Roberta Comunian

A preliminary study of lactic acid bacteria in whey starter culture and industrial Pecorino Sardo ewes’ milk cheese: PCR-identification and evolution during ripening

Lactic acid bacteria isolated from industrial Pecorino Sardo cheese, manufactured from thermized ewes milk, and from its natural starter culture were characterized taxonomically. Cheese samples were collected from three dairies at different stages of production and 543 colonies were isolated. PCR-based taxonomic identification revealed that thermophilic lactic acid bacteria belonging to Lactobacillus delbrueckii, Lactobacillus helveticus and Streptococcus thermophilus species constituted the dominant lactic microflora isolated. Mesophilic facultatively heterofermentative lactobacilli of the L. casei group and enterococci were also isolated from the cheeses, together with starter lactic acid bacteria (SLAB). The counts of mesophilic lactobacilli and enterococci increase during ripening. The three batches of cheese differed in the range of the species isolated in the whey starter culture and their evolution in cheese during ripening. Differences in the microflora composition of industrial and homemade Pecorino Sardo cheese were also examined.