Fascination with transglutaminase has been inescapable since first reading about the enzyme on Alex and Aki's food blog. They used it to fuse chicken skin to fish. After a few days of internet research and fitting together puzzle pieces of information found on vague postings, I contacted a rep at Ajinomoto USA. After messing around with the product for a few days, this is where I've succeeded and failed.
The transglutaminase used by most chefs (included Wylie Dufresne on Iron Chef America) is supplied by Ajinomoto and is labelled Activa RM. The link here shows 3 different TGMs supplied by the Japanese company, but the RM is the common one used by chefs in the 'modern thinking' movement. Ajinomoto is mostly known for producing MSG and other products in the Asian market. TGM has been used for years in the industrial food industry. Just look at products such as reshaped chicken patties and Japanese fish cakes. Why can't a chef in a fine-dining situation take something so unique and push it in new directions? Why should industrial food scientists have all of the fun?
Ok, here is what I know about TGM in a nicely condensed version.
TGM is an enzyme that is found naturally in humans, animals, and some plants and microbes. In most basic terms, it binds proteins of any kind together. In the form sold by Ajinomoto, the TGM comes in an airtight foil package of fine white powder. Once opened, the enzyme's shelf life is roughly one month. To assist with this duration, use the powder quickly and re-seal (under sous vide if possible) and freeze it. This will prevent it from expiring for a little while.
The enzyme can be applied to food by directly sprinkling it, or by making a slurry mixed with water. Although I have not tried the slurry method, my success with sprinkling has proven TGM's ease of use. Once applied to proteins, the binding begins... and this takes a certain amount of time. You can speed up the process by allowing the meat and enzyme to sit at 130F. This is optimum temperature for the microscopic little guys. However, once you hit temperatures of 150F they will start to die (an easy way to understand this is to compare it to yeast). If you are refrigerating the proteins treated with enzyme, allow it to sit overnight (as recommended by Ajinomoto). The binding reaction will work under refrigeration and even in the freezer, though much slower. It seems only high heat will stop or kill the enzyme. To hold meats in the form I wanted, using the sous-vide seemed to be the best way to hold items in shape while waiting for them to bind. The sprinkle and slurry methods work for fusing solid pieces of protein to each other, but for ground meat mixtures it becomes necessary to use a ratio of 1% TGM to the weight of the protein (this is an incredible easy ratio to remember). Using a gram scale for this is much easier as conversions are simply a matter of weighing the meat, and sliding the decimal over 2 spaces to the left to get the TGM weight.
Given this information, what can we do with this stuff? Well, we can stick all kinds of meats and proteins to each other... fun! In my first attempt to work with TGM, this is what I did. Note: These tests were done solely to experiment with TGM on various proteins (cooked, cured, fatty, different animal proteins). This is just a base point to create from (and to know what works well and what doesn't).
Beef: Fuse a bacon strip to filet mignon. Mix into ground beef to make a more durable hamburger patty. The bacon fusing worked well and even allowed me to completely enclose the filet without using skewers or twine. This allowed for a cleaner looking final product. The hamburger mixed with TGM made for a much more durable patty, but the burger had too much chew. This is one of the few problems I incurred with TGM... just like gelatin, you want to use only as much as you need because adding too much with undesirably affect the texture.
You can also see how nice the rolled beef tenderloin scraps came out. Industrial companies already use this technique to trim waste and promote consistency. Think about those individually wrapped filet mignon that are all somehow the same exact round shape and size. Technically, it is still a steak made from beef tenderloin, so there is no 'truth in menu' violation here.
Chicken: Fuse prosciutto to a chicken wing. Fuse a rolled stuffed chicken breast to completely enclose upon itself. The prosciutto completely sealed itself to the chicken wing here. Although I will never encase a chicken wing with prosciutto again, I did this to test the boundaries of the TGM. When testing on the chicken breast (as with roulades) I wrapped small cubes of ham and bacon inside a chicken breast roll. By totally enclosing the chicken meat around the filling, I could do dishes like chicken cordon bleu in different ways. I actually was able to grill the roulade without skewers or twine and make a healthier version of the recipe.
