VIABILITY OF ESCHERICHIA-COLI O157-H7 IN-GROUND AND FORMED BEEF JERKYPREPARED AT LEVELS OF 5 AND 20-PERCENT FAT AND DRIED AT 52, 57, 63, OR 68-DEGREES-C IN A HOME-STYLE DEHYDRATOR

Beef jerky batter was prepared to fat contents of about 5 and 20% and inoculated with about 10(8) cfu g(-1) of a five-strain inoculum of Esc herichia coli O157:H7. Pathogen numbers were determined in the raw bat ter and in the strips formed from it after drying at 52, 57, 63, and 6 8 degrees C for times that ranged from 2 to 20 h. For both the high an d low fat products, pathogen numbers were reduced by about 5 log(10) c fu g(-1) within 4 h drying at 68 degrees C and within 8 h drying at 63 degrees C. At 57 degrees C, a 5-log(10)-unit reduction was achieved w ithin 10 h drying for the 5% fat product and within 16 h drying for th e 20% fat product. At 52 degrees C, a 5-log(10)-unit reduction was ach ieved within 10 h drying for the 5% fat product and within 20 h drying for the 20% fat product. In at least one of the three trials for all four drying temperatures tested, the pathogen was present following en richment of the samples in synthetic media. The calculated D values de creased from 2.59, 2.48, 1.23, and 1.17 as the temperature increased f rom 52, 57, 63, and 68 degrees C and as the fat content decreased from 20 to 5%. However, there was no direct correlation between the moistu re-to-protein ratio and either the doneness of the strips or the viabi lity of the pathogen. These data indicate that the fat content and the time and temperature at which strips are dried directly impact the vi ability of E. coli O157:H7 in ground and formed beef jerky. (C) 1998 E lsevier Science B.V.