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P3-150 Investigating the Effects of Lactic-Citric Acid (LCA) Blend and Sodium Lauryl Sulfate on the Inhibition of Shiga Toxin-producing Escherichia coli (STEC) in Broth System

Wednesday, August 3, 2016
America's Center - St. Louis
Armitra Jackson-Davis, Alabama Agricultural and Mechanical University, Huntsville, AL
Deborah Abraham-Bethel, Alabama Agricultural and Mechanical University, Huntsville, AL
Marciauna Daniel, Alabama Agricultural and Mechanical University, Huntsville, AL
Michelle Oliver, Alabama Agricultural and Mechanical University, Huntsville, AL
Jamie Harrington, Alabama Agricultural and Mechanical University, Huntsville, AL
Lamin S. Kassama, Alabama Agricultural and Mechanical University, Huntsville, AL
Introduction: Food grade organic acids are used to control undesirable microbes in foods and are commonly diluted in water to facilitate application of desired concentrations of antimicrobial agents. Water is a poor wetting agent for hydrophobic environments. In hydrophobic environments this problem can be circumvented by use of a food grade processing aid.  Sodium lauryl sulfate (SLS) is a surfactant that is generally regarded as a safe food additive.

Purpose: The purpose of this study was to investigate the ability of a lactic-citric acid (LCA) blend and SLS to control the growth of Shiga toxin-producing Escherichia coli (STEC) in a broth system. 

Methods: Rifampicin-resistant E. coli O157:H7 and a cocktail of non-O157:H7 strains were evaluated separately (8.0 log CFU/g).  A blend solution of LCA at concentrations of 1%, 2%, and 2.4% and SLS at concentrations of 0.05%, 0.25%, and 0.5% were evaluated individually and in combination.  A set of samples were inoculated with E. coli O157:H7 while another set was inoculated with a cocktail of non-O157:H7 strains (O26, O45, O103, O11, O121, O145, O104:H4).  Samples were stomached and plated onto Sorbitol MacConkey agar infused with rifampicin (100 µg/ml) and incubated at 37°C for 24 h. Three replications were conducted.

Results: The ANOVA showed no individual effects (P > 0.05) of the LCA blend or SLS on the control of O157:H7 and the non-O157:H7 cocktail in the BHI broth. Applying the combined SLS (0.05% and 0.5%)) and LCA blend (2.4%) in the broth significantly (P < 0.01) reduced the non-O157:H7 by 5 log CFU/g and 2.9 and 4.6 log CFU/g in O157:H7 strains. Increasing the SLS concentration (0.25%) in LCA blend (2.4%) was more effective (P < 0.01) on O157:H7, showing 5 log CFU/g reduction.      

Significance: This work will assist with providing new information on enhancing the wettability and the exposure of pathogens to antimicrobial treatment.

Back to: Poster Session 3 – Antimicrobials, Laboratory and Detection Methods, Microbial Food Spoilage, Modeling and Risk Assessment, Retail and Food Service Safety and Sanitation
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