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< prev - next > Food processing KnO 100641_How to make sausages (Printable PDF)
How to make sausages
Practical Action
The chopped meat mass should be well mixed and then either stuffed into casings or placed in
shallow pans and held under refrigeration to enable the fermentation to take place. Any air
pockets under the casings would discolour the meat and allow the growth of spoilage micro-
organisms or pathogens before the pH falls. Casings are therefore punctured to allow any air to
escape. Similarly, in pans, the meat mixture must be kneaded to remove air pockets and
covered to prevent contact with air. After fermenting in pans, the sausage meat is remixed and
stuffed into casings as firmly as possible and the stuffed casings are tied or clipped, with a
loop to suspend the sausages during further processing.
The two types of fermented sausage are semidry (or quickly fermented) and dry (or slowly
fermented) sausages. In both groups there are hard types that can be cut into thin slices and
spreadable soft types.
Dry fermented sausages
Dry sausages have a long shelf life without refrigeration because of their high salt (more than
4%) and low moisture contents (25 - 35% water). Their water activity (aw) = 0.85 - 0.91,
which prevents the growth of bacteria and most moulds. Dry sausages made from salted,
spiced pork and/or beef sausages are found in the warmer climates of Mediterranean
countries. The main types are pepperoni, different types of salami, cervelats and many small-
diameter dry sausages. Dry sausages are usually sold as ‘new’ (about 20% weight loss from
original weight), ‘moderately dry’ (about 30% weight loss) or ‘dry’ sausages (about 40% weight
loss). The properties of the final product depend on the formulation, degree of grinding of the
meat, fermentation time, temperature and time of drying (or ‘ageing’), the type and size of the
casing, and for some the intensity of smoking. They are made from either coarsely chopped
meat (e.g. Italian salamis, some types of sucuk); moderately chopped meat (most small-
diameter sausages); or occasionally finely chopped meat. Spices contribute mostly to the
flavour of dry sausages but they also inhibit spoilage bacteria, while stimulating the growth
and acid production by some lactic acid bacteria. In traditional processes, fermentation is by
naturally occurring bacteria, and to achieve a safe product it is important to optimise the
growth conditions for the bacteria. This involves adding sugar to promote growth, controlling
the temperature, and adding curing salts to inhibit the growth of spoilage or pathogenic
bacteria. The raw sausage mixture, containing meat, fat, curing salts and sugar, is placed in
15 -18 cm deep pans and kept for 2 - 4 days at 3 - 4°C. A shorter fermentation time, within
24 hours, can be achieved at a higher incubation temperature (35 - 41°C). Lactic acid
bacteria use added sugars to produce lactic acid, which causes the pH to fall. A low pH (below
5.2) is very important for the correct preservation of sausages and the development of
desirable taste and texture. It is also required to adequately bind the meat and for colour
development in the sausage. A pH value below 4.8 influences the taste and extends the shelf
life, but it does not contribute to better binding properties of the final product than that
achieved at pH 5.2.
Alternatively, a starter culture of lactic acid bacteria produces consistent and controlled
acidification that inhibits growth of undesirable micro-organisms and a uniform texture and
colour in the final product. Starter cultures are mainly Lactobacillus, Pediococcus,
Leuconostoc and Streptococcus species. Spanish mixed-culture preparations also include
micrococus sp. The starter culture and seasoning ingredients are added to the chopped meat
and mixed in thoroughly. The speed at which the pH falls, and hence the fermentation time,
depends partly on the type and amount of sugar that is used: in general, 0.3-2.0% sugar
(sucrose) is used, but dextrose is fermented more quickly and cause rapid acidification,
whereas lactose or corn syrup are only fermented by some types of bacteria (or more slowly)
and the speed of acidification is reduced. If dextrose is used, the amount of added sugar is
lower, whereas corn syrup must be added at higher levels to compensate for the slower
If the mixture is not cured in pans but stuffed directly into casings, the sausages are held for
about 10 days at 3°C before hanging them at 22 - 24°C with a relative humidity of 80% for
48 hours. Natural casings are preferred for dry sausages because they adhere closely to the
sausages as they shrink during drying or smoking, whereas plastic casings do not. Sausages