Preparation of trilayer film with slow-release, antioxidant, and antibacterial activities and its effects on scallop preservation

Scallops are renowned for their delicious taste and rich nutritional profile, including high contents of eicosapentaenoic acid and docosahexaenoic acid. However, they are highly susceptible to spoilage caused by lipid oxidation and microorganism proliferation. Therefore, in this study, trilayer films based on gelatin/gelatin-dextran/gelatin with different concentrations (0%, 0.3%, 0.6%, 0.9%, and 1.2%, w/w) of active fillers (citronellal and α-tocopherol) were developed to preserve scallop adductor muscle during cold storage. Scanning electron microscopy images showed that each layer was well-bonded with no gaps, indicating the successful preparation of the trilayer films. The addition of citronellal and α-tocopherol resulted in a porous cross-section with a slightly rough surface and increased hydrophobicity of the trilayer films. With increase in concentrations of citronellal and α-tocopherol, the thickness, opacity, antioxidant capability, and antibacterial activity of the trilayer films increased, while water vapor permeability and mechanical properties decreased. Both citronellal and α-tocopherol showed controlled release properties in four food simulants, with the longest release times in 95% (v/v) ethanol solution. Furthermore, the incorporation of 1.2% (w/w) of active fillers into the trilayer film significantly enhanced the chemical and microbiological stabilities of the scallop adductor muscles, thereby prolonging their shelf life by six days during cold storage. The developed trilayer films showed excellent controlled release, antibacterial properties, and antioxidant capabilities, indicating their potential for effective preservation of aquatic food products.