Technological properties and biogenic amines production by bacteriocinogenic lactococci and enterococci strains isolated from raw goat's milk

Technological properties and biogenic amine (BA) production were analyzed in fifty-six bacteriocinogenic lactococci and enterococci strains isolated from raw goat milk. Fifteen lactococci strains were able to reduce milk pH to 5.3 or lower, after 6 h while enterococci strains were initially slow in producing acids. L. lactis subsp. lactis GLc06 and three E. faecalis (GEn20, GEn22, and GEn23) presented high proteolytic activity. GLc06 and E. faecalis GEn22, also showed a high percentage of autolysis already after 4 h, reaching to 71.11 % and 97.67 % after 24 h, respectively. No strain was able to secrete EPS and L. lactis subsp. lactis GLc22 and 25 Enterococcus were able to produce diacetyl. L. lactis subsp. lactis GLc05 and other 23 Enterococcus strains presented a high tolerance to NaCl at 10% (w/v). Considering the BA production, 12 strains (5 lactococci and 7 enterococci) were capable to form tyramine and 4 strains (1 lactococcus and 3 enterococci) were capable to form 2-phenylethylamine, but in very low amounts. GLc06 presented a great acidifying, proteolytic and autolytic activity and GLc05 was capable to grow at high NaCl concentrations (10 % w/v), possessing a medium autolytic and proteolytic activity. Some enterococci strains presented the ability to produce diacetyl and a high autolytic and extracellular proteolytic activity and also presented resistance to high NaCl concentrations. The interesting technological properties presented by some bacteriocinogenic strains can justify their use by the dairy industry, aiming both safety due to bacteriocin production and technological transformations in fermented products.