Starter cultures for mild yoghurt are a combination of various strains of the typical bacteria of the yogurt culture, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. These two species live in coexistence and when added to milk trigger lactic acid fermentation and formation of fermented milk of appropriate sensory properties, such as stable texture and pleasant taste. The textural attributes depend on composition of milk and production of exopolysaccharides (EPS) by yoghurt bacteria, whereas lactic acid, acetaldehyde and diacetyl represent some of the most characteristic flavour components that are produced during lactic acid fermentation. For the purpose of producing mild yoghurt, producers of starter cultures offer mixes of yoghurt bacteria that give yoghurt high viscosity and mild taste. This kind of yoghurt is more popular among inhabitants of the Western countries, who are used to milder taste. At the same time the sweet taste of the product also allows a lower addition of sugar in fruit yogurt, which is in accordance with the guidelines of healthy eating.