Twin-Screw Extruder for Aquatic Feed

Twin-Screw Extruder for Aquatic Feed

Functional Introduction:

The twin-screw extruder combines strong mixing, shearing, and maturation in one continuous process to produce composite extruded feed or molded matrix materials with controlled internal structure. Intermeshing twin screws convey, knead, and shear in positive-displacement mode, so residence time and energy input can be set independently. Matrix density, cohesion, and pore structure are determined by process parameters rather than raw material lot — critical when the extrudate is the input to downstream freeze-drying.

Key Performance Data

• Screw configuration: co-rotating intermeshing twin screws with modular elements and kneading blocks.
• L/D ratio: 20: 1–32: 1.
• Throughput: 300–2,000 kg/h depending on density, screw speed, and die.
• Screw speed: 200–600 rpm, with specific mechanical energy as the control variable.
• Barrel temperature: multi-zone independent control, set per formulation.
• Moisture control: in-line water/steam injection with closed-loop control — the key parameter for extrudate density and freeze-drying behavior.
• Die and cutter: interchangeable die plates and variable-speed cutter; one platform handles aquatic granules and freeze-dried stick matrix.

Process Value

Mixing distributes water, steam, and minor ingredients uniformly. Shearing develops the protein-starch network and controls degree of cook, determining shape retention through freezing. Maturation builds cohesion before the die so the strand cuts cleanly. On a single-screw machine these functions are coupled to screw speed; on the twin-screw platform they are separately adjustable, allowing one machine to run dense aquatic granules and low-density freeze-dried stick base without mechanical rebuild.

Application Scenarios:

• Extrusion molding of aquatic functional granule base: die and cutter set granule diameter/length; barrel profile sets cook degree and water stability.
• Pre-treatment for freeze-drying core structure (e.g., freeze-dried fish stick base): produces a uniform matrix that freeze-dries without collapse, effectively deciding final texture and reconstitution.

Case Reference: a leading meat production enterprise in East China

Bolaike supplied this twin-screw extruder to a leading East China meat production enterprise for its expansion into freeze-dried fish-based pet treats, with freeze-dried fish sticks as the lead product. Its earlier single-screw trial produced density gradients along the strand, causing uneven texture and shape-retention failures after freeze-drying. The twin-screw extruder was specified to decouple mixing, shearing, and maturation: in-line water/steam control, screw configuration set for the fish-protein formulation, and barrel temperature fixed per SKU for batch-to-batch consistency. Die and cutter were configured for sticks, with granule capability retained on the same platform. The result is a forming stage with consistent density, fewer post-freeze-drying rejections, and documented process parameters rather than operator-dependent settings.