Microbiological safety of commercial prime rib preparation methods: thermal inactivation of Salmonella spp. in mechanically tenderized beef roasts

Authors: CALLE, ALEXANDRA - University Of Nebraska; Porto-Fett, Anna; Shoyer, Brad; Luchansky, John; THIPPAREDDI, HARSHAVARDHAN - University Of Nebraska

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/2015
Publication Date: 11/18/2015
Citation: Calle, A., Porto Fett, A.C., Shoyer, B.A., Luchansky, J.B., Thippareddi, H. 2015. Microbiological safety of commercial prime rib preparation methods: thermal inactivation of Salmonella spp. in mechanically tenderized beef roasts. Journal of Food Protection. 78:2126-2135.

Interpretive Summary: Prime rib is one of the most preferred cuts of beef due to its tenderness, flavor, and juiciness. It is typically prepared by searing for a short time at high temperature, followed by cooking at relatively low temperature, and then is finished by extended holding (1 to 11 hours) at warm temperature to achieve a rare or medium degree of doneness as preferred by most consumers. Given the association of pathogens such as Shiga toxin-producing Escherichia coli and Salmonella spp. with raw and undercooked beef, and given the lower temperature cooking and extended warm holding of prime rib coupled with the growing interest in using mechanically tenderized cuts of meat, there is the potential for a threat to public health associated with this product. Thus, we inoculated the surface of boneless beef ribeye with Salmonella and then passed the meat once through a mechanical tenderizer. Next, we seared and then cooked the meat in a convection oven to a doneness ranging from rare to well and held the product for extended, warm, for up to 11 hours. The results revealed that Salmonella were transferred from the surface into the deeper tissues of the meat. Our experiments also confirmed that it was necessary to sear, cook prime rib to a degree of doneness of medium to well, and then hold the roasts in a warming oven for up to 8 hours to appreciably reduce pathogen levels throughout the prime rib roasts.

Technical Abstract: A survey of food service operations in a medium-size Midwestern city was conducted to evaluate the microbiological safety of prime rib preparation methods relative to survival of Salmonella spp. in both intact and tenderized (non-intact) product. All six restaurants visited seared rib eye roasts (air temperatures in oven between 204° and 260°C), followed by cooking to a target internal temperature of ca. 48.9°C, and then holding at temperatures ranging from 48.9°C to 71°C for periods of 1 to 11 h. Searing resulted in minimal destruction of Salmonella spp., with 1.35 and 1.23 log CFU/g reductions for intact and non-intact rib eye, respectively, after 15 min at an 260°C. Cooking to internal temperatures of 37.8° and 48.9°C resulted in additional reductions of 3.99 (intact) and 4.19 (non-intact) log CFU/g, respectively, in intact rib eye. Lower reductions were observed (2.86 and 3.58 log CFU/g, respectively) in non-intact (mechanically tenderized) rib eye. Pathogen levels remained relatively unchanged for intact rib eye cooked to 37.8° or 48.9°C and for non-intact rib eye cooked to 49.9°C when held at 60°C for up to 8 h. In contrast, pathogen levels increased ca. 1.5 log CFU/g in non-intact rib eye cooked to 37.8°C when held at 60°C for 8 h. Thus, current practices of searing, cooking to low temperatures, and holding to relatively low temperatures may pose a food safety risk to consumers in terms of inadequate lethality to Salmonella spp., especially if non-intact rib eye is used in the preparation of prime rib.