EFFECT OF SOLUBLE POLYLACTIC ACID DURING REFRIGERATED STORAGE OF GROUND MEATS INOCULATED WITH ESCHERICHIA COLI O157:H7 1

Ground beef, ground pork, and commercial breakfast sausage were inoculated (6.5 log 10 CFU/mL) with a five strain mixture of Escherichia coli 0157:H7 and treated either with sterile water, or 1% or 2% solutions of soluble polylactic acid (SPLA) in sterile water and stored at 4C for 1, 24, 72 and 168 h. After 168 h, 2% SPLA was significantly (p0.05) more effective than both 1% SPLA and sterile water in reducing E. coli 0157:H7 and resulted in overall reductions of 1.68, 1.70, and 1.32 log 10 CFU/mL for beef, pork, and pork sausage, respectively, when compared to control samples. The meat samples treated with 1% and 2% SPLA maintained significantly (p 0.05) lower pH values throughout refrigerated storage of 168 h with the higher concentration sustaining pH values from 3.83 to 3.92. Although the inhibitory effect of this acid increased with storage time, E. coli 0157:H7 survived these acidic conditions, with water activity levels ranging from 0.972 to 0.991.