Inactivation of Staphylococcus aureus in raw milk cheese by combinations of high-pressure treatments and bacteriocin-producing lactic acid bacteria.
OBJECTIVE
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.


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 degrees C, 10 min) or 500 MPa (10 degrees 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.


CONCLUSIONS
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.
Arqués
J L
JL
Departamento de Tecnología de Alimentos, INIA, Madrid, Spain.
Rodríguez
E
E
Gaya
P
P
Medina
M
M
Guamis
B
B
Nuñez
M
M
D000898:Antibiosis; D001430:Bacteriocins / Q000096:biosynthesis*; D002611:Cheese / Q000382:microbiology*; D005516:Food Microbiology; D005519:Food Preservation; D017045:Lactococcus / Q000378:metabolism*; D011312:Pressure; D013211:Staphylococcus aureus
D001430:Bacteriocins