1. First, I would like to talk about the types of emulsified sausages . 

In the understanding of our compatriots, cooked sausage products mean only cooked sausages, frankfurters, small sausages, shpikachki and meat loaves. That is, finely ground minced meat (emulsion) in a casing of different diameters or without a casing (in the form of meat loaf). This is not quite true, the concept of "cooked sausage products" is not so narrow.

If we approach the issue of meat emulsion fundamentally, we need to take a broader look at the entire spectrum of sausage products. After all, semi-smoked sausages, salami, cervelats, minced dry-cured sausages and pates are also an emulsion of meat protein and fat in various proportions and states.

To understand this issue, I suggest taking a look at the generally accepted classification of sausage mince.

1. Finely emulsified mince. These are all types of cooked sausages with homogeneous fine mince. For example, sausages like Doctor's, frankfurters, wieners, meat loaves, and also some types of pates.
2. Finely emulsified minced meats with inclusions of large fractions of lard, meat, offal, vegetables, nuts and plant seeds. For example, Amateur boiled, Mortadella, Veal sausage and other various combinations of this type.
3. Coarsely ground minced meats – all types of salami with small and large patterns, cervelats (including dried and smoked), sausages such as Krakow, Odessa, Tallinn, etc.
4. Coarsely chopped minced meats – all types of piece hams (restructured), hams in forms, meat rolls, canned hams. Such meat products can be either boiled, boiled-smoked, dried or raw smoked.

All these groups are united by one technological principle – the need to create an emulsion from meat protein, fat and water. The emulsion is created by grinding meat fibers, releasing salt-soluble and water-soluble proteins from muscle cells and forming strong protein-fat-water bonds.

Grinding can be achieved by cutting with a meat grinder, using cutter knives, or by rubbing pieces of meat together while mixing.

2. The ideal parameters for creating a fine emulsion of cooked sausages with the strongest properties: the ratio of protein/fat/water is 4:1:2. Thus, for each part of fat, 4 parts of protein and 2 parts of water are needed for its complete and strong emulsification. The finer the mince is ground, the larger the contact surface of the particles and the more proteins are released into the space between the small pieces of mince, forming a kind of three-dimensional "sponge" of protein particles, fat and water. This "sponge" is usually called the "protein matrix" of mince.

From these "ideal parameters" the legendary recipe for "Doctor's" cooked sausage was created almost 100 years ago. Of course, the given "ideal" ratios are suitable for modeling in laboratory conditions. We do not have the ability to grind minced meat to the state of complete destruction of all cells, some of them remain whole in the finished sausage mince in the form of a filler, not an emulsion.

In reality, lean meat cannot be equated to pure protein, just as fatty raw materials cannot be considered pure fat. Therefore, usually there is more than 1 part of fatty raw materials in generally accepted recipes for cooked sausages, because fat is “packaged” in fat cells and during the grinding process, this “packaging” of many of these cells remains intact, not destroyed during grinding. This means that such fat cells will be able to participate in binding only with their side walls and there will not be enough of them to form a meat emulsion in its “ideal proportion”, as written above.

Phosphates, citrates and salt are substances that help break down the walls of meat cells and whip the mince into a fine suspension.

Thus, in reality, with tolerances for “under-grinding”, the ideal ratio for home reproduction can be considered to be 3:1:1 (phosphate-free recipes) or 3:1:2 (with phosphates).

Based on these considerations, you should select raw materials for making sausages at home. For example, 50% lean raw materials and 50% semi-fat, in total give approximately the same ratios. Semi-fat raw materials are half conditionally fat (pork belly with layers of fat, for example). In total, we get 3 parts of lean raw materials (2 parts of lean raw materials and 1 part of semi-fat) to 1 part of fat (from semi-fat raw materials), all this is conditional, of course. 

Simply put, from practice, the ratio of 50:50 lean and semi-fat raw materials allows you to create a stable minced meat emulsion at home for any cooked sausages, hot dogs, frankfurters. The meat can be of any animal.

