Aims: To investigate the combined effect of high-pressure treatments (HPT) and milk inoculation with bacteriocin-producing lactic acid bacteria (BP-LAB) on the survival of Staphylococcus aureus during ripening of raw milk cheese. Methods and Results: Cheeses were manufactured from raw milk artificially contaminated with S. aureus at ca 5 log CFU ml-1, a commercial starter culture and one of seven strains of BP-LAB, added as adjuncts at 0.1%. HPT of cheeses were performed on days 2 or 50 at 300 MPa (10°C, 10 min) or 500 MPa (10°C, 5 min). On day 3, S. aureus counts were 6.46 log CFU g -1 in control cheese. Milk inoculation with different BP-LAB lowered S. aureus counts on day 3 when compared with control cheese by up to 0.46 log CFU g-1, HPT at 300 MPa on day 2 by 0.45 log CFU g-1 and HPT at 500 MPa on day 2 by 2.43 log CFU g-1. Combinations of BP-LAB with HPT at 300 and 500 MPa on day 2 lowered S. aureus counts on day 3 by up to 1.02 and 4.00 log CFU g-1 respectively. Conclusions: The combined effect of milk inoculation with some of the BP-LAB tested and HPT of cheese on S. aureus inactivation was synergistic. Significance and Impact of the Study: The combination of HPT at lower pressures with BP-LAB inoculation is a feasible system to improve cheese safety in case of deleterious effects on cheese quality caused by HPT at higher pressures.
|Journal||Journal of Applied Microbiology|
|Publication status||Published - 14 Feb 2005|
- High pressure
- Lactic acid bacteria
- Staphylococcus aureus