Sensory and rheological screening of exopolysaccharide producing strains of bacterial yoghurt cultures

Yoghurts were produced with 24 different cultures differing in their ability to produce exopolysaccharides (EPS). Rheological and sensory analyses showed large differences in texture properties in the yoghurt samples. EPS production was found to have a major effect oil the texture properties, but varying textures within the EPS +/- groups were also found. Yoghurts fermented with EPS-producing cultures showed increased mouth thickness and ropiness and tended to be creamier than yoghurts without these cultures; in contrast, these yoghurts had the lowest syneresis and highest gel firmness (initial gel strength before the yoghurt was subjected to shear). Correlations between rheological parameters and sensory texture attributes included G* correlating with gel firmness, while viscosity measured at 241 s(-1) correlated with mouth thickness. An interesting viscometry relationship was found between ropiness and hysteresis loop area