Evaluation of amino acid-decarboxylative microbiota throughout the ripening of an Italian PDO cheese produced using different manufacturing practices

To investigate the presence of biogenic amines (BAs) in Montasio cheese produced by using different cheese manufacturing practices. Three batches of Montasio cheese were made in the following way: batch A using raw milk and natural milk culture, batch B with thermized milk and natural milk culture and batch C with thermized milk and natural milk culture added of a commercial starter culture. During 120 days of ripening analyses were performed for microbial counts and BA content; indeed, the potential to produce BAs was screened in lactic acid bacteria and Enterobacteriaceae isolates. At the end of ripening, the total BA contents of cheeses from batches A, B and C were 166·3, 207·3 and 29·8 mg kg⁻¹, respectively. Amino acid decarboxylase activity was widespread among isolates. The BA content of Montasio cheese from the three batches was below the threshold proposed as potentially toxic. The highest BA content was found in cheese produced using thermized milk and natural milk culture; therefore, the thermal treatment of milk was not enough by itself to reduce the counts of decarboxylase-positive bacteria in cheese. The use of selected starters guaranteed a low BA content in Montasio cheese. The study of the effects of some technological processes on the incidence of decarboxylative microbiota in 'protected denomination of origin' cheeses could provide useful information on the hygienic risk related to their production.