Adsorption layer and foam film properties of mixed solutions containing β-casein and C12DMPO

Kotsmar, Csaba; Arabadzhieva, D.; Khristov, Khr.; Mileva, Elena; Grigoriev, D. O.; Miller, R.; Exerowa, D.

doi:10.1016/j.foodhyd.2008.07.022

Cited by 17 publications

(22 citation statements)

References 49 publications

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“…As previously reported by Bhandari and Roos, interactions between ionic surfactants and the amino acids of the proteins are primarily electrostatic. When all polar binding sites are saturated (in our study for molar ratios > 10), further interaction takes place via hydrophobic interactions which leads to hydrophilization of the complexes and a decreased surface activity , which is consistent with decreasing surface pressure for high molar ratios.…”

Section: Resultssupporting

confidence: 82%

“…For that reason, a molecular understanding of protein–surfactant mixtures at interfaces is of great importance. So far mainly macroscopic quantities including surface tension, , interfacial dilational rheology, , ellipsometry, and thin film measurements were applied to surfactant–protein mixtures. − …”

Section: Introductionmentioning

confidence: 99%

“…4 For that reason, a molecular understanding of protein−surfactant mixtures at interfaces is of great importance. So far mainly macroscopic quantities including surface tension, 5,6 interfacial dilational rheology, 7,8 ellipsometry, 9 and thin film measurements 10 were applied to surfactant−protein mixtures. 11−13 Using these techniques, information on protein−surfactant interactions can only be deduced indirectly, and thus, a direct observation is still missing.…”

Section: ■ Introductionmentioning

confidence: 99%

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Mixed Layers of β-Lactoglobulin and SDS at Air–Water Interfaces with Tunable Intermolecular Interactions

et al. 2014

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Mixtures of β-lactoglobulin (BLG) and sodium dodecyl sulfate (SDS) were studied at pH 3.8 and 6.7 under equilibrium conditions. At these pH conditions, BLG carries either a positive or a negative net charge, respectively, which enables tunable electrostatic interactions between anionic SDS surfactants and BLG proteins. For pH 3.8, vibrational sum-frequency generation (SFG) and ellipsometry indicate strong BLG-SDS complex formation at air-water interfaces that is caused by attractive electrostatic interactions. The latter complexes are already formed in the bulk solution which was confirmed by a thermodynamic study of BLG-SDS mixtures using isothermal titration calorimetry (ITC). For acidic conditions we determine from our ITC data an exothermal binding enthalpy of -40 kJ mol(-1). Increasing SDS/BLG molar ratios above 10 leads to a surface excess of SDS and thus to a charge reversal from a positive net charge with BLG as the dominating surface adsorbed species to a negatively charged layer with SDS as the dominating surface species. The latter is evidenced by a pronounced minimum in SFG intensities that is also accompanied by a phase change of O-H stretching bands due to a reorientation of H2O within the local electric field. This phase change which occurs at SDS/BLG molar ratio between 1 and 10 causes a polarity change in SFG intensities from BLG aromatic C-H stretching vibrations. Conclusions from SFG spectra are corroborated by ellipsometry which shows a dramatic increase in layer thicknesses at molar ratios where a charge reversal occurs. The formation of interfacial multilayers comprising SDS-BLG complexes is, thus, caused by cancellation of electrostatic interactions which leads to agglomeration at the interface. In contrast to pH 3.8, behavior of BLG-SDS mixtures at pH 6.7 is different due to repulsive electrostatic interactions between SDS and BLG which lead to a significantly reduced binding enthalpy of -17 kJ mol(-1). Finally, it has to be mentioned that SFG spectra show a coexistence of BLG and SDS molecules at the interface for BLG-SDS molar ratios > 2.

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Section: Resultssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Mixed Layers of β-Lactoglobulin and SDS at Air–Water Interfaces with Tunable Intermolecular Interactions

et al. 2014

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“…The dynamics of adsorption of βCS in presence of different surfactants have been studied frequently during the past decade, however, mostly via traditional simultaneous adsorption. ,− There are limited studies on the sequentially formed mixed layers. For example βCS/C 12 DMPO (dodecyl dimethyl phosphine oxide) and βCS/SDS (sodium dodecyl sulfate) have been investigated in the recent years focusing on the difference of the interfacial behavior of the mixed adsorbed layers resulting from two different pathways, that is, simultaneous adsorption from mixed solution and sequential adsorption of the individual components.…”

Section: Introductionmentioning

confidence: 99%

Adsorption and Dilational Rheology of Mixed β-Casein/DoTAB Layers Formed by Sequential and Simultaneous Adsorption at the Water/Hexane Interface

et al. 2013

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The interfacial behavior of β-casein (βCS) has been investigated in presence of the cationic surfactant dodecyl trimethyl ammonium bromide (DoTAB) at the water/hexane interface and compared to that obtained for the water/air interface. The used experimental technique is a drop profile analysis tensiometer specially equipped with a coaxial double capillary, which allows investigation of sequential adsorption of individual components besides the traditional simultaneous adsorption of two species. This method also provides the dilational rheological measurements based on low frequency harmonic drop oscillations. The tensiometric results show that the equilibrium states of the mixed βCS/DoTAB layers built up on the two different routes do not differ significantly, that is, the general compositions of the mixed layers are similar. However, the results of dilational rheology for the two adsorption strategies are remarkably different indicating different dynamic characteristics of the adsorbed layers. These findings suggest that the respective mixed layers are more proteinlike if they are formed via sequential adsorption and more surfactant-like after simultaneous adsorption. In contrast to the W/A interface, at the W/H interface proteins remain at the interface once adsorbed and cannot be displaced just by competitive adsorption of surfactants.

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“…6 For multicomponent systems, recent studies have shown that natural proteins with large adsorption energies, such as b-casein and lysozyme, are not easily displaced from the air-water interface by competitive adsorption with a range of ionic or non-ionic surfactants. [7][8][9] Combined, these studies emphasise the value of experimental tools amenable to precise molecular change, to enable clearer structure-functionformulation delineation.…”

Section: Introductionmentioning

confidence: 99%

The effects of acid hydrolysis on protein biosurfactant molecular, interfacial, and foam properties: pH responsive protein hydrolysates

Dimitrijev-Dwyer

James

et al. 2012

Soft Matter

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Adsorption layer and foam film properties of mixed solutions containing β-casein and C12DMPO

Cited by 17 publications

References 49 publications

Mixed Layers of β-Lactoglobulin and SDS at Air–Water Interfaces with Tunable Intermolecular Interactions

Mixed Layers of β-Lactoglobulin and SDS at Air–Water Interfaces with Tunable Intermolecular Interactions

Adsorption and Dilational Rheology of Mixed β-Casein/DoTAB Layers Formed by Sequential and Simultaneous Adsorption at the Water/Hexane Interface

The effects of acid hydrolysis on protein biosurfactant molecular, interfacial, and foam properties: pH responsive protein hydrolysates

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