Food Extrusion Equipment
Food extrusion equipment has a very long history, with meat extruders being used to make sausages as long ago as the 1870s. In the 1930s, dry pasta and breakfast cereals were extruded in mass production and many bakeries began to adopt food extruders.
Since then, food extrusion technology has crept into everyday kitchen appliances such as herb and coffee grinders, meat mincing machines and pasta makers.
Industrial food processing
The favorable characteristics of the food extrusion process lead to consistent quality, uniformity and efficient yields in the bulk manufacture of edible products. Food can be profiled into cooked or cold-formed consumables of all sizes, colors, shapes and textures.
Foods high in starch extrude well, for example pasta, breads, cereals, snacks and confectionery. The food extruder machine mixes the ingredients uniformly, using heat developed from the friction of the process as well as any additional cooking heating provided, before passing the material through a die to form the final product.
Reactions and changes in state of the food material within the extruder barrel and at the die face contribute to different food processing results that are designed into the final product. Some food types, for example cereals and snack chips, are formed using the dramatic expansion or puffing up that occurs when the material is released through the die.
Custom-made extrusion dies can impart additional characteristics to the end product, for example a long die gives vegetable protein the fibrous look of real meat, or a die cast in bronze imparts a rougher surface to pasta for better sauce retention.
Factors affecting food extrusion
As with any extrusion process, critical factors are the material composition and flow properties, barrel length screw speed, temperature, pressure, moisture, die shape and cutter speed. These all need to be strictly monitored and controlled to ensure the final food product has the required qualities of look, feel and taste.
Most food production is carried out at fairly low moisture levels i.e. below 40%, since moisture decreases mix viscosity and acts to plasticize the material. The increased density of a moist mixture lowers torque and reduces die pressure so ‘wet extrusions’ require twin shaft feeding and mixing and improved temperature process control.
Another factor affecting the texture of final products is its salt content, affecting the aeration of the product and consequently its expansion after extrusion. Salt also influences food color, since the resulting absorption of water affects the ability of the material to brown. It does, however, provide a useful carrier for helping to distribute colors and flavors evenly throughout the product.
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For efficient, high quality food production choose Diamond America food extrusion equipment.
Diamond America Extrusion Test Facility
Diamond America provides a fully equipped test facility for new product process and formulation testing for all applications.