SURVIVAL OF LISTERIA-MONOCYTOGENES IN 3 ZIMBABWEAN FERMENTED MILK-PRODUCTS

The growth and survival of Listeria monocytogenes was studied in tradi tionally fermented unpasteurized and pasteurized milk and in an indust rially fermented milk marketed in Zimbabwe. Inoculated milk samples we re incubated at 20 degrees C for 24 h, and then one set of samples of each type of milk was stored at ambient (20 degrees C) and a duplicate set at refrigeration (5 degrees C) temperatures for a further 96 h. T he industrially fermented milk was least favorable to the survival of L. monocytogenes, followed by traditionally fermented unpasteurized mi lk and traditionally fermented pasteurized milk when these milks were stored at ambient temperature. A different trend was observed when the milks were stored at refrigeration temperature with traditionally fer mented unpasteurized milk allowing the least survival of L. monocytoge nes followed by industrially fermented milk and traditionally fermente d pasteurized milk. More L. monocytogenes survived in all the three fe rmented milks when they were stored at refrigeration temperature than at ambient temperature.