Application of Decanter Centrifuge in Separation of Soybean Peptides

1. Process Application in Three Stages of Soybean Peptide Production

1.1 Raw Material Leaching: Coarse Crude Fiber Separation after Defatted Soybean Meal Slurrying (Primary Separation)

• Function: Separate coarse soybean dregs containing crude fiber and soybean hull impurities; overflow clear liquid is crude soybean protein solution as feedstock for subsequent enzymolysis. Discharged cake moisture content ranges from 68% to 72%, available for secondary water extraction to recover residual peptides for higher product yield.
• Advantage: Continuous feeding, free of filter cloth clogging and adaptable to fluctuating feed concentration.

1.2 Post-enzymolysis Primary Separation: Removal of Undigested Macromolecular Protein & Fine Residues (Core Working Section)

• Liquid overflow: Rich in target small-molecule soybean peptides (300～3000 Da), directly delivered to activated carbon decolorization, concentration and spray drying to produce finished soybean peptide powder.
• Solid cake discharged via spiral conveyor: Denatured undigested macromolecular protein and fine soybean residues, which can be recycled for secondary enzymolysis or processed into feed-grade protein powder as by-product.

1.3 Isoelectric Precipitation & Acid Precipitation for Deep Purification

• Overflow clear liquid: High-purity aqueous soybean peptide solution with low ash content and reduced bitter taste, improving finished peptide purity by 8%～12%.
• Discharged solid: Acid-precipitated crude protein residue for by-product recovery.

Defects of traditional process: Plate-and-frame filtration requires filter aids such as diatomite, intermittent manual cake discharge, resulting in over 10% peptide loss. Decanter centrifuge needs no filter aid, runs under fully sealed continuous condition and increases peptide recovery rate by 5%～9%.

2. Food-grade Decanter Selection & Standard Operating Parameters

2.1 Model Selection (All contact parts in SUS304/SUS316L food-grade stainless steel, spiral blades with tungsten carbide overlay for abrasion resistance)

2.2 Operating Process Parameters for Soybean Peptide Working Condition

1. Separation factor G: 2200～3000 G (Medium-high G-force balances clarification efficiency and cake dewatering against relatively high viscosity of peptide solution)
2. Bowl rotating speed: 2200～2900 rpm; differential speed: 5～12 rpm (Lower differential speed improves solid dewatering with slightly turbid overflow; medium differential speed is preferred for peptide production)
3. Feed solid content: 3%～15%, feed temperature: 45～60℃ (inherent temperature of raw enzymolysis liquid)
4. Discharge index: Overflow turbidity ≤15 NTU; discharged cake moisture: 65%～72%

3. Exclusive Advantages for Soybean Peptide Production

1. Fully sealed continuous production: Prevent oxidation and browning of soybean peptides by avoiding air exposure, optimizing finished product color and flavor while mitigating bitter taste.
2. Excellent adaptability to feed fluctuation: Tolerant to variable particle size ranging from 0.005 mm fine protein flocs to 0.5 mm coarse soybean residues and fluctuating solid content; disc separator is prone to clogging and filter equipment suffers frequent filter cloth blinding.
3. Compatible with CIP (Clean-in-place) sanitization: Sanitary structural design for in-situ cleaning, compliant with GMP food regulation and eliminating hidden risks of residual protein spoilage.
4. Value-added by-product utilization: Separated crude protein residues are collected and processed into feed-grade soybean protein powder to maximize overall economic benefit.

4. Downstream Matching Process Flow

5. Troubleshooting & Process Optimization

1. Turbid overflow with residual fine solids entrained: Slightly raise bowl rotating speed, reduce differential speed and cut down feed flow rate.
2. Excessively wet cake (moisture＞75%): Lower differential speed, adjust to shallow pond depth to extend dewatering residence time in conical bowl section.
3. High-viscosity hydrolysate: Preheat feed liquid to 55～60℃ to reduce viscosity and enhance separation performance.