Effect of ionic strength on inactivation kinetics of Escherichia coli O157:H7 by electron beam in ground beef, chicken breast meat, and trout fillets

The ionic strengths (IS) of ground beef, chicken meat, and trout fillets were modified to intermediate and highest with 3.5% and 7.0% NaCl, respectively. The samples with modified and unaltered (native) IS were inoculated with Escherichia coli O157:H7 and subjected to electron beam (e-beam). The water activity (a(w)) of the meat samples were 1.0, 0.96-0.97, and 0.94 for native, intermediate, and highest IS. The D-10-values were calculated from survivor curves. The D-10-values for E. coli ranged from 0.19 kGy in trout (highest IS) to 0.31 kGy in beef and chicken (highest IS). Regardless of the meat type, the increased resistance of E. coli to e-beam was only observed at the highest IS. The difference of the D-10-value for E. coli in samples at intermediate and native IS was insignificant. Regardless of the IS, the E. coli in trout was most sensitive, while the difference of E. coli resistance to e-beam in ground beef and chicken meat was insignificant.