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Classification of extruded food products

Thursday, 17 August 2017 18:44

What is food extrusion?

Extrusion is a technology for obtaining products by forcing a thick paste through the forming hole of the head of the extruder.

What products can be obtained using extrusion?

This technology is used in the food industry to produce a wide range of food products, including chewing gum, Various meat and fish semi-finished products, fast food products such as cereals, baby food, ready-to-eat breakfasts, snacks, lumpy soy products, textured vegetable protein, modified starch, etc. Confectioners use food extruders for filling confectionery and other products, ice cream.

Classification of extruded food products

The above list includes only a small number of products obtained through the use of thermoplastic extrusion. In fact, this list can be significantly expanded. It should be noted that all of these products brings together the content of proteins and polysaccharides, according to the results of the study extrudates structure.

Researchers distinguish the macro- and micro-structure of extrusion products. The macrostructure, in contrast to the microstructure, can be determined visually without the use of special methods and analysis tools. The microstructure of such products is determined only by various instrumental physicochemical methods of investigation, for example, by optical and electron microscopy methods. The size of microstructure elements ranges from 0.1 to 10 μm.

Macrostructure of extrusion food products

Snacks and corn flakes are therepresentatives of a porous macrostructure. Fish and meat semi-finished products are distinguished by a fibrous macrostructure, pasta - homogeneous.

Microstructure of extruded food products

Optical and electronic macroscopy have demonstrated that the direction of orientation of microfibers and pore walls of extruded food products is determined by the direction of motion of the extruded mixture in the forming extruder head. Such a microstructure is called anisotropic. Products with a homogeneous macrostructure are characterized by an isotropic microstructure, which is due to the lack of preferential orientation of the elements.

Depending on the type of macrostructure of the extrusion products, the ratio of the proteins and starches contained therein also varies. The starch content is much higher (up to 80%) in products with a porous or homogeneous macrostructure. Extrudates with a fibrous macrostructure, in contrast, contain much more protein (up to 80%), and less starches.

Considering this, we can come to the following conclusion: the microstructure of extruded products with a high content of starches can be anisotropic and isotropic, and the microstructure of extrudates with a high protein content is only anisotropic.