Title page for ETD etd-09272002-125139


Type of Document Master's Thesis
Author Raiden, Renee Mary
Author's Email Address rraiden@vt.edu
URN etd-09272002-125139
Title Efficacy of Detergent Rinse Agents to Remove Salmonella and Shigella spp. from the Surface of Fresh Produce.
Degree Master of Science
Department Food Science and Technology
Advisory Committee
Advisor Name Title
Sumner, Susan S. Committee Chair
Eifert, Joseph D. Committee Member
Pierson, Merle D. Committee Member
Keywords
  • Shigella
  • Detergents
  • Fresh Produce
  • Salmonella
Date of Defense 2002-08-16
Availability unrestricted
Abstract
Fresh produce has been implicated in several foodborne outbreaks. A primary site of microbial contamination for produce occurs on the surface during production and handling. An approach to reduce contamination is to sample the surface of produce. This study used different detergent agents at 22°C and 40°C to determine their efficacy for recovery of pathogenic bacteria, from surfaces of several produce types and examined survival of organisms in detergents over time. Strawberries, tomatoes and green leaf lettuce were dip inoculated in a 6-6.5 LOG CFU/ml cocktail of nalidixic acid resistant organisms. After drying, produce were rinsed with either 0.1 % sodium lauryl sulfate (SLS), 0.1% Tween 80, or water at different temperatures. Rinse solutions were plated onto Tryptic Soy agar supplemented with 50-ppm nalidixic acid (TSAN). About 4 LOG CFU/ml of Salmonella, and 3-LOG CFU/ml Shigella were recovered, with slightly lower recovery from tomatoes. Inoculated strawberries rinsed with SLS, displayed minimal recovery at ~1.5-LOG CFU/ml at 22°C, and <1-LOG CFU/ml at 40°C. When whole strawberries treated with SLS were analyzed, few Salmonella were recovered. Lack of recovery of Salmonella rinsed with SLS, suggests SLS may be inactivating Salmonella, especially at elevated temperatures. Detergent solutions were inoculated with 3-LOG CFU/ml cocktail and incubated for up to 32 hours at 22°C, and 40°C. Aliquots were plated onto TSAN at varying times. All solutions at 40°C allowed Shigella to grow. SLS gave initial drops in Salmonella populations followed by slight recovery. SLS may cause an initial injury of Salmonella. While organisms were able to survive in detergents, the application of detergents to produce was no more effective in recovery of organisms from produce than water.
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