This study addressed the effect of different amounts of added propylene glycol alginate (PGA) on the stability of stirred yoghurt as determined by measuring its acidity, pH value, water-holding capacity, whey syneresis and sensory evaluation. The aim was to determine the optimal addition amount of PGA. The results that addition of PGA remarkably inhibited the postacidification of yoghurt during storage, enhanced water-holding capacity, deceased whey syneresis, and resulted in an improved texture and taste. Added PGA was beneficial for the stability of yoghurt in a concentration-dependent manner. From a cost-effectiveness point of view, the optimal amount of PGA in stirred yoghurt is 0.3％.