Soy Protein Isolate Production Solutions

Our soy protein isolate production line employs the proven alkaline extraction and acid precipitation technology, featuring continuous, automated, and controlled processing. It ensures high protein yield (≥90% dry basis), superior functional properties (gelation, emulsification), and meets stringent food-grade standards. Suitable for processing low-denaturation defatted soybean meal into high-value protein isolates, the line integrates precision pH control, efficient separation, and spray drying to deliver consistent and economical production for the food industry.

Key Process of Soy Protein Isolate Production

1.Raw Material Pretreatment & Alkaline Extraction Section

Low-denaturation defatted soybean meal undergoes critical preparation for optimal protein solubility:
Mixing Slurrying: Meal is mixed with softened hot water (50-55°C) at controlled ratios (1:10 to 1:15) in extraction tanks
Alkaline Dissolution: pH is precisely adjusted to 7.5-8.5 using food-grade sodium hydroxide to maximize protein solubility
Controlled Extraction: Stirred extraction at maintained temperature and pH for 30-60 minutes ensures complete protein dissolution

2.Primary Solid-Liquid Separation Section

Centrifugal Separation: Decanter or disc stack centrifuges efficiently separate protein-rich liquid (extract) from insoluble fibrous residue (okara)

Okara Recovery: Wet okara, a fiber-rich by-product, is collected for feed or further processing

3.Acid Precipitation Section

Isoelectric Precipitation: Protein extract pH is precisely lowered to 4.4-4.6 using food-grade hydrochloric acid

Protein Curd Formation: At this isoelectric point, proteins aggregate into visible curd while sugars and minerals remain soluble

Precision Control: Automated pH monitoring ensures optimal precipitation yield and purity

4.Secondary Separation & Washing Section

Curd Separation: Centrifugation separates the protein curd from the soluble whey fraction

Multi-Stage Washing (Critical): Curd is reslurried with softened water and recentrifuged 1-2 times to remove impurities, sugars, and ash—significantly improving product purity, flavor, and color

5.Neutralization, Sterilization & Modification Section

pH Adjustment: Washed curd is neutralized to pH 6.8-7.2 with sodium hydroxide, redissolving proteins into uniform slurry

Heat Treatment: High-Temperature Short-Time (HTST) pasteurization (e.g., 85°C, 15s) ensures microbial safety and modifies functional properties

Functional Enhancement: Optional enzymatic hydrolysis or homogenization for customized solubility and emulsification profiles

6.Drying & Powder Handling Section

Spray Drying (Core Technology): Protein slurry is atomized and dried in hot air (inlet 150-200°C, outlet 80-90°C) to produce fine powder with controlled moisture (≤7%)

Fluidized Bed Finishing: Secondary drying and cooling in vibrating fluidized beds ensure final moisture specification and improved powder flowability

Powder Refinement: Sieving and metal detection ensure consistent particle size and product safety

Key Advantages

High Protein Purity & Functionality

Advanced alkaline extraction and multi-stage washing ensure protein content ≥90% with excellent gel strength, emulsification, and solubility tailored for meat, dairy, and beverage applications.

Automated & Controlled Process

PLC-based control system with real-time pH, temperature, and flow monitoring ensures batch-to-batch consistency. Precision control at every stage maximizes yield and quality.

Efficient By-Product Utilization

Integrated recovery of okara (high-fiber feed) and whey (sugar source) supports sustainable operations and improves overall process economics.

Flexible Product Specifications

Modular design allows for production of various SPI grades—from standard isolates to enzymatically modified versions with enhanced solubility or specific functional properties.

Key Equipment

Plate Heat Exchangers

For precise temperature control during slurry heating (pasteurization) and cooling. Compact design with high heat transfer efficiency, suitable for CIP cleaning.

Sedimentation Tank

A crucial unit for gravity-based separation following the initial extraction or during intermediate stages. Designed with a large-volume, conical-bottom configuration to allow for the efficient settling of fine suspended solids or protein curd. Equipped with slow-speed scrapers for gentle solids removal and optional lamella plates to enhance separation surface area. Constructed from food-grade stainless steel with polished interior surfaces to prevent material adhesion, this tank ensures improved liquid clarity and reduces the load on downstream centrifugal equipment. Its operation is integral to maximizing yield and overall process efficiency.

Decanter Centrifuges

Core separation equipment for both primary (okara removal) and secondary (curd/whey separation) stages. High G-force design ensures efficient solid-liquid separation with automatic solids discharge.

FAQ

Q.What protein purity can be achieved?
- A: Our standard production line consistently produces soy protein isolate with ≥90% protein content (dry basis). Optimized washing can achieve even higher purity levels.
Q.Is the process suitable for food-grade production?
- A: Yes, the entire system follows food-grade design principles. All contact surfaces are food-grade stainless steel, and the process includes mandatory pasteurization for microbial safety.
Q.How are by-products handled?
- A: The process generates two main by-products: okara (soy fiber) which is excellent for animal feed, and whey

Q.What are the main functional properties?
- A: Key functionalities include high gel strength, excellent water/oil binding capacity, and good emulsification. Properties can be modified through controlled processing parameters.
Q. What is the production capacity range?
- A:Standard lines are available from 1 TPD to 50 TPD. Custom designs can be developed for pilot-scale or larger commercial requirements.

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