The combined effect of high hydrostatic pressure, heat and bacteriocins on inactivation of foodborne pathogens in milk and orange juice


Alpas H. , BOZOGLU F.

WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY, vol.16, no.4, pp.387-392, 2000 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 16 Issue: 4
  • Publication Date: 2000
  • Doi Number: 10.1023/a:1008936607413
  • Title of Journal : WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY
  • Page Numbers: pp.387-392
  • Keywords: Bacteriocin, Escherichia coli O157 : H7, hydrostatic pressure, Listeria monocytogenes, Salmonella, Staphylococcus aureus, LACTIC-ACID BACTERIA, ESCHERICHIA-COLI MUTANTS, LISTERIA-MONOCYTOGENES, PEDIOCOCCUS-ACIDILACTICI, PEDIOCIN ACH, STORAGE, COMBINATION, QUALITY, RESISTANCE, SENSITIVITY

Abstract

The objective of this study was to combine pressure (345 MPa) with heat (50 degrees 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 degrees 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 degrees 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 degrees C for 24 h and at 37 degrees 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 degrees C up to 30 days to test the effect of treatment and samples showed no growth whereas all the controls were positive.