Meat glue is primarily made of an enzyme called transglutaminase, a naturally occurring protein that forms strong bonds between pieces of meat, fish, or poultry. Commercial meat glue products typically blend this enzyme with carrier ingredients like maltodextrin (a starch-based powder) or sodium caseinate (a milk protein) to make it easier to measure and apply evenly.
The Core Ingredient: Transglutaminase
Transglutaminase is a protein-crosslinking enzyme found throughout nature, in everything from human blood to fish muscle. It works by creating covalent bonds between two specific amino acids, lysine and glutamine, that are abundant on the surface of meat proteins. These bonds are the same type your body creates naturally during wound healing and tissue repair. Once formed, they’re extremely strong and essentially permanent, which is why glued meat holds together through cooking.
The commercial version used in food processing is called microbial transglutaminase because it’s produced by bacteria rather than extracted from animals. A soil bacterium called Streptoverticillium mobaraense is the primary source. Manufacturers grow these bacteria in fermentation tanks, then harvest and purify the enzyme they produce. Japan’s Ajinomoto Co. was the first to manufacture it at industrial scale, launching the brand name “Activa” in the early 1990s, which remains the most recognized product line in the industry.
What’s in the Package Besides the Enzyme
Pure transglutaminase is potent in tiny amounts, so commercial formulations dilute it with food-grade carriers. The exact blend depends on the intended use. Some versions contain maltodextrin, a common starch derivative that acts as a bulking agent so chefs can sprinkle the powder evenly. Others include sodium caseinate, a milk-derived protein that gives the enzyme something to grab onto immediately, speeding up the bonding process. Gelatin is another common addition in formulations designed for cold-set applications like restructured deli meats.
These carrier ingredients matter if you have food allergies. The FDA requires that transglutaminase enzyme be listed in a product’s ingredient statement, and formulations containing lactose or caseinate may need milk allergen labeling.
A Second Type: Thrombin From Animal Blood
There’s another substance sometimes called meat glue that works differently. Thrombin, the enzyme responsible for blood clotting, can also bind pieces of meat together. It’s extracted from cattle and pig blood, often paired with fibrinogen (another blood protein) to create a two-part binding system. The European Food Safety Authority reviewed thrombin derived from bovine and pig blood and found no safety concerns under intended conditions of use, though it’s less common than microbial transglutaminase in most kitchens and processing plants.
Where Meat Glue Shows Up in Food
You’ve almost certainly eaten transglutaminase without knowing it. About 20% to 25% of the world’s surimi production goes into imitation crab, and the enzyme plays a key role in giving that product its firm, springy texture. Fish muscle actually contains its own natural transglutaminase, but manufacturers add the microbial version to strengthen the gel and improve consistency.
In restaurants, chefs use it to create uniform portions from irregular cuts, bond bacon around filets, or fuse different proteins into a single piece. In food manufacturing, it appears in restructured steaks, chicken nuggets, sausages, and processed deli meats. One commercial formulation, Activa TG-B, has been shown to improve tenderness and sensory quality in restructured beef steaks made with up to 17% fat content.
The Food Safety Catch
The FDA classifies microbial transglutaminase as Generally Recognized as Safe (GRAS). The enzyme itself is not toxic and breaks down during cooking. The real concern is bacterial contamination. A whole steak only has bacteria on its outer surface, which is why you can safely eat it rare. But when you glue two pieces of meat together, surface bacteria from both pieces end up trapped in the center of the new cut. If the restructured product is then cooked like a whole-muscle steak (seared on the outside, pink in the middle) those interior bacteria may survive.
This is why restructured or “formed” meat products need to be cooked to a higher internal temperature than whole cuts. The bonded seam should reach the same temperature you’d use for ground beef: 160°F (71°C) for beef and pork, 165°F (74°C) for poultry.
Concerns for People With Celiac Disease
Research published in Frontiers in Pediatrics has raised questions about microbial transglutaminase and celiac disease. The enzyme can cross-link with gliadin, a protein fragment from gluten, creating new molecular complexes that the immune system may recognize as a threat. These altered gliadin complexes showed a 94.9% sensitivity and 93.9% specificity as markers of intestinal damage in pediatric celiac patients.
The concern is that microbial transglutaminase mimics the function of tissue transglutaminase, the body’s own enzyme that is the recognized autoantigen in celiac disease. When the microbial version modifies gliadin in the gut, it may change the protein’s shape and electrical charge enough to trigger an immune response in susceptible people. The bonds created by microbial transglutaminase are also resistant to all known human digestive enzymes, meaning these modified protein complexes persist in the gut longer than unmodified gluten fragments would. For people with celiac disease or gluten sensitivity, this is worth being aware of when eating processed meat products that may contain both transglutaminase and gluten-based fillers.