Cheese
For some cheeses, the milk is curdled by adding acids such as vinegar or lemon juice. Most cheeses are acidified by bacteria. This bacteria turns milk sugars into lactic acid. Rennet is then used to finish the curdling. Vegetarian alternatives to rennet can also be used. Most of these are made by fermentation of a fungus called 'Mucor miehei'. Other alternatives us species of the 'Cynara' thistle family.