Reciprocal Meat Conference Abstracts

Evaluation of The Reduction of E. Coli in Beef Top Rounds at Temperatures Lower than 54.4°C

---

Abstract

ObjectivesThe CDC states that Salmonella is a leading cause of gastroenteritis in humans and continues to be significant in relation to public health concerns for the meat and food industries. This may be attributed to inadequate heating/cooking. The lowest temperature and holding time the USDA recommends in Appendix A to achieve a 6.5-log10 reduction in Salmonella is 54.4°C for 112 min. Limited research exists in using lower temperatures for top rounds to comply with Appendix A standards. Some companies wish to utilize lower temperatures to maintain juiciness and tenderness during the reheating process. This study was conducted in an USDA inspected meat facility, therefore, surrogate bacteria that are approved for use by the USDA as surrogates for Salmonella were utilized. This study evaluated the reduction of Escherichia coli in top rounds cooked to internal temperatures of 54.4°C or lower to determine if temperatures lower than 54.4°C would achieve a 6.5-log10 reduction in accordance with Appendix A.Materials and MethodsA local company provided their proprietary brine and rub ingredients and raw meat materials for the experiment. A cocktail of 5 stains of Escherichia coli (ATCC BAA-1427, 1428, 1429, 1430, 1431) were utilized. These 5 stains are approved surrogates by the USDA to be used for inplant verifications studies. Top rounds were dip inoculated with E. coli to start with a 7.5-log10 CFU per a gram inoculation level on the meat. Top rounds were pumped 15% with a brine solution and then rubbed with the rub. They were then placed into netting and placed on a smokehouse trolley in the smokehouse. The combination of temperatures and times held were 54.4°C for 2 and 3 h, 51.7°C for 3 and 5 h, and 48.9°C for 10 and 12 h. Times were determined utilizing a model from the North American Meat Institute. Internal temperatures were continuously monitored with Type-K Thermocouples. Inoculations were prepared by inoculating TSB with each E. coli strain and allowed to grow at 37°C for approximately 24 h. MacConkey Agar was utilized to determine E. coli survival. The experiment consisted of three replications with two samples per replication. Data were analyzed using excel and the GLM procedure of SAS (SAS Inst. Inc., Cary, NC) to determine average reduction of E. coli in top rounds.ResultsTop rounds had a 4.0-log10 reduction (var = 0.78) at 54.4°C when held for 2 h and a 4.38-log10 reduction (var = 0.48) when held for 3 h. This is different than Appendix A, as only 50% relative humidity was utilized in the smokehouse schedule to maintain the low cooking temperature. According to Appendix A a 90% relative humidity should be utilized during the cooking process. When held at an internal temperature of 51.7°C a 3.79-log reduction (var = 0.01) was achieved when held for 3 h and a 4.23-log10 reduction (var = 0.28) when held for 5 h. Top rounds that were cooked to 48.9°C and held for 10 h resulted in a 2.87-log10 reduction (var = 0.18) and when held for 12 h resulted in a 2.91-log10 reduction (var = 0.17).ConclusionResults suggest that 50% relative humidity and the low cooking temperatures were not sufficient to achieve the 6.5-log10 reduction that is mandated by Appendix A.

Keywords: salmonella, Beef, E. coli, Appendix A

How to Cite:

Krage, E., Mendes, B., Henson, J. & Mckeith, A. G., (2018) “Evaluation of The Reduction of E. Coli in Beef Top Rounds at Temperatures Lower than 54.4°C”, Meat and Muscle Biology 1(2). doi: https://doi.org/10.221751/rmc2016.110