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Complexes of β-lactoglobulin and high methyl-esterified pectin as a one-shot delivery system for reinforcing oil/water interfaces

Electrostatic complexation of negatively charged polysaccharides with β-lactoglobulin (β-lg) has been shown to bolster the protein films at oil/water interfaces thereby improving emulsion stability. However, recent sub-phase exchange experiments demonstrated that highly charged polysaccharides such...

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Bibliographic Details
Published in:Soft matter 2021-09, Vol.17 (37), p.8517-8522
Main Authors: Ramamirtham, Sashikumar, Williams, Martin A.K, Zare, Davoud, Weeks, Mike, Whitby, Catherine P
Format: Article
Language:English
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Summary:Electrostatic complexation of negatively charged polysaccharides with β-lactoglobulin (β-lg) has been shown to bolster the protein films at oil/water interfaces thereby improving emulsion stability. However, recent sub-phase exchange experiments demonstrated that highly charged polysaccharides such as low methyl-esterified pectin are complementary only if sequentially introduced to a pre-formed interfacial β-lg film. In this study, results of transient interfacial shear rheology show that, by using high-methylesterified pectins instead, complexes can be formed in pre-mixed solutions with β-lg at pH 4 that can lead to reinforced protein films at dodecane/water interfaces. Using this one-shot adsorption of such complexes, pectins as well as short chain polysaccharides like homogalacturonan nearly doubled the steady state shear elastic moduli as compared to that of a pure β-lg film. The lag times of film formation were established to be primarily decided by the charge density and pattern on the polysaccharide. Based on the results from mixed solutions of β-lg monomers, it is proposed that the polysaccharide at pH 4 strengthens the resulting interfacial layer by concatenating adsorbed β-lg molecules thereby establishing cross-links in the aqueous phase. Once protein-polysaccharide complexes reach the interface, proteins adsorb while remaining electrostatically bonded to the polysaccharide. The polysaccharide reinforces the interfacial film by linking the adsorbed protein molecules together.
ISSN:1744-683X
1744-6848
DOI:10.1039/d1sm00989c