The main condition for creating a strong sausage emulsion is maintaining a temperature during grinding that does not exceed 10...12 degrees Celsius . When these temperatures are exceeded during mechanical action (meat grinder, blender, cutter), fat cells are destroyed and fat droplets are released into the mince structure. There is too much fat, the mince turns white, becomes similar to mayonnaise. There is not enough protein capable of binding to this fat released from the cells. Subsequently, this process leads to fatty swelling under the casing during heat treatment. The structure of the sausage will be loose and similar to pate. This process is irreversible, whitened mince can no longer be corrected, so monitor the temperature of the mince during grinding. If necessary, stop and freeze.

3. The process of emulsification of finely ground minced meats is traditionally divided into several stages :

Ideally, the minced meat to be ground was pre-frozen (to 0…-4 degrees inside). Such minced meat does not need to be cooled during the grinding process using cold water, ice or freezing, interrupting the process. In this case, ice water or ice is added in two parts. First, the first half during the grinding of lean raw materials (for example, beef), the second half - when adding fatty raw materials to the ground lean meat.

If the raw material was not frozen, then moisture is added in the form of ice water or fine ice (preferably). It is introduced fractionally, in parts throughout the grinding process, constantly monitoring the temperature of the mince. I repeat, it should not rise above 10 ... 12 degrees Celsius. When gradually introduced in small portions, the entire volume of this moisture is completely absorbed into the mince, and it remains thick.

1. First of all, the lean raw material is ground in a cutter (blender) without water. At this stage, all the salt from the recipe is added. Thick mince and a high concentration of salt at the initial stage of fine grinding of mince help to destroy muscle fibers as quickly as possible and dissolve the entire available volume of salt-soluble proteins. 

At this stage, phosphates, citrates in pure form or their mixtures with spices are added to speed up emulsification and release of meat protein.

After 2-3 minutes of grinding, a large amount of meat extract containing meat protein is released into the mince. Fatty raw materials can be added.

2. Frozen fatty raw materials and bulk ingredients (spices, dry milk, egg powder, starch) are added at a temperature not exceeding 5...6 degrees Celsius. Fatty raw materials are easily destroyed, forming a strong emulsion. Bulk ingredients - dry milk, starch, egg powder, flour bind the moisture not used to create the emulsion. But do not forget that high-quality fine grinding of meat raw materials does not require the addition of dry components!
3. When the temperature reaches 10...12 degrees Celsius, the fine final grinding of the minced meat should be stopped. At this stage, lard is usually added, which is chopped into pieces, as well as structural inclusions (large pieces of meat, spices, nuts).

The minced meat is ready for stuffing and subsequent heat treatment.

4.  Errors leading to defects made during grinding.

Why is it so important to observe the temperature regime when grinding? The fact is that when grinding on a cutter, blender and especially on a meat grinder (with dull knives or large gaps between the knife and the grate) local overheating of the mince is possible, leading to heating of the fat and to local denaturation of the protein, its boiling, and, as a result, to the destruction of the emulsion in the protein matrix.

 Unbound fat is the main reason for defective sausage products. It is the cause of broth-fat edema - this is when we get dry mince and broth under the casing separately instead of a homogeneous, dense and juicy sausage.

5. Methods for preventing fat and broth swelling when mincing meat.

In essence, all methods of preventing defects come down to banal adherence to the principles of forming fine emulsions. We will list them:

1. It is necessary to create conditions for maximum release of meat protein from muscle cells into the minced mass. The grinding sequence is crucial in this matter. To do this, first grind the low-fat raw material with salt, phosphate and citrate mixtures with fractional addition of water, and then add the fatty raw material.
2. Maintaining the grinding temperature. Muscle fibers are easily destroyed and release protein at a temperature of about zero degrees, so it is better to slightly freeze the raw material before grinding. This measure will also give us an extra time reserve during grinding for maximum extraction of soluble proteins into the mince.
3. Care should be taken to ensure that the cutting edges are sharp and that there are no gaps in the cutting parts of the mincer, blender or cutter mechanisms. Dull knives heat the mince very much and quickly lead to its overheating with subsequent formation of broth edemas.

6. Functional additives.

For additional lightening and release of meat protein from muscle fibers, sodium phosphates and citrates are commonly used in sausage production . 

Phosphates (salts of phosphoric acid) in minced meat break the bonds between actin and myosin molecules and create the maximum number of free protein bonds for creating emulsions from water and fat. This is why they are most often used in industrial production of meat products.

