The effect of heteropolysaccharide-producing strains of Streptococcus thermophilus on the texture and organoleptic properties of low-fat yoghurt

Heteropolysaccharide-producing Streptococcus thermophilus strains (LY03, ST 111, or 5077) were compared with nonropy S. thermophilus strains (NR or 5137), in respect of texture development of low-fat yoghurt produced at 42 degrees C. Whether milk solids were added or not, lower syneresis and improved texture and sensory properties were obtained in yoghurts produced with S. thermophilus LY03 or S. thermophilus 5077 compared with nonropy strains. Texture effects, lower syneresis and improved sensory properties because of the use S. thermophilus ST 111 were only noticeable in the presence of milk solids. Milk solids had no significant effect on the textural parameters of nonropy strains.