2 degrees Celsius to 6 degrees Celsius. Zhongguancun Online said that yogurt needs to be refrigerated to control the activity of lactic acid bacteria and make its activity stable. The shelf life is 2 to 3 weeks at the temperature of 2 to 6 degrees Celsius. Traditional old yogurt, called solidified yogurt, is solid. It is necessary to take fresh milk as raw material, put semi-finished products into predetermined packages, and conduct refrigerated fermentation for 72 hours after sealing, which takes a long time to make and has a relatively short shelf life.