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KEEPING QUALITY AND DELIVERY OF SAUSAGES TO RETAILERS

The distribution of sausages in tropical and subtropical regions should follow principles essentially similar to those applicable in temperate climates but practical details have to be modified according to local conditions. The complexity of the sausage nutritional and flavouring picture causes special relationships between customers and their sausage suppliers. The most successful marketing of sausages has now become a mutual effort between customer and sausage manufacturer. The customer needs to know what effects the sausages have for his health and what price he is obliged to pay. The sausage manufacturers have to know how to produce the desired products, requiring knowledge of meat and nonmeat sausage raw materials, their quality profiles, processing operations, required methods of storage and, increasingly so, the complex picture of supply.

An efficient sausage manufacturer should provide consumers with a flow of sausage products of the type, quality and amount that are desired. In those cases where the sausage manufacturer is not properly informed of consumers' requirements or fails to pay attention to such information, consumers have little interest to buy his products and prices tend to be low.

New products and their marketing methods are gradually created and must be in harmony not only with customs, education and economical power of the public concerned but also with public health requirements.

KEEPING QUALITY

The major concern of meat processing in tropical and subtropical countries is the development of safe sausage products through the rational use of raw materials, adequate processing methods and maximum performance of hygienic requirements. From the processing plant to the sausage manufacturer a beef or pork carcass must have sufficient shelf life. Meat with the best shelf life is the easiest ro process. The surest way to produce poor quality sausages is to process discoloured or in any other way spoiled meat.

The microflora of sausages is essentially different from that of carcass meat. Although particular problems arise with specific sausage products in general it may be said that for all sausages, three basic requirements must be for a hygienically satisfactory product: (a) conditions of sausage production must be such that should toxigenic organisms be present in or gain access to the product prior to, during or after processing, no bacterial toxins are formed, (b) the final sausage product should not contain microorganisms likely to be pathogenic to man, and (c) the total bacterial count of the sausage product should be reasonably low so that no decomposition or development of undesirable flavour occurs during the period of processing, distribution or storage. Special problems may arise if the sausages are to be held in particularly warm and humid conditions promoting bacterial growth.

The first and second requirements mean in general terms that the meat raw materials should be free from toxigenic and pathogenic organisms and must be boned, trimmed, ground, chopped and processed at a temperature at which significant growth of these organisms is unlikely to occur; alternatively, the time of processing at an undesirable temperature should be shortened so that even if such organisms may be present, no significant growth or production of toxin occurs. The hygienic quality of a sausage product therefore has to be assessed primarily on freedom from pathogens, potential pathogens and their toxic products (sporing anaerobes, enteric organisms of typhoid, paratyphoid, dysentery and Salmonella groups and certain staphylococci and perhaps streptococci).

The third requirement demands the selection for sausage manufacture of sound good quality meats and other raw materials and the observance of reasonable standards of hygiene during all stage of the process. A point that should be made clear is that a low total viable bacterial count represents in general an index of reasonable care in manufacture and reduces the occurrence of “souring” and other types of spoilage.

Spoilage microorganisms commonly found in the meat processing environment are bacteria, yeasts and moulds, all of which, together with some physical and chemical factors, can render a meat or sausage inedible and unattractive by destroying the colour, flavour and structure. The growth of microorganisms in meats and in finished sausages is affected by processing temperature, available water and its activity in meat, oxygen, pH-value and the salt and nitrite contents. Most influential are temperature and water. Apart from these factors, the shelf life of sausages is determined by the initial bacterial count of meat and other sausage components.

Temperature.

One easy way to increase sausage shelf life is to lower the temperature of all rooms need in the processing, and storage of meats and sausages. The meats undergoing sausage processing should be processed at such temperatures that bacterial growth cannot occur until the pH and water activity values are sufficiently reduced to inhibit microbial action. Where there is a lack of such conditions, it may be necessary to work at temperatures at which bacterial growth may in theory occur but the processing should be accelerated and a suitable compromise arrived at in which in practice bacterial growth is not found to be significant. In other words, good shelf life and other quality characteristics of finished sausages result from the hygienic conditions present during processing, including hygiene of personnel, methods of processing applied which impede microbiological activity, conditions at which the sausages are subsequently held during storage, transport and sale. If the minimum conditions are not respected, the sausages are subject to spoilage and deterioration at an earlier storage time thant normal. On the contrary, hygienic meat handling and processing markedly extend sausage commercial life.

The required temperature conditions of sausage storage should be fully respected since, if they are unsatisfactory, the precautions taken during processing may be largely nullified by the undue proliferation of the residual flora.

Water activity.

