Development and quality characterization of liquid Kashk by incorporating psyllium (Plantago ovata Forsk) hydrocolloid gel

The functionality of psyllium hydrocolloid gel (PHG, 0.1–0.75%) to improve physicochemical (pH, syneresis, physical stability and lightness), rheological (viscosity and flow behavior), microstructural and sensorial characteristics of an ethnic acid-fermented dairy product “Kashk” with different contents of dried Kashk powder (DKP, 15–25%) was investigated. Results showed the low-viscous liquid Kashks containing 0.1% PHG at all DKP levels had the highest syneresis, instability and lightness amounts. Scanning electron microscopy and laser diffraction particle size analysis exhibited the increasing PHG content by 0.5% reduced aggregated particles size in a uniform monomodal distribution, whereas the weaker interaction of polysaccharide-casein at 0.75% PHG led to an increase in the number of unadsorbed polysaccharides. A highly negative correlation was also found between the viscosity and phase separation percentage, and between the particles size and overall acceptability sensory attribute. According to the quality evaluations, the best formulation was composed of 25% DKP and 0.5% PHG.