Prevalence of Species on Food Contact Surfaces in Washington State Apple Packinghouses.

The 2014 caramel apple listeriosis outbreak was traced back to cross-contamination between food contact surfaces (FCS) of equipment used for packing and fresh apples. For Washington state, the leading apple producer in the United States with 79% of its total production directed to the fresh market, managing the risk of apple contamination with within the packing environment is crucial. The objectives of this study were to determine the prevalence of spp. on FCS in Washington state apple packinghouses over two packing seasons and to identify those FCS types with the greatest likelihood to harbor spp. Five commercial apple packinghouses were visited quarterly over two consecutive year-long packing seasons. A range of 27 to 50 FCS were swabbed at each facility to detect spp. at two sample times, (i) postsanitation and (ii) in-process (3 h of packinghouse operation), following a modified protocol of the FDA's method. Among 2,988 samples tested, 4.6% ( = 136) were positive for spp. Wax coating was the unit operation from which spp. were most frequently isolated. The FCS that showed the greatest prevalence of spp. were polishing brushes, stainless steel dividers and brushes under fans/blowers, and dryer rollers. The prevalence of spp. on FCS increased throughout apple storage time. The results of this study will aid apple packers in controlling for contamination and harborage of and improving cleaning and practices for sanitation of the FCS on which spp. are the most prevalent. Since 2014, fresh apples have been linked to outbreaks and recalls associated with postharvest cross-contamination with the foodborne pathogen These situations drive both public health burden and economic loss and underscore the need for continued scrutiny of packinghouse management to eliminate potential niches. This research assesses the prevalence of spp. on FCS in apple packinghouses and identifies those FCS most likely to harbor spp. Such findings are essential for the apple-packing industry striving to further understand and exhaustively mitigate the risk of contamination with to prevent future listeriosis outbreaks and recalls.