Abstract
Post-harvest cross-contamination of produce with bacterial human pathogens reduces the usefulness of produce as a source of wholesome human food. The application of nano-encapsulated natural antimicrobials, including essential oil components of plants, can help protect produce safety by decontaminating produce from microbial pathogens. The primary objective of this research was to determine the efficacy of antimicrobial interventions on pathogen-inoculated spinach samples stored refrigerated (5 °C) for up to 10 days, or refrigerated (5 °C) for 5 days with subsequent moderate (15 °C) or severe (25 °C) temperature abuse thereafter until a total of 10 days had elapsed. The secondary objective of the study was to determine the capacity of antimicrobial interventions to inhibit and/or reduce pathogen numbers on spinach when inoculation followed intervention treatment, simulating cross-contamination of spinach following post-harvest sanitizing of spinach. Rinsed spinach was portioned into samples and inoculated with cocktailed antibiotic-resistant pathogens to 6.1±0.1 log10 CFU/cm2 for each pathogen. Treatments of geraniol-loaded polymeric nanoparticles (GPNs) (0.5 wt.% geraniol), unencapsulated geraniol (0.5 wt.%), and 200 ppm free and available chlorine (FAC; pH 7.0) were applied to pathogens-inoculated or non-inoculated spinach samples. Following treatment, samples were collected for determining pathogen survival or were covered and held to determine changes in microbial populations (inoculated pathogens and naturally contaminating microbial hygiene indicators) during post-treatment simulated refrigerated and/or temperature-abuse storage. Changes in pathogen numbers were assessed periodically over 10 days for refrigerated (5°C), moderately (15°C) or severely (25°C) temperature-abused spinach. Immediately following treatment by FAC, unencapsulated or nanoparticle-entrapped geraniol, E. coli O157:H7 and Salmonella counts on spinach ranged from 1.5 to 6.1 log10 CFU/cm2. Geraniol-loaded nanoparticles reduced pathogens to non-detectable numbers (detection limit: 0.5 log10 CFU/cm2) on refrigerated and moderately temperature-abused samples (15°C) within 7 days of storage post-treatment, and after 10 days of severe thermo-abuse storage (25°C). Conversely, FAC treatment did not reduce pathogens to non-detectable numbers for refrigerated spinach, and was not observed to inhibit pathogen growth in temperature-abused samples. Application of encapsulated geraniol can reduce pathogens on spinach surfaces, preventing their transmission to consumers, aiding the retention of produce wholesomeness and utility for human consumption and nutrition.
Highlights
Microbial pathogens have been associated with a variety of produce-borne human disease outbreaks, with an apparent increase in the frequency of outbreaks in recent years (CDC, 2012a,b; Gould et al, 2013; Slayton et al, 2013; Jung et al, 2014; Angelo et al, 2015). Painter et al (2013) reported leafy green produce commodities were the most frequently implicated pathogen transmission vehicles in US human foodborne disease cases, as well as the food vehicle type second most frequently linked to hospitalizations resulting from foodborne disease
While proper refrigeration is known to inhibit the growth of these pathogens on several foods, multiple research groups have reported the capability of E. coli O157:H7 and Salmonella to replicate on both intact and damaged leafy green vegetables, indicating a need for advanced decontamination technologies to reduce the risk of microbial pathogen transmission to consumers (Roever, 1998; Lang et al, 2004; Kroupitski et al, 2009; Khalil and Frank, 2010; Neal et al, 2012; Sant’Ana et al, 2012)
Researchers previously reported the application of 0.5% trans-cinnamaldehyde dispersed in tryptic soy broth (TSB) produced a 3.3 log10cycle reduction in E. coli O157:H7 numbers on baby spinach leaves following 10 min exposure at 23°C (Viazis et al, 2011)
Summary
Microbial pathogens have been associated with a variety of produce-borne human disease outbreaks, with an apparent increase in the frequency of outbreaks in recent years (CDC, 2012a,b; Gould et al, 2013; Slayton et al, 2013; Jung et al, 2014; Angelo et al, 2015). Painter et al (2013) reported leafy green produce commodities were the most frequently implicated pathogen transmission vehicles in US human foodborne disease cases, as well as the food vehicle type second most frequently linked to hospitalizations resulting from foodborne disease. Painter et al (2013) reported leafy green produce commodities were the most frequently implicated pathogen transmission vehicles in US human foodborne disease cases, as well as the food vehicle type second most frequently linked to hospitalizations resulting from foodborne disease. The enteric bacterial pathogens Escherichia coli O157:H7 and Salmonella enterica have previously been identified to cause human disease following consumption of pathogencontaminated leafy green vegetables. While proper refrigeration is known to inhibit the growth of these pathogens on several foods, multiple research groups have reported the capability of E. coli O157:H7 and Salmonella to replicate on both intact and damaged leafy green vegetables, indicating a need for advanced decontamination technologies to reduce the risk of microbial pathogen transmission to consumers (Roever, 1998; Lang et al, 2004; Kroupitski et al, 2009; Khalil and Frank, 2010; Neal et al, 2012; Sant’Ana et al, 2012)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
