Water used in fresh produce washing is a potential vehicle of foodborne pathogen contamination. This work focused on assessing the sanitizing efficacy of ethanol mist to reduce Salmonella populations on the surfaces of tomatoes and cantaloupes. Ethanol (70%) mist was applied to whole tomatoes and cantaloupe rind plugs using a Biomist sanitation system, which uses CO2 as a carrier gas to spray vapors through a fine droplet spray nozzle. Fresh red tomatoes (Solanum lycopersicum) and cantaloupe (Cucumis melo) plugs were inoculated with Salmonella enterica Newport to a concentration of log 7 CFU/tomato and log 7 CFU/cm2 respectively. Application time (5, 10, and 15 sec), dry vs. wet surface, and stem scar contamination were evaluated on tomatoes, while only application time was evaluated on cantaloupe. Application of ethanol mist for 10 seconds was the most effective treatment time, reducing Salmonella by 3.3 log CFU/tomato. Application of ethanol mist was more effective on dry opposed to wet tomato surfaces by approximately 0.7 log CFU/tomato. Ethanol mist application to inoculated tomato stem scars reduced Salmonella 1.2 log CFU/tomato. Additionally, Salmonella decreased by 1.3 log CFU/cm2 on cantaloupe rind plugs at 10 seconds, again the most effective treatment time. Ethanol mist resulted in sufficient reductions of Salmonella populations on dry tomato surfaces, but was limited in effectiveness if the surface was wet, or if Salmonella adhered to the stem scar. Furthermore, this technique was overall not an efficient method to sanitize cantaloupe surfaces. / Master of Science in Life Sciences / Water is often used in washing and moving fresh produce during harvesting. However, this water is often found to be a source of contamination that can cause the fruits or vegetables to become unsafe to eat. In order to resolve this problem, a mist-type sanitizing system is being explored to wash fresh produce in packinghouses. In this experiment, a mist of ethanol (70%) was applied to whole tomato and cantaloupe plugs using a Biomist sanitation system, which turns liquids into a mist. Whole fresh tomatoes and cantaloupe plugs were infected with Salmonella enterica bacteria. Tomatoes and cantaloupe plugs were treated with ethanol mist for various times of 5, 10, or 15 seconds. Additionally, tomatoes were treated with ethanol to compare a wet surfaced tomato, as well as the tomatoes stem scar (where the vine of the tomato is attached during growing). Ethanol mist application was most effective at 10 seconds, but there was very little difference in bacterial elimination when all the times were compared to the untreated tomatoes. In addition, the mists effectiveness decreased if the surface of the tomato was wet compared to dry, and was even less effective if the bacteria were located where the vine attaches. Also, the ethanol mist has very little effect if bacterial contamination is present on a cantaloupes surface. If a harvested tomato remains dry post harvest, ethanol mist may make for a good washing system. However, it is probably not the best for rough surfaced produce like cantaloupes.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/101549 |
| Date | 28 June 2019 |
| Creators | Wesolowski, Michael Christopher |
| Contributors | Food Science and Technology, Williams, Robert C., Huang, Haibo, Boyer, Renee R. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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