Abstract
Fresh produce can be contaminated at any stage along the food supply chain. In this study,
apple was chosen to determine the time course of biofilm formation by Listeria
monocytogenes (ATCC 19115), as well as to compare the efficacy of different household
washing methods such as scrubbing with hands under running tap water, soaking with and
without commercial vegetable wash with different treatment times in removing the biofilm
formation by L. monocytogenes on apple surface. The biofilm formation was quantified
using crystal violet assay and the result showed that L. monocytogenes took 18 hrs to
form matured biofilm on apple surface. Besides, scrubbing apples with hands under
running tap water for 30 s and 60 s were the most effective method which significantly
removed (P<0.05) biofilm formed on the apple surface with approximately 5.93 log
reduction. Soaking apples with vegetable wash for 5 mins and 10 mins were also found to
be significantly effective (P<0.05) in reducing L. monocytogenes biofilm. Since L.
monocytogenes can form matured biofilm on fresh produce, therefore efficient washing
step is important before consuming fresh produce to lower the risk of foodborne illness.