Evaluation of metabolic activities of enterococci isolated from Pecorino Abruzzese cheese

Enterococci, which represent a considerable part of the natural microbiota of Pecorino Abruzzese, were investigated for biochemical activities considered to have a potential role in cheese ripening. Acidifying activity was weak, while interesting differences were identified for proteolytic and peptidolytic capability, particularly on H-Lys-β-NA. The presence of C-4 esterase and C-8 esterase lipase, as well as enzymes such as phosphohydrolases and acid phosphatase was confirmed by means of API ZYM. SPME-GC analyses of volatile compounds revealed the production of ethanol, diacetyl and, of particular interest, acetoin after 15 days at 10 °C, with important differences among the species. After 15 days at 10 °C, Enterococcus faecalis isolates were generally the most active, giving the highest results for most of the biochemical activities investigated, and also some Enterococcus durans showed interesting metabolic features that might be important to the development of the peculiar sensory properties of this cheese.