Effect of ethanol on the stability of sodium caseinate stabilised emulsions

Abstract

Proteins are commonly used as emulsifying agent in food applications, although they are highly affected by their environment, with the presence of ethanol being just one parameter known to influence their properties. An increasing level of ethanol is expected to result in a reduced emulsification efficiency of the protein and, therefore, emulsion processing in the absence of this solvent should lead to more stable oil-in-water emulsions. Sodium caseinate was either dispersed in the presence or absence of heat and/or ethanol and multiple physicochemical properties of the resulting protein aggregates were determined. Further, oil-in-water emulsions were created in a microfluidizer at varying levels of ethanol in the aqueous phase and two different points of its addition in the processing route. The resulting emulsion properties were investigated. Stable oil-in-water emulsions could be prepared at each applied ethanol level (≤50 wt%) and for both examined processing routes. The point of ethanol addition only had an impact if the concentration of this solvent was higher than 25 wt% - with a processing in absence of ethanol being beneficial. This concentration was also found to be a threshold for the interactions between ethanol and dispersed sodium caseinate as higher ethanol levels resulted in significantly changed protein properties.