Abstract
Hydrophilic and hydrophobic (φ) interactions among amphiphiles play critical roles in interfacial properties of proteins and other smaller amphiphiles and affect the creation and stability of foams and emulsions in food systems. Contribution of small amphiphiles on H-bonding and hydrophobic (φ) interactions at a model interface comprising of a water-hydrophobized surface interface as reflected by contact angle (θ) of fatty acid free bovine serum albumin (FAF-BSA), bovine serum albumin (BSA), and β-lactoglobulin variant A (β-LGA) was investigated. Amphiphiles were used with either protein in neutral water or α-bromonaphtalene (α-BrN) (22°C) to obtain θ-H2O and θ-α-BrN measurements, respectively. θ-α-BrN reflected influence of φ-interactions on θ since α-BrN molecules do not partake significantly in H-bonding. Ionic nature of the amphiphiles had no significant effect. Dramatic difference was between zwitterionic Z8 and Z12. At 1%, Z8 significantly increased H-bonding in BSA and β-LGA by 26% and 55%, respectively, whereas Z12, which is more hydrophobic, decreased it by 50% and 21%. At the same concentration, φ-interactions were enhanced by Z8 for BSA by 37% and by all amphiphiles except Z12 for FAF-BSA.
Highlights
Amphiphiles are surface active molecules that are characterized in solution by their ability to populate interfacesZ
We have reported that solid-liquid (SL) contact angle measurements of a sessile drop, of various amphiphile containing dispersions, on a uniformly hydrophobized glass surface, were statistically comparable to the surface activity of the amphiphiles determined by other standard methods [5]
Data indicate significant changes in the way Bovine serum albumin (BSA) performed in the presence of surfactants compared to fatty acid free bovine serum albumin (FAF-BSA)
Summary
Surface-active agents such as emulsifiers and most food proteins have a molecular structure consisting of distinctly separate hydrophobic and hydrophilic zones. Presence of such hydrophobic zones in the interior of water causes distortion of its structure increasing energy of the system. Less work is needed to expel these zones compared to water molecules to the surface or interface resulting in increased surface activity of these agents [3] Their presence and size decreases work needed to create unit surface area; a phenomenon essential for foam and emulsion making. The subsequent article in this series looks at the influence of the same amphiphiles on the surface and energy and emulsifying properties of the same proteins [15]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
