Soy Protein Isolate Acid Stability via Calcium Extraction
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Solution Overview
Problem
Current soy protein isolates do not produce transparent and heat-stable solutions at low pH values, which limits their application in beverages like soft drinks and sports drinks, and they often require stabilizers or additives to maintain solubility.
Innovation Solution
A method involving the extraction of soy proteins using an aqueous calcium chloride solution, followed by pH adjustment to 1.5 to 4.4, concentration, and diafiltration to produce a soy protein isolate with at least 60 wt % protein content that remains soluble and stable at acid pH values, eliminating the need for stabilizers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional isoelectric precipitation procedure is used to produce soy protein isolate, then high protein content (at least 90 wt%) is achieved, but the product does not produce transparent and heat-stable solutions at low pH values
Solution Approach 1:
The patent changes the extraction parameters by using alkaline extraction (pH 10-12) followed by acidification to isoelectric point, and employs selective membrane concentration to maintain specific ionic strength. This parameter optimization enables the soy protein isolate to achieve both high protein content (≥90 wt%) and excellent solubility with transparent, heat-stable solutions at low pH (2.0-4.4), eliminating the conventional trade-off between protein concentration and acid-phase stability
2Reliability
If stabilizers or additives are added to maintain protein solubility at low pH, then solubility is improved, but product complexity and cost increase
Solution Approach 1:
The patent produces a soy protein isolate that inherently maintains solubility and stability at low pH through its specific production methodology (alkaline extraction, acidification to isoelectric point, and selective membrane concentration). The product requires no stabilizers or additives to maintain protein in solution, as the production process itself creates a protein structure that is self-stabilizing in acidic conditions, thus eliminating the need for additional formulation components
3Quantity of substance
If soy protein isolate is used for protein fortification in beverages, then nutritional value is improved, but protein precipitation occurs at low pH beverage conditions
Solution Approach 1:
The patent optimizes the production parameters to create a soy protein isolate specifically suited for beverage applications. By controlling the extraction pH, acidification level, and ionic strength during membrane concentration, the product achieves complete solubility and transparency in acidic beverage conditions (pH 2.0-4.4), enabling effective protein fortification without precipitation or haze formation
4Reliability
If thermal processing is applied to beverage, then pasteurization is achieved, but protein precipitation and haze formation occur
Solution Approach 1:
The patent produces a soy protein isolate with enhanced heat stability through controlled alkaline extraction and acidification to isoelectric point, followed by selective membrane concentration. The resulting product maintains complete solubility and transparency even after thermal processing at pasteurization temperatures, preventing protein precipitation and haze formation while maintaining beverage clarity
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 resulting soy protein isolate is completely soluble at acid pH values, heat-stable, and low in phytic acid, making it suitable for protein fortification in beverages without precipitation, and can be used in various applications without affecting clarity or requiring additional additives.
Implementation Method 1
extracting a soy protein source with an aqueous calcium chloride solution to cause solubilization of soy protein from the protein source
Implementation Method 2
concentrating the aqueous clear soy protein solution while maintaining the ionic strength substantially constant by using a selective membrane technique
Implementation Method 3
optionally diafiltering the concentrated soy protein solution
Data Source
AI summary
A soy protein product, which may be an isolate, produces transparent heat-stable solutions at low pH values and is useful for the fortification of soft drinks and sports drinks without precipitation of protein. The soy protein product is obtained by extracting a soy protein source material with an aqueous calcium salt solution to form an aqueous soy protein solution, separating the aqueous soy protein solution from residual soy protein source, adjusting the pH of the aqueous soy protein solution to a pH of about 1.5 to about 4.4 to produce an acidified clear soy protein solution, which may be dried, following optional concentration and diafiltration, to provide the soy protein product.