Immobilization of casein micelles for probing their structure and interactions with polysaccharides using scanning electron microscopy (SEM)

Martin, A.H.; Goff, H. Douglas; Smith, A.K.; Dalgleish, Douglas G.

doi:10.1016/j.foodhyd.2005.08.004

Cited by 80 publications

(91 citation statements)

References 27 publications

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“…MSD slopes decrease as the amount of κ-carrageenan increases, reaching values of 0.85 indicating a loss of the original mobility of the micelles and a tendency to a visco-elastic system. This decrease in the diffusion of the micelles is caused by the specific interactions of the charged polysaccharide with κ-casein on the surface of the casein micelles, and it has been previously reported 14,15 . High enough concentrations κ-carrageenan can create a self supporting gel and at 0.03% the polymer network allows the casein micelles to move only short distances.…”

Section: Resultssupporting

confidence: 52%

“…Previous reports, based on microstructural, DWS and ultrasonic analyses of milk with κ-carrageenan clearly demonstrated that κ-carrageenan chains interact with the casein micelles forming very loose bridges 14,15 . The results shown in Figure 4 support this view, and show that small amounts of polysaccharide already affected the general colloidal state of the system.…”

Section: Resultsmentioning

confidence: 94%

“…At pH around neutral, both casein micelles and κ-carrageenan carry a net negative charge; however, interactions between them occur via localized electrostatic attractions between the sulfated groups of the κ-carrageenan and a very short positively charged region of the κ-casein 10 . It has been previously shown that bridging between the casein micelles occurs via helix-helix interactions of the polysaccharide chains 15 , and there is still a significant mobility of the casein micelles in the system 14 .…”

Section: Introductionmentioning

confidence: 99%

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Phase Separation Behavior of Caseins in Milk Containing Flaxseed Gum and κ-Carrageenan: A Light-Scattering and Ultrasonic Spectroscopy Study

2010

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The physico-chemical properties of skim milk containing κ-carrageenan (in the concentration range 0-0.06% w/v), flaxseed gum (in the concentration range 0-0.40% w/v), or a mixture of both polysaccharides were studied using dynamic light scattering, under diluted conditions, as well as in situ, undiluted, using diffusing wave spectroscopy (DWS) and ultrasonic spectroscopy. Flaxseed gum causes phase separation in milk mixtures, because of thermodynamic incompatibility between the casein micelles and the polysaccharide chains. Confocal microscopy and ultrasonic spectroscopy showed that while the addition of 0.01% κ-carrageenan was not sufficient to hinder phase separation, when 0.03% was added, the helixhelix interactions between κ-carrageenan molecules were sufficient to form a network and stabilize the system. DWS clearly demonstrated that clusters of casein micelles still form even at very low concentrations of polysaccharides (below the visible phase separation threshold) and that κ-carrageenan hinders visible phase separation by decreasing the mobility of the casein micelles.

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Section: Resultssupporting

confidence: 52%

Section: Resultsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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Phase Separation Behavior of Caseins in Milk Containing Flaxseed Gum and κ-Carrageenan: A Light-Scattering and Ultrasonic Spectroscopy Study

2010

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“…16 Clean, dry, and polished carbon planchets (diameter 12.7 mm; Canemco & Marivac, Lakefield, QC, Canada) were sputter coated with thickness of ∼35 nm of Au/Pd (ratio 60:40; using an Emitech K550, Ashford, Kent, UK), directly immersed into a 2-mM solution of 11-mercaptoundecanoic acid in 100% ethanol and left for at least 18 h to form a self-assembled monolayer (SAM). The terminal carboxyl groups of the SAM were modified by carbodiimide chemistry using N hydroxysuccinimide and N-ethyl-N-(dimethyl-aminopropyl) carbodiimide.…”

Section: Microstructural Studiesmentioning

confidence: 99%

Influence of Cross-linked Waxy Maize Starch on the Aggregation Behavior of Casein Micelles During Acid-induced Gelation

et al. 2010

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The influence of cross-linked waxy maize starch on the aggregation behavior of casein micelles was investigated using a combination of physico-chemical techniques. Milk was homogenized at two different temperatures (55 and 65°C) and then heated at 95°C for 5 min in a pilot scale system. The possible interactions between modified starch and milk proteins during lactic acid fermentation were evaluated. While 1% starch did not show differences in the whey protein complexes formed during heating compared to milk with no starch (as measured by size exclusion chromatography), a higher (2.5%) concentration of starch clearly showed an increased amount of heat-induced whey protein aggregates. The gelation pH also increased significantly with 2.5% starch compared to that of the control samples. The storage modulus (G′) increased with increasing levels of starch, and confocal microscopy confirmed that the microstructure of the casein gels was altered by the presence of modified starch. Milk-starch mixtures preheated and homogenized at 55 or 65°C exhibited similar physico-chemical behavior during acidification. The results suggested a lack of interaction between starch granules and casein micelles during acidification, and scanning electron microscopy images collected with a self-assembled monolayer technique also confirmed that starch granules were not attached to milk caseins but only embedded in the protein gel matrix.

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“…Morphological and elasticity studies on the hierarchical networks of casein proteins have been carried out by AFM (Uricanu et al, 2004). Martin and his coworkers probed the interactions of casein micelles with polysaccharides using scanning electron microscopy on gold-coated surfaces (Martin et al, 2006). FTIR and light scattering experiments are also popular for studying the structure and stabilizing interactions of the micelles (Gebhardt et al, 2006.…”

Section: The Build-up Of Casein Micellesmentioning

confidence: 99%

Self-assembling macromulecules on surfaces

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Immobilization of casein micelles for probing their structure and interactions with polysaccharides using scanning electron microscopy (SEM)

Cited by 80 publications

References 27 publications

Phase Separation Behavior of Caseins in Milk Containing Flaxseed Gum and κ-Carrageenan: A Light-Scattering and Ultrasonic Spectroscopy Study

Phase Separation Behavior of Caseins in Milk Containing Flaxseed Gum and κ-Carrageenan: A Light-Scattering and Ultrasonic Spectroscopy Study

Influence of Cross-linked Waxy Maize Starch on the Aggregation Behavior of Casein Micelles During Acid-induced Gelation

Self-assembling macromulecules on surfaces

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