Purpose: The purpose of this study is to investigate the effect of nisin and its combination with organic acids in controlling Listeria monocytogenes ATCC 7644 on fresh-cut tomato under different storage temperatures (4, 10 and 25°C).
Methods: Artificially inoculated tomato slices (108 CFU/ml) were dipped in nisin alone (5,000 IU/ml) and in combination with organic acids (acetic and citric acid at 3 and 5% concentration, respectively). Chlorine solution (sodium hypochlorite) at 200 mg/L chlorine was used as control. Stored slices were monitored for 6 days. Antimicrobial treatment effect was also investigated on physicochemical parameters (pH, total soluble solid, titratable acidity, vitamin C and Chroma values-CIE L* a* b*) at 4°C.
Results: After six days of storage along the storage temperature, nisin dip statistically (P≤ 0.05) resulted in 1 to 3-fold log reduction, while nisin treatment with citric acid had no significant difference. Control treatment was comparatively least effective. Treatment with acetic acid resulted in ~3 to 4-fold log reduction. Antimicrobial treatments resulted in lowered pH, reduced total soluble solids and total titratable acidity at 10 and 25°C. However, vitamin C content increased with no significant change in the color consistency of the tomato slice
Significance: The result of this study showed the promising potential synergy of nisin with organic acids in controlling L. monocytogenes on fresh tomato slices and also to maintain its keeping quality.