Inactivation of Listeria monocytogenes ATCC 7644 on fresh-cut tomato using nisin in combinations with organic salts.
The inhibition of Listeria monocytogenes ATCC 7644 on fresh-cut tomato was investigated using nisin alone, and in combinations with organic salts. Nisin at a concentration of 5000UI/mL was introduced alone or in combination with an organic salt (sodium citrate or sodium acetate each at 3 and 5g/100mL each) on fresh-cut tomato previously inoculated with 10(8)CFU/mL of L. monocytogenes ATCC 7644. Chlorine at 200ppm was used as a control. The inoculated samples were incubated at different temperatures (4, 10 and 25°C) and examined at 0, 24, 48 and 72h. The effects of the antimicrobial treatments on quality parameters of tomato (pH, soluble solids, titratable acidity and vitamin C) were also evaluated, and colour parameters were observed at the lowest storage temperature for 10 days. Both nisin and the organic salts inhibited growth of L. monocytogenes, but the combinations of two compounds were more effective. The nisin-sodium citrate (5%) combination was significantly (p≤0.05) effective, while chlorine was least effective against L. monocytogenes. The quality parameters were substantially retained, especially at 4°C, suggesting good shelf stability at a low temperature. These results substantiate the use of the cheap and eco-friendly approach to reducing this pathogen of health concern in common fresh produce.
Department of Biotechnology and Food Technology, Durban University of Technology, Durban, South Africa. Electronic address: debbyoladunjoye@yahoo.com.
Adebola O
AO
Oladunjoye
Department of Biotechnology and Food Technology, Durban University of Technology, Durban, South Africa.
Suren
S
Singh
Department of Biotechnology and Food Technology, Durban University of Technology, Durban, South Africa.
Oluwatosin A
OA
Ijabadeniyi
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015169:Colony Count, Microbial; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods; D005520:Food Preservatives; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000302:isolation & purification; D018551:Solanum lycopersicum / Q000382:microbiology*; D050296:Microbial Viability / Q000187:drug effects; D009561:Nisin / Q000494:pharmacology*; D012492:Salts / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D005520:Food Preservatives; D012492:Salts; D009561:Nisin
Fresh produce; Listeria monocytogenes; Nisin; Quality parameters; Sodium acetate; Sodium citrate