Cook/Chill Foodservice Systems: Microbiological Quality of Beef Loaf at Five Process Stages

Abstract

Preparation and service of hot entrees in hospital cook/chill foodservice systems require two heat processes. After preparation and mixing, beef loaves composed of ground beef and eggs were heat-processed initially to end-point temperatures of 45, 60, 75, or 90 C in a convection oven operating at 121 ± 6 C; stored 24 h at 6 ± 1 C; portioned into 100-g slices; and single portions were microwave-heated to ⩾ 74 C. Four heat treatments of beef loaves were compared to a fifth treatment which excluded initial heating. Quality of beef loaf was evaluated by mesophilic and psychrotrophic aerobic plate counts, coliform counts, streptococcal counts and pH. Microbial reductions caused by handling and processing were: aerobic mesophilic plate count, 88 to 99%; psychrotrophic aerobic plate count and coliform count, ⩾ 99%; and streptococcal count, 71–99%. Increasing end-point temperature of initial heat processing consistently (P ⩽ 0.05) decreased mesophilic and psychrotrophic aerobic plate counts. Coliform counts and streptococcal counts did not show a statistical relationship to end-point temperature of initial heat processing. No statistically significant differences existed in any microbiological counts among five treatments of beef loaf portions after microwave-heating. Varying end-point temperature of initial processing had no consistent statistical effect on the pH of beef portions. Temperatures of ⩾ 74 C for microwave-heating of beef portions after chilled storage and before service are strongly recommended since chilling 5000 g of beef loaf to ⩽ 7 C required 10 to 14 h at 6 C.