|Liao, Ching Hsing|
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: February 15, 2000
Publication Date: October 15, 2000
Citation: Liao, C., Ukuku, D.O., Fett, W.F. 2000. Factors limiting the efficacy of sanitizer treatments for fresh produce. Meeting Abstract. 29th Annual Meeting, Nov. 19-25, 2000, Honolulu, HI. Technical Abstract: Fresh fruits and salad vegetables including sprouts and melons contaminated with Salmonella have been implicated as the causes of several disease outbreaks in the last few years. We have investigated the attachment of Salmonella to three different types of produce and the response of attached bacteria to sanitizer treatments. Results showed that attachment of Salmonella to pepper disks was not affected by prolonging the exposure tim (from 0.5 to 16 min) of pepper disks to bacterial suspensions but was directly affected by the cell density of the bacterial suspension used for inoculation. Population and scanning electron microscopic (SEM) studies revealed that attachment occurred mainly on the surfaces of injured tissue and on the stem and cavity ends of the apple fruits. When attached bacteria on pepper disks were washed with 1.76 % (w/v) NaOCl, 0.36 % (w/v) Ca(OCl)2, 6 % (v/v) H2O2, or 3 % (w/v) Na3PO4, 5 to 13 % of attached bac- teria survived. Resistance of attached Salmonella to sanitizer treatments increased with time after inoculation for both pepper disks and whole cantaloupe. Formation of biofilms on four types of sprouts by the native microflora was demonstrated by using SEM and confocal scanning laser microscopy. The effectiveness of sanitizer treatments may be further limited if human pathogens become part of biofilms. Attachment and formation of biofilms represent two important factors limiting the efficacy of sanitizer treatments for fresh produce.