Selection of yoghurt starter culture from indigenous isolates of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus on the basis of technological properties

Abstract

The aim of this study was to explore the potential of indigenous strains of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus as yoghurt starter culture, for this purpose some important technological properties were studied. The strains of Lactobacillus delbrueckii subsp. bulgaricus Lb5, Lb7, and Streptococcus thermophilus St4 and St7, produced more than 0.7% acidity after 6 h of incubation in skim milk media. The acetaldehyde was detected as major aroma compound produced by mixed culture M1 (Lb5:St4) i.e., 19.95 ppm at 43 °C. Yoghurt was prepared with different combinations of the culture and sensory analysis performed by a trained panel revealed that pleasant yoghurt was prepared with mixed culture of Lactobacillus delbrueckii subsp. bulgaricus Lb5 and S. thermophilus St4. The results suggested that these strains have potential to be used as starters for yoghurt production.