The amount of watetr needed for growth depends upon many factors — nature of the organisms, available nutrients, etc. When the composition of a sausage product is appropriately formulated, the amount of water required for microbial growth may considerably be reduced and the sausage product shelf life increased.

The state of water in sausages has a direct effect on microbial, chemical and enzymatic reactions. This water activity or the aw-value, also sometimes expressed as the “free” water content in the sausage, is by definition the quotient of the steam pressure present in the meat and the saturation steam pressure of the pure water under identical temperature conditions (Ps/Po). The aw-value of a water-free substance equals 0, that of bidistilled water, 0.1.

The aw-value of lean meat is about 0.99. In traditional sausage manufacture, aw is reduced either by drying or by addition of curing salts, nonionic solutes, such as sugar, spices and different additives. It means that the aw-value can be influenced by appropriate formulation of the sausages as well as by processing methods. Fat, water and salt contents directly influence aw-value. In sausages where fat and water contents are substantial and highly variable, it is important to understand fully the role that changes in composition play on the product stability. Thus, the addition of 1 percent level of fat reduces the aw-value by 0.00045. In the same manner, the addition of 1 percent sodium chloride reduces the aw-value by about 0.0060 while 1 percent of sugar and 1 percent of soy or milk protein reduce the aw-value by about 0.0020–0.0025 and 0.0012–0.0013 respectively.

A raw sausage meat mixture containing 30 percent fat, 3 percent salt, 2 percent sugar and 2 percent soy protein has an initial aw-value of 0.9521. The final aw-value of the product depends upon the degree of heating and water losses due to evaporation. At aw-value levels below 0.95 most gramnegative microorganisms are unable to develop and they are gradually replaced by lactobacilli and osmotolerant cocci. At aw-values lower than 0.88 to 0.90 multiplication of bacteria and yeasts is basically stopped.

Fig. 39

Fig. 39 WATER ACTIVITY VALUES INHIBITING THE GROWTH OF MICROORGANISMS.
(To inhibit the growth of the most prevalent species of bacteria, the water content of meat must be reduced to a value below 30% and/or the water activity adjusted to below 0.90. Reducing the water content of sausages to prevent spoilage often requires addition of salt to an undesirable level or drying to an excessive extent.)

The reduction to an aw of 0.92 can be accomplished with no substantial change in product quality. The extent of the aw reduction required is, however, dependent on a number of processing and storage parameters that differ for different sausage types.

The measurement of aw is of particular importance to evaluate the preservability of meat raw materials and final sausage products. By measuring in a closed chamber, the relative humidity is determined, which is in equilibrium with the humidity of the sausage sample. Measuring instruments (aw-meters) based on electronic technology have been developed which afford the user a rapid and easy aw determination of meat products.

Control of sausage spoilage and deterioration.

The main forms of sausage spoilage and deterioration are the excessive proliferation of bacteria in the sausage content or on the surface, the excessive growth of moulds on the sausage surface, the oxidative deterioration of sausage fat causing product rancidity, and the excessive dehydration of sausage superficial layers including casings.

The rate at which these four forms of spoilage and deterioration can occur vary widely. For example, processing under unhygienic conditions may cause souring, gas formation, off-odours, etc. within a few hours after production or the spoilage process can be somewhat delayed and will develop during a longer time period, perhaps in the consumer's home. High storage temperatures and high humidity, poor handling and other adverse conditions may similarly accelerate bacterial and fungal development, especially on the surface of the products. On the contrary, dry air atmosphere, high temperatures and particularly high air circulation rates contribute essentially to development of rancidity and surface dehydration, often accompanied by discoloration and other organoleptic changes.

Surface spoilage, especially of sausage products containing enough moisture, is normally shown either by the appearance of slime, because of excessive bacterial proliferation, or by an abundant generally greyish-white growth of mould. A somewhat lower storage temperature and especially nonexcessive dehydration of the surface may be helpful in this regard and may retard spoilage considerably. If spoilage occurs in the interior of the sausage, it is usually due to adverse hygienic production conditions as well as to the poor hygienic quality of processed raw materials.

Mould formation on sausage products is generally the result of keeping them in damp, poorly ventilated rooms or of improper packaging. Of the known mould fungi, the Aspergillus, Penicillium and Mucor species are especially apt to establish themselves on sausages, the surface of which they cover first with their white and then grey or greyish-green tufts. It should be noted that these changes are basically of a superficial nature and do not otherwise adversely affect the sausages. Slightly or moderately mouldy sausages are, as a rule, neither injurious to health nor spoiled. After removal of the mould by washing with vinegar or a salt solution they can be passed as food. Only when highly spoiled and with a marked mouldy flavour, the sausage is unfit for consumption.

