The Effect of Commercial Exopolysaccharide-Producing Starters on the Rheological Properties of Stirred Yoghurt

Yoghurt is one of the most important dairy products consumed in human society. So, increasing the quality of yoghurt is very important. Several strains of lactic acid bacteria, used as starter cultures to make yoghurt products, produce exopolysaccharides that can improve the textural properties of the products. In this study, the physical (syneresis), rheological (viscosity and firmness), and sensorial properties of yoghurt samples produced with exopolysaccharide-producing starter cultures (Hansen, Saco, and Fermentotec) were investigated during 21 days of storage. Samples with Fermentotec starter culture had lower syneresis and were more viscous and firm than those made with Hansen and Saco starter cultures, and yoghurts produced with Fermentotec starter were whiter, firmer, and more cohesive and adhesive than samples produced with Hansen and Saco. Results showed that the Cross model is the best-fitting model for three types of products. Fermentotec starter is recommended for improving the quality of stirred yoghurt.