Mathematical quantification of inactivation of Vibrio parahaemolyticus on two types of surface soiled with different substrates

Survivability of foodborne pathogens on food-processing surfaces is an important factor in understanding and quantifying bacterial transfer to foods (i.e. cross-contamination). This study examined the survival of Vibrio parahaemolyticus on two different surfaces in a laboratory-based simulation. V. parahaemolyticus was inoculated onto both polypropylene and stainless steel surfaces following contamination with saline solution (SS), tryptone soya broth (TSB), or seafood purge. V. parahaemolyticus remained viable on polypropylene for 10 days, but was undetectable within 24 h on the stainless steel surface. The survivability was similar on polypropylene in the presence of all contaminating substrates, as shown by data from the Weibull and biphasic models (adjusted-R2 > 0.91). However, for stainless steel, SS and TSB prolonged the survival of V. parahaemolyticus to 144 and 120 h, respectively. Survivability data revealed a shoulder period in the first 4 h and a slight tailing effect at the end of the survival curve in the presence of seafood purge, which suggested that the biphasic model might be appropriate (adjusted-R2 = 0.9442). These results indicate that the biphasic model may accurately estimate pathogen survival for cross contamination exposure. Integrating the survivability model into quantitative studies will help understand cross contamination.