Phase Behavior Characteristics Of Skim Milk Protein-polysaccharide Multicomponent Systems Influenced By κ-carrageenan

In our work, the basic phase separation behavior of three different polysaccharide andmilk protein was fistly studied. Then investigation on phase characteristics of milkprotein-polysaccharide multicomponent systems with different concentrations ofκ-carrageenan was carried out to simulate realistic dairy product. Effect of κ-carrageenan onthe transformation of phase behavior helped us understand the unique characteristic ofκ-carrageenan and examine the mechanism underlying interaction between biopolymers. Thispreliminary research can provide basic theory for futher stuy and practical production.Firstly, the phase diagrams of skim milk protein-polysaccharide stabilizer wasdetermined to detect the phase separation behavior, methods of rheology and microscopywere also used to analyse the differences of characteristics of milk protein-polysaccharidesystems. The resules showed that skim milk protein and polysaccharide stabilizer used in thisstudy were strongly incompatible when they mixed. Thermodynamic incompatibility of milkprotein and polysaccharide decreased in the following order: konjac glucomannan> CMC>pectin. Samples comprised of konjac glucomannan/CMC and milk protein showedpseudoplastic flow and addition of sucrose can enhance the pseudoplastic of mixtures. Forsystems contained with pectin and protein, Newtonain flow behavior was exhibited and therewas not significantly influence on increasing pseudoplastic by addition of sucrose.In order to improve the phase separation phenomenon between polysaccharide andprotein, κ-carrageenan was added to preserve uniformity in mixtures. Rheology, lightscattering and microscopy were conducted to investigate on characteristics of milkprotein-polysaccharide multicomponent systems with different concentrations ofκ-carrageenan. Transformations of phase behavior in different polysaccharide with milkprotein were compared to discuss and understand the underlying mechanism. Microstructureshowed that phase behavior of milk protein in system contained different polysaccharidetransformed differently by the action of κ-carrageenan. When the concentration ofκ-carrageenan increased to0.05%w/w, pseudoplastic and frequency independence weregreatly enhanced for all systems, and samples performed weak-gel behavior. The percentageof large particle size was also increased for all systems containing0.05%κ-carrageenan.Homogenization is a common process in dairy products, thus it is is of primaryimportance to research on characteristic of homogenized samples. It may also give us a betterunderstanding on the mechanism of how κ-carrageenan inhibits phase separation. Atmicrostructural level, all samples which were homogenized after adding κ-carrageenan appeared some degree of incompatible phenomenon. However, samples which werehomogenized before adding κ-carrageenan behaved relatively uniformity. Homogenizationorder had a great influence on rheological characteristic of κ-carrageenan/konjacglucomannan/milk protein/sucrose system, but showed little influence on that ofκ-carrageenan/CMC or pectin/milk protein/sucrose system.