Structure–function relationships in zinc- and calcium-crosslinked gelatin–alginate–carnosine macromolecular films: effects on anthocyanin stability in red currant (Ribes rubrum L.)

This study examines the effects of zinc- and calcium-mediated crosslinking on the structure–function relationships, transport behaviour and anthocyanin stability of gelatin–sodium alginate–carnosine films during red currant ( Ribes rubrum L.) storage. The study aimed to determine how the type of crosslinking ion affects the polymer structure. The effects on the functional properties of the films and anthocyanin stability were also evaluated. Zinc-crosslinked systems formed more compact and homogeneous polymer structures. They showed higher tensile strength (33.13 ± 4.50 MPa), lower water vapor transmission rate (45.3 ± 3.8 g m −2 24 h −1 ), and higher density (1.5019 ± 0.0019 g cm −3 ). Calcium-crosslinked systems showed lower tensile strength and higher water vapor transmission rates. These results indicate differences in polymer structure and transport properties between the two crosslinking systems. Anthocyanin content varied depending on the crosslinking system and storage time, with differences between Zn 2+ - and Ca 2+ -crosslinked films changing throughout storage. Zinc-crosslinked films showed higher anthocyanin retention during the early stages of storage. Calcium-crosslinked systems showed relatively higher retention at later stages. These results indicate that the effect of the crosslinking ion on anthocyanin retention varied with storage time. Overall, the results show that zinc- and calcium-mediated interactions influence the structure and functionality of gelatin–alginate–carnosine films. They also affect the mechanical, transport, and barrier properties of the films. These findings provide useful information for the development of protein–polysaccharide films for the preservation of bioactive compounds in fresh fruit.