Cold plasma inactivates salmonella on grape tomatoes in a commercial PET plastic container without affecting quality

Authors: Niemira, Brendan; MIN, SEA CHEOL - Seoul Women'S University; ROH, SI HYEON - Seoul Women'S University; Fan, Xuetong; Sokorai, Kimberly; Boyd, Glenn; Sites, Joseph

Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2017
Publication Date: 6/26/2017
Citation: Niemira, B.A., Min, S., Roh, S., Fan, X., Sokorai, K.J., Boyd, G., Sites, J.E. 2017. Cold plasma inactivates salmonella on grape tomatoes in a commercial PET plastic container without affecting quality. [Abstract] Annual Meeting of the Institute of Food Technologists. Las Vegas, Nevada., Volume 1, Page 1.

Interpretive Summary:

Technical Abstract: Introduction: The number of outbreaks of foodborne illnesses associated with the consumption of fresh tomatoes has increased. Little research has been conducted on the effects of direct treatment of cold plasma (CP) on the microbial decontamination and preservation of bulk tomatoes packaged in commercial plastic containers. Thus, the objectives of this study were to investigate the effects of dielectric barrier discharge atmospheric cold plasma treatment (DACPT) on the inactivation of Salmonella in grape tomatoes, by including sample position, volume fraction, and rolling as the treatment variables and evaluate the effects of DACPT on the microbiological safety and quality of grape tomatoes during storage at 10 and 25 degrees C. Methods: Grape tomatoes, washed and inoculated with Salmonella (approximately 8 log CFU/tomato), were packaged in a polyethylene terephthalate (PET) commercial clamshell container. All samples were CP-treated at 35 kV at 1.1 kHz for 3 min. One–way analysis of variance with Tukey’s range test was used for statistical analysis. Results: DACPT resulted in approximately 1 log CFU/tomato reduction of Salmonella, irrespectively of the size of container, the number of grape tomatoes, and the position of the tomato in the container (P > 0.05). Rolling during treatment significantly increased the Salmonella reduction rates to 3.1±0.3 and 3.3±0.8 log CFU/tomato and those of indigenous aerobes to 1.3±0.3 and 1.5±0.2 log CFU/tomato in the single-layer and double-layer configurations of the tomato samples, respectively. The growth of Salmonella, total aerobes, and yeast and molds on dielectric barrier discharge atmospheric CP-treated grape tomatoes was effectively prevented during storage for 21 days at 10 degrees C. DACPT did not influence the tomato color index (a*/b*), firmness, weight loss, pH, total soluble solid content, and lycopene concentration of grape tomatoes at 10 and 25 degrees C (P > 0.05). Significance: The DACPT integrated with rolling effectively inactivated Salmonella and indigenous microorganisms of grape tomatoes, preserving the quality properties of tomatoes during storage at 10 and 25 degrees C. The efficiency in inactivating Salmonella was not affected by the size of container, the number of grape tomatoes, and the position of the tomato in the container. Summary: Rolling the package led to > 3.0 log reductions of Salmonella inside the PET package. Additionally, DACPT did not result in any significant differences in surface morphology, color, CO2 generation, or weight loss between the treated and untreated samples or among the samples that were in different positions in all configurations. The reductions in microorganism in a commercial plastic package observed in the present study demonstrated the potential for DACPT to be used as a post-processing technology to decontaminate packaged bulk tomatoes.