Handbook of Meat Processing

Curing 127

is separated from the rest of the myofi bers

(Fig. 6.5 , B to C). As these protein units

become independent of the others in the salt

solution, they are dissolved in a chemical

sense. Dissolving means that the attractive

forces between dissolved molecules or ions

no longer exist, and the molecules/ions move

freely in the solvent.

As the myofi brillar proteins are well coor-

dinated and organized in the myofi bers (Fig.

6.6 ) by cytoskeletal proteins, Z - line proteins,

and the forces between the fi laments such as

the actomyosin complex, only a part of the

proteins becomes dissolved. Under the physi-

ological concentrations of a cell (equivalent

to about 1% NaCl = 0.17 M), the myofi bers

are insoluble. Increasing the salt concentra-

tion to about 2%, as is the custom in cooked

hams and emulsion type sausages, causes a

majority of myofi bers to swell and only a

minority to dissolve.

Heating of Meat and

the Addition of Salt

Heating means that the native structures of

many constituents and membranes of cells

(in our case, muscle and fat cells of meat) are

denatured.

The lipid bilayers of meat ’ s cellular mem-

branes lose their integrity around 40 ° C at the

pH of meat < 5.8, as we see in the enhanced

in ice crystals and are not free in movement,
and thus they are not available for chemical/
enzymatic reactions. Ice has an a w value
below 1.00. In this way, freezing prevents
one aspect of microorganism growth and
food spoilage. In chilled fresh meat, the
a w = ca. 0.99. A 2% salt solution has an a w
value around 0.97. Adding 2% salt to a meat
batter in emulsion type sausages or pat é , the
a w is reduced to 0.96 – 0.97. For some micro-
organisms, this a w is already too low for
growth. In raw meat products with higher salt
concentrations like salami or raw ham, a w
falls < 0.93. Bacteria do not grow any longer;
only molds can cope with such low a w values
(Lawrie 1998 ).

Physical Action of Salt at Ambient

and Chill Room Temperatures

Despite the water layers around salt ions that
are dissolved in water, they are still attracted
to each other by opposite charged ions, e.g.,
the charged side chains of amino acids like

• COO^ −^ or −NH+ 3 in meat proteins.
  The water - surrounded ions of a salt brine
  added to meat diffuse into the muscle cells,
  or when added into a batter with disrupted
  myofi bers, they may penetrate between the
  fi brillar proteins. The salt ions themselves
  thus become immobilized together with their
  surrounding water layers (Fig. 6.4 ). But by
  moving the ions and water in between the
  protein chains of the myofi bers, the attractive
  forces of the ions in the protein side chains
  themselves become weaker, and the myofi -
  bers swell by molecular movement. Figure
  6.4 shows schematically that the myofi bers ’
  structure gets wider by salt diffusion.
  This swelling allows more water mole-
  cules to move in between the protein chains.
  The volume of the myofi bers increases (Fig.
  6.5 , from A to B). The disruption of the per-
  pendicular and longitudinal fi xed proteins of
  the myofi bers caused by the knives in a bowl
  chopper is considerable, and in the course of
  swelling from salt, a part of the protein chains
  
  
  • OOC-
  
  
  
  


• NH 3 +


• COO–
  +H
  3 N +
  H 3 N
  +H 3 N

NH 3 +

• 
  


• COO–


• OOC-

Cl–

Cl–

Na+

Na+

+Na CL– -COO– Na+

Cl– -

• COO– Na+
  Cl–
  Na+


• 
  

+H

3 N

swelling

Figure 6.4. Diffusion and immobilization of water

surrounded salt ions into myofi brillar structures. The

width of myofi bers increases through swelling.