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United States Department of Agriculture

Agricultural Research Service

Research Project: INTEGRATED APPROACH TO PROCESS AND PACKAGE TECHNOLOGIES

Location: Residue Chemistry and Predictive Microbiology

Title: Inactivation of Salmonella on tomato stem scars by edible chitosan and organic acid coatings

Authors
item Jin, Zhonglin
item Gurtler, Joshua

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 2012
Publication Date: July 1, 2012
Citation: Jin, Z.T., Gurtler, J. 2012. Inactivation of Salmonella on tomato stem scars by edible chitosan and organic acid coatings. Journal of Food Protection. 75(8):1368-1372.

Interpretive Summary: Foodborne pathogens can contaminate the surfaces of fresh fruits and vegetables. Pathogens attached on stem scars are more difficult to be removed than other smooth surface of tomatoes by current washing and sanitizing practices. This study was conducted to develop antimicrobial coating solutions for destroying Salmonella on the stem scar of tomatoes. Tomato stem scars were inoculated with Salmonella and coated with edible chitosan and acid solutions. The antimicrobial coating treatments reduced 99.9999% of Salmonella on the stem scar of tomatoes. Results from this study provide producers an alternative antimicrobial intervention for decontamination of tomatoes.

Technical Abstract: This study investigated the efficacy of antimicrobial coatings on inactivation of Salmonella on the surface of tomato stem scars, which was inoculated with a four-strain cocktail of Salmonella (S. Montevideo. S. Newport. S. Saintpaul, and S. Typhimurium) and coated with acid-chitosan solutions. The chitosan coating with 3 acids (3A+chitosan), chitosan coating with 1 acid (1A+chitosan), and a 3 acid solution without chitosan (3A solution) reduced the populations of Salmonella by 6.0, 3.6 and 5.3 log cycles, respectively. Addition of allyl isothiocyanate (AIT, 10 ul/ml) to the 3A+chitosan coating did not significantly (p less than 0.05) increase the antimicrobial efficacy. While the populations of Salmonella in the controls (ca. 7.5 log CFU/stem scar) did not change significantly throughout a 14-day storage period at 10 deg C, Salmonella cells were reduced to undetectable levels (greater than 0.7 log CFU/stem scar) in the samples treated with 3A+chitosan coating after 2 days of storage, and no growth was observed for the rest storage period. Results from this study demonstrate that acid+chitosan coatings provide an alternative antimicrobial intervention for decontamination of tomatoes.

Last Modified: 4/16/2014