Transition Device for Textured Protein Foodstuff

Abstract

A device for transferring molten proteinaceous extrudate material from the exit of an extrusion cooker barrel to a cooling die whilst promoting or maintaining laminar flow of said molten extrudate.

1 . A method of designing a device for transferring molten proteinaceous extrudate material from the exit of an extrusion cooker barrel to a cooling die whilst promoting or maintaining laminar flow of said molten extrudate; said device having an internal channel through which said extrudate flows comprising a laminar flow development zone and having a length Le; said method including:
 Selecting an internal channel diameter (d);   Determining the average flow velocity (v) of the extrudate in said diameter;   Determining the density (p) of the extrudate;   Determining the viscosity (μ) of the extrudate;   Determining the hydraulic diameter (L) of the extrudate flowing in said channel;   Determining the Reynolds Number (Re) for the extrudate flow in said channel;   Calculating the length Le by applying the formula: Le=0.006×d×Re.   
     
     
         2 . A method of designing a device for transferring molten proteinaceous extrudate material from the exit of an extrusion cooker barrel to a cooling die whilst promoting laminar flow of said molten extrudate; said device having an internal channel through which said extrudate flows comprising a first laminar flow development zone having a minimum length Le; and a subsequent cylindrical laminar flow zone; said method including:
 Selecting an internal channel diameter of the cylindrical laminar flow zone with reference to the geometry of the cooling die (d) in metres;   Determining the average flow velocity (v) of the extrudate in said diameter in m/s;   Determining the fluid density (ρ) of the extrudate in kg/m 3 ;   Determining the dynamic viscosity (μ) of the extrudate in Pa·s;   Determining the hydraulic diameter (L) of the extrudate flowing in said channel; where the hydraulic diameter is the equivalent diameter of said channel if it were circular, otherwise the ratio of four times the cross-sectional area of the channel to the wetted perimeter of said channel;   Determining the Reynolds Number (Re) for the extrudate flow in said channel where Re=(ρ·v·L)/μ;   Calculating the minimum length Le of said first laminar flow development zone by applying the formula: Le=0.06×d×Re;   Designing said device to have a laminar flow development zone having a flow length substantially equal to the calculated minimum length Le;   Fabricating a transition device having a laminar flow development zone having a flow length substantially as calculated in the previous step; and   Installing said transition device between said extrusion cooker barrel and said cooling die.