158 Chapter 7
geneizing intermediate - and high - viscosity
fl uids. The coarse batter fl ows through a
narrow gap between two disks, a rotative disk
(the rotor) and a static disk (the stator).
Intense shear stress in the gap is due to the
high rotation speed (from about 1000 to
2000 rpm) and the narrowness of the gap (50
to 1000 μ m). Many of the factors that increase
the effectiveness of droplet disruption also
increase the manufacturing costs. Typically,
colloid mills with droplet diameters between
1 to 5 μ m can be used to produce emulsion
(McClements 1999 ). Compared with cutters,
fi ner and more regular batters are obtained in
colloid mills. These devices can be combined
in different ways, depending on the amount
of production (Figure 7.2 ). Although chop-
ping technology has been used for a long
time, it is still used to develop new products.
For example, a process for manufacturing
very low - fat sausages (maximum fat content
of 4%, i.e., 60% – 80% fewer calories than
traditional sausage products) was recently
performed in Germany (Pointner 2007 , patent
DE102005026752 2007).High Pressure
High - pressure application has been shown to
act on myofi brillar proteins in a similar
manner to salts, so both sodium chloride and
phosphates can be reduced (Cheftel and
Culioli 1997 ; Fern á ndez - Mart í n et al. 2002 ).
The effect of pressure on meat products ’
binding properties depends on various
factors, such as animal species, type of
muscle, pH and ionic strength, level of fat
and protein, treatment conditions (i.e., pres-
sure level 100 to 700 MPa), time, and tem-
perature (Iwasaki et al. 2006 ; Trespalacios
et al. 2007 ).
For comminuted meat products, high
pressure can be used at several levels during
manufacturing: (1) at low temperature (0 –
5 ° C) prior to chopping (MacFarlane et al.
1986 ; Crehan et al. 2000 ), (2) on commi-
nuted batter prior to heating (MacFarlaneperatures of up to 75 ° C. This causes denatur-
ation of the proteins, which then form
unwanted small lumps in the sausage meat
and partly lose their ability to bind water.
Cooking
The fi nal texture of comminuted meat prod-
ucts is primarily the result of the protein gel
network that is formed upon processing
(Lavelle and Foegeding 1993 ). For example,
in poultry meat batters prepared with salt and
phosphate, the structure existing in the raw
state (i.e., 20 ° C) is reinforced by protein
gelation during cooking (Barbut et al. 1996 ).
A failure to form the gel can produce an
excessive loss of water and fat, producing a
mushy and mealy texture (Whiting 1987 ).
Heat processing produces a sol - gel transition,
causing protein unfolding and the formation
of an ordered, three - dimensional network
stabilized by hydrophobic interactions and
hydrogen bonding (Whiting 1988 ). Heat -
induced protein aggregation is usually an
irreversible process, meaning that the aggre-
gates cannot be broken down by physical
means. This results in an immobilization
of the fat, water, and other constituents
(Mandigo 2004 ). During cooking, fat separa-
tion is due to creaming, fl occulation, and
coalescence, whereas water exudation
depends on polyphosphates, sodium chloride
concentration, and water content.
Technology
Mechanical Energy
Lean and fat fragmentation and structuration
require a high level of energy from mechani-
cal energy. Mincers are dedicated to meat
fragmentation. Mixers achieved protein solu-
bilization and ingredient mixing. Cutters are
very polyvalent devices, as they can achieve
fragmentation, protein solubilization, and
structuration. Colloid mills are dedicated to
structuration; they are suitable for homo-