Ross, 20% of the total protein is made up by collagen. (See "Stromal Proteins" below.) The animal`s age has a terrific effect on the amount of collagen and myosin. Collagen is insoluble in water and forms a gel. In dealing with cohesive forces in meat binding, a commercial plant usually resorts to pressure. You know... pressure applied by presses etc. This binding is stronger if two conditions are met. First, exudates must form on the surface of the meat, and second, the meat is heated to 150 degrees Fahrenheit. (Does the commercial "water-boiled ham" come to mind?) How do we do it at home? Salt. Simply salt! Salt extracts collagen and myosin, and if we are to have any binding to speak of, it must be put back into the meat, upon mixing or simply added to the bowl cutter. Many people are hesitant to reintroduce the exudate. They shouldn`t be. You wouldn`t believe what`s in that stuff other than just blood. Pour it back into the mixture and remember, the leaner the meat, the more exudates may be extracted.
As we handle and prepare meat for sausage, there are a few other things we should not overlook. Besides the age of the animal, the pH acidity very much affects its water-holding ability. And if the meat has been frozen, muscle fibers have been damaged by ice crystals. This affects not only the water-holding ability, but the protein extraction as well. Fresh meat will always bind more easily than previously frozen meat.
Now, if you are just not finding any exudate, you may consider the use of a "special meat binder" which is phospate. The stuff works incredibly well, but when mixed with a little salt, it works dynamically well!
I don't use it because I'm not totally convinced of its safety, although our government has given it the okay. Literally every commercial meat supplier uses the stuff.
There are 3 categories of meat proteins. The (1.)
myofibrillar proteins are called the "contractile" proteins for the way they act upon muscle e.g.
rigor mortis. Myofibrillar proteins are composed of 55%
myosin - generally considered the single most important because of their long, highly-charged, "filament" molecule that is present in lean muscle.
Actin and
myosin are primarily responsible for creating the "sticky gel" that holds mixed, comminuted meat together.
The (2.)
stromal proteins are in connective tissue and are primarily collagen, composing about 20 - 25% total body protein in the skin, sinews, tendons, etc. They are designed to transmit force to hold things together, thus they are generally tough and inert. Stromal proteins are of little or no value in processed meats as they have little binding ability. Further, as an animal ages, its meat becomes tougher due to the stromal protein`s unique make-up of 33% glycine and 10% hydroxyproline - responsible for non-charged or "non-polar" molecules having a minimally low isoelectric point. Stromal protein is generally considered a problem in processed meats and "high collagen meats" are often limited to 15 - 25% maximum, although chopped, ground, powdered collagen which can be dispersed, can be useful in forming a gel when heated. They may also be useful in retaining water and fat.
The (3.)
sarcopolasmic proteins are found in intracellular fluid and compose 30% of total muscle protein. They contribute only 20% to binding ability and the isoelectric point of its molecules is low, although they do
contribute to tenderization through postmortem
glycolysis, effecting a
pH change. Don`t be too hard on the sarcopalasmic proteins though, because they potentially
add flavor contributions from a process known as "protein hydrolysis".
So, ol` pard... add a little salt and keep mixing. If it doesn`t start to become sticky, you may have to use a little bad language and add a quart of 34° honey-molasses mixture!
Best Wishes,
Chuckwagon