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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #310907
Title: Reduction of Escherichia coli O157:H7 and Salmonella on fresh-cut produce by caprylic acid

Author
item Patel, Jitu
item KEELARA, SHIVARAMU - University Of Maryland
item KUMAR, VENKITANARAYANA - University Of Connecticut

Submitted to: Journal of Food Processing and Preservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/19/2015
Publication Date: 3/16/2015
Citation: Patel, J.R., Keelara, S., Kumar, V.N. 2015. Reduction of Escherichia coli O157:H7 and Salmonella on fresh-cut produce by caprylic acid. Journal of Food Processing and Preservation. 39(6):2234-2239.

Interpretive Summary: Caprylic acid, naturally occurring in coconut oil, is a GRAS (generally recognized as safe) ingredient approved by the FDA for food application. We evaluated caprylic acid (CA) as a produce wash for killing E. coli O157: H7 and Salmonella on fresh produce. Spinach, Romaine lettuce, and Iceberg lettuce leaves inoculated with a cocktail of five E. coli O157: H7 or Salmonella strains were treated with CA (10, 25, and 50 ppm) or chlorine (50 ppm) for 60 sec. Treated fresh produce was then stored at 4°C for 14 days. The CA treatment at 25- and 50-ppm significantly reduced E. coli O157:H7 and Salmonella on fresh produce compared to wash treatment with control (water) and chlorine. A 10 ppm CA treatment significantly reduced E. coli O157:H7 on Iceberg lettuce leaves. E. coli O157: H7 and Salmonella populations were reduced further during storage. Salmonella was more sensitive to CA treatment than E. coli O157:H7. The antibacterial activity of CA on spinach leaves was dependent on exposure time when evaluated at 5 ppm conc. Results indicate that CA could effectively be used to reduce E. coli O157: H7 and Salmonella on fresh produce. This information will be useful to other scientists and the produce industry.

Technical Abstract: Caprylic acid (CA) was evaluated for reducing E. coli O157: H7 and Salmonella on spinach and lettuce leaves. Spinach, Romaine lettuce and Iceberg lettuce leaves were inoculated with a cocktail of five E. coli O157: H7 or Salmonella strains, air dried for 30 min, and then dipped in caprylic acid (10, 25, and 50 ppm) or chlorine (50 ppm) solution for 60 sec. Residual treatment solution was removed by dipping in sterile water and then stored at 4°C in oxygen-permeable polyethylene bags for 14 days. Samples treated with water served as control. Produce samples were analyzed at 0, 7, and 14 days for surviving populations of E. coli O157: H7 and Salmonella. The CA treatment at 25- and 50-ppm significantly reduced these pathogens on fresh produce compared to wash treatment with control (water) and chlorine. A 10 ppm CA significantly reduced E. coli O157:H7 on Iceberg lettuce leaves. E. coli O157: H7 and Salmonella populations were reduced further during storage. The antibacterial activity of CA on spinach leaves was dependent on exposure time when evaluated at lower level (5 ppm). Results indicate that caprylic acid could effectively be used to reduce E. coli O157: H7 and Salmonella on fresh produce.