Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 27, 2001
Publication Date: N/A
Interpretive Summary: Fresh-cut produce is a rapidly developing industry that offers the consumer both convenient and nutritious food. However, along with the rapid development of this industry, new problems may arise in the food safety area. Various antimicrobial compounds, which are effective in reducing foodborne pathogen populations on whole produce, are not as effective on fresh-cut produce. Also, the extensive use of these antimicrobial compounds has resulted in various foodborne pathogens developing resistance to these sanitizers. Bacteriophages, or viruses of bacteria, may be a viable alternative to antimicrobial compounds. We have shown that a mixture of phages, which specifically target the foodborne pathogen Salmonella, can consistently reduce populations of this pathogen on fresh-cut honeydew melons. The fresh-cut produce industry may find that the use of phages as biocontrol agents may be a successful strategy to reduce the potential for outbreaks of foodborne diseases.
The foodborne human pathogen Salmonella choleraesuis subsp. choleraesuis (Smith) Weldin serotype enteritidis (former Salmonella enteritidis) survived on fresh-cut Red Delicious apples and honeydew melons at temperatures of 5, 10 and 20 degrees C. The population of the bacterium increased up to 3.5 log units on Red Delicious apple slices at 20 degrees C over seven days in jars simulating commercial modified atmosphere packaging. No Salmonella growth occurred on apple slices stored at 5 and 10 degrees C during the first two days. The bacterial populations increased by 1.5 log units on slices stored at 10 degrees C between the second and the fifth day. On honeydew melons, the populations increased by up to six log units at 20 degrees C over five days. Treatment of fresh-cut honeydew melon slices with a mixture of phages specific to the Salmonella strain used, resulted in a decrease of bacterial populations. With an initial bacterial concentration of 10 exp 6 colony forming units (CFU) per ml on the fresh-cut fruit, the treatment with the phage mixture reduced bacterial numbers up to 3.5 log units on honeydew melons (pH 5.7 - 5.9) stored at 5 and 10 degrees C and up to 2.5 log units on fruit stored at 20 degrees C. On 'Red Delicious' apple slices (pH 4.1 - 4.7), there was no significant reduction in bacterial populations as a result of the phage treatment. The phage mixture consistently reduced populations of S. enteritidis on fresh-cut melon. For the duration of the experiment this reduction was independent of the temperature or sampling time.