
Souring is a food preparation technique that causes a physical and chemical change in food by exposing it to anacid. This acid can be added explicitly (e.g.,vinegar,lemon juice,lime juice, etc.), or can be produced within the food itself by amicrobe, such asLactobacillus.
Souring is similar topickling orfermentation, but souring typically occurs in minutes or hours, while pickling and fermentation can take a much longer amount of time.

Dairy products produced by souring include:Clabber,Cheese,Crème fraîche,Cultured buttermilk,Curd,Filmjölk,Kefir,Paneer,Smetana,Soured milk,Sour cream, andYogurt.
Grain products include:Idli,Sourdough, andSour mash.
Others foods produced by souring include:Ceviche,Kinilaw, andKey lime pie.[1]