Set type yoghurt production by exopolysaccharide producing Turkish origin domestic strains of Streptococcus thermophilus (W22) and Lactobacillus delbrueckii ssp. bulgaricus (B3).

Summary Lactobacillus delbrueckii spp. bulgaricus (B3) and Streptococcus thermophilus (W22) with high exopolysaccharide (EPS) production were combined with commercial culture in various percentages and used in yoghurt production. Lactic acid and acetaldehyde contents, titratable acidity, tyrosine, viscosity and consistency values, and EPS level were measured throughout storage for twenty one day with 10-day intervals. The yoghurt sample produced with commercial culture only (control) had the highest level of acidity. Tyrosine content of the yoghurt produced by wild strains (sample D) was higher than that of others, whereas acetaldehyde and EPS levels were lower. The domestic strains did not influence the viscosity of yoghurt significantly (P>0.01). On contrary, the gel firmness of yoghurts produced with Lactobacillus delbrueckii spp. bulgaricus (B3) was lower than the other samples. The yoghurt sample made by isolated strains only had the highest viscosity values. Yoghurt produced by using isolated strains was found not to be acceptable by the panellists.