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E. coli 0157 Cooking Recommendations for Tenderized Beef, Minute Steaks and Burgers An Initiative of the E. coli O157 Research and Education Strategy Research and Education Strategy Contents P2 Mechanically Tenderized Steaks P3 Mechanically Tenderized Roast Beef About the E. coli O157 Research and Education Strategy The E.coli O157 Research and Education Strategy was developed in consultation with Canadian beef processors to address the key food safety issues arising from the 2012 recall with a view to prevent a future reoccurrence. A major focus of the Strategy was in relation to the food safety of the so called “non-intact” product category where bacteria may be transferred into the centre of the beef product during processing. Ultimately, research conducted under the Strategy contributed to the scientific rationale for new labels for tenderized beef across Canada. The pages that follow summarize the key findings for mechanically tenderized beef steaks and roasts, as well as minute steaks and burgers. The research carried out under the Strategy was made possible by financial support from the Alberta Livestock and Meat Agency, the Beef Cattle Research Council and the National Beef Check-off. In Memoriam Dr. Gill was employed by the Meat Research Institute of New Zealand in his early career before he was recruited in 1990 by Agriculture and Agri-Food Canada (AAFC). He worked as a senior research scientist in the field of meat microbiology at the AAFC Research and Development Centre in Lacombe, Alberta for 25 years until his death in December 2014. P4 Minute Steaks Dr. Colin Gill 1943 - 2014 P5 Cleaning Tenderizing Equipment P6 Beef Burgers Dr. Gill believed in the importance of practically oriented research and he spent a great deal of time in packing plants and other commercial facilities in Canada to assess and enhance production practices. Among Dr. Gill’s many achievements was his contribution to the design and implementation of the carcass pasteurizer for which he was granted three patents. Just as important as his scientific ability was his passion for the work he conducted. He was 71 at the time of his death and never once declined to take on a new project related to beef safety. Some of his most important work was conducted in his last five years including the mentoring of Dr. Xianqin Yang who is now carrying on his research at the AAFC Lacombe Research and Development Centre in Lacombe. Dr. Gill produced approximately 250 scientific manuscripts that have been cited more than 3,000 times in publications by scientists around the world. Dr. Gill was an essential contributor to the research conducted under the E. coli O157 Research and Education Strategy and his contribution is gratefully acknowledged by the Canadian Cattlemen’s Association. Mechanically Tenderized Steak Beef Quality and Mechanical Tenderization Beef tenderness has been shown to be a major contributor to consumer satisfaction. Tenderness in beef is determined by the amount and type of connective tissue and muscle fibres. Tenderness can be improved by aging as well as by cooking methods, such as the use of moist heat over extended periods, which can soften connective tissue. The overall tenderness of meat can also be improved by cutting through muscle fibres and connective tissue using blades or needles. Mechanical tenderization can enhance eating quality, especially beef made from parts of the animal used in locomotion which are naturally tougher. Tenderness is enhanced without changes to the nutritional value of beef. About Mechanically Tenderized Beef Mechanical tenderization has been used by the Canadian beef industry for many years at retail stores, meat processors and in the restaurant sector. Mechanical tenderization can also occur at home, as tenderizing tools intended for consumer use are available. Regardless of where it is used, mechanical tenderization is typically performed by passing blades or needles through meat products. Often this tenderizing treatment does not produce visible changes to the product. Steak A was turned over every four minutes while cooking to a 63°C internal temperature. Steak B was turned every 60 seconds while cooking to the same 63°C internal temperature. Doneness level in steak B is more even throughout the steak. Conclusions Research on Tenderized Steaks Due to the potential for bacteria on the exterior of beef to be transferred to the centre of the product it is important that mechanically tenderized beef products are not cooked to less than medium-rare (63°C or 145°F). In the case of steaks, research performed at the AAFC Lacombe Research and Development Centre indicated that the edges of a steak may at times be cooler than the centre. If