BLBS102-c18 BLBS102-Simpson March 21, 2012 13:30 Trim: 276mm X 219mm Printer Name: Yet to Come
18 Biochemistry of Fermented Meat 339Table 18.4.Safety Aspects: Generation of Undesirable Compounds in Dry Fermented Meats.Compounds Route of Formation Origin Concentrations (mg/100g)Tyramine Microbial decarboxylation Tyrosine <16.0
Tryptamine Microbial decarboxylation Trytophan <6.0
Phenylethylamine Microbial decarboxylation Phenylalanine <3.5
Cadaverine Microbial decarboxylation Lysine <0.6
Histamine Microbial decarboxylation histidine <3.6
Putrescine Microbial decarboxylation Ornithine <10.0
Spermine Microbial decarboxylation Methionine <3.0
Spermidine Microbial decarboxylation Methionine <0.5
Cholesterol oxides Oxidation Cholesterol <0.15Source: Adapted from Maijala et al. (1995), Shalaby (1996), Hern ́andez-Jover et al. (1997) and Demeyer et al. (2000).lactic acid bacteria and nitrite (Lucke 1985). ̈ Listeria monocy-
togenesis limited in growth ataw<0.90 combined with low
pH values and specific starter cultures (Hugas et al. 2002).Es-
cherichia coliis rather resistant to low pH andawbut is reduced
when exposed toaw<0.91 (Nissen and Holck 1998). Adequate
prevention measures consist in correct cooling and a hazard
analysis critical control point (HACCP) plan with application
of good manufacturing practices (GMP), sanitation, and strict
hygiene control of personnel and raw materials.
In recent years, most attention has been paid to biopreservation
as a way to enhance preservation against spoilage bacteria and
foodborne pathogens. The bioprotective culture consists in a
competitive bacterial strain that grows very fast or produces
antagonistic substances like bacteriocins. Another precise way
consists in the direct addition of purified bacteriocins. Those
bacteriocins belonging to group IIa (also called pediocin-like)
that display inhibition againstListeriahave been reported to be
the most interesting for the meat industry (Hugas et al. 2002).
Parasites like Trichinella spiralisare almost eliminated
through modern breeding systems. Pork meat free of trichinae
must be used as raw material for fermented sausages; otherwise,
heat treatments of the sausage to reach internal temperatures
above 62.2◦C are required to inactivate them (Sebranek 2004).
The generation of undesirable compounds, listed in Table
18.4, depends on several factors. The most important factor is
the hygienic quality of the raw materials. For instance, the pres-
ence of cadaverine and/or putrescine may be indicative of the
presence of contaminating meat flora. Another factor is pro-
cessing conditions, which may favor the generation of biogenic
amines; however, the type of natural flora or microbial starters
used for the process is the most important issue, because the
presence of microorganisms with decarboxylase activity can in-
duce the generation of biogenic amines. In general, tyramine
is the amine generated in higher amounts, and it is formed by
certain lactic acid bacteria that exhibit enzymatic activity for
decarboxylation of tyrosine (Eerola et al. 1996). Tyramine re-
leases noradrenaline from the sympathetic nervous system, and
the peripheral vasoconstriction and increase in cardiac output
result in higher blood pressure and risk for hypertensive crisis
(Shalaby 1996). However, the estimated tolerance level for tyra-
mine (100–800 mg/kg) is higher than for other amines (Nout1994). The amines derived from foods are generally degraded
in humans by the enzyme monoamine oxidase (MAO) through
oxidative deamination reactions. Those consumers using MAO
inhibitors are less protected against amines and are thus suscep-
tible for risk situations such as hypertensive crisis when ingest-
ing significant amounts of amines. Other amines may also cause
problems; for example, phenylethylamine, which may cause mi-
graine and an increase in blood pressure; or histamine, which
excites the smooth muscles of the uterus, the intestine, and the
respiratory tract. Biogenic amines may be typically found in tra-
ditional fermented meat products (Roseiro et al. 2010). One way
to reduce health risks from amines consists in the use of starter
cultures that are unable to produce amines but are competitive
against amine-producing microorganisms. Additionally, the use
of microorganisms that exhibit amine oxidase activity and are
able to degrade amines, the selection of raw materials of high
quality, and the use of GMP assures products of high quality
and reduced risks (Talon et al. 2002). Finally, the generation of
nitrosamines during the process is almost negligible due to the
restricted amount of nitrate and/or nitrite that can be initially
added and the low amount of residual nitrite remaining by the
end of the process (Cassens 1997, Honikel 2010).
The processing conditions may favor the oxidation of
cholesterol. Some generated oxides can be involved in
cardiovascular-related diseases (e.g., 7-ketocholesterol andα-
5,6-epoxycholesterol), but in general, the reported levels of all
cholesterol oxides is very low, less than 0.15 mg/100 g, for
exerting any toxic effect (Demeyer et al. 2000).FINISHED PRODUCT
Once the product is finished, it is packaged and distributed.
Fermented sausages can be sold as either entire or as thin slices
(Fig. 18.8). The developed color, texture, and flavor depend on
the processing and type of product. Main sensory properties are
described in the forthcoming sections.ColorThe color of the sausage depends on the moisture and fat content
as well as its content of hemoprotein, particularly myoglobin.