3.2. Post acidification
To optimise the experiment process and mimic the custom of Chinese consumers (keeping yoghurt at room temperature), the post acidification of yoghurts were tested at 25 C. The commercial starter (YF-L812), which was characterised by very low post acidification, was used as control. Xu et al. reported that the titratable acidity of the starter culture YF-L812 only increased 14.5 T after being stored at 6 C for 30 d. The change of control culture and combinations in pH during the storage period was shown in Figs. 1 and 2.