394 Chapter 22
cultures (Vignolo and Fadda 2007 ; Castellano
et al. 2008 ). Differences in the production
technology of dry and semidry fermented
sausages highly infl uence their safety, the
degree of drying and the ripening time being
the most important features. Hurdles that
combine a pH/a w drop, pH/a w drop and heat
treatment, and a w drop and heat treatment
will ensure safety of both dry and semidry
products. Nevertheless, these conditions are
seldom found in either dry (relatively higher
pH and lower a w ) or semidry (relatively
lower pH and higher a w ) fermented sausages.
Since the effect of hurdles works well at pH
values of ≤ 5.3 and parallel a w values at ≤ 0.95,
there is a rather limited opportunity to meet
food safety requirements with short - or
medium - time ripened semi dry sausages,
while traditionally long - time ripened dry
sausages are in a much better position.
Experimental data suggest that heating
semidry sausages is the only effective method
for a 5 - log reduction of EHEC and L. mono-
cytogenes , and is a further safety - improving
solution (Chikthimmah et al. 2001 ). During
fermented sausages ’ production and storage,
meat undergoes major chemical changes,
leading to the formation of harmful biologi-
cal compounds, such as polycyclic aromatic
hydrocarbons and lipid oxidation products,
nitrosamines being hardly ever formed, since
high temperatures and secondary amines nec-
essary to react with nitrite are not present
(Honikel 2008 ). On the other hand, the risk
for biogenic amines and micotoxin produc-
tion, either by starter organisms (LAB, CNC,
and molds) or spoilage microbiota, is higher
for dry fermented sausages due to the intense
aminogenesis that occurs during fermenta-
tion (Vidal - Carou et al. 2007 ) and surface
molding.Trends in Fermented
Sausage Production
The history of meat products during the last
twenty - fi ve years can be divided in terms ofgrowth of a selection of pathogens, from
mesophilic to psychrotrophic organisms, and
since most pathogens are mesophiles, meat
obtained in good hygienic conditions would
presumably not be implicated as sanitary
risks. Still, the growth of pathogenic bacteria,
overcoming the existent natural hurdles, can
occur. Food poisoning from Staphylococcus
aureus , Salmonellae , and Clostridium has
been traditionally implicated in fermented
dry sausage (Mataragas et al. 2008 ). On the
other hand, emergent pathogens within the
genera Campylobacter , Yersinia , Listeria
monocytogenes , and enterohemorrhagic E.
coli (EHEC) have also been involved in out-
breaks caused by fermented sausage (CDC
1995 ; Sofos 2008 ). Since there is no epide-
miological evidence for the involvement of
fermented sausages in recent outbreaks of
listeriosis, up to 100 cells of L. monocytogens
per gram can be tolerated (ICMSF 2002 ).
Fermented sausage conditions, curing addi-
tives, and the presence of LAB starter cul-
tures may act as signifi cant hurdles for the
control of these pathogens (Table 22.4 ).
However, they are not suffi cient to prevent
the survival of L. monocytogenes or EHEC
during the manufacturing process; preva-
lence, survival, and growth in traditional
meat products have recently been reported by
Skandamis and Nychas (2007). An additional
hurdle to reduce the risk of L. monocytogenes
would be the use of competitive bacteriocin -
producing starter cultures or bioprotective
Table 22.4. Main hurdles inhibitory to patho-
gens present in dry and semidry fermented
sausages
Pathogen Hurdles
Staphylococcus aureus pH < 5.1; a w < 0.86;
bacteriocins
Salmonella pH < 5.0; a w < 0.95;
NaCl/NaNO 2
Clostridium perfringes LAB (acid and
bacteriocins)
Yersinia enterocolitica LAB (acid)
Campylobacter jejuni LAB (acid)
Listeria monocytogenes a w < 0.90; bacteriocins
Escherichia coli (ECEH) LAB (acid)