Combination of hydrostatic pressure and lacticin 3147 causes increased killing of Staphylococcus and Listeria

The use of hydrostatic pressure and lacticin 3147 treatments were evaluated in milk and whey with a view to combining both treatments for improving th e quality of minimally processed dairy foods. The system was evaluated usin g two foodborne pathogens: Staphylococcus aureus ATCC6538 and Listeria inno cua DPC1770. Trials against Staph. aureus ATCC6538 were performed using con centrated lacticin 3147 prepared from culture supernatant. The results demo nstrated a more than additive effect when both treatments were used in comb ination. For example, the combination of 250 MPa (2.2 log reduction) and la cticin 3147 (1 log reduction) resulted in more than 6 logs of kill. Similar results were obtained when a foodgrade powdered form of lacticin 3147 (dev eloped from a spray dried fermentatation of reconstituted demineralized whe y powder) was evaluated for the inactivation of L. innocua DPC1770. Further more, it was observed that treatment of lacticin 3147 preparations with pre ssures greater than 400 MPa yielded an increase in bacteriocin activity (eq uivalent to a doubling of activity). These results indicate that a combinat ion of high pressure and lacticin 3147 may be suitable for improving the qu ality of minimally processed foods at lower hydrostatic pressure levels.