Application of high-pressure treatment on ovine brined cheese: Effect on composition and microflora throughout ripening

Ovine brined cheese was high-pressure (HP) treated at 200 or 500 MPa for 15 min at 20 °C on the 15th day of ripening. Compared to control cheese, HP treatment did not affect significantly (P > 0.05) the pH values, moisture, fat in dry matter, protein in dry matter and salt in moisture contents of cheeses at 90 days. The counts of total aerobic mesophilic bacteria, thermophilic lactococci, thermophilic lactobacilli and non starter lactic acid bacteria (NSLAB) were not affected by HP treatment of cheese at 200 MPa throughout ripening. After 90 days of ripening, the same microbial groups in cheese treated at 500 MPa were about 1.2, 3.6, 2.1 and 4 log units lower than in control cheese respectively. Coliforms were reduced faster at non detectable levels in HP treated cheeses than in control cheese. Regarding the bacterial enzymatic activities in cheese, aminopeptidase activity (Apep) was marginally favoured by both HP treatments. However, its activity was decreased at 90 days due probably to loss in brine. In contrast, lactate dehydrogenase (LDH) activity, following the bacteria cell lysis, was negatively affected by HP treatment at 500 MPa throughout ripening.Industrial relevanceThe data obtained from this work suggest that application of HP treatment under optimized conditions on ovine cheese in brine can be used to reduce effectively the undesirable microbial load in it and to cause moderate enhancement of aminopeptidase activity, without modifying its composition.