Heat inactivation of Escherichia coli O157:H7 and Salmonella Enteritidis in sous vide-cooked anchovy enriched with ascorbic acid at low temperature

Low-temperature cooking during the sous vide process enhances sensory properties, particularly in heat-sensitive foods. While enhancing efficiency, it also raises the risk of foodborne pathogen persistence. In this study, butterfly anchovy fillets were inoculated with a low dose of Escherichia coli O157:H7 or Salmonella Enteritidis. To amplify the effect of heat treatment, ascorbic acid (AA) was incorporated into sous vide anchovies before thermal processing at 55°C. Sampling was conducted at 5-minute intervals up to 30 min, followed by longer intervals. The initial E. coli load was 4.49 log CFU/g. The addition of AA significantly reduced (P<0.05) bacterial counts at and after the 45th min compared to the untreated control (C) group. The lowest count, 1.30 log CFU/g, was observed in the AA group at 120 min of cooking. A tailing effect was noted after 30 min of heating in both groups. On the other hand, Salmonella counts gradually declined without statistically significant differences (P>0.05) between groups. No colonies (<1.00 log/g) were detected after the 30th and 45th min in the AA and C samples, respectively. Salmonella exhibited greater heat sensitivity than E. coli. Further research is needed to assess the safety of incorporating AA into low-temperature cooked sous vide seafood.