Growth and survival of Listeria monocytogenes on minimally processed, osmotically dehydrated broccoli with or without antimicrobial treatment

Growth and survival ofListeria monocytogenes on minimally processed broccoli, with and without osmotic dehydration and chemical pretreament, stored under modified atmospheric conditions was evaluated. Inoculated fresh broccoli florets were osmotically dehydrated by immersion in a saturated NaCl solution then chemically treated by immersion in a sanitizer solution before packaging. Fresh broccoli florets were packaged in gas permeable film, with and without atmospheric evacuation, and stored at either 4 or 10°C for 15 days. L. monocytogenes increased 2 logs on fresh broccoli florets stored at 10°C but increased only slightly less than 1 log during storage at 4°C. When inoculated onto osmotically dehydrated broccoli, L. monocytogenes increased 5 logs at 10°C and 2 logs at 4°C. L. monocytogenes was more resistant to antimicrobial treatment when broccoli was stored at 10° than at 4°C. Metabisulfite was better at controlling growth of L. monocytogenes than was hypochlorite when broccoli was stored at 10°C. The effects of antimicrobial treatment were similar for both osmotically dehydrated and nonosmotically dehydrated broccoli. Osmotic dehydration neither increased or decreased the resistance of L. monocytogenes to antimicrobial treatment.