Abstract:
Microbial contamination of meat during storage is the primary cause of global foodborne illness risks, which urgently requires monitoring of meat spoilage using biorenewable sources. This research developed a polysaccharide-based intelligent packaging system utilizing a bilayer structure, where chitosan was blended with gelatin in the first layer. In contrast, sodium alginate (SA) formed the second layer, thereby enabling the optimal incorporation of pH-sensitive compounds. The alginate layer incorporated betalains from beetroot extract (BTE), stabilized with apple polyphenols (AP) through co-pigmentation. The polysaccharide matrix significantly enhanced BTE-AP complex stability, confirmed through FTIR analysis showing hydrogen bonding networks and XRD studies demonstrating improved crystallinity. DSC validated thermal stability, while rheological studies revealed AP concentration effects on alginate matrix properties. The synergistic interaction between chitosan-gelatin and SA layers enhanced mechanical properties and created effective barriers to water and oxygen. The polysaccharide system exhibited strong antibacterial and antioxidant activities. The strategic use of alginate proved crucial for stabilizing BTE-AP complexes via molecular interactions, such as hydrogen bonding and π-π stacking. The bilayer system effectively monitored beef freshness through color changes from red to yellow during spoilage of beef, supported by statistical analysis and smartphone app-collected RGB values. These intelligent films can serve as spoilage indicators in food packaging systems throughout the food chain. This study introduces novel approaches in pH-sensitive film applications using co-pigmentation techniques, with potential use in freshness monitoring of animal-derived food products.