DOI: https://doi.org/10.55373/mjchem.v27i6.108

Keywords: Gellan gum; chitosan; coating; fish feed pellets

Abstract

Fish feed pellets play a critical role in aquaculture; however, their performance is often compromised by structural degradation and nutrient leaching upon water exposure. To mitigate these issues, natural biopolymers were selected as coating materials. Gellan gum (GG), an anionic polysaccharide, exhibits strong gel-forming capacity and film integrity. Chitosan (CH), a cationic biopolymer, is recognized for its bioadhesive and antimicrobial characteristics. Pellets were sequentially coated with GG and CH in one or two cycles (GG:CH 1:1 and 2:2) and evaluated using Fourier-transform infrared spectroscopy (FTIR), elemental analysis, swelling behavior, optical microscopy, and scanning electron microscopy (SEM). FTIR analysis confirmed the incorporation of the coatings, indicated by broadening of the O–H band (3300–3400 cm⁻¹) and a shift in the carbonyl region. These spectral modifications suggest hydrogen bonding between GG and CH, supporting the existence of synergistic intermolecular interactions. Swelling ratio assessments demonstrated a marked reduction in water uptake for coated samples. The uncoated control exhibited the highest swelling ratio at 146.2%, while GG:CH (1:1) and GG:CH (2:2) samples showed ratios of 113.5% and 92.9%, respectively. These findings indicate that the crosslinked GG–CH network, despite containing polar functional groups, limits water penetration due to steric hindrance and intermolecular forces. Microscopy confirmed the formation of a uniform film, with the GG:CH (2:2) group displaying the thickest and most cohesive layer. Elemental analysis detected minor changes in carbon, hydrogen, and nitrogen composition, indicating altered surface chemistry that may enhance nutrient retention. SEM analysis further revealed improved adhesion and reduced porosity in coated pellets. Collectively, these results demonstrate that GG–CH biopolymer coatings enhance pellet stability and minimize nutrient loss, offering a sustainable approach to improving feed efficiency and promoting aquatic health in aquaculture.