2009_Book_FoodChemistry

12.7 Meat Products 599
and smoked. Praha ham is a special cooked ham
which is often baked in a bread dough.
12.7.2.1.3 Bacon
Back fat from the pig is salted, washed, dried, and
cold smoked.
12.7.2.2 Sausages
Sausage manufacturing consists of grinding,
mincing or chopping the muscle tissue and other
organs and blending them with fat, salts, seasonings
(herbs and spices) and, when necessary,
with binders or extenders. The sausage mix or
dough is then stuffed into cylindrical synthetic
or cellulose casings or tubings of traditional
sausage shape or, often, natural casings, such
as hog or sheep intestines or the hog’s bun (for
liver sausage) are used. They are sold as raw,
precooked or cooked, and/or smoked sausages.
The composition of ham and sausage products
is shown in Table 12.20. The different types of
sausages have in common that a continuous,
hydrophilic salt/protein/water matrix stabilizes
a disperse phase (coarse meat/fat particles, fat
Table 12.20. Protein and fat content of ham and sausage
products
Product
Caloric
Moisture Protein Fat value (kJ)
% % % (kJ/100g)
Salami
(German style) 40 21 33 1578
Cervelat sausage 41 20 34 1598
Knackwurst 60 12 26 1166
Bratwurst (pork) 57 12 29 1277
Hunter’s sausage 64 16 16 864
Gelbwurst 58 11 27 1186
Munich Weisswurst
(white sausage
Munich style) 62 11 25 1112
Bockwurst 59 12 25 1129
Liver sausage 52 12 29 1351
Rotwurst 56 12 29 1277
Ham, raw 43 18 33 1527
Ham, cooked 70 23 4 539
Bacon, marbled 20 9 65 2558
globules, insoluble proteins, connective tissue,
and seasoning particles). The stability of systems
of this type is influenced by the pH value, ionic
strength, melting range of the lipids, and by the
protein content. In finely ground systems with
emulsion character, the grinding temperature
is also important for stability. A temperature
of 14 ◦ C is regarded as optimal, unstable products
resulting at T > 20 ◦ C.
In the emulsions mentioned above, a monomolecular
protein film is formed around the fat globules
present (Fig. 12.31). The importance of the different
protein components as film formers decreases
in the following order: myosin > actomyosin >
sarcoplasma proteins > actin. The hydrophobic
heads of the myosin molecules evidently dip into
the fat globules, while the tails interact with actomyosin
in the continuous phase. The monomolecular
myosin layer formed in this way should have
a thickness of ∼130 nm. On the outside, there
is probably a multimolecular actomyosin layer
which binds water and contributes to the stabilization
of the emulsion because of its viscous,
elastic, and cohesive properties. Higher temperatures,
which lead to destabilization (see above),
probably cause increased protein/protein interactions
in the actomyosin layer which, in turn, result
in a decrease in the water binding, elasticity
losses, and disturbances in the myosin film.
While the formation of myosin films on fat globules
is responsible for the stabilization of raw
sausages with emulsion character, protein/protein
interactions and gel formation are important for
the stabilization of fat and water in the system in
the case of cooked and boiling sausages.
Fig. 12.31. Schematic representation of a sausage emulsion
(according to Morrissey et al., 1987)