Meat fermentation is a biological process that preserves the meat and provides distinct properties such as flavor and tenderness.
Traditionally, fermentation relied on the natural microbial load of the meat but, in modern production, a selected microbial culture is added.
During the fermentation process, fermentable sugars (dextrose or fructose) that are present in the meat or added by the manufacturer are transformed into an acid, called lactic acid.
The formation of lactic acid in the product leads to an increase in acidity. The more acidic the meat product is the lower the pH will be.
The pH of fresh meat is approximately 5.6-5.8. The pH of fermented meat is usually below 5.3.
Besides lactic acid, there are a variety of other products that are formed during the fermentation process. These include organic acids, carbon dioxide and alcohols that give the fermented products distinct flavor and texture.
For many years, sausages have been inoculated with a concentrated and selected mixture of bacteria, called starter culture or inoculums, to begin fermentation. The use of starter cultures means that the proper type of bacteria in the amount required is added to the sausage emulsion to ensure efficient and safe fermentation.
There are two species of bacteria that are primarily responsible for converting sugars into lactic acid:
· Lactobacilli spp used in slow fermentation processes
· Pediococci spp used in rapid fermentation processes
(In Europe, as well as in Turkey, these genera are most often used in combination with micrococci and staphylococci.)
Depending on their pH and aw levels, raw fermented sausages are classified as: semi-dry sausages and dry sausages.
Semi-dry (quickly fermented) sausages differ greatly from dry sausages by their “tangy” flavor resulting in lactic acid accumulation. Semidry sausages are usually stuffed in medium and large diameter natural or artificial casings.
The length of production (smoking and fermentation) of these sausages depends on their type, but rarely exceeds several days.
The pH of semidry sausages is clearly acid; 4.8 to 5.4.
Semidry sausages are regularly smoked and only exceptionally slightly cooked by the heat applied in the smokehouse at various temperatures, mostly not exceeding 45°C and sometimes raising to 60°C. After smoking the sausages are usually air-dried for a relatively short time.
Semidry sausages usually contain an important proportion of beef meat. Their shelf life is surprisingly good due to low water activity. Semidry sausages have improved stability if stored in the chiller, protected from humidity rather than at room temperature.
Properties of dry (slow-fermented) sausages depend not only on the bacterial fermentation, but are also strongly influenced by biochemical and physical changes occurring during the long drying or ageing process.
The length of production, either with or without smoking, and drying periods depends on some factors; such as diameter and physical properties of casings, sausage formulation, choice and methods of preparing meat, conditions of drying etc., but overall processing time require up to 90 days.
The final pH of dry sausages is usually between 5.0-5.5. It increases during the second part of this long ageing process.
Dry sausages are made from selected, mainly coarsely chopped, meat. Their water content is under 50% for sucuk and 35% for other dry sausages.
Some of dry sausages are subjected to cold smoking (12 to18°), but sometimes not; in some countries they are often heavily spiced with red pepper or garlic or heavily smoked and strongly salted.
The formulation, degree of grinding, level of fermentation, smoking intensity, temperature of ageing and type and size of casing as well as other factors determine the properties of the final product.
In the preparation of dry sausages natural casings are preferred because they adhere closely to the sausages as sausages shrink.
The shelf life of dry sausages is excellent, which may be especially attributed to the high salt-to-moisture ratio. These sausages are normally kept without refrigeration.
Raw sausages, which are not submitted to the smoking process, are known as air-dried sausages.
The principle of dry sausages is salami of different types produced in many countries as small-diameter dry sausages. Dry sausages may be hard, intended for slicing and soft style sausages, which can be spread.
Selection of raw materials
Chilling of meat and fat (0 to 7˚C.)
Comminution and blending of meat and fat
(bowl chopper or mincer and vacuum mixer)
Addition of spices and curing salt
(as well as carbohydrate and starter culture if applicable)
Air removal (vacuum chopper or vacuum mixing)
Stuffing (vacuum stuffer)
Drying of surface of sausage
Smoking (if applicable)
Incubation (if starter culture is added)
Ripening and drying
Process ﬂow for dry sausage manufacture
The main ingredients used in fermented sausages are; meat, salt, nitrite or nitrate salts, sugar, acidulants, starter cultures and spices.
Only the highest quality of meat should be used in fermented sausages. When selecting meat, three criteria are important:
Wholesomeness- free of pathogens, parasites, chemical residues and physical hazards. Functional characteristics- composition, pH and binding properties. Color- meat color is affected by species, freshness and pH. For optimal meat quality:
Chill fresh meat rapidly and keep cold Use meat soon after slaughter (within three days) If not use immediately, freeze meat as soon as possible.
Most fermented products contain between 2.5-3% salt. The main characteristics salt brings to the fermented products are flavor and binding. The salt used in meat products should be free of impurity; which if present in meat could lead to fat oxidation.
To inhibit the growth of Clostridium Botulinum spores and development of their toxins in shelf stable cured products. Nitrate, rather that nitrite, is added in the process of slow fermented sausages. Nitrate itself does not have a significant impact on bacterial growth, therefore has to be transformed to nitrite. Bacteria called Micrococci that are usually contained in the starter cultures make this transformation possible.
Sugars are added to provide nutrition for fermenting bacteria. The most common sugaradded is dextrose, but other sugars such as sucrose, corn syrups, glucose and brown sugar. The more sugar that is used, the more lactic acid results, so the lower the pH will be.
Acidulants are acid substances that may be used to reduce the pH of the emulsion. And spices are aromatic substances that are usually added to improve the flavor of the product.
Should People “At Risk” Eat Dry Sausages?
Because dry sausages are not cooked, people “at risk” (the elderly, very young children, pregnant women and those with weakened immune systems) might want to avoid eating them. The bacterium E. coli O157:H7 can survive the process of dry fermenting, and recently some children became ill after eating dry cured salami containing the bacteria.
SAUSAGE STORAGE CHART
If the sausage has a “use-by” date, follow that date. It is the last date recommended for the use of the product while at peak quality. The date has been determined by the manufacturer of the product. If the sausage has a “sell-by” date, or no date, store it for the times recommended below. Sausage Storage Chart Type of Sausage Refrigerator – Unopened Refrigerator – After Opening Fresh Sausage, uncooked 1 to 2 days (included in unopened storage) Fresh Sausage, after cooking by consumer (not applicable) 3 to 4 days Hard/Dry Sausage indefinitely in refrigerator; 6 weeks in pantry 3 weeks in refrigerator, or until it turns rancid Hot Dogs and other Cooked Sausage 2 weeks 7 days Summer Sausage (Semi-dry) 3 months 3 weeks Freeze if you can’t use within times recommended above for refrigerator storage. Once frozen it doesn’t matter if the date expires because foods kept frozen continuously are safe indefinitely. However, for best quality use within 1-2 months.