Traditional Fermented Sausages

Traditionally made fermented sausages are made without starter cultures or sugar and relies entirely on bacteria present in meat and in surounding microflora. Before the starter cultures were discovered there was a practice of adding fermented sausage mass from the previous production to a new sausage mass that will be stuffed into casings. This increased the number of lactic bacteria in a new sausage mass. This questionable practice today was called "backslopping" and is very seldom used as it introduces not only lactic bacteria that are needed for fermentation but also any unwanted bacteria that had developed in the previous sausage mass.

Home made traditionally fermented products are made in conditions that take advantage of the weather conditions that are typical for a particular season of the year. There is little one can do to finely tune the temperature or relative humidity levels. Because of that, temperature range and humidity levels are somewhat more relaxed than stringent requirements of comercial drying rooms. It should be noted that if the temperature goes up the relative humidity goes down and vice versa.

Making traditional slow-fermented sausage

Traditionally manufactured sausages are predominantly made from pork, pork fat (back fat) and beef. About 80% lean meat and 20% fat are the most often used proportions and selection of spices plays a secondary role. One of the reasons is that there is not much original spice aroma retained by the sausage is that it is drying for 3 months and hanging in storage for another 6 months. The taste and flavor of the sausage is the result of a long drying period when many naturally occuring reactions take place with meat protein producing a very characteristic and desired flavor.

The beginning of the process is very similar to making any kind of a sausage (grinding, mixing, stuffing) the main difference being the utmost attention directed towards the freshness of meat, cool production temperatures, cleanliness of the equipment and personal hygiene. The second part of the process (fermenting, drying, storage) is completely different and requires basic knowledge of the theory that governs the making of fermented and air dried products.

1. Meat selection. Meat of a healthy animal is clean and has no bacteria. Some bacteria reside on an animal's skin and inside its intestinal tract (casings). Bacteria which is present everywhere are introduced when we start to process meats: every time a knife cuts meat, the blade introduces new bacteria which multiply and slowly migrate towards the inside of the piece. As more cuts are made, the easier it is for bacteria to penetrate the piece. This is why ground meat (small particles) has the shortest shelf life. Bacteria will find their way into the sausage mass that will be stuffed into the casings by the following:

We can not eliminate bacteria altogether but we can restrict their growth to the minimum and this is the most important step during the manufacturing of fermented sausages. It should be noted that placing meat in a refrigerator will not stop the growth of bacteria but merely slow it down. At this temperature (4º C, 40º F) they will double up in number every 12 hours anyhow. If we have 300 bacteria in 1 gram of meat and we keep this meat for one day (24 hrs) in a refrigerator we will have 1200 bacteria at the start of the grinding. But if we have 1000 bacteria in our meat to start with, after 24 hours we will have 4000 bacteria and a commercial producer will not process this meat for fermented sausages but he may use it for making fresh meat products (they will be cooked to 160º F, 72º C before consumption).

The example above shows how crucial it is to select fresh meat for making air dried sausages and processing it (grinding, mixing and stuffing) as soon as possible and at the lowest temperatures. If those conditions are not met we may be doomed on day one and we will waste 3 months of our time on producing a low quality sausage or even throw it away.

2. Curing. Adding salt, sugar and nitrate to meats has been practiced for centuries and the general consensus is that curing contributes positively to the color, flavor and shelf life of the product. The curing step has been employed in traditionally made fermented sausages (without cultures) to increase the number of lactic acid, color and flavor forming bacteria. When making fermented sausages the main purpose of curing was twofold:

The curing step is simply adding extra time for beneficial bacteria to develop. Although the process will be slow due to cold temperatures, the bacteria count will somewhat increase. There is a little problem with this curing procedure as other bacteria such as spoilage and pathogenic (dangerous) will grow as well, and when subsequently introduced to the fermenting chamber they will also multiply. Fortunately, they are little salt tolerant and their growth is slowed down by salt and nitrite. Besides, those millions of bacteria (culture) introduced to meat will start competing for nutrients with beneficial, spoilage and pathogenic bacteria and their growth would be severely restricted. There is no need to perform this curing process when starter cultures are added to meat. We are assured of a huge number of lactic acid bacteria which will start the fermentation process as soon as the stuffed sausage is placed in a warm fermentation room. Placing the sausage mix that includes starter bacteria in a refrigerator makes little sense and will unnecessarily increase the number of spoilage and pathogenic bacteria.

