Life

Dairy farming

Milk bacteria, such as Streptococcus thermophilus and Lactobacillus bulgaricus, are the micro-organisms most commonly used in dairy farming. These bacteria, which come in the form of bacilli or cocci, are anaerobic (they do not need oxygen to survive) and transform simple sugars (glucose and lactose) into lactic acid through a metabolic process which is known as fermentation. Lactic acid alters the chemical and physical features of milk, transforming it into something else: yoghurt. Butter-making also needs the aid of some micro-organisms: the typical taste of this product is due to the presence of diacetyl, a substance released by the milk bacteria that develop as the milk cream ages. Some bacteria can produce substances, such as bacteriocins and nisins, that have an antibiotic effect, i.e. they fight the harmful bacteria that could contaminate cheese. Special bacteria, known as “proponic”, develop in some types of cheese, such as Emmenthal and Gruyère, and produce large amounts of carbon dioxide. The gas forms gaps in the cheese paste which when aged exhibits the famous “holes”.