Influence of polysaccharide addition on stability of a cheese whey kefir-milk mixture

Abstract

A kefir-type drink was prepared by fermentation with kefir granules of cheese whey containing fructose and black raisin extract. Milk (20%) was then added to improve its rheological and sensory properties and in order to prevent casein coagulation and sedimentation in the acid environment of the mixture, a number of polysaccharides were evaluated as stabilizers. Xanthan appears to be more effective at relatively low concentration levels (0.2%) compared to guar gum while high methoxyl pectin, a well-known acid milk drink stabilizer was less effective in this respect even at concentrations as high as 1%. Particle size and rheology measurements pointed out to the importance of the weak gel properties of xanthan solution in stabilizing the system against ‘wheying off’ while other stabilization mechanisms such as particle network formation as a result of depletion flocculation in the case of guar gum or pectin adsorption at the casein particle surface resulting in steric stabilization appear to be less dominant.