Let’s speculate that we have 500 lactic acid bacteria in 1 gram of meat to be cured. At 42º F (6º C) they might double under perfect conditions (no salt and no nitrite). That means that after 48 hours we end up with 8,000 bacteria ready to start fermentation. This number pales in comparison with 10 million (10, 000,000)/g bacteria which are introduced with a starter culture. This proves without any doubt the advantage of using starter cultures. As mentioned earlier, the curing step is seldom practiced today as every manufacturer adds starter cultures to the sausage mix to better control the process. Nevertheless, it is still a fine and recommended procedure for making unfermented meats and sausages which will be subsequently smoked and cooked.

Original way to cure meat was as follows:

This time could be shortened to 48 hours by grinding meats with a plate as smaller particles are penetrated faster by salt and nitrite. A cured sausage mix has a tendency to firm up and the stuffing process becomes harder to perform especially when using home equipment. For this reason the sausage mix was re-ground with a correct final plate, often 3/16" and mixed with spices. Back fat is salted only as it does not contain myoglobin and there is no need to mix it with nitrite (no color forming will occur).

3. Grinding. All grinders, even manual types, generate heat which warms up the meat. If possible meat processing should be done at temperatures not higher than 12º C (54º F). "Take what you absolutely need" should be applied to all processes and that means that only the necessary amount of meat to complete a particular operation should be taken out of a cooler. Don't take 50 lbs of meat out of a refrigerator when operating a manual grinder which is slow. Take what you need. Make sure that the meat is very cold or even partially frozen as this allows for cleaner cuts and keeps the meat temperature down. Fat should be partially frozen to prevent smearing which affects drying.

4. Mixing. Adding water to facilitate mixing is a common practice when making sausages but in the case of fermented sausages this technique is strongly discouraged. Water removal (lowering water activity Aw) is one of the hurdles employed to safeguard the sausage against microbial spoilage and bringing extra water in beats the purpose of drying. It does not matter much when making a smoked/cooked sausage as this water will evaporate rapidly during smoking and cooking. Besides, cooking will kill all bacteria anyhow. In case of a fermented sausage this water becomes a wonderful playground for bacteria.

5. Stuffing. Natural casings of different diameter or synthetic fibrous casings can be utilized. More attention must be dedicated to the preparation of the casings for the following reasons:

The parts of the animal that are most contaminated with bacteria are skin and intestinal tract (casings). Although casings are cleaned, washed and packed in salt nevertheless they still remain contaminated and can contribute to the total contamination (bacteria count) of the sausage. The following steps must be undertaken to minimize the danger of contamination:

6. Mixing of all ingredients should be done at the temperature between 0º and 5º C (32º-41º F). Higher temperatures may start fementation too early which will lead to quality problems later (rancid taste, case hardening). In such a case the sausage mass should be cooled down in a refrigerator before proceeding to the stuffing.

A typical process:

No sugar nor starter cultures added
Temperature Humidity Time Notes
Fermentation 12º-16º C, 54º-61º F 82-98 % 3-8 days The temperature must not exceed 22º C, 72º F. Expected pH value 5.2. pH below 5.0 may lead to sourly sausage.
Drying 12º C, 54º F 75-80 % 2-3 months Higher temperatures must be avoided. Expected pH around 5.3, expected Aw 0.88.
Storage 12º-18º C, 54º-66º F 75-80 %    

Mediterranean style products (Italy, Spain) produce sausages that are only air-dried

Northern style products (Germany, Poland) produce sausages that are smoked and air-dried. A thin, cold smoke (no more than 20º C, 68º F), humidity 70-80%, produced from burning hard wood logs is applied after the fermentation stage. Good air draft (ventilation) is needed.

