High Quality Content by WIKIPEDIA articles! Yoghurt or yogurt is a dairy product produced by bacterial fermentation of milk. Fermentation of lactose produces lactic acid, which acts on milk protein to give yoghurt its texture and its characteristic tang. Soy yoghurt, a non-dairy yoghurt alternative, is made from soy milk. Dairy yoghurt is produced using a culture of Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus bacteria. Milk is heated and cooled for an hour. While it is heated, the bacteria are added for fermentation.