Phasengleichgewichte in Wasser/Eiweiß/Polysaccharid‐Systemen. 1. Systeme Wasser/Casein/saures Polysaccharid

Abstract

Phase Equilibrium in Water/Protein/Polysaccharide Systems. Part 1. Systems Water/Casein/ Acid Polysaccharide. Taking as examples the most important protein matters, albumins, globulins, glutelins and prolamins as well as acid and neutral polysaccharides the incompatibility of protein and polysaccharides in aqueous media was shown to be a general phenomenon. Unlike synthetic polymers incompatibility of protein and polysaccharides only occurs under certain conditions. Taking into account specific intermolecular interactions makes it possible to predict the conditions for liquid phase layering for any concrete system by means of simple thermodynamic considerations. Incompatibility can be defined by elimination of the possibility of complex formation between protein and polysaccharides and by the raising of selfassociation of at least one polymer. Phase equilibrium in the systems water/casein/alginate, water/casein/carboxymethylcellulose, water/casein/gummi arabicum were thoroughly examined and isothermic phase diagrams of these systems were given. Furthermore, the ways for regulation of compatibility of casein and acid polysaccharides were discussed.

Edible table (bio)spread containing potentially probiotic Lactobacillus and Bifidobacterium species

“…Sodium alginate exists in solution as a conformationally disordered ‘random coil’ 106 . Casein can form an aqueous multiphase system with sodium alginate when the total polymer systems exceed 4% w/v 107–110 . The degree of incompatibility increases with increasing salt concentration.…”

Interfacial tension of aqueous biopolymer mixtures close to the critical point

“…The caseinate at neutral pH is thus negatively charged, like alginate. Both biopolymers are well known, widely used in industry, and the thermodynamic behaviour of the ternary water-caseinate-alginate systems is known from literature [6,[25][26][27][28].…”

“…In the latter situation, each phase becomes enriched in either polysaccharides or proteins. Liquid-liquid phase separation in biopolymer mixtures is the rule, but it occurs at relatively high concentrations and at particular physico-chemical conditions depending on the polyelectrolytic properties and the self-association behaviour of the mixed macromolecules [6,7]. The term 'water-in-water emulsion' was introduced to distinguish them from oil-in-water and water-in-oil emulsions [5].…”

Thermodynamic compatibility of sodium caseinate with different pectins. Influence of the milieu conditions and pectin modifications

“…The isoelectric point of sodium caseinate is about 4.6 and the compatibility was tested at a low ionic strength of 0.06 M for pH values of 6.0, 7.0 and 8.0, respectively. Such pH values slightly above the IEP of the protein were already recommended by Antonov et al [5] for testing the compatibility of proteins insoluble at the IEP and acid negatively charged polysaccharides. At these pH the caseinate is negatively charged, too.…”

“…Pectins were tested for their compatibility with different proteins, such as blood serum albumins, egg, milk and soy proteins in liquid systems [2,3,[5][6][7][8] and also in gels [9,10]. The influence of the pectin structure on the thermodynamic compatibility with proteins was examined by Semenova et al [11], using human serum albumin and by Antonov et al [12] using gelatine.…”