Trisodium phosphate enhanced phage lysis of Listeria monocytogenes growth on fresh-cut produce

Trisodium phosphate enhanced phage lysis of Listeria monocytogenes growth on fresh-cut produce

Combination of bacteriophage and trisodium phosphate (TSP) to inactivate Listeria monocytogenes inoculated on fresh-cut produce was investigated. Fresh-cut tomato and watermelon inoculated with L. monocytogenes cocktail at log 107 CFU/g were treated with Listex P100 bacteriophage (108 PFU/g) alone, and in combination with TSP at 10, 30 and 60 mg/ml using chlorine at 200 mg/L as control. Treated samples were stored at 4 and 10 C for 6 days. Effect of treatment on pH and colour of treated samples was evaluated. Phage treatment alone significantly (p < 0.05) reduced L. monocytogenes on fresh-cut tomato by approximately 0.5 and 0.6 log CFU/ml and on fresh-cut melon by 1.30 and 1.49 log CFU/ml at 4 and 10 C respectively. Addition of phage-TSP at 10 mg/ml was only effective on fresh-cut melon, but phage-TSP at 30 and 60 mg/ml approximately reduced inoculated tomato by 1 and 2 logs, and melon by 2 and 5 logs at 4 and 10 C respectively. Chlorine treatment showed 1e2 log reduction. Phage titer declined rapidly on tomato unlike melon, pH and colour parameters slightly increased with treatment combinations with no impairment on both samples. Phage-TSP combination could serve as effective tool to control listeriosis outbreak in fresh produce.

Adebola O. Oladunjoye* , S. Singh, Oluwatosin A. Ijabadeniyi

Department of Biotechnology and Food Technology, Durban University of Technology, South Africa

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