a steak is turned over only once the temperature reached throughout the steak can be inconsistent. By turning over the steak at least twice when cooking to 63°C, the temperature will be more even which is helpful from both a food safety and an eating quality perspective. Mechanically tenderized beef steaks and roasts are now required by Health Canada to be labelled so they can be recognized by consumers. These labels also include cooking instructions which indicate that tenderized beef should be cooked to a minimum internal temperature of 63°C for both steaks and roasts. This temperature corresponds to a medium-rare doneness level. An additional instruction is provided for steaks that recommends to turn the steak over at least twice during cooking. These procedures are easy to follow and already utilized by the majority of Canadians for cooking untenderized beef products. 2 Mechanically Tenderized Roasts How Canadian Consumers Cook Beef Roasts A survey of Canadian consumers commissioned by the Canadian Cattlemen’s Association showed that the majority of Canadian consumers prefer to cook their roasts in ovens (77%) or slow cookers/crock pots (54%).1 Roasts of small sizes (2 kg or less) are preferred by more than 80% of the respondents. Oven temperatures in the range of 160 to 180°C are used by about 50% of Canadian consumers. More than 90% of Canadian consumers cook their roasts to internal temperatures of 63°C or higher. Research on Mechanically Tenderized Roasts Laboratory research was performed at the AAFC Lacombe Research and Development Centre to determine the minimum internal roast temperature at which a very high level of E. coli O157:H7 could be inactivated. E. coli O157:H7 bacteria were injected into the roasts at various points to simulate mechanical tenderization. Approximately 10 million E. coli O157:H7 bacteria were placed into eye of round roasts and prime rib roasts of 0.6 to 2.1 kg in weight. Such high levels of E. coli bacteria would not be found in reality, however they are utilized to test cooking methods of tenderized beef in the laboratory. The roasts were cooked in conventional or convection toaster ovens operated at various temperatures. The slow cooker was tested at the high or low heat settings. The reduction in numbers of E. coli O157:H7 at each location in the meat as a result of cooking was determined. Slow Cookers and Tenderized Roasts After innoculation E. coli O157:H7, roasts were cooked to 60°C or 63°C (medium rare) internal temperature in the slow cooker at either low or high setting. No surviving E. coli O157 could be found when roasts were cooked to 63°C at either high or low settings although not all E. coli were destroyed at the 60°C internal roast temperature. Convection Ovens and Tenderized Roasts Eye of round roasts were cooked to 65, 60, or 63°C at the centre of the roast in a convection oven operated at 120, 140, 180, and 200°C. At the lowest oven temperature of 120°C it was necessary to cook roasts to 65°C at the centre to destroy the high level of E. coli used. While not all E. coli were killed at 63°C the reduction is likely sufficient to ensure product safety as very high levels of bacteria were used in the experiment. When the oven was operated at 140 or 180°C all E. coli were killed even at 60°C internal roast temperature. At 200°C oven temperature all E. coli were killed at 63°C with some bacteria survival at 60°C. Conventional Ovens and Tenderized Roasts When conventional ovens were operated at 120°C all of the bacteria were killed at 63°C internal temperature. At 60°C there was limited surviving bacteria even with the very high numbers used in the laboratory experiment. However, when the oven was operated at 210°C it was necessary to cook the product to 71°C. Conclusions Both the temperature at which the oven is operated and the internal temperature of the beef roast following cooking are important to food safety. It is recommended that mechanically tenderized roasts be cooked at 140 to 180°C oven temperature to a product temperature of 63°C. At oven temperatures higher than 180°C with small roasts it would be advisable to cook mechanically tenderized roasts to higher temperatures. 