Nettle (Utrica dioica) Essential Oil Incorporation in Edible Film from Caspian Whitefish (Rutilus frisii kutum) Scale: Physical, Antimicrobial, and Morphological Characterization

Abstract

Byproducts from the processing of fish are a good source of gelatin. Biodegradable films including Caspian whitefish scale gelatin (CWFSG) enriched with nettle essential oil (NEO) at different levels of 0, 0.5%, 1%, and 1.5% (v/w protein) were prepared. Concerning the mechanical properties, increased concentration of NEO resulted in increased values of elongation at break and decreased values of tensile strength (TS). The incorporation of NEO at 0.5% decreased the film solubility, which then remained stable at higher concentration. This incorporation also led to an increase in water permeability, moisture content (especially at 1.5% of NEO), and turbidity. Scanning electron microscopy (SEM) images showed that the control sample had a smooth and homogenous surface, while the presence of fine cracks in the structure of edible films enriched with dose-dependent. NEO had a significant effect on the physical and mechanical changes of the edible films. CWFSG-NEO from 0.5% to 1.5% displayed an inhibitory effect in a concentration-dependent manner against Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus, while no effect was observed on Pseudomonas aeruginosa. Safe and environmentally friendly CWFSG films enriched with NEO at 1% could be used as an active packaging in the food industry as an alternative to synthetic packaging.