Chiang Mai Journal of Science

     The increasing demand for biopolymers in the food industry has increased interest in using alternative resources. Kefiran, which is produced by microorganisms found in kefir grains, is a versatile exopolysaccharide (EPS) that can form gel, an important biopolymer for the food manufacturing. In this study, kefiran extracted by using an EPS isolation method was characterized by rheological analysis according to power law model and determination of functional properties and texture profile analysis. The effects on apparent viscosity (η_a) and flow properties of kefiran concentrations ranging from 1.1 to 3.1% (w/v) were investigated. The results indicated that kefiran solutions at low concentrations exhibited behavior close to Newtonian, whereas at higher concentrations, they showed pseudoplastic (shear-thinning) behavior. This shear-thinning behavior is attributed to hydrogen bonding between hydroxyl groups and water molecules, which contributes to the formation of an entangled polymer network. The results showed that isolated kefiran at a high degree of purity (93.0%) was able to possess good texture profile properties and with a high degree of water holding capacity (WHC) (90.3%), and bloom strength value (53.0 g). Kefiran had a gelling temperature of 14 °C. This study confirms that extracted polysaccharide can be especially used as a gelling agent in fermented dairy products and can also be successfully used as a texture improver biopolymer in food systems.