Title: Inactivation of natural microflora and Escherichia coli K-12 on cantaloupe rind surfaces using wet steam treatments Authors
Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: July 28, 2013
Publication Date: July 31, 2013
Citation: Ukuku, D.O., Geveke, D.J., Chau, L.I., Bigley Jr, A.B. 2013. Inactivation of natural microflora and Escherichia coli K-12 on cantaloupe rind surfaces using wet steam treatments. International Association for Food Protection. 1:1. Technical Abstract: The presence of human bacterial pathogens on cantaloupe rind surfaces and transfer to fresh-cut pieces during preparation continue to be a microbial safety hazard for the produce industry and consumers alike. A prototype flash steam lab unit was used to treat cantaloupe rind surfaces inoculated with Escherichia coli K-12 bacteria at 5.2 log CFU/cm2. The cantaloupe rind surfaces were placed at a distance of 8.9 cm from the outlet of the flash unit and the effect of wet steam treatment at 65 +/- 2 deg C for 60s, 120, and 180 s was investigated. The initial population of aerobic mesophilic bacteria, yeast and mold and lactic acid bacteria on control cantaloupe rind surfaces averaged 6.5 +/- 0.22, 2.8 +/- 0.12 and 3.3 +/- 0.12 log CFU/cm2, respectively. Steam treatment at 60s, 120s and 180s reduced the aerobic mesophilic bacteria to 4.2, 3.1 and 2.3 log CFU/cm2, respectively. At 120 and 180 s, the surviving inoculated populations of E. coli bacteria and lactic acid bacteria on cantaloupe rind surfaces averaged 0.6 and 0.9 log CFU/cm2, respectively while yeast and mold populations were below the detection limit. Plating of E. coli on Violet Red Bile Agar versus the same agar with an overlay containing 4-methylunbelliferyl-beta-D-glucuronide (MUG) indicated the treatment killed, as opposed to injured, the microorganism. The results of this study suggest that wet steam treatment can be used to reduce microbial populations of cantaloupe rind surfaces. We are currently investigating the inactivation of human bacterial pathogen by this system with the aim of enhancing microbial safety of whole and fresh cut cantaloupe pieces to reduce or eliminate illness and costly recalls due to foodborne outbreaks.