Influence of Different Acidifying Strains of Lactobacillus delbrueckii subsp. bulgaricus on the Quality of Yoghurt

The aim of this study was to analyze four different acidifying strains of Lactobacillus delbrueckii subsp. bulgaricus and their influence on the quality of yoghurt. The results showed L. bulgaricus IM1 and L. bulgaricus IM2 were fast acidifying strains, and L. bulgaricus IM3 and L. bulgaricus IM4 were slow acidifying strains. When the four strains were mixed with Streptococcus thermophilus TA040, the fermentation time of the yoghurt starter culture LS1 (IM1 and TA040) and LS2 (IM2 and TA040) was shorter than that of the yoghurt starter culture LS3 (IM3 and TA040) and LS4 (IM4 and TA040). However, yoghurt samples fermented by LS3 and LS4 had weaker post-acidification, higher viscosity and more exopolysaccharide (EPS). In addition, the highest acetaldehyde and diacetyl contents were observed in yoghurt fermented by the slowest acidifying yoghurt starter culture (LS4). Therefore, selecting slow acidifying L. bulgaricus strain is a considerate design to integrate advantageous performance of strains.