If sugar and starter cultures are used use the following parameters for fermentation:

temperature: 20º C (68º F)

umidity: 85%

time: 3-5 days

and monitor pH values

Note: some manufacturers don't carry out the fermentation stage at all and the stuffed sausage is directly submitted to the drying process at 6º -15º C (42º -59º F)

Staphylococcus aureus starts to grow fast at 15.6C (60º F) and higher. For this reason, sausages made without starter cultures should not exceed this temperature. When cultures are used, lactic acid bacteria produce lactic acid and this increases acidity of the meat, inhibits growth of Staph.aureus. This pathogen can survive high salt levels and funtions remarkable well at low moisture level (down to Aw 0.86). Staph.aureus is sensitive to acidity (low pH).

7. Fermentation means increasing the temperature of a stuffed sausage which allows the naturally occuring bacteria in meat to grow and react with the meat. As a rule the higher the temperature, the faster bacteria growth and their energy to react with meat or any other food. For most bacteria the best temperature for growth is around our body temperature (36.6º C, 98.6º F). This temperature is too high for any kind of traditionally made slow-fermented products. Unless a pH meter is used to check the acidity of the sausage, it is hard to predict when fermentation ends and when drying begins. Once pH value reaches 5.2 there is no need to lower it further as it will affect the taste and color of the sausage and at this point there is little need for bacteria to produce more lactic acid and lower pH even more. The flavor of the product will taste sour and the color will suffer too. This may be acceptable for a fast-fermented economy sausage but not for a traditional sausage.

Fermenting is the crucial step and proper temperature plays a very important role. At 18º-24º C (66º-76º F), fermentation normally lasts 1-2 days. At lower temperatures, 10º-12º C (50º-54º F), it will last about 1 week. During fermentation the relative humidity can vary between 75 and 95%. If possible it should be kept at 92-95%. To stop the fermentation process we lower the temperature to 12º C (54º F) and that stops lactic bacteria from fermenting sugars. The remaining sugar will be utilized for the development of flavor and stronger color.

To prevent the growth of mold or for this extra flavor after fermentation sausages can be cold smoked (20º C, 68º F) and then air dried. Cold smoking is basically drying meats with smoke.

7. Drying is accomplished at 10º-14º C (50º-58º F) and will last for 4-12 weeks. If drying temperatures are higher, the drying process may be accomplished in 1-3 weeks. During drying the relative humidity can vary between 70-85%. If possible it should be lowered gradually to around 75%.

Time of drying is affected by:

8. Storing. When the sausage reaches water activity Aw 0.89 or lower it is considered microbiologically stable and can be kept at cool room temperatures. Sausages should be kept at 12º-18º C (54º-56º F) in a dark (to prevent color change and fat rancidity), well ventilated area (to prevent mold growth). The humidity should be about 75% (higher humidity favors the growth of mold, lower humidity will dry out more moisture and decrease the weight of the product).

Notes:

Ingredients. Only top quality ingredients should be used (fine salt, sugar, nitrite/nitrate, freshly ground spices, etc,) but use of fresh spices (garlic, onion, parsley, oregano, etc) is prohibited. Fresh spices contain moisture and bacteria of unknown nature and may contaminate and spoil the sausage. If starter cultures are used they should be stored at low temperatures according to supplier recommendations. At least 2.5 % salt (25 g salt/1 kg of meat) should be added which will help to lower water activity and inhibit the growth of bacteria. which will help to lower water activity and inhibit the growth of bacteria.

If sugar is added, the amount should be based on pH value of the mixed sausage mass (before stuffing). Typical values of meats selected for commercial production are: pork: pH-<5.9-6.0, beef: pH-<5.8. About 2-4% sugar (2-4 g/per 1 kg of meat) are most often added.

In a finished sausage the pH of 5.3 and Aw of 0.88 are signs of quality product.

Microbiological Control:

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