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Effect of ionic strength on the interfacial viscoelasticity and stability of silk fibroin at the oil/water interface
Author(s) -
Tang Xiaoxiao,
Qiao Xiuying,
Miller Reinhard,
Sun Kang
Publication year - 2016
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.7829
Subject(s) - fibroin , viscoelasticity , silk , interface (matter) , materials science , composite material , ionic strength , chemical engineering , polymer science , chemistry , engineering , wetting , organic chemistry , aqueous solution , sessile drop technique
BACKGROUND The amphiphilic character and surface activity endows silk fibroin with the ability to reside at fluid interfaces and effectively stabilize emulsions. However, the influence of relevant factors and their actual effect on the interfacial viscoelasticity and stability of silk fibroin at the oil/water interface has received less attention. In the present study, the effect of ionic strength on the interfacial viscoelasticity, emulsification effectiveness and stability of silk fibroin at the oil/water interface was investigated in detail. RESULTS A higher ion concentration facilitates greater adsorption, stronger molecular interaction and faster structure reorganization of silk fibroin at the oil/water interface, thus causing quicker interfacial saturation adsorption, greater interfacial strength and lower interfacial structural fracture on large deformation. However, the presence of concentrated ions screens the charges in silk fibroin molecules and the zeta potential decreases as a result of electrostatic screening and ion‐binding effects, which may result in emulsion droplet coalescence and a decrease in emulsion stability. CONCLUSION The positively‐charged ions significantly affect the interfacial elasticity and stability of silk fibroin layers at the oil/water interface as a result of the strong electrostatic interactions between counter‐ions and the negatively‐charged groups of silk fibroin. © 2016 Society of Chemical Industry