Phosphates allow you to get the most juicy, tender product that will be easily digestible by humans. Adding phosphates allows you to bind and saturate the mince with moisture. Up to 20...25% additional moisture in the mince of cooked sausage will give it juiciness and will contribute to the correct formation of the mince emulsion. Adding more moisture will lead to a loose consistency of the mince, and using phosphates without adding water will lead to a dry and dense texture in sausages.

Citrates (citric acid salts) only contribute to the swelling of muscle fibers and facilitate their mechanical destruction. Additionally, citrates help preserve the bright red pigment of meat formed during the interaction of sodium nitrite (from nitrite salt) and meat myoglobin. It is the ability to preserve sodium nitrite from destruction during the color formation of minced meat that allows its required amount to be reduced by 2 times in recipes. Thus, nitrite salt in the presence of citrates can be used in a mixture with table salt in a percentage ratio of 25:75. While in citrate-free sausage recipes, it is permissible to replace nitrite salt with table salt by only 50%.

Products with citrates are not as juicy as those with phosphates. But the big advantage of citrates is that they are safe for the human body and therefore are approved for use in children's sausages and hot dogs.

Adding citrates allows you to bind only 10...15% of additional moisture, unlike phosphates, which, as mentioned above, are capable of binding another 20...25% of water to the mince, but the very presence of citrates in the mince gives it a fuller taste and a bright red color.

We should not forget about the possible harm from overdosing on phosphates in the diet of modern people. After all, along with sausages, phosphates are also used in processed cheeses, and as fertilizers for plants, as water softeners in household filters and in water supply systems, as well as in vegetables, etc.

Optimal dosages for home use: pure phosphates – 2…4 g/kg of minced meat, citrates – 4…6 g/kg. Do not exceed these norms.

The combined use of phosphate and citrate functional mixtures is not permitted!

7. Stuffing and forming sausage .

The high viscosity of fine emulsions usually results in an abundance of small air bubbles, which create pores in the finished product. Pores should be removed, if possible, by hand kneading or beating.

When stuffing the casing using meat grinders or auger syringes, special attention should be paid to possible overheating of the mince on the auger due to friction. This can lead to broth swelling in the finished product. This is described in detail above.

8. Sedimentation and maturation of finely ground sausages .

Finely ground minced meat does not require long salting and maturation. Salting occurs simultaneously with grinding, and the fine fraction of minced meat is salted in 10-30 minutes after grinding. Therefore, minced meat for cooked sausages, frankfurters, and wieners is traditionally made from unsalted frozen raw materials.

Before heat treatment, finely emulsified mince is usually kept warm for 20-40 minutes (+18...25 degrees Celsius) for uniform heating. This allows you to get a brighter and more stable pink color of sausages and reduces the formation of small pores on the cut of finished sausages. Longer keeping of cooked sausages in the heat can lead to banal souring of mince and obtaining inedible rejects.

9. Heat treatment  of cooked sausages .

All sausages are processed thermally at a temperature not exceeding 80 degrees Celsius until reaching 69…72 degrees inside the product. The time of thermal processing depends on the diameter of the sausage stick. For example, sausages will be ready in 20…30 minutes when placed in an environment preheated to 80 degrees, and cooked sausage in an 80 mm casing will be ready in approximately 2.5…3 hours. Focus on the temperature inside the product. If the product is overcooked and the temperature inside the product rises above 72 degrees, there is a high probability of getting a defect in the form of swelling under the casing.

The heat source is not important, it can be hot water, steam, oven or smokehouse. The main parameter is that the heating temperature should not exceed 80 degrees Celsius.

Possible errors during heat treatment:

1. Overheating sausages above 80 degrees Celsius always results in defects in the form of broth swelling.
2. Do not heat sausages above 72 degrees Celsius inside. This often leads to a loose structure of the mince and broth swelling.

10.  Cooling of sausages.

Due to high humidity, cooked sausages do not last long. Therefore, ready sausages should be cooled quickly in order to quickly pass the temperature of 38 ... 25 degrees Celsius inside. After all, heating sausages to 72 degrees inside does not provide complete sterilization, but only kills live forms of bacteria, but from spores at a favorable temperature of 38 ... 25 degrees bacteria quickly develop again. This is why cooked sausages are quickly cooled to + 2 ... + 4 degrees Celsius in ice water or in the refrigerator.