THE ROLE OF TEMPERATURE AND ACIDULANT ON THE POSTHARVEST CONTROL OF Escherichia coli 0157:H7 IN RAW GROUND BEEF SLURRIES

A study to determine the effects of acetic acid and temperature on the survival rate of Escherichia coli 015:H7 in raw ground beef slurries was carried out using standard procedures. Acetic acid at concentration of 8.50% v/v (pH 3.8) had the highest effect in inhibiting the growth of E. coli 0157:H7 at all temperatures (4°C, 30°C and 56°C). Statistically, there was significant difference (p<0.05) on the survival rate of E. coli 0157:H7 at various acetic acid concentrations when slurries were incubated at 4°C. The population levels of the pathogen in slurries with 8.50%v/v acetic acid decreased from 9.38 to 2.33 log CFU ml-1 on the 7th day and complete growth inhibition was recorded on the 8th day. Of the three temperatures used, 56°C had the highest effect in controlling the growth of the organisms with E. coli 0157:H7 populations decreasing from 9.38 to 2.88 log CFU ml-1 on the 5th day at 8.50% v/v acetic acid. However, no significant difference (p>0.05) in growth was observed between 6 to 8 days of incubation. There was complete growth inhibition on the 8th day using all concentrations of acetic acid. The combination of acetic acid and high temperature range are therefore viable potential strategies to control E. coli 0157:H7 populations in raw ground beef slurries.