by Dave Arnold
Transglutaminase (TG) â€“aka meat glue, the stuff that allows you to bond proteins together â€“has been taking a pounding in the blogosphere recently and, as a proponent of the enzyme, so have I.Â At the risk of preaching to the converted (sorry, loyal readers) Iâ€™mÂ setting theÂ record straight.Â Â TG is a great tool used by conscientious cooks to achieve fabulous and fantastic culinary results. It is also natural. Donâ€™t know about meat glue? Read my primer.
In March an Australian TV tabloid show called Today Tonight did an â€œexposeâ€ on meat glue.Â Hereâ€™s Â the lead in:
The industry wide secret butchers donâ€™t want you to know about. Major suppliers have been caught using a special product known as meat glue to stick together scraps of meat to sell as prime cuts. But while this product has been banned overseas, thereâ€™s no law prohibiting its use here.
This video has gone somewhat viral over the last month. I encourage you to watch it.Â It is horse hockey.
In this video youâ€™ll see some classic bad journalism techniques â€“like getting a butcher who doesnâ€™t like the idea of meat glue to demonstrate it wearing a face mask. The reportersÂ make some nutty claims.
Claim: Meat glue is an industry wide secret butchers donâ€™t want you to know about. Major suppliers have been caught using a special product known as meat glue to stick together scraps of meat to sell as prime cuts.
Truth: Many of the hundreds of horrified comments are reactions to this allegation that companies are defrauding customers by selling glued together scraps of meat as â€œprime cuts.â€Â This phrase has been repeated so often that everyone takes it for fact. The Australian show did not point to even one case of a company committing fraud using meat glue. I searched the internetÂ looking for a documented case of fraud and was unable to find one.Â The segment does show a commercial restructured piece of meat, but they donâ€™t show the label because it could not possibly have been sold as a prime cut. That would, indeed, be fraud (in the US anyway) for which the perpetrator could do jail time.Â In the US, any meat that has been glued or restructured must be labeled â€œformedâ€ or â€œreformed.â€ See the FSIS ruling on the subject here (this page really cuts through the crap. Ajinomoto fought to make sure that glued meats are clearly labeled as restructured, but not for altruistic reasons: they wanted to to use TG without being required to add â€œenzymeâ€ to the ingredient label — which they can, because it is used in minute quantities and is considered a processing aid). Furthermore, TG is only one of many, many methods companies could use to bind meats together and defraud customers if they so chose (such as alginates, carrageenan, salt with tumbling, gelatin, compression).
Restaurants donâ€™t have the same stringent labeling requirements than meat packers do. It would be possible for a disreputable restaurant to TRY to pawn off scraps of meat as whole-muscle cuts.Â The restaurant would likely be unsuccessful in the long run because their customers would know (see the next claim). Any restaurant using meat glue to cheat their customers should be shut down â€“but I have never seen or heard of such a case.Â The chefs I know who use meat glue care about their customers and the quality of their food.
Claim: Even an expert canâ€™t tell if meat has been glued. You are getting ripped off without knowing it.
Answer: Anyone that has used meat glue knows this is untrue.Â The bonds in a glued piece of meat are clearly visible. The smaller the scraps of meat that are glue together, the more obvious the glue-job. Unless I am trying to produce a special effect â€“like the mokume-gane fish dish I created a while back, I try to keep the number of glue joints in a piece of meat to a minimum â€“usually one or two.Â Why? Because Iâ€™m not using meat glue to rip someone off, but to create a piece of meat that will cook better, more evenly and more consistently. Iâ€™m trying to make it better for the diner.
Claim: Meat Glue has been banned in the EU, and might be made from pigâ€™s or cowâ€™s blood.
Answer: False. Tranglutaminase is being legally used in the EU right now. The TG all the chefs use is produced by a naturally-occurring microbe.Â There is a second type of meat glue derived from animal sources (thrombin) that was banned in the EU, but not for safety reasons.Â It passed the safety test and was rejected because EU regulators didnâ€™t understand the purpose of it and saw the potential for fraud. God help us if regulators get to choose what makes good food. Safety and preventing fraud: important , and a politicianâ€™s job. Telling me what it takes to make good food â€“stay out. See this article on the ban and Ajinomotoâ€™s response.
Claim: Meat glue is unsafe because of the high bacteria count in meat-glued products.
Answer: This is the only claim with a shred of truth.Â The most important information I give chefs in meat glue training is: be aware that using TG can introduce bacteria into the interior of your product. The interior of whole muscle meat is relatively sterile. Most contamination is on the outside.Â When we cook a traditional rare steak, the searing kills the bacteria on the outside and we are left with uncooked, but fairly safe, rare-meat at the center.Â The danger with TG is that a cook might bond two pieces of meat together and treat them like a whole muscle cut without any further precautions… a serious error. Here are the safety guidelines I follow:
- If a meat is going to be thoroughly pasteurized (such as chicken or short ribs, which can’t really be cooked to most consumers’ taste and visual satisfaction until they have been thoroughly pasteurized), meat glue is adding no further risk to normal food preparation.
