Extruded Starch Products with Low Shear and High Cook
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Solution Overview
Problem
Extruded products made from starch-bearing materials, such as corn or wheat flours, tend to be sticky and have high cold water viscosities due to high shear extrusion processes, making them difficult to produce using conventional extrusion methods and requiring expensive batch processes.
Innovation Solution
Controlled extrusion conditions, specifically a total specific thermal energy (STE) to specific mechanical energy (SME) ratio greater than 4, combined with initial pretreatment to achieve high cook values and low cold water viscosity, using a twin screw extruder with optimized steam injection and screw geometry to minimize shear and maximize thermal energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional high shear extrusion is used to process starch-bearing materials, then the extrusion process is simple and continuous, but the products become sticky and have high cold water viscosities
Solution Approach 1:
The patent changes the critical parameters of specific thermal energy (STE) and specific mechanical energy (SME) inputs, maintaining STE/SME ratio between 4-35 and STE input between 100-500 kJ/kg. This parameter optimization reduces shear-induced starch damage while preserving extrusion efficiency, thereby reducing stickiness and cold water viscosity without sacrificing manufacturing simplicity
Solution Approach 2:
The patent applies preliminary steam injection and heating before extrusion to pre-cook the starch-bearing material. This preliminary thermal treatment partially gelatinizes the starch, reducing its tendency to form sticky networks during extrusion and subsequent cooling, thus addressing the stickiness issue while maintaining continuous processing
2Temperature
If high shear extrusion is used to achieve high cook values, then the cooking effect is improved, but the cold water viscosity increases
Solution Approach 1:
The patent optimizes the balance between thermal and mechanical energy inputs, maintaining STE/SME ratio between 4-35. This controlled energy distribution achieves sufficient cook values (50-90% gelatinization) while preventing excessive shear-induced starch damage that would cause high cold water viscosity. The specific energy ranges (STE: 100-500 kJ/kg, SME: 3-20 kJ/kg) are calibrated to achieve this balance
Solution Approach 2:
The patent reduces reliance on high-shear mechanical action for achieving cook values and replaces it with controlled thermal energy input. By maintaining STE/SME ratio ≥4, the process substitutes mechanical shear with thermal gelatinization, achieving cooking effects without the harmful mechanical damage to starch structure that causes high viscosity
3Productivity
If conventional extrusion is used to process starch-bearing grains, then the processing cost is reduced, but the products require expensive batch processes due to stickiness issues
Solution Approach 1:
The patent optimizes extrusion parameters (STE/SME ratio, steam injection rates, screw speed, barrel temperature) to produce non-sticky products that can be continuously processed without requiring expensive batch interventions. The controlled energy inputs (STE: 100-500 kJ/kg, SME: 3-20 kJ/kg) enable continuous production while avoiding the need for costly post-processing or batch operations
Solution Approach 2:
The patent applies preliminary steam injection and heating before extrusion to pre-treat the starch-bearing material. This pre-cooking reduces the stickiness problem during extrusion, enabling continuous processing without requiring expensive batch process interventions or additional post-processing steps, thus maintaining both productivity and cost-effectiveness
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Produces non-sticky, low cold water solubility extruded products with high cook values, equivalent to conventionally produced starch-bearing grains, without the need for synthetic surfactants or emulsifiers, at a reduced cost and with improved processing efficiency.
Implementation Method 1
the total specific thermal energy (STE) and specific mechanical energy (SME) inputs from the method give a total STE/SME ratio of at least about 4
Implementation Method 2
Steam and/or water may be injected into the barrel during such processing
Implementation Method 3
the total specific thermal energy (STE) and specific mechanical energy (SME) inputs from the method give a total STE/SME ratio of at least about 4
Implementation Method 4
followed by low-shear extrusion
Implementation Method 5
the products are non-sticky and exhibit low cold water viscosities and high cook values
Data Source
AI summary
Improved extruded starch-bearing products (e.g., starches, starch-bearing legumes, starch-bearing grains and formulations containing any of the foregoing) are provided having relatively high cook values and low cold water viscosities. The products are prepared by initial preconditioning to partially cook the starting material(s), followed by low shear extrusion cooking, with a total STE/SME ratio of at least about 4.