1. National survey of 1,000 Canadian consumers commissioned by the Canadian Cattlemen’s Association and conducted by an independent market research firm. 3 Minute Steaks About Beef Minute (Cubed) Steaks One of the popular ways of mechanically tenderizing meat is cubing in which a machine with two sets of pointed discs cut muscle fibers from boneless cuts without tearing them (Figure 1). Cubing can also be done manually using a butcher’s mallet. In the cubing process, irregular pieces of meat can also be “knitted” together to form a more attractive cut. Cubed steak is also called a minute steak because it can be cooked quickly. to 63°C and flipped twice there was not always an adequate reduction of E. coli O157. When minutes steaks were turned three times and cooked for a total of eight minutes or were turned four times and cooked for six minutes, E. coli O157:H7 throughout the steaks was eliminated. The average final temperatures reached under these conditions was 72 and 67°C, respectively. Conclusions One cooking method to ensure the safety of minute steaks is to turn them over twice during cooking to 71°C. The majority of Canadians already prepare minute steaks in this manner. Canadian Minute Steak Cooking Practices A survey of Canadian consumers showed that the majority prefer to cook their minute steaks by pan frying (63%) and to a degree of doneness of medium (71°C) or higher (68%). The vast majority of consumers (96%) flip their minute steaks once or more during cooking.1 A Research on Minute Steaks Laboratory research was performed at the AAFC Lacombe Research and Development Centre. Approximately 10 million E. coli O157:H7 were injected at multiple locations into minute steaks of approximately 125 grams in weight. Such high levels of E. coli bacteria would not be found in reality, however they are utilized to test cooking methods of minute steaks in the laboratory. B The inoculated minute steaks were cooked on a hot plate operated at 200°C, to simulate medium to high heat pan frying. Various cooking times and flipping frequencies were examined along with several end-point internal temperatures. When minute steaks were turned over twice during cooking to a final temperature of 71°C at the thickest point of the meat, it was possible to destroy one million or more E. coli O157. This type of reduction is considered by Health Canada to ensure food safety. When minute steaks were cooked Fig. 1 Mechanical tenderizer (A) and its mechanisms (B) used for making minute steaks. 4 Cleaning Tenderizing Equipment Cleaning Meat Tenderizing Equipment There are two objectives when cleaning meat tenderizing equipment. These are the removal of food particles and residues to obtain visibly clean equipment, and sanitizing to reduce numbers of bacteria on the equipment to acceptable levels. Tenderizing equipment can be more challenging to clean because of the presence of numerous thin blades or needles. If the equipment is not adequately cleaned and sanitized it is possible that bacteria will be transferred to meat that is passed through the equipment during tenderizing operations. Research on Cleaning Procedures The procedures used in a commercial operation for cleaning mechanical tenderizers and their effectiveness were studied. Microbiological samples were taken from the tenderizing equipment (Ross Industrial model TC700) before cleaning, immediately after cleaning and also before use on the morning of the next day. Following cleaning at the commercial operation it was found that the number of bacteria on equipment varied by a factor of 10 from day-to-day. Further, the numbers of bacteria on the equipment after use was similar to levels found on the cleaned equipment just before use the next morning. This indicates that while the equipment appeared visibly clean, bacterial contamination remained. However, in most instances the bacteria that remained after cleaning were of the types more likely to contribute to spoilage than foodborne illness. The results of the microbiological testing were shared with cleaning personnel and several aspects of the cleaning methods were studied in the laboratory. Laboratory testing found that washing equipment with warm (55°C) water was very similar in effectiveness as hot (90°C) water. While hot water would be expected to help inactivate bacteria, it can also alter the detergent properties of cleaning agents and result in films of denatured protein to form on the equipment. It was also found that drying equipment following cleaning helped prevent growth of bacteria overnight. Drying may be particularly helpful to some facilities that are not able to store cleaned equipment at refrigeration temperatures until use the next morning. 