Propionibacteria are used in the Swiss cheese industry to achieve the characteristic eyes and nutty flavour of Emmental or Swiss-type cheese. The aim of the present work was to further understand the influence of 2 different propionibacterial cultures, Prop 96 and P-culture, on the characteristics of Emmental cheeses. The P-culture has a strong ability to metabolise aspartate. Biochemical, microbiological and sensory analysis clearly revealed that the cultures lead to completely different Emmental cheeses. Compared to Prop 96, the P-culture yielded higher propionibacterial counts and showed an increased utilisation of lactate and aspartate with resulting higher contents of free short chain acids and carbon dioxide. As a result, the flavour of the concerned cheeses was more intense and the number and size of eyes, as well as height of the cheeses were greater. It can be concluded that the ability of propionibacteria to utilise aspartate must definitely be taken into consideration for the selection of cultures. Even though excessive aspartase activity has hidden dangers such as late fermentation, a moderate activity may influence the properties of Emmental cheeses positively and accelerate ripening. The aspartase activity is most probably an important indicator for the growth rate of propionibacteria in Emmental cheese