Effect of κ-carrageenan on milk protein polysaccharide mixtures

The effect of kappa-carrageenan (0, 0.025, 0.05%) on phase separation between polysaccharides (0.36% of locust bean gum (LBG), guar gum, or xanthan gum) and milk proteins (from 10.5% skim milk powder) in solution was studied. Xanthan gum was seen to be the most incompatible with milk proteins, followed by guar gum and LBG. Casein micelles were more incompatible with all polysaccharides than whey proteins. Whereas at either concentration kappa-carrageenan inhibited visual phase separation, it was seen by transmission electron microscopy that samples with kappa-carrageenan showed microscopic phase separation. Samples with 0.05% kappa-carrageenan and either LBG or guar gum and all samples with xanthan gum could be described rheologically as weak gels, while those with no or 0.025% K-carrageenan and either LBG or guar gum could be described as concentrated solutions. Thus, no correlation was seen between the inhibition of macroscopic phase separation by kappa-carrageenan and the formation of a weak gel in solution. (C) 2003 Elsevier Ltd. All rights reserved.