The Self-Assembly and Structure of Caseins in Solution

Morris, Gordon A.

doi:10.1080/02648725.2002.10648034

Cited by 18 publications

(8 citation statements)

References 96 publications

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“…% lysine (see SWISS-Prot entries P02662, P02663, P02666 and P02668 for α s1 -, α s2 -, β-and κ-casein amino acid sequences, respectively -see also Morris, 2002), giving a theoretical value for free amino groups of 0.50 mmoles per gram, which is in good agreement abovevalue determined experimentally. A small reduction in free amino groups was observed following freeze-drying of the sodium caseinatemaltodextrin mixture, with a greater reduction upon heating at 60 °C for 2 days (Table 2).…”

Section: Conjugation Of Sodium Caseinate and Maltodextrinsupporting

confidence: 74%

“…The spread in molecular weights is due to the heterogeneity of casein and the polydispersity of the maltodextrin. This is further complicated in the "native" state (not denatured by SDS and urea) by concentration and structure dependent casein aggregation (Morris, 2002), which made it is impossible to determine molecular weights using size-exclusion chromatography.…”

Section: Discussionmentioning

confidence: 99%

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Investigation into the physical and chemical properties of sodium caseinate-maltodextrin glyco-conjugates

Morris¹,

Sims²,

Robertson³

et al. 2004

Food Hydrocolloids

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Casein-maltodextrin glyco-conjugates were prepared using an economical, foodgrade process based on the Amadori re-arrangement of the Maillard reaction.The resultant glyco-conjugates were slightly yellow in colour and the degree of discolouration was dependent on heating time. Formation of glyco-conjugates was demonstrated by determining the reduction of free amino-groups by the Ophthaldialdehyde (OPA) assay and sugar reducing ends by gas chromatography-mass spectrometry (GC-MS). Increases in molecular weight were monitored by SDSpolyacrylamide gel electrophoresis (PAGE) and were in agreement with those predicted for the conjugation of casein monomers with malto-oligosaccharides of average DP 7-10. 2D-Urea-SDS-PAGE demonstrated that both protein and saccharide components co-migrate, indicating that covalent bonds were upon heating.This resulted in increases in mass-to-charge ratio of the materials, which suggested decreases in pI. These observed chemical and physical changes were reconciled with previously documented improvements in emulsifying properties.

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Section: Conjugation Of Sodium Caseinate and Maltodextrinsupporting

confidence: 74%

Section: Discussionmentioning

confidence: 99%

Investigation into the physical and chemical properties of sodium caseinate-maltodextrin glyco-conjugates

Morris¹,

Sims²,

Robertson³

et al. 2004

Food Hydrocolloids

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“…28,57 In that case, an additional population of larger particles with an hydrodynamic diameter between 100 nm and 200 nm was observed that strongly correlates with our results. Aggregates of similar size are also found in pure κ-casein and β-casein solutions 12,58 and these structures were named as minimicelles (20 nm in diameter). 59 On Figure 3a, the micellar surface may suggest that the interior of the micelle could be readily accessible from its exterior.…”

Section: Casein Micelle Size Morphology and Repartition Associated Wmentioning

confidence: 95%

Multiscale Characterization of Casein Micelles Under NaCl Range Conditions

et al. 2011

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Micellar casein (MC) dispersions were studied at a constant protein concentration of 5 wt % in high NaCl environment. The micellar edifices were characterized as to their morphology, size, and content of proteins in the supernatant after ultracentrifugation. Additionally, changes in secondary structures of the protein upon salt increase were followed by Fourier Transform Infrared Spectroscopy (FTIR). For the first time, the estimations of secondary structural elements (irregular, ß-sheet, α-helix and turn) from Amide III assignments were correlated with results from Amide I. Casein micelles dispersions in water were characterized by Transmission Electron Microscopy (TEM) by a spherical shape and a size between 100 and 200 nm. A salt increase resulted to a destabilization of the micelle and the formation of mini-micelles more or less aggregated. The size of the new edifice was almost similar to the native micelle. These TEM observations were confirmed by a constant casein micelle hydrodynamic diameter determined by Dynamic Light Scattering (DLS) and ranging between 150 and 180 nm. Upon salt increase, FTIR revealed an increase in irregular structures and a concurrent decrease in ß-sheet structures. Secondary structural elements percentages were almost similar from Amide I and Amide III. The use of these multiscale techniques led to a better understanding of the micellar edifice under high salt environment. Around 3% NaCl addition, a good correlation was observed between destabilization of the micellar edifice, modifications of the caseins secondary structure and repartition of caseins between supernatant and pellet after ultracentrifugation.

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“…Biopolymer particles can be constructed from proteins and polysaccharides based on a number of different physicochemical phenomena that utilize either single or mixed biopolymer systems. Caseins, a group of proteins from milk, naturally assemble into nanometer‐sized micelles through a combination of hydrophobic attraction and salt bridge formation (de Kruif 1999; Morris 2002; Dalgleish and others 2004). Globular proteins from whey, egg, and soy can be induced to form biopolymer particles under conditions where protein–protein interactions are favored, but the protein concentration is not high enough to form a gel, for example, by heating, pH adjustment, and/or addition of salts (Hoffmann and van Mil 1997, 1999; Verheul and others 1998; Le Bon and others 1999; Broersen and others 2006; Akkermans and others 2007; Schmitt and others 2007).…”

Section: Introductionmentioning

confidence: 99%

Core‐Shell Biopolymer Nanoparticles Produced by Electrostatic Deposition of Beet Pectin onto Heat‐Denatured β‐Lactoglobulin Aggregates

Santipanichwong¹,

Suphantharika²,

Weiß³

et al. 2008

Journal of Food Science

101

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The purpose of this study was to produce and characterize core-shell biopolymer particles based on electrostatic deposition of an anionic polysaccharide (beet pectin) onto amphoteric protein aggregates (heat-denatured beta-lactoglobulin [beta-lg]). Initially, the optimum conditions for forming stable protein particles were established by thermal treatment (80 degrees C for 15 min) of 0.5 wt% beta-lg solutions at different pH values (3 to 7). After heating, stable submicron-sized (d=100 to 300 nm) protein aggregates could be formed in the pH range from 5.6 to 6. Core-shell biopolymer particles were formed by mixing a suspension of protein aggregates (formed by heating at pH 5.8) with a beet pectin solution at pH 7 and then adjusting the pH to values where the beet pectin is adsorbed (< pH 6). The impact of pH (3 to 7) and salt concentration (0 to 250 mM NaCl) on the properties of the core-shell biopolymer particles formed was then established. The biopolymer particles were stable to aggregation from pH 4 to 6, but aggregated at lower pH values because they had a relatively small -potential. The biopolymer particles remained intact and stable to aggregation up to 250 mM NaCl at pH 4, indicating that they had good salt stability. The core-shell biopolymer particles prepared in this study may be useful for encapsulation and delivery of bioactive food components or as substitutes for lipid droplets.

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The Self-Assembly and Structure of Caseins in Solution

Abstract: Caseins are defined as the group of phosphoproteins from milk which are precipitated at pH 4.6 and 20 C and were first separated in the 1950s (

Cited by 18 publications

References 96 publications

Investigation into the physical and chemical properties of sodium caseinate-maltodextrin glyco-conjugates

Investigation into the physical and chemical properties of sodium caseinate-maltodextrin glyco-conjugates

Multiscale Characterization of Casein Micelles Under NaCl Range Conditions

Core‐Shell Biopolymer Nanoparticles Produced by Electrostatic Deposition of Beet Pectin onto Heat‐Denatured β‐Lactoglobulin Aggregates

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