143Chapter 7
Emulsifi cation
Irene Allais
Defi nition
“ Emulsifi ed ” meat products are generally
defi ned according to their appearance: meat
particles are so fi ne that they are not visually
distinguishable on the smooth product
surface.
“ Emulsifi ed ” meat products are consumed
all over the world. Hundreds of different
products are available for consumers. They
can be classifi ed according to various criteria
(Table 7.1 ). They are very convenient, and
there is little or no waste from these products
(Sebranek 2003 ).
From a processing point of view, com-
minuted meat products are generally classi-
fi ed according to the main stabilizing
treatment used in the processing. “ Emulsifi ed ”
meat products can be either raw - cooked or
precooked products (Heinz 2007 ). For meat
products, it should be underlined that the
emulsifi cation step is always followed by a
thermal treatment that aims to stabilize the
multiphase batter and to attain the fi nal
sensory properties. Raw - cooked products are
often named “ cold emulsions. ” The product
components are raw (i.e., uncooked) when
they are fi nely comminuted. The resulting
viscous batter is portioned and submitted to
heat treatment (Figure 7.1 a).
Precooked meat - products named “ hot
emulsions ” are characterized by two heat
treatment procedures. The fi rst heat treatment
is the precooking of some raw materials
(fatty tissues), usually in the range of 80 ° C,
and the second heat treatment is the cooking
of the fi nal product (Figure 7.1 b).
Sensu stricto, an emulsion consists of two
immiscible liquids with one of the liquids
dispersed as small droplets in the other,
called the continuous phase (McClements
1999 ). The term “ meat emulsion ” has been
used as a general term to describe fi nely
chopped meat mixture. Yet this term is ques-
tionable. In cold emulsions, the mixture is
not a true emulsion but a multiphase media.
The dispersed phase is itself a multiphase
media containing solid fat particles with a
size ranging from 1 to 50 μ m, liquid fat drop-
lets, and air bubbles. The continuous phase
is a mixture of water, proteins, salt, carbohy-
drates, and many fi brous particles (Girad
1990 ). This media is structured but neither
homogeneous nor an isotrope. Still, some
controversy exists regarding the mechanism
involved in meat emulsion ’ s stabilization
(Ruiz - Carrascal 2002 ). Traditionally, the
most widely accepted theory viewed meat
batters as behaving like a “ classic ” oil - in -
water emulsion, where fat particles were dis-
persed in a continuous aqueous solution, and
meat proteins formed an interfacial protein
fi lm around fat particles. On the other hand,
some studies have indicated that the gel -
forming ability of meat proteins is the main
stabilizing factor (Regenstein 1988 ; Gordon
and Barbut 1992 ). Micrographs taken in
poultry meat batters showed that an orga-
nized matrix arrangement already exists prior
to cooking (Barbut et al. 1996 ). Results from