Rationale for the use of chitin and chitosan for pseudo-encapsulation of fish feed

This article presents a comprehensive scientific and technological rationale for the use of chitin and its derivative chitosan to create protective inert shells (pseudocapsules) on fish feed pellets. The relevance of this work stems from the need to address key issues in modern aquaculture related to the loss of water-soluble nutrients, lipid oxidation, and microbiological spoilage of feed, particularly when using alternative, high-fat ingredients, including plant-based ones. The authors demonstrate that chitin, a high-molecular-weight aminopolysaccharide obtained from crustacean shells, possesses a unique combination of properties that make it an ideal material for pseudoencapsulation. These include chemical inertness, mechanical strength, heat resistance, non-toxicity, biodegradability, and, crucially, pronounced barrier and antimicrobial properties. The resulting chitinous film prevents the leaching of vitamins, amino acids, and minerals into water, protects fats from rancidity, inhibits the growth of pathogenic microflora (including Staphylococcus aureus), and thereby significantly increases the shelf life of the feed. In terms of technology, the article describes an improved production process, including extrusion, vacuum impregnation of pellets with liquid components, and final application of a chitinous coating. This allows for programmable feed properties, such as buoyancy and sinking speed, and ensures high water stability of the pellets, which is critical for feeding valuable fish species (sturgeon, salmon). The practical value of the study is confirmed by the results of production trials on sturgeon. The use of pseudoencapsulated compound feed increased nutrient digestibility by 10-12%, increased weight gain by 10-12%, and reduced feed conversion by 15%. The economic effect resulted in a reduction in feed costs per unit of production by 8-12%. The presented starter and grower feed formulations meet the physiological needs of fish, and microbiological analysis confirmed their environmental friendliness and improved sanitary properties. Thus, the study demonstrates that pseudoencapsulation using chitin and chitosan is an effective innovative solution. It aims to improve the nutritional value, shelf life, and cost-effectiveness of compound feed, thereby contributing to the sustainable development of industrial aquaculture.