Stevia Extraction Using High-Concentration Alcohol and pH Adjustment
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Solution Overview
Problem
Traditional methods for extracting chlorogenic acid and stevioside from Stevia rebaudiana result in hydrolysis of isochlorogenic acid, contamination of resin with low-polar impurities, and inadequate separation efficiency, leading to substandard product quality and resource waste.
Innovation Solution
A method involving high-concentration short-chain alcohol extraction, followed by liquid-liquid extraction with a low-polar organic solvent to remove impurities, and pH adjustment for effective adsorption using specific resins to separate stevioside and chlorogenic acid, preventing hydrolysis and enhancing purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If water extraction is used to extract chlorogenic acid and stevioside from Stevia rebaudiana, then the extraction process is simple and cost-effective, but isochlorogenic acid undergoes hydrolysis resulting in reduced proportion of isochlorogenic acid and increased proportion of degradation products
Solution Approach 1:
The patent changes the extraction parameter from water to high-concentration short-chain alcohol (70-95% ethanol or methanol), which prevents hydrolysis of isochlorogenic acid while maintaining extraction efficiency. This parameter change resolves the contradiction by providing a solvent that does not cause hydrolysis like water does.
Solution Approach 2:
The patent performs preliminary removal of low-polar impurities through liquid-liquid extraction with low-polar organic solvents before the main extraction and purification steps. This preliminary action prevents impurity contamination of resins and improves subsequent purification efficiency.
2Quantity of substance
If ethanol extraction followed by resin adsorption is used, then glycosides and flavonoids can be obtained, but low-polar impurities contaminate the resin causing rapid pollution and reduced resin service life
Solution Approach 1:
The patent performs preliminary removal of low-polar impurities through liquid-liquid extraction with low-polar organic solvents (such as petroleum ether or dichloromethane) before the main extraction and purification steps. This preliminary action prevents impurity contamination of resins, thereby extending resin service life and reducing pollution.
Solution Approach 2:
The patent extracts and removes low-polar impurities from the extract solution using low-polar organic solvents in a liquid-liquid extraction process. This separation step takes out the harmful low-polar impurities before they can contaminate the purification resins.
3Ease of manufacture
If traditional extraction methods are used, then the process is straightforward, but separation efficiency is inadequate resulting in substandard product quality
Solution Approach 1:
The patent segments the extraction and purification process into distinct steps: (1) extraction with high-concentration short-chain alcohol, (2) removal of short-chain alcohol, (3) liquid-liquid extraction to remove low-polar impurities, (4) pH adjustment to alkaline, (5) stevioside adsorption resin separation, and (6) chlorogenic acid recovery. This segmentation improves manufacturing precision while maintaining reasonable process complexity.
Solution Approach 2:
The patent uses parameter changes including pH adjustment (to alkaline conditions) and solvent system changes (high-concentration alcohol followed by low-polar organic solvent extraction) to improve separation efficiency and product purity while maintaining process feasibility.
4Manufacturing precision
If comprehensive utilization method is implemented with multiple purification steps, then product purity and yield are improved, but process complexity increases
Solution Approach 1:
The patent uses high-concentration short-chain alcohol as a universal extracting solvent that can simultaneously extract both stevioside and chlorogenic acid from Stevia rebaudiana, eliminating the need for separate extraction processes for different compounds. This multi-functionality reduces overall process complexity while maintaining high purity and yield.
Solution Approach 2:
The patent combines the extraction of multiple active ingredients (stevioside and chlorogenic acid) into a single extraction step using high-concentration short-chain alcohol, followed by integrated purification steps that handle both compounds simultaneously. This merging approach reduces the number of separate operations required.
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 method prevents isochlorogenic acid hydrolysis, improves the yield and quality of stevioside and chlorogenic acid, extends resin service life, and promotes comprehensive resource utilization with reduced water consumption and waste, resulting in high-purity products.
Implementation Method 1
extracting Stevia rebaudiana powder with a high-concentration short-chain alcohol aqueous solution to obtain an extract solution
Implementation Method 2
Stevioside molecules contain different numbers of glycosyl fragments, which are poor in fat solubility
Implementation Method 3
subjecting the extract solution to liquid-liquid extraction with an organic solvent, and taking water layer to obtain a low-polar impurity-removed extract solution
Implementation Method 4
passing the extract solution through a stevioside adsorption resin to separate a stevioside extract
Implementation Method 5
passing the post-column solution through a chlorogenic acid adsorption resin to obtain chlorogenic acid extract
Data Source
AI summary
An industrialization method for comprehensive utilization of Stevia rebaudiana. The major improvement is in that the Stevia rebaudiana is extracted by using a high-concentration alcohol solution, then the extracted solution is purified by using an organic solvent, and the pH of the extracted solution is adjusted to be alkaline according to the acidic characteristic of chlorogenic acid to enable the chlorogenic acid to be formed into a salt and have an increased polarity so as to achieve effective separation of the chlorogenic acid and a glucoside component in an adsorption process. The method allows the high-quality stevioside and chlorogenic acid to be obtained, significantly improves the comprehensive utilization rate of Stevia rebaudiana, reduces the waste of natural Stevia rebaudiana resources, reduces the resource consumption in a production process, reduces waste discharge, and is a high-benefit green production process.