Effect of the konjac glucomannan concentration on the rheological behaviour and stability of sodium caseinate oil-in-water emulsions

Abstract

The objective of this study was to quantify the effect of konjac glucomannan (KGM) on the rheological properties, particle size, and stability of sodium caseinate oil-in-water emulsions, proposed as model emulsions using milk proteins and an alternative thickening hydrocolloid with beneficial properties. Rheology of aqueous phases was investigated since it could contribute to emulsion properties. Liquid-like behaviour was observed in the aqueous phase mixtures, as the KGM rheology; however, emulsions showed solid-like behaviour, associated with a weak emulsion gel network formed by a depletion-flocculation phenomenon. Under flow conditions, the aqueous mixtures showed shear-thinning behaviour and zero-shear viscosity like KGM aqueous solutions, while emulsions at high shear rates were fitted to the Ostwald-de Waele relationship. The instability processes observed were quantified using the time at which clarification began and clarification rate. Emulsions containing 0.75% KGM or higher reduced gravity-induced creaming and phase separation up to 32 days.