|OLIVER, MICHELLE - Alabama A & M University|
|DANIEL, MARCIAUNA - Alabama A & M University|
|KASSAMA, LAMIN - Alabama A & M University|
|JACKSON-DAVIS, ARMITRA - Alabama A & M University|
Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2016
Publication Date: 5/1/2016
Citation: Porto Fett, A.C., Oliver, M., Daniel, M., Shoyer, B.A., Stahler, L.J., Shane, L.E., Kassama, L.S., Jackson-Davis, A., Luchansky, J.B. 2016. The effect of deep frying or conventional oven cooking on inactivation of Shiga toxin-producing cells of Escherichia coli (STEC) in meatballs. Journal of Food Protection. 79(5):723-731.
Interpretive Summary: The objective of this study was to evaluate the fate of STEC cells in meatballs following cooking on a deep-fryer or an electric convection oven. Ground veal or a blend of ground veal-beef-pork were inoculated with cells of ca. 10 million cells of STEC, mixed with liquid whole eggs and seasonings, and then shaped into 40-g balls. Meatballs were stored at -20 degree C (i.e., frozen) or at 4 degree C (i.e., fresh) for up to 18 h before cooking in the deep-fryer in pre-heated canola oil (176.7C) or in the convection oven (pre heated at 176.7 degree C) for up to 20 min. As expected, regardless of the cooking method or the state of the meat prior to cooking, the longer the cooking time, the greater the kill of STEC within meatballs. Our results validated that deep frying fresh meatballs for up to 5.5 min or frozen meatballs for up to 9.0 min was sufficient for killing 100,000 cells of STEC that was distributed throughout the meat. Similar results were observed when fresh and frozen meatballs were baked for up to 12.5 or 20 min, respectively. Results of this work provides new information on the effect of storage temperature and cooking on inactivation of STEC in meatballs. These results will help establish guidelines and best practices for cooking meatballs at food service and in the home.
Technical Abstract: We investigated the effects deep frying or oven cooking on inactivation of Shiga toxin-producing cells of Escherichia coli (STEC) in meatballs. A finely-ground veal and/or a beef-pork-veal mixture were inoculated (ca. 7.0 log CFU/g) with an eight-strain, genetically-marked cocktail of rifampicin-resistant STEC strains (STEC-8: O111:H, O45:H2, O103:H2, O104:H4, O121:H19, O145:NM, O26:H11, and O157:H7). Inoculated meat was mixed with liquid whole eggs and seasoned bread crumbs, shaped by hand into 40 g balls, and stored at -20 degree C (i.e., frozen) or at 4 degree C (i.e., fresh) for up to 18 h. Meatballs were deep fried (canola oil) or baked (convection oven) for up to 20 min at 176.7 degree C (350 degree F). Cooked and uncooked samples were stomached and plated onto Sorbitol MacConkey agar with rifampicin (100 ug/ml) followed by incubation at 37 degrees C for 24 h. Up to four trials and three replications for each treatment for each trial were conducted. Deep frying fresh meatballs for up to 5.5 min or frozen meatballs for up to 9.0 min resulted in reductions of STEC-8 ranging from ca. 0.8 to greater than 5.7 and ca. 0.6 to greater or equal than 5.9 log CFU/g, respectively. Likewise, significant (p greater than 0.05) reductions of ca. 0.5 to greater or equal than 5.7 and ca. 0.9 to greater or equal than 6.0 log CFU/g were observed for frozen and fresh meatballs, respectively, that were oven cooked for 7.5 to 20 min. This work provides new information on the effect of storage temperature and subsequent cooking on inactivation of STEC-8 in meatballs. These results will help establish guidelines and best practices for cooking meatballs at food service and in the home.