18D-8

M. OBAIDAT and D. Y. C. Fung. Dept. of Animal Sciences and Industry, Kansas State Univ., 1600 Mid Campus Dr., 202 Call Hall, Manhattan, KS 66506-1600

The ideal indicator of fecal contamination should be positively correlated to the level of contamination; and enumeration should be rapid, precise, specific, and sensitive to the target organism. The strongest candidates are Escherichia coli, enterococci, and Clostridium perfringens. This research aimed to compare the specificity and sensitivity of the three microorganisms as indicators of fecal contamination of raw ground beef. Study I evaluated the prevalence rate of the three microorganisms in raw ground beef. Study II compared the percent recovery of the microorganisms from raw ground beef intentionally contaminated with the microorganisms. Study III examined the coefficient of determination (R²) of the linear regression curve of the three microorganisms from ground beef intentionally contaminated with bovine feces at different levels (0, 0.1, 0.3, 0.5, and 0.7% w/w). Study I showed the prevalence rates of E. coli, enterococci, and C. perfringens in raw ground beef were 44.4%, 16.7% and 0%, respectively. The percent recovery of the inoculated ATCC cultures in study II was not significantly different among microorganism types. The R² values of the linear regression curves in study III were as follows; enterococci (R²=0.93); C. perfringens (R²=0.86) and E. coli (R²=0.69). C. perfringens is the most specific indicator, as natural counts were recovered in the lowest amount. Furthermore, clostridia spores do not multiply in ground beef as easily as E. coli or enterococci; making clostridia a more suitable indicator or ‘ruler' for measuring fecal contamination. Future studies need to be performed to quantify feces in meat to strengthen this theory. Study II showed that the recovery of inoculated C. perfringens was similar to the other microorganisms. In addition, C. perfringens gives an acceptable correlation to fecal contamination, and can be enumerated in 8 to 9 hours. This data indicates that C. perfringens should be considered a viable alternative to current fecal indicators.

Session 18D, Food Microbiology: General
2:00 PM - 5:30 PM, Sunday PM Room Hall I-2

2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana