Microbiological characteristics of Parmigiano Reggiano cheese during the cheesemaking and the first months of the ripening

The aim of this work was to gain a comprehensive view of the microbiologica l characteristics of milk, natural whey starter, and cheese during the firs t months of ageing of Parmigiano Reggiano. A significant presence of differ ent microbial groups in raw milk from the initial moments of production was rapidly substituted by various lactic acid bacteria. Natural whey starter contained a large number of thermophilic lactic acid bacteria (Lactobacillu s helveticus, L. delbrueckii ssp. lactis, L. delbruckii ssp. bulgaricus) an d some facultatively heterofermentative lactic acid bacteria belonging to L . rhamnosus. Thermophilic lactic acid bacteria disappeared within 30 d. Rod -shaped mesophilic facultatively heterofermentative lactic acid microflora, consisting of L. casei, L. paracasei sap. paracasei, L. paracasei ssp. tol erans, L. rhamnosus and pediococci, progressively increased up to the fifth month of ageing. Results showed that thermophilic lactobacilli were derive d from natural whey starter whereas Streptococcus thermophilus originated f rom raw milk. Further, natural whey starter was the source of L. rhamnosus which was present throughout the entire period of the cheese ageing. The ot her components of non-starter lactic acid microflora derived from raw milli .