Restraining Factors of Fish Feed Water Stability

As the world feed industry develops continually, the requirements for various indexes of pellet feed have become higher and higher, not only requiring good inner quality (like nutritional property, disease prevention and industry environmental protection, etc.), but also requiring high external quality (like color and taste of pellets, size, diffusion rate and so on). The particularity of living environment requires formula feed with great stability in water, avoiding fast scatter, dissolution and loss, so stability is an important index for quality assurance. Showing influence factors of fish feed pellet water stability as follows:

The particle size of fish feed has a significant effect on the stability. On the one hand, if the fineness of pulverization is large, it is easy for water to permeate pellet feed and cause scattering; on the other hand, grinding particle size also has definite influence on process flow, such as mixture and tempering steam, etc. While small particle size can make raw materials sufficient and even mixing, in favor of material tempering, stimulating natural binder component for better bonding effect, and meanwhile, the swelling property of material is close to accordance, all of which assist in obtaining better stability in water. As raw material granularity determines the surface area of feed composition, the thinner particle size, the larger surface area and the stronger ability to absorb the moisture in the steam before granulation, which can prolong the dwell time in fish body, promote the absorption effect and reduce water pollution. In general, after grinding, fish feed raw material should pass 40 mesh standard sieve and less than 20% oversize product for 60 mesh standard sieve, while prawn feed raw material should pass 60 mesh standard sieve.

The size of circular mould compression ratio also has certain impact on fish feed stability in water. Big compression ratio will produce fish feed with high pellet hardness, compact construction and long time water-tolerate property, and normal circular mould compression ratio is 14-17 for fish feed while 17-20 for prawn feed.

Through adding steaming to soften materials with more plasticity, the materials are easy for extrusion forming, thereby enhancing the granulating function of fish feed pellet extruder. Moreover, water stream heat can make starch of bait full gelatinization, make protein denaturation and help starch turn into soluble carbohydrate so as to improve digestive utilization ratio. Moreover, the improvement of granule density brings bright and clean appearance that is uneasy to be eroded, increasing stability in water. 

In the process of fish feed production, moderate binding agent can advance the stability of feed in water.