Concentration dependent effects of dextran on the physical properties of acid milk gels

The effect of dextran from Leuconostoc mesenteroides (DEX₅₀₀), added to milk prior to acidification with glucono-δ-lactone (GDL) or Streptococcus thermophilus DSM20259, was studied with respect to polysaccharide concentration. The incorporation of 5–30 g/kg DEX₅₀₀ significantly affected gelation behavior. Increasing DEX₅₀₀ concentrations resulted in a linear increase of gel stiffness (GDL gels: R² = 0.96; microbial acidification: R² = 0.94; P < 0.05) and 30 g/kg DEX₅₀₀ resulted in a 2-fold higher stiffness compared to gels without polysaccharide. The respective stirred gels depicted a significant reduction in syneresis, which decreased from 30.4% (0 g/kg DEX₅₀₀) to 22.0% (30 g/kg DEX₅₀₀) for chemically acidified gels after 1 d of storage. Physical characteristics of DEX₅₀₀ in aqueous solution were helpful to explain its behavior in the complex system milk.