The microstructural and mechanical properties of acid-set mixtures of sodium caseinate (2% w/w)/barley β-glucans (2-6% w/w) were studied in an effort to evaluate the effect of these polysaccharides on the texture of fermented dairy products. The phase behavior of the blends was investigated using small deformation dynamic oscillation, differential scanning calorimetry, optical microscopy, and polymer blending-laws analysis. The work aimed to assess the topology of the phase separated mixture, the water holding capacity of its polymeric phases, and the thermal stability of the constituent networks. The mixed network properties were dominated by the protein component at low concentrations of β-glucans (≤3% w/w). In the concentrated regime, the system seems to have a bicontinuous topology governed by the mechanical strength and thermal stability of the β-glucan network structure. Results could assist in optimising the use of sodium caseinate and β-glucans as functional or as bioactive ingredients in acid-set dairy products.