Influence of xanthan gum on the formation and stability of sodium caseinate oil-in-water emulsions

Studies have been made of the changes in droplet sizes, surface coverage an d creaming stability of emulsions formed with 30% (w/w) soya oil, and aqueo us solution containing 1 or 3% (w/w) sodium cascinate and varying concentra tions of xanthan gum. Addition of xanthan prior to homogenization had no si gnificant effect on average emulsion droplet size and surface protein conce ntration in all emulsions studied. However, addition of low levels of xanth an (less than or equal to0.2 wt%) caused flocculation of droplets that resu lted in a large decrease in creaming stability and visual phase separation. At higher xanthan concentrations, the creaming stability improved, apparen tly due to the formation of network of flocculated droplets. It was found t hat emulsions formed with 3% sodium caseinate in the absence of xanthan sho wed extensive flocculation that resulted in very low creaming stability. Th e presence of xanthan in these emulsions increased the creaming stability, although the emulsion droplets were still flocculated. It appears that crea ming stability of emulsions made with mixtures of sodium cascinate and xant han was more closely related to the structure and rheology of the emulsion itself rather than to the rheology of the aqueous phase. (C) 2001 Elsevier Science Ltd. All rights reserved.