Fish: Fuse strips of salmon and tuna together to make a hybrid fish. Fuse chicken skin to seabass. This was the salmon/tuna I created (perfect for people who can't make up their minds on what to eat for dinner). Interesting for the possibility of still cooking the 'fish' rare or medium rare.
The idea of fusing chicken skin to fish was taken from ideas in food as stated above. We attached the skin to a piece of seabass and seared it before finishing in the oven. The result was amazing to eat. The chicken skin also acted as barding for the fish and gave it that chicken skin crispiness. We want to create the ultimate southern dish using this technique... fusing chicken skin to catfish and having Chef Mike chicken fry it!
Shellfish: Fuse 2 pieces of shrimp together. Mix into ground shrimp and roll into a cylinder. Fuse cooked crabmeat together and form into shapes.
Here are a couple of 'shrimp filet mignon' that I made by pureeing the raw shrimp with TGM (using 1% TGM by weight to the shrimp). The shrimp 'mousse' was rolled into a cylinder and allowed to bind. Afterwards, we cut the shrimp into raw filets which could be seasoned and grilled just like a piece of beef. (Imagine doing an inverted surf and turf.)
Here on the right was another use of the shrimp/TGM mixture. After pureeing the two together, I loaded it into my Wiltons cookie press and shot 'noodles' out into a pot of 130 degree water (if you are like me and do not have a thermocirculator, then just monitor the water temp as much as possible). I used these noodles later on to make shrimp knots.
The 'very useful' cookie press
I want to note here that I did try to make the WD50 fish noodles using the same method, but they dispersed into clouds of fish matter as soon as they hit the water. Although I have not yet figured out why this happened, I was able to still use the fish by spreading it out into a sheet and cutting it into shapes to make seabass mcnuggets. I believe that the biggest part of the problem with the fish noodle failure was the lack of a controlled constant temperature. Without thermocirculators to keep the water in motion and at a set temp, it is difficult to retain accuracy. It is perhaps also related to the texture of the fish flesh. Dufresne used tilapia on Iron Chef America to make the noodles, although I'm not sure what other types of fish he has used before.
Deli: Fuse together different combinations of deli meats. The deli meat experiment was done mainly for research, and to find out if TGM works on cooked and cured meats as well as raw. It does. The TGM binds protein and it doesn't seem to care if those proteins have been cooked or not. I even fused sliced smoked salmon into roulades and other shapes. The photo here is sliced turkey breast that was sprinkled, rolled, and set.
Eggs: Fuse boiled eggs. Add to caviar. Ok, as an afterthought to all of this, I started to wonder about the proteins in eggs. I was able to slice a boiled egg directly in half and fuse it back together. However, when I tried the same thing with caviar (sprinkling and tossing TGM into it) it did not have any affect. I know that salt does aid in the enzymes reaction, but possily too much salt will stop it. Besides there are other things in keta caviar that may prevent the reaction... excessive fat, liquid, etc. It may still be useful for things such as encasing caviar within a roulade of smoked salmon, giving it just a little more solidity.
This has been the extent of my experimentation so far. We have also formed pureed shrimp into sheets in the same way as the seabass. The possibilities are unlimited. I could take those shrimp sheets and make ravioli out of shrimp... possibly filled with pasta. Just use some more TGM to seal the raviolis. What about freezing a sauce into small cubes, and encasing it with shrimp sheets so that when you heat it up and cut it open, the sauce would pour out? Another thing I've just used TGM for was to make a crabcake with no binder... just seasoned crabmeat shaped into a short cylindrical form. I used this on a non-dairy menu and called it the '100% crabcake.' After it was fused overnight, I just seared it off and served it.
Ajinomoto sells the enzyme for about $50 a kilogram. I've been told that they are trying to push for a smaller pack size (due to perishability) in the US, but nothing has been laid out yet. Write the company for a sample and try it yourself.