|SWARTZ, RICHARD - Pennsylvania State University|
|KULAS, MEGAN - Kansas State University|
|STRASSER, HANNAH - Delaware Valley College|
|MUNSON, MADISON - Drexel University|
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2014
Publication Date: 5/1/2015
Citation: Swartz, R.S., Luchansky, J.B., Kulas, M., Shoyer, B.A., Shane, L.E., Strasser, H., Munson, M., Porto Fett, A.C. 2015. Thermal inactivation of Shiga toxin-producing Escherichia coli within cubed beef steaks following cooking on a griddle. Journal of Food Protection. 78:1013-1017.
Interpretive Summary: There is a food safety concern associated with the consumption of beef products enhanced via tenderization processes, such as cubing, since this practice may transfer pathogenic bacteria from the surface into the meat. Although foodborne pathogens, such as Shiga toxin-producing Escherichia coli (STEC), can be eliminated when tenderized meat is properly cooked, if consumed undercooked, there is a potential risk to public health. Thus, the objective of this study was to quantify the fate of STEC cells within cubed beef steaks following cooking on a non-stick griddle. Beef cutlets were surface inoculated with cells of STEC, and then one (single cubed steak) or two cutlets (double cubed steak) were passed through a tenderizer as part of the cubing process. Prior to cooking, extra virgin olive oil was heated to 191.5C (375F) on an aluminum non-stick griddle using an electric hot plate. Cubed steaks were individually cooked for up to 3.5 min per side. As expected, the longer the cooking time, the greater the kill of STEC within cubed steaks. Our results validated that cooking single or double cubed steaks on a non-stick griddle heated at 191.5C for at least 1.25 and 3.0 min per side, respectively, was sufficient for killing ca. 100,000 cells of STEC that was distributed throughout the meat as a consequence of cubing. In addition, these findings will be useful for establishing cooking guidelines for cubed steaks, and therefore, for reducing STEC illnesses associated with consumption of undercooked tenderized meat.
Technical Abstract: The objective of this study was to quantify thermal inactivation of Shiga toxin-producing Escherichia coli (STEC) cells within knitted/cubed beef steaks following cooking on a non-stick griddle. Both faces of each beef cutlet (ca. 64 g; ca. 8.5 cm L X 10.5 cm W X 0.75 cm H) were surface inoculated (ca. 6.6 log CFU/g) with 250 ul of a rifampicin-resistant cocktail comprised of single strains from each of eight target serogroups of STEC (STEC-8; O26:H11, O45:H2, O103:H2, O104:H4, O111:H-, O121:H19, O145:NM, and O157:H7). Next, inoculated steaks were: i) passed once through a mechanical tenderizer and then passed one additional time perpendicular to the orientation of the first pass through the tenderizer (single cubed steak = SCS) or ii) passed once through a mechanical tenderizer, and then two tenderized cutlets were knitted together by passage concomitantly through the tenderizer two additional times perpendicular to the orientation of the first pass through the tenderizer (double cubed steak = DCS). Prior to cooking, 30 ml of extra virgin olive oil was heated to 375F (191.5C) on a hard-anodized aluminum non-stick griddle using a flat-surface electric ceramic hot plate. In each of three trials, three single or three double cubed steaks were individually cooked for up to 3.5 min per side. Regardless of steak preparation (i.e., single vs. double cubed steaks), as expected, the longer the cooking time, the higher the final internal temperature, and the greater the inactivation of STEC cells within cubed steaks. The average final internal temperatures of SCS and DCS cooked for up to 3.5 min ranged from 59.8 to 94.7C and 40.3 to 82.2C, respectively. Cooking SCS or DCS on an aluminum griddle set at ca. 191.5C for 0.5 to 2.5 min or 1.0 to 3.5 min per side, respectively, resulted in total reductions of ca. 1.0 to equal or greater than 6.8 log CFU/g in pathogen numbers. These data validated that cooking SCS or DCS on a non-stick aluminum griddle heated at 191.5C for at least 1.25 and 3.0 min per side, respectively, was sufficient to achieve a 5.0-log reduction of STEC-8.