Handbook of Meat Processing

Cooked Sausages 323

excludes oxygen can reduce oxidation.

Consequently, sausages are not, or they need

not be, susceptible for rancidity, provided

that nitrite and ascorbates are used, and even-

tually phosphates. Also, by avoiding a long

freeze storage of meat raw materials, using

appropriate packaging, and avoiding micro-

bial spoilage, the risk of rancidity can be

reduced (Pegg and Shahidi 2000 ).

Safety Aspects

With a hygienically well - organized produc-

tion process and a satisfactorily cooked

product, the sausage contains only a few

hundred living microbes per gram, and those

usually are not particularly capable of prolif-

erating at cold storage temperatures. Common

salt inhibits proteolysis, and nitrite and other

antioxidative agents inhibit oxidation. The

main role of nitrite, however, is to inhibit

pathogenic bacteria. Most of these bacteria

are strongly infl uenced by nitrite at the

levels used in sausages (Pegg and Shahidi

2000 ). The primary reason for the use of

nitrite in meat products is its specifi c capacity

to inhibit the growth of Clostridium botuli-

num. This is increasingly important, as the

trends are for the use of vacuum packaging

(anaerobic), lowering the salt content,

improved hygiene (less competing fl ora), and

in - package pasteurization (hardly any vege-

tative fl ora). In these circumstances, the

strictly anaerobic spore - forming C. botuli-

num may start growing and become toxic, if

the packages are stored for longer period of

times, and especially if temperature abuse is

involved (Korkeala 2006 ). However, nitrite

is by no means a guarantee for full safety.

Recent and Future Trends

The salt intake in modern industrialized

countries has been connected to elevated

blood pressure and consequently to an

increase in coronary heart disease. Only the

cooking, minerals and vitamins remain in the
batter. The vitamins are destroyed to a certain
extent, depending on the vitamin and the
process. About 10% – 20% of the vitamins of
the B group are destroyed during the prepara-
tion. Vitamin A is quite resistant to cooking,
but about one - third can be lost by chopping
(Niinivaara and Antila 1972 ; Lawrie and
Ledward 2006 ). Smoking may reduce the
biological value of proteins, the signifi cance
of which depends on the relative surface area
and the intensity and length of smoking. In
most cases however, the reduction is not
substantial.
Connective tissue proteins (collagens)
denature when sausage is cooked, and they
are also largely comminuted by chopping,
especially in fi nely chopped sausages. Ninety
percent of the denatured collagen will be
hydrolyzed in the human digestive track and,
consequently, used as energy or for protein
synthesis (Bailey and Light 1989 ). The bio-
logical value of collagen is, however, very
low as such, but in combination with other
proteins, it may have some value. A protein
effi ciency ratio (PER) of 2.5 for good - quality
proteins allows for a collagen content of up
to 30% of the meat proteins (Bailey and Light
1989 ). Therefore, most cooked sausages
fulfi ll this requirement.
The oxidative changes in fats or mem-
brane phospholipids can cause rancidity.
Also, oxidative changes may cause polymer-
ization of fats as well as proteins. Heme iron
is a strong prooxidant, and particularly in
freeze - stored meat and cooked meat, the oxi-
dation may be very fast (the worst combina-
tion is food prepared from freeze - stored
meat). Microbes may also increase oxidative
changes in meat. In sausages, however, there
are effi cient antioxidative agents. Nitrite sta-
bilizes heme iron, which results in a much
lower oxidation rate. Phosphates also have an
antioxidative effect as they chelate prooxida-
tive cations. Ascorbates are also antioxidants,
although they are primarily used as color
enhancers. Finally, the use of packaging that