Food Biochemistry and Food Processing

652 Part VI: Fermented Foods

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 releases
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). How-
ever, the estimated tolerance level for tyramine
(100–800 mg/kg) is higher than for other amines
(Nout 1994). The amines derived from foods are
generally degraded in humans by the enzyme mono-
amine oxidase (MAO) through oxidative deamina-
tion reactions. Those consumers using MAO in-
hibitors are less protected against amines and are
thus susceptible for risk situations such as hyperten-
sive crisis when ingesting 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 hista-
mine, which excites the smooth muscles of the
uterus, the intestine, and the respiratory tract. 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 microor-
ganisms that exhibit amine oxidase activity and are
able to degrade amines, the selection of raw materi-
als 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).

The processing conditions may favor the oxida-

tion of cholesterol. Some generated oxides can be

involved in cardiovascular-related diseases (e.g., 7-

ketocholesterol and 5,6-
-epoxycholesterol), but in

general, the reported levels of all cholesterol oxides

is very low, less than 0.15 mg/100g, for exerting any

toxic effect (Demeyer et al. 2000).

FINISHED PRODUCT

Once the product is finished, it is packaged and dis-

tributed. Fermented sausages can be sold as either

entire or as thin slices (Fig. 28.8). The developed

color, texture, and flavor depend on the processing

and type of product. Main sensory properties are

described below.

COLOR

The color of the sausage depends on the moisture

and fat content as well as its content of hemoprotein,

particularly myoglobin. Color is also influenced by

pH drop rate and the ultimate pH, but it may be also

affected by the presence of spices like red pepper.

An excess of acid generation by lactobacilli may

also affect color.

The characteristic color is due to the action of

nitrite with myoglobin. Nitrite is reduced to nitric

oxide, favored by the presence of ascorbate/erythor-

bate. Myoglobin and nitric oxide may then interact

to form nitric oxide myoglobin, which gives the

characteristic cured pinkish-red color (Pegg and

Shahidi 1996). This reaction is favored at low pH.

Long-processing sausages using nitrate need some

time for the growth of Micrococcaceae before pH

Table 28.4.Safety Aspects: Generation of Undesirable Compounds in Dry Fermented Meats

Compounds Route of Formation Origin Concentrations (mg/100 g)

Tyramine Microbial decarboxylation Tyrosine
16.0
Tryptamine Microbial decarboxylation Trytophane
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
0.15
Sources:Adapted from Maijala et al. 1995, Shalaby 1996, Hernández-Jover et al. 1997, Demeyer et al. 2000.