Increasing the microbial inactivation of Staphylococcus aureus in sauces by a combination of enterocin AS-48 and 2-nitropropanol, and mild heat treatments

Staphylococcus aureus was challenged with the cyclic bacteriocin AS-48 in four commercial sauces singly and in combination with sublethal heat treatments (50–60 °C, for 5 min) and with 2-nitro-1-propanol (2NPOH). Heating at 60 °C in combination with AS-48 (25 μg/ml) reduced initial counts (4.1–4.5 log CFU/ml) below detection limit (1.0 log CFU/ml), while a combined treatment at 55 °C inhibited proliferation of staphylococci in sauces for 24 h at 22 °C. In BHI broth, enterocin AS-48 (0–15 μg/ml) acted synergistically with 2NPOH (0–220 mM), reducing the concentrations of both antimicrobials required for inactivation of S. aureus. In sauces, enterocin AS-48 (25 μg/ml) plus 2NPOH (25 mM) reduced initial cell concentrations (4.1–5.0 log CFU/ml) below detectable levels within 8–24 h, depending on the sauce. The combinations of enterocin AS-48 and 2NPOH or sublethal heat are interesting for testing as part of hurdle technology aimed at reducing the risks for proliferation of S. aureus in sauces.