To ensure maximum spoilage control, the sausages should be held at temperatures as follows:

Table 12 EXPECTED SAUSAGE SHELF LIFE AT VARIOUS TEMPERATURES
Sausages No refrigeration 10 – 15C 0 – 4C Freezing
fresh several hours 1 – 2 days 2 – 4 days about 5 – 7 days; if protected 1 – 3 weeks
semidry several hours 10 – 15 days not recommended
dry 1 – 5 weeks 3 – 6 weeks not recommended
smoked, precooked 10 – 15 hours   2 – 4 days
(often more)
1 – 3 weeks
emulsion-type 8 – 12 hours 1 – 3 days 3 – 5 days 6 – 10 days
cooked several hours 2 – 3 days some varieties may be kept frozen for 2 – 3 weeks
  1. Fresh and smoked precooked sausages: at 0–4°C for 2–4 days; if frozen, they have to be kept no longer than a week; if no refrigeration is applied, sausages should be consumed within several hours;

  2. Emulsion-type sausages: at 0–4°C for 3–5 days or at below 10°C for 1–2 days; if frozen they have to be kept no longer than 6–10 days; if sausages are not refrigerated they should be consumed within 8–12 hours;

  3. Semidry sausages: at below 15°C for 10–15 days; if the sausages are held without refrigeration in a dry ventilated place, their shelf life will be several days;

  4. Dry sausages: should be kept well protected from air humidity and circulation in a cool dark place.

Discolouration of the sausage surface in the absence of spoilage occurs because of excessive drying, leading to the formation of a peripheric dried dark brown or dark grey ring of coagulated proteins.

Rancidity develops in all sausages but especially in those manufactured from long-stored chilled or frozen meats and fats and usually is associated with excessive air circulation and low air humidity.

DELIVERY OF SAUSAGES TO RETAILERS

The method of sausage transportation from the place of production to place of consumption rather than the processing methods themselves distinguishes sausage making in warm and temperate climates. The best method of sausage delivery from the plant to the retail shop is by a motor vehicle.

Motor trucks should be especially designed for sausage delivery. The truck body must be sufficiently insulated to prevent the transfer of heat, humidity or dirt from the exterior. The trucks can be refrigerated with ice, dry ice or mechanical equipment.

Dry ice or mechanical equipment is indispensable if transport distances are long. Precautions must be taken to avoid condensation on the sausage surface during loading, transport and unloading. The door of the vehicle can be protected by some type of curtain during loading and unloading to prevent penetration of outside air as far as possible.

Fresh, cooked and small-diameter emulsion-type sausages are transported and kept in specially designed containers. Semidry and dry sausages are hung for sale and storage; the same is recommended for all large-diameter sausages.

The decision whether to store and transport the sausages in chilled or frozen form or without any refrigeration is of critical importance for sausage manufacturers marketing their own products. The use of refrigeration to transport sausages, if the transport distances are long, has great influence on their keeping life and presentation. However, it should always be kept in mind that there is a definite consumer preference for fresh products, and chilled products are by far preferred over frozen. The products which do not need to be refrigerated should be well protected by suitable methods.

Sale of sausages.

Besides considering market demands over the different seasons, an efficient sausage manufacturer will follow closely day-to-day market fluctuations both of raw materials he is using and his final product to try to avoid selling his sausages at a time of a temporary fall in prices.

Many sausage manufacturers are able to sell the sausages themselves; some may sell the sausages to retail or wholesale shops. All sellers must acquire specialized knowledge and experience in handling and recommending the product's utilization and serving methods.

Sausage marketing can most efficiently be undertaken by the sausage manufacturer himself. In that case, he will enjoy not only the advantages of his specialization to serve better his customers but will also be able to discuss directly with the consumer any critical points, remarks and preferences regarding his products. Thus the problem of quality control of his sausages will be enormously simplified.

Normally, fresh and cooked sausages should be sold to the consumer public immediately after production. This practice guarantees the best organoleptic quality and the lowest risk for the consumer, as well as the maximum profitability for the sausage manufacturer. The cold storage of these products should be considered only as an exceptional operation. Smoked precooked sausages must be sold not later than 1–2 days after production, regardless of storage conditions, because they quickly change their organoleptic and other properties. The semidry and dry sausage should also be produced and sold strictly according to market demand.

If intended for longer storage, the sausages should be prepared under highly hygienic conditions, be free from visible spoilage or other defects, properly packaged, if necessary, and should be in a very good general condition. If these conditions are not fulfilled, there is a grave risk that stored sausages will be unsuitable for consumption on reaching the market.

