Preparation and Characterization of Emulsion‐Based Fucoidan‐Whey Protein Film Activated With Geranium Essential Oil for Food Applications

ABSTRACT Emulsion–based edible films are novel active films that can improve food quality and their shelf life due to slow release of their active ingredient. In this study, fucoidan‐ whey protein (FW) composite film with different concentration of geranium essential oil (EO) nanoemulsions [0.5% (w/w) and 1% (w/w)] were prepared (FW‐0.5 and FW‐1). The physicochemical, thermal, morphological, and mechanical properties [tensile strength (TS), elongation at break (EB)], as well as the antioxidant and antimicrobial properties, were investigated. Gas chromatography analysis detected citronellol (30.26%), geraniol (16.41%), and linalool (12.43%) as the main compounds of geranium EO and smaller amount of monoterpene hydrocarbons (such as α‐pinen, p‐cymene, and limonene) and sesquiterpene alcohols (such as globulol and pogostol). Also, the addition of a higher concentration of geranium EO nanoemulsion (1%) made the film thicker (0.13 ± 0.01 mm) than the neat FW film (0.12 ± 0.01 mm) ( p < 0.05). The incorporation of EO nanoemulsion reduced water vapor permeability, and FW‐1 had an excellent barrier against water vapor (1.05 ± 0.28 g/m.s.Pa) when compared to the control film (1.33 ± 0.34 g/m.s.Pa) ( p > 0.05). Moreover, active FW films loaded with EO nanoemulsion had lower TS and EB values ( p < 0.05). TS and EB of neat FW film were 5.30 ± 0.46 MPa and 3.11% ± 0.83%, respectively, while these parameters lowered to 1.52 ± 0.65 MPa and 67.96% ± 4.70%, respectively in FW‐1 ( p < 0.05). Active FW films had higher L* values, lower a*, b* values, and opacity in comparison with neat FW films ( p < 0.05). Moreover, the addition of EO nanoemulsions improved thermal stability, and the active FW film (FW‐1) had higher thermal stability. SEM images exhibited a smooth surface in all FW films and a compact, dense structure in the cross‐section of FW films loaded with EO nanoemulsion. FTIR also confirmed the encapsulation of geranium EO and its compatibility with FW films. Moreover, active FW films, especially FW‐1 exhibited higher antioxidant (72.91% ± 2.53%) than FW film (35.39% ± 3.19%) and possessed stronger antimicrobial activity against Gram‐negative ( E. coli ), Gram‐positive ( S. aureus ) and fungi ( C. albicans ). This study suggested the potential applications of active FW film for food packaging.