Emulsifi cation 157achieved, a colloidal structure is obtained: a
solid phase containing nonsoluble proteins,
muscle particles, and connective tissue dis-
persed in a liquid aqueous phase containing
salts, soluble proteins, and carbohydrates
(Schut 1976 ).Structuration
During this step, similar phenomena as in
true emulsions occur: fat particles are frag-
mented to reduce their size, and solubilized
proteins in salts must surround the fi nely
chopped fat particles. Fat stabilization during
chopping is due both to the formation of an
interfacial fi lm surrounding the fat globules
and to the physical entrapping of the fat glob-
ules within the protein matrix (Barbut 1998 ).
As fat particles ’ size decreases, the emulsion
stability will increase, provided there is suf-
fi cient protein to coat all the fat particles. A
lack of emulsifi er will result in insuffi cient
binding, leading to a soft texture or excessive
losses. Excessive amounts of emulsifi er
could result in a hard texture, often character-
ized as tough and rubber - like (Mandigo
2004 ). Like other mixing processes, chop-
ping is characterized by an optimum state
where the separation of water and fat from
the product is minimal (Brown and Toledo
1975 ; Girard 1981 ). Generally, this optimum
point is determined according to the fi nal
chopping temperature. “ Underchopping ”
results in interfacial surfaces with thick
layers of myofi brillar segments around the
fat globules and without effi cient distribution
of proteins and/or fat throughout the interface
(Mandigo 2004 ). “ Overchopping ” leads to
a thin protein fi lm having a low mechanical
strength unable to stop fat droplets ’ migra-
tion to the product surface, where they form
small pockets of fat called “ fat caps. ”
Temperature increases during chopping
cause the melting of part of the fat and a
decrease in the surface tension of the fat par-
ticles. For cold - emulsions, in conventional
cutters, the knives can reach local peak tem-7.1 b). Another method is to start with poached
fats fragmentation, and then caseinate and
hot liquid are added. Caseinate proteins solu-
bilizate, and the structuration starts. Then
fragmented liver is added, and the structura-
tion is achieved. The emulsifi cation step is
always followed by a cooking step.
Lean Fragmentation
Fragmentation is very specifi c to emulsifi ed
meat products. Contrary to true emulsions
made from immiscible liquids, muscles are
structured media that have to be disorganized
to enable emulsifi cation. During fragmenta-
tion, fi ber bundles are separated and their
membranes are broken. Sarcoleme is broken
and myofi brils are liberated, actomyosin
swells, and water can be captured (Schut
1976 ). The collapse of the myofi brillar struc-
ture is promoted by mechanical action such
as comminution, mixing, tumbling, and mas-
saging (Fernandez - Martin et al. 2002 ). The
disruption of the myofi brillar structure is also
achieved by the addition of salt and phos-
phates (Pearson and Tauber 1984 ) or by an
increase in pH (Samejima et al. 1985 ; Wang
and Smith 1992 ; Xiong 1992, 1997 ; Zayas
1997 ).
Solubilization of Meat Proteins
Many of the functional properties of bio-
polymers in food emulsions are governed by
their interactions with water, and they are
only exhibited when they are fully dissolved
and evenly distributed throughout the
aqueous phase (McClements 1999 ). Protein
solubility is, for instance, a prerequisite step
for emulsifi cation, gelation, and water reten-
tion (Xiong 1994 ). Myofi brillar proteins ’
solubilization requires a minimal ionic
strength of 0.5 M; this condition is usually
met in processed meats (Offer and Trinick
1983 ; Xiong 1993 ). Main factors acting on
meat protein solubilization are salt content
and pH. After meat protein solubilization is