Handbook of Meat Processing

Smoking 235

the deposited compounds, as well as by the

thermal conditions of smoking. In electro-

static smoking, the rapidly formed thick,

sticky coat of smoke components is initially

not fi xed to the meat surface and can be

easily removed (Fig. 12.1 ). However, during

subsequent heating to the desired tempera-

ture, rapid penetration of the smoke compo-

nents into the mass of the meat takes place.

Most phenols accumulate on the skin, on

the sausage casing, and under the surface at

about a 6 mm deep layer, especially in the

fatty tissue. However, in some products, even

as much as 60% of the total mass of phenols

can diffuse into deeper layers. Carbonyl

compounds and acids are rather equally dis-

tributed throughout the mass of some smoked

meat products.

The smoke compounds accumulated in

the meat cannot be 100% recovered by

extraction, since many of them interact

chemically with the meat components. The

proteins and lipids of meat contain various

reactive groups, which in appropriate condi-

tions, especially at high temperature, can

react with phenols, carbonyl compounds, and

acids of the smoke. The most reactive are the

• SH, – NH 2 , and – NH – C( = NH)NH 2 groups
  of amino acid residues in proteins and of
  nonprotein nitrogen compounds, as well as
  the polyenoic fatty acids and different reac-
  tive oxygen species and oxidation products
  like · O 2 −^ , · OH, RO · , ROO · , and ROOH.
  Smoke compounds may react with amino
  acids in meat products, leading to a signifi -
  cant decrease in the contents of amino
  acids in acid hydrolysates (Seuss 1986 ).
  Coniferaldehyde and sinapaldehyde present
  in the smoke condensates were not recovered
  from the smoked meats in the experiments of
  Lustre and Issenberg (1970) , possibly due to
  their interactions with the meat proteins. A
  signifi cant decrease in the contents of smoke
  carbonyl compounds caused by reactions
  with gelatine was shown by Ziemba (1969).
  High loss of available lysine in sausage
  casings due to smoking was found by Ruiter

an electrostatic fi lter. If the meat is placed on
a metal conveyor connected by a conducting
wire to the ground, and a corona discharging
wire electrode under high voltage is arranged
nearby, the smoke particles in the space
between the meat and the electrode get
ionized and deposited under the effect of
the electrostatic fi eld (Fig. 12.1 ). At a proper
distance between the product and the elec-
trode, a thick, viscous layer of smoke com-
ponents can be deposited in a few minutes.
Usually, the installation works at about 20 to
60 kV at an electrode distance of 7 to 20 cm.
In the conditions for electrostatic smoking,
not only deposition of the dispersed, ionized
smoke particles is accelerated, but also that
of the components of the vapor phase. This
happens because the rapid movement of the
particles creates an “ electrical wind, ” which
increases the motion of the smoke toward the
meat surface.

Diffusion and Interactions

The components deposited on the product
and dissolved in the humid surface fi lm grad-
ually diffuse into the deeper tissues due to the
concentration gradient. The rate of diffusion
is controlled by the properties of meat and of

–40 kV

Figure 12.1. Artist ’ s view of the principle of electro-
static smoking. (Courtesy of Pawe ł Kowalski.)