Mold-Ripened Sausages 373characterizing shelf life and safety (Sebranek
2004 ; Incze 2007 ), although M : P - values are
listed sometimes in recipes (Wahl 2004 ). As
a matter of fact, a w - or a w - and pH - value are
more informative, and critical values of M : P
ratio do differ in Europe and in the United
States (Incze 2007 ). It has to be mentioned
that the importance of salt is missing from
this M : P ratio; in other words, it gives fairly
little information on the level of inhibition of
microorganisms.Molds and Mycotoxins
Due to the discovery of afl atoxins, research
on mold toxins (mycotoxins) began and
developed by leaps and bounds. The pres-
ence of molds on foods and feeds became
more suspicious than before, and a wide
range of experiments and analyses were
started, testing molds for their capability of
toxin production. As a result of this research
work, several hundreds of mycotoxins were
detected (P ü ssa 2008 ), and new ones are still
to come. In the course of this testing of dif-
ferent types of commodities, foods of plant
and animal origin were investigated equally.
Mold - covered salami and country ham were
examined in this way as well (Leistner et al.
1965 ; Bullerman et al. 1969 ; Burmeister and
Leistner 1970 ; Ciegler et al. 1972 ; Wu et al.
1974 ). The aims of these experiments were
manifold:- to gather information on the most common
molds growing on salami and cured meat
products; - to test them for growth and mycotoxin pro-
duction on the foods in question (artifi cial
inoculation, challenge tests in modern
terminology); - to test the effect of intrinsic and extrinsic
factors on mycotoxin production, thus
fi nding ways for inhibition.
As a result of these experiments, it has
become clear that mycotoxin production can
Similarly, lowered pH and/or low a w does
not support the growth of Listeria monocyto-
genes ; this is why it is accepted that in these
types of products (belonging to RTE), a
maximum of 10^2 /g CFU is tolerated, although
zero tolerance was the rule earlier.
In challenge tests, if starter culture was
applied, it was found that the number of
Listeria monocytogenes decreased by 2 to 3
logs in artifi cially inoculated dry sausages
affected by fermentation and smoking; this
change was observed to be less during storage
in sausages without starter culture (Ingham
et al. 2004 ; Farber et al. 2007 ).
Low - Acid, Traditional Dry Sausages
Unlike lactic starter - produced sausages, the
higher pH of these traditional sausages (5.6 –
6.2) has no inhibitory effect whatsoever
against undesirable microorganisms. In order
to fulfi l the safety requirement, low tempera-
ture is practically the only possibility for
inhibiting the growth of pathogenic and
spoilage microorganisms effi ciently, because
neither initial salt concentration (a w ) nor
curing additive exerts a remarkable effect.
This low temperature (defi nitely below 15 ° C,
preferably 10 ° – 12 ° C) has to be maintained as
long as water activity value decreases during
drying to a value of about 0.92 – 0.93, yet
temperature should be raised moderately,
which is necessary for mold growth (16 ° –
18 ° C or somewhat higher). As a result of
further drying, water activity decreases, and
as is generally accepted, dry sausages (with
or without mold) can be considered to be safe
at an a w - value of 0.89 – 0.90 and also below,
at ambient (room) temperature, just as in sau-
sages with a combination of low pH and rela-
tively low a w. This safety measure means that
because of the low a w - value, undesired
microbes die off.
It is more common in the United States to
use the moisture : protein (M : P) ratio rather
than the water activity value (a w ) for distin-
guishing semidry and dry sausages and for