under various conditions as a function of the bulk Composition were established. Oxidation induces dealloying and enrichment of PdO on the Surface, while H2 reduction results in realloying with just slight Surface enrichment of Pd. Gold helps Pd to resist oxidation and enhances its activity for CO oxidation at low temperature.
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Disclosure of the Surface Composition of TiO2‑Supported Gold–Palladium Bimetallic Catalysts by High-Sensitivity Low-Energy Ion Scattering Spectroscopy
2018Co-Authors: Yanping Zheng, Mingshu Chen, Huilin WanAbstract:It is well-known that there is a critical relationship between the Surface Composition and activity for a bimetallic catalyst. However, the Surface is normally reconstructed under different conditions, which makes the Surface more complicated. In this work, TiO2-supported colloidal PdxAuy-NPs with different atomic ratios were prepared and treated under oxidation, reduction, and actual catalytic reaction conditions. The Surface Composition and structure were measured using X-ray photoelectron spectroscopy (XPS) and high-sensitivity low-energy ion scattering spectroscopy (HS-LEIS). Phase diagrams of the Surface Compositions under various conditions as a function of the bulk Composition were established. Oxidation induces dealloying and enrichment of PdO on the Surface, while H2 reduction results in realloying with just slight Surface enrichment of Pd. Gold helps Pd to resist oxidation and enhances its activity for CO oxidation at low temperature
