Growth inhibition of heat-injured Enterococcus faecium by oligophosphates in a cured meat model

Cells of two heat-resistant strains of Enterococcus faecium were heated and incubated in meat suspensions containing curing ingredients. The concentrations of the curing ingredients were those frequently used for pasteurized ham-type products, except that the concentrations of the oligophosphates (triphosphate and diphosphate) varied. Heating tests at 69 °C were performed with inoculated meat suspensions in heat-sealed plastic pouches. Numbers of bacteria were counted immediately after heating and in parallel series of heated pouches incubated at 37 °C. Plating was performed in Tryptone Dextrose Yeast Meat Peptonised Milk Agar (TDYMP); in TDYMP Agar to which the curing ingredients were added; and in TDYMP Agar to which the curing ingredients except oligophosphates were added. clusion of oligophosphates in the heating medium increased the heat-injury sustained by the E. faecium cells, and in combination with rather severe heat treatment even completely blocked the growth of surviving organisms in the meat suspension incubated at 37 °C. esence of oligophosphates in the culture medium TDYMP Agar severely reduced the counts of freshly heated cells; however, this effect disappeared after repair and growth of the surviving organisms in the meat suspension.