GMA scientists recently published two original research projects in the Journal of Food Protection.
The first published study was:
Thermal resistance parameters for Shiga toxin-producing Escherichia coli in apple juice
This study was to establish the thermal inactivation parameters of the six serotypes of non-O157 Shiga toxin-producing Escherichia coli(STEC) to determine if thermal treatments designed for E. coli O157:H7 would be effective against these non-O157 STEC serotypes.
The specific objective was to determine the heat resistance of a number of non-O157 E. coli strains relative to O157 strains, as a means of ensuring adequate processing parameters for these potential pathogens in single-strength apple juice without pulp. The results show that the recommended process for a 5-log reduction of Cryptosporidium will result in at least a 5-log reduction of O157 and non-O157 STEC in apple juice. Therefore non-O157 STEC do not pose an additional threat for pasteurized apple juice that receives the recommended minimum thermal treatment of 71.1˚C for at least 6 s. In the study, the D-value distributions showed that the heat resistance of non-O157 serotypes in apple juice is lower than or comparable to that of E. coli O157:H7.
This study was authored by Enache, E.*, E. C. Mathusa, P. H. Elliott, D. G. Black, Y. Chen, V. N. Scott, and D. W. Schaffner.
The second study published was:
Inactivation of Shiga Toxin-Producing Escherichia coli in Single-Strength Lemon and Lime Juices containing preservatives
This study is a follow-up to GMA’s previously published study on “Inactivation of Escherichia coli O157:H7 in single-strength lemon and lime juices” (Enache et al., 2009). Knowing that lemon and lime juices may not always undergo the pasteurization treatment because of quality issues, FDA recommended the abovementioned study to find other means to meet the 5-log pathogen reduction performance standard in these products.
The objective of the study was to determine the inactivation of six non-O157 Shiga toxin-producing Escherichia coli(STEC) serotypes in comparison to O157 in commercially produced shelf-stable lemon and limes juices. The validation tests confirmed that storage of the juices containing preservatives at room temperatures (22°C) for three days (72 h) will ensure a greater than 6-log reduction of O26, O45, O103, O111, O121, O145 and O157 STEC. These results demonstrate that non-O157 STEC had comparable survival abilities to those of E. coli O157:H7 strains in acidic food products, such as lemon and lime juices, pH 2.5 ± 0.1; therefore the storage conditions deemed to inactivate E. coli O157:H7 will similarly inactivate the non-O157 serotypes.
This study was authored by Kataoka, A. , E. Enache*, M. Sohail and P. H. Elliott, and D. G. Black.