ISSN:
1573-0972
Keywords:
Bacteriocin
;
Escherichia coli O157:H7
;
hydrostatic pressure
;
Listeria monocytogenes
;
Salmonella
;
Staphylococcus aureus
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Abstract The objective of this study was to combine pressure (345 MPa) with heat (50 ∘C), and bacteriocins (5000 AU/ml sample) for a short time (5 min) for the inactivation of relatively pressure-resistant strains of four foodborne pathogens: Staphylococcus aureus, Listeria monocytogenes, Escherichia coli O157:H7 and Salmonella in pasteurized milk and orange juice. Without bacteriocin addition, 5.5 log-cycle reduction was obtained for S. aureus 485 in milk whereas more than 8 log-cycle reduction was achieved for all the other strains studied. After storage of samples for 24 h at 4 ∘C, S. aureus 765 also gave positive results on selective media, where no growth was observed for all the other micro-organisms assayed. Incubation of the same pressurized samples at 37 ∘C for 48 h showed growth of L. monocytogenes strains in addition to S. aureus strains, where still no growth was observed for E. coli O157:H7 and Salmonella strains in their respective selective media. For orange juice samples, more than 8 log-cycle reduction was achieved for all the bacterial species studied. No growth was seen for these species on their respective selective media agar plates after storage at 4 ∘C for 24 h and at 37 ∘C for 48 h. When a bacteriocin-based biopreservative (BP1) was combined with pressurization, more than 8 log-cycle reduction in cell population of the resistant strains of S. aureus and L. monocytogenes were achieved in milk after pressurization. Milk samples were stored at 25 ∘C up to 30 days to test the effect of treatment and samples showed no growth whereas all the controls were positive.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1008936607413
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