L-Cysteine Hydrochloride Crystallization for Low-Yellowness Color Control
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Solution Overview
Problem
Existing methods for producing L-cysteine hydrochloride crystals face issues with coloration due to coloring substances and impurities that are not removed by activated carbon, leading to deteriorated color quality.
Innovation Solution
A method involving continuous chromatography, filtration, concentration, addition of hydrochloric acid, and cooling to recover L-cysteine crystals, which includes steps of obtaining a separated solution, filtering, concentrating, adding hydrochloric acid before or after concentration, and cooling to control chromaticity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If activated carbon is used to remove coloring substances from fermentation broth, then purification is improved, but color-inducing impurities remain that develop color during crystal production
Solution Approach 1:
The patent applies preliminary action by adding hydrochloric acid to the fermentation broth before the concentration and crystallization steps. This pre-treatment converts color-inducing impurities into colorless forms, preventing them from developing yellow color during subsequent processing. The acid treatment is performed in advance to eliminate the coloration problem before it manifests in the final product.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the pH of the fermentation broth through hydrochloric acid addition. This chemical parameter change transforms the state of color-inducing impurities, converting them from colored to colorless forms. The pH adjustment fundamentally alters the chemical properties of impurities to prevent color development during crystallization.
2Productivity
If continuous chromatography is used for separation and purification, then production efficiency is improved, but additional purification steps are required to remove coloring substances
Solution Approach 1:
The patent merges multiple functions into a single step by combining the chromatography separation with the color prevention treatment. The hydrochloric acid addition is integrated into the chromatography process flow, allowing simultaneous separation of L-cysteine and prevention of color induction in one unified operation, thereby reducing the need for separate purification steps.
Solution Approach 2:
The patent converts the harmful effect of color-inducing impurities into a beneficial outcome by using hydrochloric acid treatment. The same impurities that would normally cause yellow coloration during concentration are transformed into colorless compounds through acid treatment, turning a potential defect into a non-issue and eliminating the need for additional color removal steps.
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 method achieves L-cysteine crystals with uniform yellowness of 4.0 or less, reducing color-inducing substances and maintaining high purity.
Implementation Method 1
a process for producing L-cysteine hydrochloride hydrate (WO 2019-151769 A1), which separates and purifies L-cysteine fermentation broth in its natural state using a continuous chromatography process
Implementation Method 2
Although activated carbon is mainly used to remove the coloring substances
Implementation Method 3
adding hydrochloric acid to the filtrate or the concentrate before or after step (c)
Implementation Method 4
cooling the concentrate to recover L-cysteine crystals
Data Source
Figure 1(a)~1(c)
AI summary
The present invention relates to a method for producing L-cysteine hydrochloride crystals with reduced yellowness from an L-cysteine process liquid derived from a fermentation liquid. The method for producing L-cysteine crystals comprises the steps of: (a) obtaining an L-cysteine separation solution from a fermentation solution containing L-cysteine; (b) filtering the L-cysteine separation solution to obtain a filtrate; (c) concentrating the filtrate to obtain a concentrate; (d) adding hydrochloric acid to the filtrate or concentrate before or after step (c); and (e) cooling the concentrate to recover L-cysteine crystals.