Bi-fluid nozzle spray drying for pregelatinised starch
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Solution Overview
Problem
Conventional methods for producing pregelatinised starches, such as roll drying and spray cooking/drying, result in starches with reduced thickening and gelling power and are energy inefficient, necessitating a more efficient process that maintains the hydrated granular structure and enhances thickening capabilities in cold liquids.
Innovation Solution
A process involving a bi-fluid nozzle that atomizes an aqueous slurry of non-pregelatinised starch with superheated steam, followed by further steam treatment in a reactor to produce pregelatinised starch with superior viscoelastic properties, including higher cold water viscosity and intact granules, using a temperature range of 150° to 650° C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If roll drying or spray cooking/drying is used to produce pregelatinised starches, then the starch can be used for thickening, but the thickening power and gelling tendency are reduced due to partial destruction of the hydrated granular structure
Solution Approach 1:
The invention changes the thermal parameters by using superheated steam at specific temperatures (105-350°C) and controlled exposure times to achieve partial gelatinisation without complete degradation of the granular structure, thereby maintaining thickening power while enabling ease of manufacture
Solution Approach 2:
Superheated steam acts as an intermediary heating medium that transfers thermal energy efficiently to the starch granules, enabling controlled gelatinisation at lower temperatures compared to conventional methods, thus preserving the hydrated granular structure and thickening capabilities
2Productivity
If conventional roll drying or spray cooking/drying processes are used, then pregelatinised starch can be produced, but the processes are not energy efficient
Solution Approach 1:
The invention utilizes the phase transition of water to superheated steam, which provides intense but controlled heating action. This phase change mechanism enables rapid and uniform heating of starch granules, improving energy efficiency while maintaining productivity
Solution Approach 2:
The invention replaces conventional mechanical heating systems with a thermal field generated by superheated steam injection. This substitution enables more efficient heat transfer and energy utilization, reducing the energy input required while maintaining production rates
3Reliability
If high temperature heating is applied to gelatinise starch, then thickening can be achieved, but the hydrated granular structure is partially destroyed
Solution Approach 1:
The invention applies partial action by using controlled superheated steam treatment at specific temperatures (105-350°C) and limited exposure times, which is sufficient to achieve the necessary gelatinisation for thickening while avoiding excessive heat that would destroy the granular structure
Solution Approach 2:
Superheated steam serves as a controlled intermediary heating agent that delivers thermal energy in a regulated manner, enabling the starch to undergo gelatinisation while preserving the integrity of the hydrated granular structure through its controlled phase transition properties
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
The process yields pregelatinised starches with enhanced thickening power and energy efficiency, characterized by a viscosity ratio of 1.00 to 1.18 and a normalised storage modulus of 15 to 30 Pa, suitable for various applications including food, feed, and pharmaceutical products, while ensuring the starch granules remain intact and microbiologically clean.
Implementation Method 1
injecting superheated steam into the internal chamber of the bi-fluid nozzle whereby the atomised aqueous slurry of non-pregelatinised starch is heated by the superheated steam in the internal chamber to produce a slurry of partially gelatinised starch
Implementation Method 2
The temperature of the superheated steam at the at least one inlet into the internal chamber is in the range of 150° to 650° C.
Implementation Method 3
atomising the aqueous slurry of non-pregelatinised starch into the internal chamber of the bi-fluid nozzle
Implementation Method 4
contacting the discharged slurry in the reactor with superheated steam to completely gelatinise the partially gelatinised starch in the discharged slurry and to dry the completely gelatinised starch
Implementation Method 5
contacting the discharged slurry in the reactor with superheated steam to completely gelatinise the partially gelatinised starch in the discharged slurry and to dry the completely gelatinised starch
Data Source
AI summary
A process for modifying starch comprises atomising an aqueous slurry of non-pregelatinised starch into an internal chamber in a bi-fluid nozzle of a spray dryer and treating the atomized slurry, in the internal chamber, with superheated steam to cause partial gelatinisation of the starch. The aqueous slurry containing partially gelatinised starch is discharged through an outlet in the internal chamber into a reactor where the droplets containing the partially gelatinised starch are subjected to further treatment with superheated steam, resulting in the completion of the gelatinisation of the starch in the reactor. Also disclosed is a bi-fluid nozzle for use in spray drying starch which comprises a nozzle body, a nozzle cap and an internal chamber located between the nozzle body and the nozzle cap. The nozzle body comprises at least one atomiser, for connection to a supply of an aqueous starch slurry, for atomising the slurry into the internal chamber and it has at least one inlet, for connection to a supply of superheated steam under pressure, for introducing superheated steam under pressure into the internal chamber. The nozzle cap comprises at least one outlet from the internal chamber. The internal chamber also comprises an interchangeable spacer element with a length of from 10 to 60 mm enabling the length of the internal chamber to be changed. A pregelatinised starch and its use in foods, especially baby foods and infant formulas, feed, pharmaceuticals, cosmetics and personal care products are also disclosed.