Introduction
Producing aquafeeds with adequate water stability and pellet durability remains a key challenge in aquaculture. Feed formulations typically combine macro ingredients such as marine proteins, plant-based raw materials, and starch sources, supported by micro ingredients including minerals, phosphates, organic acids, and binders. Water stability is particularly important for species that feed slowly or at the bottom, such as shrimp, carp, catfish, and many marine benthic fish. These species require pellets to remain intact in water for extended periods to allow detection, handling, and consumption. Insufficient pellet stability leads to to high nutrient leaching, reduced feed efficiency, and deterioration of water quality (Obaldo et al., 2002). Therefore, binders play a crucial role in maintaining pellet integrity, improving durability, and supporting consistent feed manufacturing processes.
In practice, a wide range of binders is used in aquafeed production, each exhibiting different functional properties during processing. Despite their widespread use, direct comparisons under controlled conditions remain limited, and optimizing binder selection remains an important focus in feed technology (Behnke, 2001).
Materials and Methods
A laboratory study conducted at the Borregaard Research Center (Norway) evaluated the effect of a newly developed multifunctional pelleting aid for aquafeed on water stability. The basal formulation consisted of wheat (30%), fishmeal (25%), and soybean meal (45%). Diets included a control without binder, 1% bentonite, 1% guar gum, 1% arabic gum, and the new multifunctional binder at 0.3%, 0.5%, and 1% inclusion levels. Pelleting was performed using a Münch Edelstahl Lab Pellet Press RMP 250/250. Conditioning was achieved by direct steam injection at 2 bar, targeting a temperature range of 90–100°C. After pelleting, samples (2.5 kg per treatment) were collected and cooled at ambient temperature under forced air ventilation for 20 minutes. This step ensured proper pellet hardening and stabilization prior to testing. Water stability was assessed by soaking pellets in water for 2 hours, removing fines, and determining the dry weight of the remaining intact pellets.
Results
Water stability varied significantly depending on binder type and inclusion level. The new multifunctional binder showed a clear dose-dependent improvement, increasing from 74 (0.3%) to 77 (0.5%) and reaching the highest value of 84 at 1% inclusion. Guar gum (79) was the second-best performer, followed by bentonite (72), which showed no improvement compared to the control (72). Arabic gum resulted in the lowest stability (66).
Figure 1. Water stability of pellets after 2 hours of soaking. Green bars indicate very weak pellets, orange bars indicate soft pellets, and blue bars indicate good pellet structure.
Discussion
The superior performance of the new aquafeed binder at 1% inclusion indicates enhanced binding capacity and improved cohesion within the pellet matrix. The clear dose-dependent response suggests that increasing inclusion levels strengthens inter-particle interactions, resulting in greater resistance to disintegration during prolonged water exposure. This is particularly relevant for bottom-feeding and slow-feeding species, where pellet integrity must be maintained over extended periods.
In addition to its binding functionality, the product can be considered a multifunctional binder, as previous processing trials have demonstrated its ability to improve pelleting efficiency. Reductions in electrical load during pelleting and increases in production throughput have been observed, indicating improved material flow and reduced mechanical resistance during processing (data not shown). These effects are likely related to improved lubrication and matrix plasticization during conditioning and pelleting.
The differences observed between binders further highlight the importance of binder type. Guar gum, a galactomannan polysaccharide, is known for its high viscosity and water-binding capacity, contributing to improved pellet cohesion, although its effectiveness depends on hydration and processing conditions (BeMiller, 2019). Bentonite, a clay-based binder, primarily improves physical structure through particle packing and absorption but may have limited impact on water stability compared to organic binders (Behnke, 2001). In contrast, arabic gum, a highly soluble polysaccharide, tends to disperse rapidly in water, which can reduce pellet integrity under prolonged immersion, as reflected in the lower stability values observed in this study.
Processing conditions, including moisture content, temperature, and starch gelatinization, play a critical role in pellet formation and durability (Cheng et al., 2023; Novriadi et al., 2025). These factors influence matrix formation and inter-particle bonding, directly affecting pellet resistance to water-induced disintegration. The consistent performance of the new multifunctional aquafeed binder across treatments indicates that it effectively complements these processing conditions, enhancing pellet consolidation and structural integrity.
Overall, the results confirm that both binder type and inclusion level are key determinants of pellet water stability. The improved performance of the new multifunctional binder has direct implications for feed efficiency, nutrient retention, and environmental sustainability in aquaculture systems (Lall & Dumas, 2015).
Conclusion
The new multifunctional aquafeed binder significantly improved pellet water stability, with optimal performance observed at 1% inclusion. Its effectiveness highlights its potential as a sustainable solution for aquafeeds, particularly for bottom-feeding and slow-feeding species where pellet integrity is critical.
References
Aro, T., Fatehi, P. (2017) Production and application of lignosulfonates and sulfonated lignin. ChemSusChem. 10 (9) 1861–1877.
Behnke, K.C. (2001) Factors influencing pellet quality. Feed Technology. 5 (4) 19–22.
BeMiller, J.N. (2019) Carbohydrate chemistry for food scientists. 3rd ed. Elsevier Academic Press.
Cheng, H., Samuelsen, T.A., Sørensen, M., Xue, M., Li, J. (2023) Understanding and modelling the aquafeed extrusion process for Atlantic salmon feeds. Aquacultural Engineering. 103, 102378.
Lall, S.P., Dumas, A. (2015) Nutritional requirements of cultured fish: Formulating nutritionally adequate feeds. In: Davis, D.A. (ed.) Feed and Feeding Practices in Aquaculture. Elsevier. 53–109.
Novriadi, R., Gaylord, T.G., Salze, G., Davis, D.A. (2025) Effect of extrusion conditions and pellet size on the physical properties of extruded fish feeds. Animal Feed Science and Technology. 328, 116453.
Obaldo, L.G., Divakaran, S., & Tacon, A.G.J. (2002). Method for determining the physical stability of shrimp feeds in water. Aquaculture Research, 33, 369–377.