New generation of fadders

C. Function and scope of influence of extrusion on nutrients
• Protein
Process of boiling in extruders causes increase of digestibility of protein and increases availability of amino acids in many cases. This is done by cleavage of second-degree bonds in protein molecules; high temperature applied for short time of the process does not destroy amino acids. Concurrently, extruders can denaturate antinutritional factors, such as, for example, trypsin inhibitors or noxious enzymes, not destroying amino acids.
• Starch
As a result of extrusion, digestibility of starch is very much improved through its gelatinization and expansion. Under the influence of high temperature and pressure upon starch during its movement through extruder, it can be subject to gelatinization in a time period shorter than 30 seconds. When exiting the extruder matrix, internal pressure and temperature suddenly falls down in extruded material and it expands.
• Dry extrusion influences fat in three ways:
o As a result of unique for extruders influence of friction and shearing force, fat cell walls are broken. This causes increased availability of oil for digestion processes, which, in turn, increases energy value of extruded materials.
o When extrusion of oil seeds is executed in the presence of starch, fat and starch form complex 1:10. Acidolysis is necessary for proper measurement of real fat content.
o Stability of fat is improved, since enzymes causing rancidity, such as lipases, are denatured during extrusion. Natural stabilizing components, such as lecithins and tocopherols remain fully active. The material is subject to influence of maximum process temperature only for 5-6 seconds, whereas rancidity requires much higher temperature and longer exposure time.
• Fibre
As a result of grinding and shearing in extruder cylinder, fibrous materials are crushed causing proportional growth of digestible fibre.
• Tastiness
Practice shows that materials processed in autogenous extruders obtain high level of tastiness. This results from several reasons:
o Starch is decomposed into simpler and sweeter components,
o Unpleasant volatile taste components, such as bean taste of soybean are removed when extruded material leaves extruder cylinder,
o Homogenous nature of ready product makes its texture better than the texture of raw materials.

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