2009_Book_FoodChemistry

12.6 Kinds of Meat, Storage, Processing 597
Slow thawing of frozen meat is generally considered
more favorable than rapid thawing, although
some opposing data exist. Obviously, freezing,
storage and thawing should be considered as related
process steps, which should be coordinated.
12.6.2.3 Drying
Drying is an ancient method of meat preservation.
Drying is frequently used in combination with
salting, curing, and smoking. Some processes are:
drying in a stream of hot air (40–60 ◦ C), drying
in vacuum under variable conditions, e. g., in
hot fat, and freeze-drying, the most gentle process.
The moisture content of the end product is
usually 3–10%. Important quality criteria of such
dried meat products are the rehydration capacity,
which can be determined by water uptake under
standard conditions, and the fraction of firmlybound
water. The drying process should not affect
the water holding and aroma characteristics
of the meat. The shelf life of dried meat products
is limited by the development of off-flavors
due to fat oxidation and by discoloration due to
the Maillard reaction. Dried beef and chicken are
important ingredients of many soup powders. In
addition to pieces of meat, minced meat, with or
without binders, and processed meats, e. g., meat
balls or dumplings, are also dried for this purpose.
12.6.2.4 Salt and Pickle Curing
Salt in high concentrations inhibits the growth of
microorganisms and curtails activity of meat enzymes.
Hence, salt is considered as a meat preservative.
Salting meat at a level up to 5% NaCl
causes swelling (cf. Fig. 12.26). Higher salt concentrations
(10–20%) induce shrinkage in meat
and its products, causing a decrease in moisture
to a level below that of untreated meat. The meat
retains its natural color, usually dark red, since
the myoglobin concentration increases due to the
moisture loss. The color of such meat changes
upon cooking to grayish-brown.
Salting by the addition of sodium nitrite and/or nitrate
(curing or pickling) produces products with
highly stable color (cf. 12.3.2.2.4). Since nitrite
reacts faster and less is required for color stabilization,
it is widely used in place of nitrate. Salt
curing is done either by rubbing salt on the meat
surface (dry curing or pickling), by submerging
the meat in 15–20% brine (wet pickle curing), or
by injection of brine in special automats.
Additives, such as sugar or spices, which favorably
affect the red color and formation of
meat aroma, are often added to pickling salts.
The aroma of cured meat is specific and differs
from that of noncured meat. Aroma formation is
enhanced by the microflora (Micrococcus spp.
and Achromobacter spp.) of curing brine, which
are simultaneously involved in reduction of
nitrate (NO − 3 ) and nitrite (NO− 2
) ions and thereby
contribute to the stabilization of the pinkish or
red color of cured meat.
12.6.2.5 Smoking
Smoking of meat is usually associated with
salting. Depending on the smoking procedure,
the moisture drops 10–40%. Compounds present
in smoke with bactericidal and antioxidative
properties are deposited on and penetrate into
the meat. Important smoke ingredients include
phenols, acids, and carbonyl compounds. The
concentration of polycyclic hydrocarbons in
smoke depends on the type of smoke generation
and can be largely suppressed by suitable
process management, e. g., by external smoke
generation with cleaning of the smoke via cold
traps, showers, or filters. A distinction is made
between hot smoking (50–85 ◦ C) over a period
ranging from less than one hour to several hours
(e. g., used for cooked and boiling sausages),
warm (25–50 ◦ C) and cold smoking (12–25 ◦ C)
over a period ranging from two days to several
weeks (e. g., used for raw sausage and ham).
Special smoking processes include wet smoking
processes, electrostatic processes, and the use of
smoke condensates.
12.6.2.6 Heating
Heat treatment is an important finishing process
and also serves for the production of canned meat.
Typical changes involved in heat treatment are:
development of grayish-brown color, protein coagulation,
release of juices due to decrease in
water holding capacity (Fig. 12.30), increase in