Semidry and Dry Fermented Sausages 383Toldr á 2002 ; Talon et al. 2002 ). Indeed, the
complete genome sequence of L. sakei
revealed its competitiveness to grow on meat,
resisting adverse environmental conditions
during fermentation, such as high salt and
low glucose levels and changing redox
conditions (Chaillou et al. 2005 ). On the
other hand, CNC organisms, in particular
Staphylococcus , contribute to fl avor by
catabolizing amino acid and free fatty acids,
and producing a range of volatile compounds
that enhance cured meat aroma (Stahnke
2002 ; Beck 2005 ) and play a role in color
formation through their nitrate reductase.
Yeasts and molds also contribute to fl avor
through lipolytic and proteolytic activities
and lactic acid degradation (Spotti and Berni
2007 ). From a safety point of view, the use
of bacteriocinogenic LAB as bioprotective
cultures for naturally controlling the shelf life
and safety of fermented meat products has
been extensively reported (Vignolo and
Fadda 2007 ; Castellano et al. 2008 ). Starter
cultures may be associated with potential risk
factors, such as the production of biogenic
amines, the presence of acquired genes for
antimicrobial resistance, and enterotoxin
production (Cocconcelli 2007 ; Vidal - Carou
et al. 2007 ).
With a view to starter culture selection for
semidry and dry fermented sausages, LAB
and CNC strains with useful metabolic activ-
ities and benefi ts during sausage fermenta-
tion must be selected (Table 22.1 ). Although
these requirements may be fulfi lled, fi nal
product characteristics determining the
uniqueness of the fermented sausage will be
highly dependent on the particular strains
involved. During the past few decades, the
use of commercial starter cultures in meat
fermentation has led to process stabilization
and reduction in product variability, causing
a loss of bacterial biodiversity. Pure cultures
isolated from traditional fermented meats
exhibit a diversity of metabolic activities that
diverge strongly from industrial bulk starters.
They are often more dependent on their ownripening of sausage. During the last decade,
the diversity of LAB and CNC in traditional
fermented sausages has been extensively
investigated (Lebert et al. 2007 ). The most
common LAB species identifi ed are
Lactobacillus sakei , Lactobacillus curvatus ,
and Lactobacillus plantarum , with L. sakei
prevailing. Among CNC, Staphylococcus
xylosus and Staphylococcus carnosum are
the most common species identifi ed from
traditional products. Pediococci and entero-
cocci have also been often identifi ed from
fermented sausages. Fast acidifi cation and
lower pH values can be ensured by
Pediococcus in semidry sausages in which
they grow and metabolize carbohydrates
at higher temperatures (Incze 2007 ), while
Lactobacillus are mostly used in dry sausage
production.
The earliest production of fermented sau-
sages was based on spontaneous fermenta-
tion due to the development of the microbiota
naturally present in the raw material.
Indigenous LAB usually present in raw meat
at low numbers (10^2 – 10^3 cfu/g) rapidly domi-
nate fermentation, NaCl, nitrate/nitrite, and
an anaerobic environment favoring LAB
growth and establishment in the meat fer-
mentation ecosystem. During this process,
two basic microbiological reactions occur
simultaneously and interdependently: a
decrease in meat batter pH via glycolysis by
LAB and nitric oxide production by CNC
through nitrate/nitrite reduction. Due to the
acid production by carbohydrates, LAB are
responsible for the “ tangy ” fl avor of sausages
(Demeyer 2004 ). Acidifi cation also induces
meat proteins ’ denaturation and coagulation
that, along with the drying process, favor
sausage texture development (Barbut 2007 ).
During ripening, degradation of meat pro-
teins is carried out by endogenous and bacte-
rial enzymes (Sanz et al. 2002 ). It has been
demonstrated that L. sakei and L. curvatus
isolated from meat possess proteolytic activ-
ity on muscle proteins and play an important
role in amino acid generation (Sanz and