Microbial biodiversity in raw milk cheeses: a potential source of health

Raw milk cheeses have a richer and stronger flavor intensity than cheeses made from pasteurized milk. Their particular properties are related to milk quality, to the traditional cheese-making process, but one of the main factors is the high level of biodiversity of the indigenous microbiota naturally occurring. Raw milk cheeses harbor a complex microbial community accounting for more than 200 of species. The content and the type of microorganisms strictly depend on the hygienic condition in the livestock and during milking, on the storage condition of milk, the addition of natural or selected cultures and also on the technology process applied and the ripening environment. Bacterial biodiversity is a that has to be preserved since the improvement of the hygienic conditions of livestock, milking and storage of milk have led to reduce bacterial count but also to loose part of the diversity. In this context, raw milk cheeses are an interesting source of bacterial biotypes that can be used to develop autochthonous starter and to select strains with specific properties. Lactic acid bacteria (LAB) are the main actors of the cheese making and are responsible both for the fermentation process and curd maturation during ripening of raw milk cheeses. In addition, LAB cultures can be used to inhibit the development of pathogenic and spoilage microorganisms, and to improve both food safety and shelf-life. Moreover, LAB can represent a useful strategy to produce functional foods. Besides expressing an important acidifying activity, LAB can enrich foods with bioactive compounds promoting human health such as gamma-aminobutyric acid (GABA), folate, and conjugated linoleic acid (CLA) and they can reduce cholesterol content in cheese.