D-allulose Crystallization via Temperature Gradient and Vacuum
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Solution Overview
Problem
Existing methods for producing D-allulose crystals result in ununiform particle size distribution and low crystallization yield, making them unsuitable for mass production due to issues with filtration and marketability.
Innovation Solution
The method involves adding D-allulose seed crystals to a D-allulose-containing stock solution and inducing crystallization under a temperature gradient in a metastable zone at reduced pressure, followed by controlled addition of a diluted solution to suppress new crystal nucleation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional crystallization methods are used to produce D-allulose crystals, then crystallization can occur, but the crystal particles become microcrystals with ununiform size distribution, making filtration difficult and reducing product purity
Solution Approach 1:
The patent applies parameter changes by controlling the cooling rate (0.1-10°C/hour) and maintaining specific temperature ranges (20-40°C) during crystallization. By precisely controlling these thermal parameters and the supersaturation state, the method achieves uniform crystal particle size distribution while maintaining high filtration efficiency, resolving the contradiction between manufacturing precision and productivity.
2Productivity
If rapid cooling or excessive concentration is applied to accelerate crystallization, then crystal formation speed increases, but new crystal nucleation occurs instead of crystal growth, resulting in microcrystals and reduced crystal quality
Solution Approach 1:
The patent applies dynamics by implementing a controlled, gradual cooling process rather than static or rapid cooling. The cooling rate is dynamically adjusted within 0.1-10°C per hour, allowing the system to progress through different crystallization stages optimally. This dynamic control ensures crystal growth dominates over nucleation, achieving both high productivity and precise particle size control.
3Manufacturing precision
If seed crystals are added in insufficient amounts, then crystal growth is limited, but if added in excessive amounts, then new crystal nucleation increases, resulting in microcrystals and ununiform size distribution
Solution Approach 1:
The patent applies feedback by carefully controlling the seed crystal addition amount (0.01-1% of total D-psicose) and monitoring the crystallization process. This controlled feedback mechanism ensures that seed crystals promote growth without triggering excessive nucleation, achieving uniform particle size distribution while maintaining high crystallization yield.
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
This approach produces D-allulose crystals with a cubic crystal structure and uniform particle size distribution, improving crystallization yield and facilitating smooth filtration and drying processes.
Implementation Method 1
Both the methods utilize a principle of inducing crystal growth within a metastable zone of a supersaturated state as the crystallization method of sugars. Generally, the crystallization method of sugars is carried out in the metastable zone, which means the range of the concentration of the solution from an equilibrium concentration, i.e., a saturation concentration, to the lowest supersaturation at which crystals are spontaneously precipitated.
Implementation Method 2
If the crystallization solution is excessively concentrated or cooled rapidly, the crystallization solution becomes a supersaturated state exceeding the metastable zone, and new crystal nucleation occurs instead of the crystal growth
Implementation Method 3
Korean Patent Registration No. 10-1749527 discloses a method for producing D-psicose crystals, including steps of removing impurities from a D-psicose solution to obtain a purified D-psicose solution; concentrating the purified D-psicose solution to 80 to 85 Brix(%); cooling the concentrated D-psicose solution to 30°C to 40°C at a rate of 5°C to 20°C per hour through a heat exchanger; crystallizing the 30°C to 40°C D-psicose solution within a range of 30°C to 40°C
Data Source
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AI summary
The present disclosure provides a method for producing D-allulose crystals, comprising the steps of adding D-allulose seed crystals to a D-allulose-containing stock solution, and then carrying out a crystallization reaction under a temperature gradient in which the temperature of the D-allulose-containing stock solution is reduced from an initial temperature Ti to a final temperature Tf. In the method for producing D-allulose crystals according to the present disclosure, the temperature gradient includes a temperature condition corresponding to the supersaturation state of a metastable zone, and the crystallization reaction is carried out under a reduced pressure condition of 10~100 millibars (mb). Most D-allulose crystal particles produced by the method of the present disclosure have a cubic crystal structure, and the particle size distribution of the crystal particles is uniform, resulting in good flowability. In addition, when D-allulose crystals are produced by the method of the present disclosure, the crystallization yield can be remarkably improved.