Effect of Ionic Strength and Activity Coefficient of Polyvalent Ionic Salt Solution on Demulsification of Soy Lecithin Based Oil-in-Water Emulsion
Current Topics and Emerging Issues in Chemical Science Vol. 1,
4 July 2023,
Oil-in-Water (O/W) emulsions based on lecithin have numerous applications in the food and cosmetic sectors. The stability and physicochemical properties of food grade emulsion play a key role in determining the application of the emulsion. The stability of an O/W emulsion is determined by the emulsifying solution's characteristics as well as the presence of ionic contaminants. The current experiment clearly demonstrated the importance of polyvalent Lewis acid salt solution in creating emulsion stability. Lewis acid salts solutions of NaCl, KNO3 BaCl2 MgCl2, Al2(SO4)3 and FeCl3 were implemented in the production of lecithin based O/W emulsion. The ionic activity coefficient measured from Debye-Hückel limiting law (DHLL) for Lewis metal ions Na+, K+, Ba2+, Mg2+, Al3+ and Fe3+ were found to decrease the pH value of the ionic solutions. As the ionic activity coefficient falls, the conductance of an ionic solution rises. The lecithin O/W emulsion is severely destabilized by these patterns, which also reveal a substantial order in the breakage times of various emulsion systems. Microscopic analysis accurately predicted the influence of ionic activity coefficient on emulsion instability. Droplet diameter was measured for monovalent and divalent metal ions ranging from 12-160 micrometers, and the number of larger droplets increased with increasing valence. Higher valence Al3+ and Fe3+ ionic solutions, on the other hand, completely shatter the emulsion with fast separation of the oil and water layers and lower activity coefficients. Thus, the emulsifying solution's enhanced valence and conductance, reduced ionic activity coefficient, and pH value considerably destabilize the soy lecithin-based O/W emulsion by increasing interfacial tension and retarding the emulsifier's binding capacity.