Effect of surrounding vegetation on microbial survival or die‐off on watermelon surface in an agriculture setting

Abstract

Preharvest contamination of produce with food borne pathogens has been a major food safety issue. In this study, we investigated the effect of surrounding vegetation on the survival of natural and inoculated generic Escherichia coli on watermelon rinds in an agricultural field setting. There was no significant difference (p > .05) on the populations of natural generic E. coli (1–1.46 log Most Probable Number (MPN)/sample) and coliforms (<3.99 log CFU/cm2) on watermelons harvested from low, medium, and high levels of vegetation. However, the survival rate of generic E. coli inoculated on watermelon rind discs was variable with the level of vegetation. A significant reduction in generic E. coli count was observed within 12 hr at all vegetation levels. After 108 hr, discs placed at low vegetation level had a highest die‐off reduction (3 log Colony Forming Units (CFU)/cm2) compared to medium and high vegetation levels. Practical applications To ensure preharvest produce safety, the Food Safety Modernization Act (FSMA) produce safety rule has suggested a time interval between last irrigation and harvest for potentially contaminating microorganisms to die‐off. However, a knowledge gap exists regarding the influence of surrounding vegetation on microbial die‐off rates on produce in the agricultural field. The findings of this study emphasize the importance of considering the surrounding vegetation while making decisions for developing preharvest risk management strategies based on microbial die‐off rate calculations.

Evaluation of ultraviolet (UV‐C) light treatment for microbial inactivation in agricultural waters with different levels of turbidity

“…The number of contaminated cantaloupes was higher in December, September, and June in 2010, 2011, and 2012, respectively (Denis et al, ). This seasonal variation in the microbial population may be attributed to the changes in weather conditions such as temperature, humidity, and day length (Ailes et al, ; Chhetri, Fontenot, et al, ; Chhetri et al, ). However, further study is needed to establish relationships between year‐round weather conditions and microbial quality of produce.…”

“…The rule requires that the water used for irrigation and production/processing of fresh produce must be safe and of adequate sanitary quality for its intended use. The growers are recommended to regularly monitor the microbial quality of their water sources by testing generic E. coli (FDA, ; Chhetri, ). The easily distinguishable characteristics of generic E. coli make it a principal indicator organism to assess water contamination with human pathogens (FDA, ).…”

Meeting Report: Key Outcomes from a Collaborative Summit on Agricultural Water Standards for Fresh Produce

“…One corrective measure growers can utilize is a time interval for in‐field microbial die‐off at a rate of 0.5 log per day, for a maximum of four consecutive days between the last irrigation and harvest. Limited research exists for establishing pathogen die‐off rates for specific crops, climates, and growing conditions, causing many to lack confidence in the use of this particular corrective measure (Chhetri et al., ). The analysis conducted by FDA in support of the 0.5 log/day die‐off rate evaluated nine studies that measured in‐field die‐off of E. coli O157:H7, Salmonella spp ., coliphage and Bacteroides fragilis phage (viral surrogates), and rotavirus (Snellman, Marianne, Ravaliya, & Assar, ).…”

Effectiveness of Aqueous Chlorine Dioxide in Minimizing Food Safety Risk Associated with Salmonella, E. coli O157:H7, and Listeria monocytogenes on Sweet Potatoes

“…Fresh produce commodities have been subject to numerous foodborne outbreaks in both the domestic and international markets [5]. With cross-contamination vectors including soil and irrigation water contamination as well as produce handling by field workers, postharvest sanitation is often the most vital step in reducing microbial contamination [6][7][8]. Fresh-cut produce sanitation has been well-researched.…”

“…ClO 2 has 2.5 times the oxidizing capability as Cl 2 and may be an effective alternative produce sanitizer [20]. ClO 2 offers similar sanitation efficacy as chlorine-based sanitizers while requiring far less concentration in a wide pH range (3)(4)(5)(6)(7)(8) [21]. Additionally, ClO 2 does not have issues related to the production of carcinogenic byproducts [22].…”