Fig. 40

Fig. 40 SAUSAGE RETAIL PACKAGES

(Photo courtesy of Kraemer und Grebe, GmbH & Co KG. D-3650 Biedenkpf-Wallau, W. Germany)

FAO TECHNICAL PAPERS

FAO ANIMAL PRODUCTION AND HEALTH PAPERS:

1.Animal breeding: selected articles from World Animal Review, 1977 (C* E*F* S*)
2.Eradication of hog cholera and African swine fever, 1976 (E* F* S*)
3.Insecticides and application equipment for tsetse control, 1977 (E* F*)
4.New feed resources, 1977 (E/F/S*)
5.Bibliography of the criollo cattle of the Americas, 1977 (E/S*)
6.Mediterranean cattle and sheep in crossbreeding, 1977 (E* F*)
7.Environmental impact of tsetse chemical control, 1977 (E* F*)
7 Rev.Environmental impact of tsetse chemical control, 1980 (E* F*)
8.Declining breeds of Mediterranean sheep, 1978 (E* F*)
9.Slaughterhouse and slaughterslab design and construction, 1978 (E* F* S*)
10.Treating straw for animal feeding, 1978 (C* E* F* S*)
11.Packaging, storage and distribution of processed milk, 1978 (E*)
12.Ruminant nutrition: selected articles from World Animal Review, 1978 (C* E* F* S*)
13.Buffalo reproduction and artificial insemination, 1979 (E**)
14.The African trypanosomiases, 1979 (E* F*)
15.Establishment of dairy training centres, 1979 (E*)
16.Open yard housing for young cattle, 1981 (E* F* S*)
17.Prolific tropical sheep, 1980 (E*)
18.Feed from animal wastes: state of knowledge, 1980 (E*)
19.East Coast fever and related tick-borne diseases, 1980 (E*)
20/1.Trypanotolerant livestock in West and Central Africa, 1980 - Vol. 1 - General study (E* F*)
20/2.Trypanotolerant livestock in West and Central Africa, 1980 - Vol. 2 - Country studies (E* F*)
21.Guidelines for dairy accounting, 1980 (E*)
22.Recursos genéticos animales en América, Latina, 1981 (S*)
23.Disease control in semen and embryos (E* F* S*)
24.Animal genetic resources - conservation and management, 1981 (E*)
25.Reproductive efficiency in cattle, 1982 (E*)
26.Camels and camel milk, 1982 (E*)
27.Deer farming, 1982 (E*)
28.Feed from animal wastes: feeding manual, 1982 (E*)
29.Echinococcosis/hydatidosis surveillance, prevention and control: FAO/UNEP/WHO guidelines, 1982 (E*)
30.Sheep and goat breeds of India, 1982 (E*)
31.Hormones in animal production, 1982 (E*)
32.Crop residues and agro-industrial by-products in animal feeding, 1982 (E/F*)
33.Haemorrhagic septiacaemia, 1982 (E* F*)
34.Breeding plans for ruminant livestock in the tropics, 1982 (E* S*)
35.Off-tastes in raw and reconsitituted milk, 1983 (E* F* S*)
36.Ticks and tick-borne diseases: selected articles from World Animal Review, 1983 (E* F* S*)
37.African animal trypanosomiasis: selected articles from World Animal Review, 1983 (E* F* S*)
38.Diagnosis and vaccination for the control of brucellosis in the Near East, 1983 (E*)
39.Solar energy in small-scale milk collection and processing, 1983 (E*)
40.Intensive sheep production in the Near East, 1983 (E*)
41.Integrating crops and livestock in West Africa, 1983 (E*)
42.Animal energy in agriculture in Africa and Asia, 1983 (E/F*)
43.Olive by-products for animal feed, 1982 (E* F* S* Ar*)
44/1.Animal genetic resources conservation by management, data banks and training, 1984 (E*)
44/2.Animal genetic resources cryogenic storage of germplasm and molecular engineering, 1984 (E*)
45.Maintenance systems for the dairy plant, 1984 (E*)
46.Livestock breeds of China, 1985 (E*)
47.Réfrigération du lait à la ferme et organisation des transports, 1985 (F*)
48.La fromagerie et les variétés de fromages du bassin méditerranén, 1985 (F*)
49.Manual for slaughter of small ruminants in developing countries, 1985 (E*)
50.Better utilization of crop residues and by-products in animal feeding: research guidelines
1. State of knowledge, 1985 (E*)
51.Dried salted meats: charque and carne-de-sol, 1985 (E*)
52.Small-scale sausage production, 1985 (E*)

Ar - Arabic
C - Chinese
E - English
F - French
S - Spanish
* Available
** Out of print
*** In preparation
Availability: October 1985

The FAO Technical papers are available through the authorized FAO Sales Agents or directly from Distribution and Sales Section, FAO, Via delle Terme di Caracalla, 00100 Rome, Italy

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