Positive effect of combining high pressure and biopreservation treatments on lowering the bacterial growth during storage of diced cooked ham with reduced nitrite salt

We investigated the combined effects of biopreservation and high pressure treatment on bacterial communities of diced cooked ham prepared with diminished nitrite salt. First, bacterial communities of four commercial brands of dice cooked ham from local supermarkets, sampled near the use-by-date, were characterised. The four ham microbiota showed a relative low diversity but harboured quite dissimilar communities. Two ham samples were dominated by different Proteobacteria (Pseudomonas, Serratia for one, Psychrobacter and Vibrio for the other one) while the two others were dominated by Firmicutes (Latilactobacillus and Leuconostoc). Second, sterile diced cooked ham, prepared with reduced level of nitrite was inoculated with the two Proteobacteria-rich microbiota collected from the aforementioned commercial samples together with a Lactococcus lactis protective strain. Dices were then treated at 500 MPa for 5 minutes and bacterial dynamics was monitored during storage at 8 degrees C. Applied alone, none of the treatments stabilized durably the growth of hams microbiota. Nevertheless, the combination of biopreservation and high pressure treatment was efficient to reduce the growth of Proteobacteria spoilage species. However, this effect was dependent on the nature of the initial microbiota, showing that use of biopreservation and high pressure treatment as an alternative to nitrite reduction for ensuring cooked ham microbial safety merits attention but still requires improvement.