Development of a water gradient film through film and ice-glazing approach utilizing konjac glucomannan and high acyl gellan gum for enhanced preservation of frozen snakehead (Channa argus) fillets

Fish fillets are perishable, and several commonly used preservation methods, such as freezing, ice-glazing, and plastic film packaging, aim to maintain their quality during frozen storage. This study presents a novel approach by developing a water gradient edible film using konjac glucomannan (KGM) and high acyl gellan gum (HAGG), and evaluates its effectiveness in preserving frozen snakehead (Channa argus) fillets. First, KGM/HAGG films with different weight ratios of KGM and HAGG were prepared and their properties were characterized. H-bond interactions occurred between KGM and HAGG, resulting in their compatibility and the formation of a homogeneous structure. The properties of the KGM/HAGG films, including tensile strength, elongation at break, water vapour permeability, oxygen permeability, and water swelling ratio, could be modified by changing the weight ratios of KGM and HAGG. The water gradient film was then prepared by adding water to one surface of the film, resulting in controlled swelling. This water gradient film exhibited a water gradient property before freezing and a combined film and ice-glazing property after freezing. It acted as both a moisture and oxygen barrier, while also acting as a moisture-sacrificing agent during frozen storage. When compared to unpackaged fillets, iceglazed fillets, and fillets packaged with polyethylene film, the frozen water gradient film proved to be the most effective in preserving snakehead fillets during a 150-day frozen storage period. These findings indicate that the KGM/HAGG water gradient film could be a valuable alternative to conventional preservation methods for maintaining the quality of fish fillets during frozen storage.