Differences in attachment of Salmonella to fresh produce

Authors: Patel, Jitu; Darlington, Leonora; Paroczay, Ernest

Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 3/10/2009
Publication Date: 7/14/2009
Citation: Patel, J.R., Darlington, L.K., Paroczay, E.W. 2009. Differences in attachment of Salmonella to fresh produce [abstract]. International Association for Food Protection. T5-02, P. 41.

Interpretive Summary:

Technical Abstract: Salmonella outbreaks have been associated with the consumption of fresh produce. The produce may be contaminated with Salmonella at any point throughout the food continuum. To develop effective strategies to minimize the risk of foodborne disease caused by this organism, it is essential to examine initial stages of bacterial attachment to various plant tissues. The purpose of this study was to evaluate the attachment of Salmonella spp. to different produce surfaces. Three types of fresh produce (Lettuce: romaine and iceburg, cabbage) were used in the study. Two configurations of coupons: 2-cm disk shaped produce coupons (intact surface) and 2x0.5-cm strips cut from mid-vein of leaf at the thickest point near the base of produce (cut surface) were used. Coupons/strips (n=360) were submerged into four individual Salmonella spp. and stored at 10 deg C for up to 24 h. Samples were removed periodically and analyzed for loosely attached cells (vortexed for 20 sec. in PBS/Tween20) and strongly attached cells (homogenized for 20 sec using high speed homogenizer). Attachment to produce surfaces among Salmonella spp. was variable. Attachment of S. Tennessee to produce surfaces was significantly greater than the attachment of S. Negev. Salmonella attachment to cabbage was significantly lower than the attachment to romaine or iceburg lettuce. Most Salmonella were attached to cut surface at levels 0.4-1 log CFU/ml above numbers on intact surface. However, the difference between bacterial attachment to intact and cut surfaces was not significant for lettuce. Populations of loosely attached Salmonella on cabbage and iceburg lettuce surfaces were significantly higher than the strongly attached bacterial populations on these produce. Most bacterial attachment occurred during first h of exposure to produce surface. The study shows the preferential attachment of Salmonella to produce surfaces. Further, Salmonella binds rapidly to plant tissues irrespective of the type of produce. Results may aid in understanding the contamination process and in developing effective mitigation strategies.