- If meat glue is used only on the outside of a large muscle cut (such as gluing chicken-skin to skirt steak or bacon to filet mignon), the outside must be thoroughly seared. The inside is just as safe as an unglued cut.
- If meat glue is used on a product that cannot be pasteurized (most fish, for example), three things must be true:
- You must be willing to serve the product raw.Â If you wouldn’t hack off a slice of that meat and eat it, don’t glue it and serve it rare.
- You must treat the product as if you were serving it raw — wear gloves, practice scrupulous hygiene.
- Here is the trickiest part of all, and one withÂ which I am still grappling: you shouldn’t make your customer assume an extra risk (even if you don’t believe it to be a risk) without their knowledge. I once asked a food scientist why it is OK to serve rare hamburgers and sushi, etc.Â He said, as far as he is concerned, consumers ordering those products have enough education to understand that they are assuming certain risks –which makes the risks OK. Therefore, if you serve meat that looks basically raw, then the customer isn’t being exposed to risks they aren’t already assuming, and there is no duty to provide extra warnings. If you are in a steak house and you glue two pieces of meat together that had been cut at the packing plant and possibly exposed to contamination, and you then throw that glued meat on a grill and cook it bloody rare, there is definitely a duty to warn.Â It is still OK to cook that way, but the consumer must be aware that they are ordering the equivalent of a rare hamburger (it isn’t really that bad, as I’ll explain below). An interesting case is serving a piece of rare fish that has been butchered in the kitchen, meat-glued with one joint, seared, and sliced in the kitchen. Each serving slice is a potential source of contamination just as grave as the slice that preceded the meat gluing.Â Is there an extra risk here that requires warning? Dunno.
The vast majority of the products I meat glue are thoroughly pasteurized with low temperature cooking before I serve them and are entirely safe. For those that aren’t pasteurizedÂ you need to assess your bacterial risks. The possibility for contamination increases with:
- The initial bacteria present on the product when it shows up in your kitchen (called the bacterial load)
- The cleanliness of your kitchen
- The amount of time a product is exposed to the environment
- The temperatures at which your products are stored
- The amount of surface-area exposed to the environment.
The first four considerations areÂ typical ones –the last one is a kicker.Â The reason hamburger is so dangerous is that it has a huge surface area exposed to the potentially contaminating environment of meat grinders, kitchens, hands, etc.Â All that contamination is thoroughly mixed into the center of the product.Â Hamburger is easy to abuse. A piece of meat that is brought into the kitchen whole and sliced once with a very clean knife on a very clean board has a much lower increase in potential contamination than meat you grind.
Randomness in the Blogosphere:
Some random doozies on meat glue are being bandied about. Here is the real deal.
- Transglutaminase is not an unholy abomination. It is produced in large quantities by a naturally occurring bacteria. No GMO necessary. Bacterial and yeast fermentation have brought us many of life’s great things: bread, wine, and cheese to name a few. By the way, you have different types of TG in your body right now, as part of the blood clotting pathway, the skin synthesis pathway, etc.Â The TG from bacteria is a related enzyme.
- Meat glue does not contain, nor is it related to, MSG. MSG is the sodium salt of glutamic acid (an amino acid). Meat glue is a mixture of enzymes, maltodextrin, and protein (casein or gelatin).
- I have found no evidence of meat glue being dangerous when handled properly –and I have readÂ and searchedÂ a lot.Â I invite feedback on this point.Â I have heard anecdotal claims from two (unrelated) cooks who claimed to have gotten a contact dermatitis (rash) from occupational exposure to meat glue.Â This seems possible, but I haven’t read anything in the literature.Â I always tell people not to inhale the powder (which is common sense), but have never found any record of someone who has inhaled it and been hurt (please forward data to me if you have it).
- The FSIS limits the use of pure tranglutaminse in meat products to 65 parts per million (except in chicken breast where you may use more).Â This number seems to contradict the usage statements for meat glue, which is used at up to 1 percent by weight (usually much, much, less).Â In fact, pure TG enzyme represents only a tiny percentage of Activa RM, the meat glue we use.Â Activa RM is mostly maltodextrin and casein.Â Ajinomoto specificallyÂ formulated Activa RM to add less than 65 ppm of pure enzyme when used at one percent by weight of meat.
- The relationship between coeliac disease and microbial Transglutaminase (mTG) is still being sorted out.Â There is no doubt that extra antibodies to human tissue transglutaminase (tTG) are found in coeliac sufferers. I have seen research that supports that mTG can cause problems for coeliacs, and research that says it doesn’t. I have not found any acute cases of problems had by coeliac sufferers linked to mTG in the literature, but prudence says coelicas should avoid large quantities of TG till the data is in.
- Excess tTG is found in the tissue of people with horrible diseases like Huntington’s and Alzheimer’s. That doesn’t mean consuming TG causes those diseases any more than drinking water causes pulmonary edema. I personally detest the sort of argument that infers (illogically) that because a product is found alongside or in something horrible, it is horrible.
In conclusion: Glue with caution, but glue with pride!