The other day we were cutting beef top rounds into trimmed roasts in class. Half the class was cutting Certified Angus and the other half were using regular IBP Choice XT. XT stands for Extra Trimmed, I believe. I was asking the class to observe any differences between the two, hoping for some comments on the fat trim level or marbling scores. Instead what they noticed the most was the fact that the CAB had a discoloration on the exposed meat and the XT did not. The CAB top round was a basic untrimmed subprimal which was packaged "as is" when taken off the bone. The XT had the cap fat trimmed to 1/4 inch and the discoloration trimmed off. The grayish tint is not caused by any spoilage or pathogen, it is the result of the carcass steam cleaning process.
Steam cleaning takes place in most large beef processing plants today. It is typically a combination of whole carcass washing with water, hand held steam vacuums during evisceration, and a steam pasteurization cabinet for the whole split dressed carcass. Often carcasses are also sprayed with an organic acid to further guard against pathogens. IBP, owned by Tyson, developed the "Triple Clean" method after a huge beef recall of about 750,000 lbs in 1998. This method applied the hand held vacuum steamers and a huge car wash type steam cabinet on their line for the first time. The end result is a cleaner beef but also a sort of pre-cooked layer on some exposed cuts. The top round, flank steak, skirt and hanger steaks, and sometimes the tenderloin can be found with some slight discolorations caused by the steam. Most other cuts are protected by the exterior fat or bone coverage.
The basic reason for this extra cleaning is E. coli O157:H7 which is found in the fecal matter on the outside of the hide or in the intestinal tract. The speed of the processing and the fact that cattle often arrive with contaminated hides and intestinals makes extra cleaning a safer alternative. But all this extra cleaning is expensive and errors can be made.
Another idea is to reduce the amount of E coli before the animal leaves its feedyard. This can be done a couple of ways. First by cleaning out excessive waste so animals are cleaner and dryer when they leave. Many times, especially in rainy summer months, cattle are standing in muck. Some feedyards are a lot better about this than others and there should be a standard.
Another is to feed the cattle hay or barley a few days before slaughter. This causes a change in the intestine that helps to reduce the E. coli dramtically. This is not to say that the animal should be on pasture or not ever grain fed but simply creating a dramtic switch from a corn ration to hay for the last few days could reduce E.coli counts significantly. http://www.horizonpress.com/cimb/v/v11/67.pdf So why aren't most large processors demanding this switch to keep the cattle cleaner? Maybe its a weight loss issue or a cost that makes this impractical. But the cost of the steam cleaning must be high too.
Other interventions, such as Lactobacillus-based direct-fed microbials, vaccines and irradiation are also being suggested. Diet introduced probiotics can reduce E. coli. http://www.ncbi.nlm.nih.gov/pubmed/12747680 There is a vaccine for it too. But both of these add extra expense. One company developed a vaccine and spent $15,000,000 in doing it ( also $50,000,000 in advertising it!) http://www.npr.org/templates/story/story.php?storyId=6138682
The goal of irradiation is to "pasteurize" the carcass. This would eliminate a lot of pathogen risk and contrary to popular sentiment, it wouldn't glow in the dark. My issue with this method is when a meat is irradiated will the good flora that enables part of the flavor of a proper dry aging be destroyed? How much vitamin content will be lost? Also if the goal of irradiating is to eliminate E.coli by sterilizing it and E.coli is typically found in fecal matter then are we to accept sterilized fecal matter as a food? Not my idea of a fine dining experience.
Steam cleaning is a good idea and it has made our meat supply safer. Hay, you know that dried stuff grown in open fields, seems like a good idea too. There is no one solution but there are some that make more sense than others.