Flow properties of o/w emulsions as affected by xanthan gum, guar gum and carboxymethyl cellulose interactions studied by a mixture regression modelling

Abstract

Blends of xanthan gum (XG), guar gum (GG) and carboxymethyl cellulose (CMC) were prepared according to a simplex-centroid design (7 points) and used at 0.5% (wt/wt) in O/W emulsion formulations. Results demonstrated that interaction among XG, GG and CMC had positively influenced the droplet characteristics and flow behaviour of the prepared emulsions. There were significant (p < 0.05) decreases in droplet size (d[3,2] = 5.84–7.00 μm) of the emulsions containing binary blends (at 1:1 ratio) of XG:GG and XG:CMC as well as ternary blend of XG:GG:CMC (at 1:1:1 ratio) when compared to that of emulsion containing XG alone (d[3,2] = 11.41 μm). Regression modelling revealed that synergistic effect of ternary XG:GG:CMC blend was stronger than that of all the binary blends as evident in the yield stress and apparent viscosity of the respective emulsions. Both responses were proven to be best fitted with a special cubic model (R2 > 0.94) while coefficient of consistency was successfully fitted with a quadratic model (R2 = 0.94). The models are useful for predicting the respective responses to any blend combination of the components. In this study, ternary synergism was believed to be occurred through a specific mechanism whereby CMC might have formed its own network interpenetrating with the network from a well-known XG-GG or GG-CMC synergisms that finally resulted in more complex network structure which positively influenced the properties of the prepared emulsions.