Strength of Salmonella attachment on apple and tomato surfaces: Effect of antimicrobial treatments on population reduction and inactivation

Abstract

Presence of bacteria and its survival on produce surfaces is important in developing non-thermal processing interventions for food safety. In this study, whole apples and tomatoes were individually inoculated with Salmonella bacteria at 4.6 log CFU/g and 3.0 log CFU/g, respectively and then allowed to air dry in a laminar flow biological hood (NuareTM, Plymouth, MN, USA) before antimicrobial treatments at 0, 20 min, 30 min, 60min, 120 min, 360 min, 540 min and 1440 min post inoculation, respectively. After washing treatments, strength of attachment for Salmonella bacteria on apple and tomato surfaces was calculated. The efficacy of a new antimicrobial solution developed in our laboratory, was compared to 1.5% hydrogen peroxide and 200 ppm chlorine treatments. The relative strength of Salmonella attached on whole apples and tomatoes averaged 0.22 and 0.25, respectively. The 200-ppm chlorine and 1.5% hydrogen peroxide (H 2 O2) treatments achieved 2.8 log CFU/g inactivation, while the new antimicrobial solution led to 3.9 log CFU/g and 2.9 log CFU/g reductions on tomatoes and apple surfaces, respectively. Strength of bacterial attachment increased at 360 min post inoculation. The attachment phenomena impacted the activity of all antimicrobial treatments in reducing bacterial populations, except the organic acid solution.