Effects of celery seed oil and celery powder on thermal resistance of Escherichia coli O157:H7 in sous vide packed ground beef

Effects of celery seed oil and celery powder addition into lean ground beef on thermal resistance of Escherichia coli O157:H7. Sensory analysis was performed to determine the highest acceptable levels of celery seed oil and celery powder, and then they were determined as 2 % and 3 %, respectively. The celery seed oil (2 %) and celery powder (3 %) added ground beef samples were inoculated with E. coli O157:H7 at a level of 7 log kob/g and then heated at 55, 57.5, 60 and 62.5°C. By sampling at pre-determined time intervals counts of survivors were determined. The data was evaluated using GInaFit software according to Log-linear model, and then D and z values were calculated. D values of E. coli O157:H7 in control samples at 55, 57.5, 60 and 62.5°C were 11.64, 3.82, 1.78 and 0.99 min, respectively, while they were 11.11, 2.36. 1.43 and 0.41 min in celery seed oil added samples, and 10.59, 3.02, 1.31 and 0.35 min in celery powder added samples, respectively. All inactivation lines were linear (r2≥0.93). The differences between the D values at 55°C were not significant (p>0.05). In contrast, the D values at 57.5, 60 and 62.5°C in celery seed oil and celery powder added samples were significantly lower than those in control samples (p<0.05). The z value of E. coli O157:H7 in lean ground beef was 7.06°C (r2=0.98). By adding celery seed oil and celery powder the z values were reduced to 5.18°C (r2=0.99) and 5.57°C (r2=0.97), respectively. Therefore, it was concluded that either 2 % celery seed oil or 3 % celery powder addition may help to control E. coli O157:H7 in ground beef by reducing its thermal resistance. Keywords: Celery seed oil, celery powder, sous vide, ground beef, Escherichia coli O157:H7