Abstract:
This research studied the effects of xanthan gum (XG), guar gum (GG) and
carboxymethyl cellulose (CMC) combinations on physical properties and stability of
model salad dressings (emulsions). The experimental domain used consisted of
different proportions ofXG, GG and CMC components according to simplex-centroid
mixture design (7 points) and used at 0.5 % (wt/wt) in the emulsion formulations.
Results revealed that emulsion with ternary XG:GG:CMC mixture showed better
physical properties and higher stability compared to other emulsions. Hence, an
occurrence of synergistic interactions between XG, GG and CMC was proposed.
These interactions were found to increase the viscosity and yield stress of ternary the
emulsion, consequently resulted in increase of emulsion stability. However, these
interactions were also found to limit the binding availability of XG, GG and CMC
molecules towards metal ions which led to higher tendency for lipid oxidation. For
flow behaviour of model salad dressing, an appropriate mathematical model was fitted
to express each flow response as a function of the proportions of the blend
components that are able to empirically predict the response to any blend of
combination of the components. Result of analysis showed that yield stress and
apparent viscosity responses were successfully fitted with a special cubic model while
flow consistency coefficient was fitted with a quadratic model (R
adjusted 2: 0.94).
The equation together with contour and surface plots suggested that yield stress and
apparent viscosity of the prepared emulsions were strongly affected by synergistic
effect from ternary mixtures with higher GG level whereas the strongest synergistic
effect on consistency coefficient was contributed by a binary interaction of XG-GG at
higher GG level. The mathematical model derived from the mixture design in this
study can be used to predict the effect of interaction between XG, GG and CMC of
different proportion levels on the properties of model salad dressings.
