Mixing Procedures for Different Grades of Frozen Surimi
Type Alaska pollock and threadfin bream are often called the “ultimate duo” in the world of fish paste products. However, because each has different elasticity characteristics and protein denaturation temperatures, mixing them together (salt rubbing) requires a bit of skill.
Here are key points to note for making high-quality fish paste products.
1. Understand the Differences in Raw Material Characteristics
First, it is crucial to grasp the strengths and weaknesses of each.
Elasticity Quality
Alaska Pollock Paste: Strong and firm (springy)
Yellowtail Amberjack Paste: Supple and soft (pliant)
Color Tone
Sukesou surimi: White
Itoyori surimi: Slightly reddish/yellowish
Setting
Sukesou surimi: Relatively fast
Itoyori surimi: Very fast (also recovers quickly)
Temperature Change
Sukesou surimi: Relatively stable
Itoyori surimi: Sensitive to temperature increases
2. Specific Precautions for Stirring (Salt Rubbing)
① Timing of Addition and Thawing State
Compared to itoyori, hasukoshi has softer flesh and tends to be more heat-sensitive.
Point: Adding them simultaneously is acceptable, but if either is completely frozen, uneven friction heat will occur. Begin stirring only after both have reached a sherbet-like state (around -1°C to 2°C).
② Strict Temperature Control
This is the most critical point.
Target Temperature: Keep the final mixing temperature below 10°C (ideally around 8°C).
Reason: Itoyori is prone to gel deterioration. If the temperature rises during mixing, the elasticity is lost, resulting in a crumbly texture.
Set the timing for adding ice water (crushed ice) earlier.
③ Fine-Tuning Mixing Time
Strictly avoid overmixing.
When mixing itoyori, over-kneading makes the elastic firmness break easily.
Compared to kneading sukesou alone, it is crucial to recognize the moment when the surface becomes glossy and stickiness peaks and stop mixing promptly.
④ Timing of Salt Addition
Perform thorough salt kneading initially.
Thoroughly mix only the fish paste and salt to fully dissolve the actomyosin. This step is the key to achieving good texture, as it bonds the flexibility of threadfin and the strength of sukesou at the molecular level.
3. Impact of Mixing Ratios
Generally, Sukesou : Itoyori = 7:3 or 6:4 is considered the golden ratio.
Increasing itoyori too much makes the mixture prone to sagging during shaping. In such cases, slightly adjust the amount of polyphosphate or starch to enhance water retention.
Note: Itoyori undergoes rapid gelation at around 40°C. Therefore, the forming process after mixing must be performed efficiently.
Key Considerations for Temperature and Time During Salting in Silent Cutters
Salting (stirring) in silent cutters is the most critical process for dissolving proteins in the minced fish and forming a network of salt-soluble proteins, which are essential for elasticity.
1. The Golden Rule of Temperature Control: The 10°C Barrier
Cutter blades spin at high speed, generating friction heat that rapidly raises temperature.
Target End Temperature: Below 10°C (ideally 5–8°C)
Reason: Temperatures above 10°C trigger protein denaturation and weaken elasticity. Alaska pollock is especially sensitive, and exceeding 15°C may cause severe quality loss.
Countermeasures
Use crushed ice instead of water
Add surimi in a semi-thawed state (-2°C to 0°C)
2. Determining the Stirring Time (End Point)
Mixing time should not be determined by minutes alone, but by observing the state of the meat and the temperature.
Coarse grinding (dry grinding)
Break the meat down into smaller particles without salt.
Main grinding (salt grinding)
After salt is added, watch for the moment when the texture changes from rough and gritty to shiny and sticky.
Over-grinding risk
Excessive mixing physically cuts protein chains and results in crumbly texture.
3. Tips for Selecting the Right Fish Type
Sukesou Surimi
Extremely sensitive to friction heat. Processing should be finished quickly with sufficient ice.
Threadfin Surimi
More heat-resistant but becomes very sticky, which increases cutter load and temperature rise.
4. Checklist to Prevent Failure
[1] Ingredient Order
Secondary ingredients such as starch or egg whites should only be added after salt kneading is complete.
[2] Vacuum Processing
Vacuum cutters remove air bubbles and produce a denser texture.
[3] Blade Sharpness
Dull blades create friction heat and reduce kneading efficiency.
Quality Evaluation of Frozen Surimi
Evaluating frozen surimi quality is critical because it directly affects the final product’s elasticity.
1. Professional Evaluation Methods
Moisture Measurement: Usually adjusted to around 75%.
pH Measurement: Optimal range is pH 6.8–7.2.
Gel Strength Test: Measured using break strength and indentation.
Jelly Strength: Calculated as load × indentation.
2. Simple Evaluation Methods
① Folding Test
Shape the paste into a 3 mm disc and heat it. After cooling, fold it in half and then again.
AA: No cracks when folded into quarters
A: Slight cracks when folded into quarters
B: Cracks when folded in half
C: Breaks immediately
② Drip Test During Thawing
Observe liquid released during thawing. Spongy texture indicates protein denaturation during frozen storage.
③ Visual Whiteness Check
Place on a white plate and check color. The closer to pure white, the higher the quality.
3. Tips for Accurate Evaluation
Salt concentration during testing should be around 2–3%.
Keep mixture temperature below 10°C during kneading.
Protein condition varies depending on species, season, and storage duration. Performing a simple folding test before production helps adjust formulations.
Surimi Gel Cooking Test
The boiling test is a simple and reliable method to evaluate protein extraction and network formation.
1. Boiling Test Procedure
1. Take one spoonful of the mixture from the cutter.
2. Shape into a ball 2–3 cm in diameter.
3. Place in boiling water (90°C or higher).
4. Observe floating behavior.
5. Cool and check texture.
2. Evaluation Criteria
Good
Floats quickly, glossy surface, strong rebound, dense cross-section.
Under-kneaded
Does not float easily, rough surface, crumbly structure.
Over-kneaded
Floats but lacks elasticity or has uneven surface.
3. Why Floating Matters
When proteins are properly dissolved, they trap fine air bubbles that create buoyancy. Quick floating indicates a well-developed protein network.
4. Practical Tips
Monitor cutter temperature simultaneously.
Good quality dumplings remain translucent white after boiling.