5 Examples of commonly used tenderizing equipment in commercial use. Microbiological testing of the equipment at the commercial facility was then conducted following cleaning with the revised procedures and holding of the cleaned equipment in a cooler until use the next morning. The findings showed more than a 90% improvement in the total number of bacteria on the equipment with the modified cleaning methods and storing equipment in a refrigerated area overnight. Conclusions While the risk of hazardous bacterial contamination of tenderizing equipment would seem to be small, appropriate cleaning as well as drying and ideally refrigeration of tenderizing equipment is necessary if such risks are to be fully addressed. In small operations where microbiological testing is infrequent or not an option, it is especially important that cleaning and sanitation procedures are well developed. The objective of removing and controlling bacterial contaminants as well as visible residue on equipment should be well understood by cleaning personnel. Beef Burgers How Canadians Cook Burgers A survey of Canadian consumers commissioned by the Canadian Cattlemen’s Association showed that 51% of Canadian consumers prefer to cook their burgers by barbecue grill (51%) and to a degree of doneness of medium (71°C) or higher (90%). Most consumers (75%) turn their burgers twice or more frequently during cooking.1 Research on Beef Burgers Laboratory research was performed at the AAFC Lacombe Research and Development Centre. Approximately 10 million E. coli O157:H7 were injected at the centre and edges of burgers of approximately 120 grams in weight. Such high levels of E. coli bacteria would not be found in reality, however they are utilized to test cooking methods for hamburger in the laboratory. Health Canada requires that cooking methods be demonstrated to be capable of eliminating large numbers of E. coli O157:H7 e.g. 100,000 bacteria reduced to zero. Burgers were cooked from frozen or chilled state using an electric barbecue. Burgers were cooked to 67 or 71°C internal temperature with flipping of the burger one to three times. During cooking to 71°C, the burgers were flipped once at six minutes, or twice at three and six minutes for chilled or four and eight minutes for frozen. When burgers were flipped once during cooking to 71°C, the elimination of E. coli O157:H7 was not complete, and higher levels remained in burgers cooked from frozen. However, when burgers were flipped twice during cooking to 71°C, E. coli O157:H7 was eliminated throughout the burgers irrespective of whether or not the burgers were frozen. Given the effectiveness of flipping burgers twice, burgers were also cooked to 67°C to determine if lower burger endpoint temperatures were safe. However, neither flipping once, twice or three times was sufficient to ensure product safety. Conclusions The recommended method for cooking burgers is to achieve an internal temperature of 71°C with flipping at least twice during cooking. This recommendation is consistent with the current practices of the majority of Canadian consumers. 1. National survey of 1,000 Canadian consumers commissioned by the Canadian Cattlemen’s Association and conducted by an independent market research firm. The average time it took to cook frozen burgers to the same final temperature with the same turning frequency was more than three minutes longer than that for chilled burgers. 6 Cooking Recommendations for Tenderized Beef, Minute Steaks and Burgers An Initiative of the E. coli O157 Research and Education Strategy Industry Commentary “The E. coli O157 Research and Education Strategy represents a partnership between Canada’s cattle production and beef processing sectors to identify priority areas for beef safety research. The work that has been undertaken as part of the Strategy has provided the scientific foundation for new labelling approaches for mechanically tenderized beef. It also provides important perspectives on how Canadians prefer to prepare beef products which can help guide industry communication and future research initiatives. “ Dennis Laycraft Executive Vice President, Canadian Cattlemen’s Association “The mechanical tenderization of steaks and roasts continues to serve as an important intervention for the Canadian industry to enhance beef tenderness, particularly for cuts from the round and chuck. The work conducted under the E. coli O157 Research and Education Strategy provides recommendations for cooking these products which are both science-based and practical. “ Andrea Brocklebank Executive Director, Beef Cattle Research Council “Robust food safety processes and systems are essential to maintaining the sustainability of Canada’s agriculture industry. Research, like that conducted through the E. coli O157 Research and Education Strategy, demonstrates Canada’s meat and livestock industry is committed to producing, processing and retailing safe and superior foods for the end user.” Gordon Cove President and CEO, Alberta Livestock and Meat Agency The CCA is a non-profit federation comprised of eight provincial member cattle associations that provide representation to a national, producer-led board of directors. The CCA’s vision is to have a dynamic, profitable Canadian beef industry with high-quality beef products recognized as the most outstanding by customers at home and around the world.