Soy Milk Protein Extraction Using Aqueous Alcohol Deoiling
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Solution Overview
Problem
Existing methods for extracting proteins from soy milk result in high oil content, leading to undesirable taste changes and the presence of lipoxygenases and trypsin inhibitors, which interfere with protein absorption.
Innovation Solution
A method involving the addition of aqueous alcohol to soy milk to form an organic-aqueous suspension, followed by pH adjustment and centrifugal separation to achieve a protein phase with less than 5% residual oil content, using ethanol or isopropanol as the solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional protein separation methods are used to recover proteins from soy milk, then protein recovery efficiency is improved (approximately 80% by weight), but oil content in the protein phase increases leading to unpleasant taste and health concerns
Solution Approach 1:
The patent extracts and removes oil and harmful substances (lipoxygenases, trypsin inhibitors) from the protein phase through a multi-step process involving aqueous alcohol addition, pH adjustment, and centrifugal separation. This selective extraction achieves residual oil content of less than 5 wt.% while maintaining high protein recovery efficiency of approximately 80% by weight.
Solution Approach 2:
The patent employs parameter changes by adjusting pH levels (shifting from alkaline to acidic conditions) and adding aqueous alcohol to alter solubility equilibria. These parameter changes enable selective precipitation of proteins while keeping oil and harmful substances in the liquid phase, allowing their separation through centrifugation.
2Object-generated harmful factors
If oil content is reduced in the protein phase, then taste quality and health safety are improved, but protein recovery efficiency may be compromised
Solution Approach 1:
The patent uses aqueous alcohol as an intermediary substance that facilitates the separation of oil and proteins. The alcohol modifies the solubility characteristics of both oil and proteins, enabling their phase separation while allowing proteins to be recovered in precipitated form with minimal oil contamination.
Solution Approach 2:
The patent replaces conventional mechanical separation methods with a chemical-physical approach using pH adjustment and aqueous alcohol addition. This substitution enables more effective separation of oil from proteins, achieving residual oil content of less than 5 wt.% while maintaining high protein recovery efficiency.
3Object-generated harmful factors
If deoiling is performed before protein extraction, then oil content is reduced, but the process complexity and cost increase
Solution Approach 1:
The patent performs preliminary action by adding aqueous alcohol and adjusting pH before the main protein separation step. This preliminary treatment modifies the system's properties to enable simultaneous separation of both oil and proteins in a single integrated process, rather than requiring separate deoiling and protein extraction steps.
Solution Approach 2:
The patent merges the deoiling and protein extraction operations into a single integrated process. By combining pH adjustment, aqueous alcohol addition, and centrifugal separation, the method simultaneously removes oil and recovers proteins, reducing process complexity compared to sequential operations.
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 effectively reduces oil content to less than 5%, minimizing taste changes and eliminating health concerns associated with hexane use, while achieving a high protein yield suitable for food and animal feed applications.
Implementation Method 1
adding an aqueous alcohol with a concentration of less than 80 vol.% to the soy milk to form an organic-aqueous suspension such that the addition of aqueous alcohol shifts the solubility equilibrium and a displacement extraction takes place
Implementation Method 2
separating an oil phase or oil from the suspension
Implementation Method 3
coagulating the proteins to form at least one protein phase by adjusting the suspension to a pH of less than pH=7 or by adding a protein coagulant-forming salt
Implementation Method 4
coagulating the proteins to form at least one protein phase
Implementation Method 5
separating the protein phase with a residual oil content of less than 5 wt.%, in particular with a residual oil content of less than 3 %, particularly preferably with a residual oil content of less than 1 %, based on the dry matter content of the protein phase from the suspension
Data Source
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AI summary
A method for obtaining proteins (17) from soy milk (12), comprising i. provision of soy milk (12); ii. concentration (21) of soy milk (12) to increase the dry matter content; iii. addition of a water-soluble organic solvent (15) to the soy milk after step ii to form an organic/aqueous suspension such that the solubility equilibrium is shifted owing to the addition of the organic solvent and displacement extraction (22) is effected, wherein the volume of organic solvent (15) added in step iii is chosen such that the content of organic solvent of the organic/aqeuous suspension is at least 15% by volume after step iii; iv. adjustment (13) of the suspension to a pH of less than pH=7 to form at least one protein phase (17); and v. removal (16) of the protein phase (17) having a residual oil content of below 5% by weight, based on the dry matter content of the protein phase (17), from the suspension; and also a method for obtaining proteins (17) from a natural mixture of substances from soy (1).