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 degrees 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 degrees 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. The inclusion 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 degrees C. The presence 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.
Houben
J H
JH
Department of Public Health and Food Safety, Faculty of Veterinary Medicine, Universiteit Utrecht, P.O. Box 80.175, 3508 TD Utrecht, The Netherlands. j.h.houben@vet.uu.nl
Tjeerdsma-van Bokhoven
J L M
JL
D000818:Animals; D015169:Colony Count, Microbial / Q000379:methods; D003470:Culture Media / Q000737:chemistry; D011756:Diphosphates / Q000494:pharmacology*; D016984:Enterococcus faecium / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D006358:Hot Temperature; D008461:Meat Products / Q000382:microbiology*; D011122:Polyphosphates / Q000494:pharmacology*; D013552:Swine; D013997:Time Factors
D003470:Culture Media; D011756:Diphosphates; D011122:Polyphosphates; C005692:triphosphoric acid